texts: Trigger a relay with a very low DC voltage

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I want to light up a couple of LEDs using a relay to trigger this event. I have a very low DC voltage, about 0.15mV to 0.20mV and I want to somehow take this voltage to a relay, that will be also connected to a battery to light up the LEDs. So far, I know how to calculate the resistors value not to blow up the leds, but don't know how to drive this low current to the relay to make it work?

Is this possible? If so, Can anyone point me in the right direction?

EDIT:
Per one suggestion, let me explain my scenario. I have a regular alarm clock that I want to use to turn those LEDs on. My grandpa can't hear good anymore and we think this would help him to remind him about certain situations. The DC voltage I'm talking about is coming from the little buzzer this thing have, and I said 0.15mV because that's what I could get from the voltimeter hehe... So the general idea is to use that small voltage to turn those LEDs on.


texts: High voltage booster with continuous output?

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I need a module that can take a DC voltage of 2V - 12V continuously as its input and produce atleast 2KV DC continuously as its output. I've come across high voltage generator boost modules but they produce output in pulse (discontinuous.) What I want to know is do such modules exist that can continuously produce thousands of volts from low input voltage? If yes what are they usually called as?
I'm aware of high voltage bench power supplies that can continuously produce thousands of volts. But I don't want that. I just want a smaller device such as a module.
Application:
I want to use the module to power a parallel plates electrostatic device.


texts:
I am currently looking to purchase laser galvanometers like this and this. However, as I'm not familiar with lasers, I'm not sure the criteria I should use to evaluate whether a given product is a good buy. What are your suggestions?

Thanks in advance!


texts: Is it possible that LED power supply is interfering with my webcams USB connection?

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Not sure it is a right place to ask this question but I'm pretty out of options. I'm building DIY home-studio LED lights out of multiple 12V LED bulbs. I'm using a dedicated power supply connected to the mains (2 wires + ground, Central-Europe style).

When I turn the lights on the camera Mobius Action Cam starts freezing randomly but frequently (few times in 20 seconds). How is that possible? What I can do to fix the problem?

The power supply is HV-12020A and seems to be pretty well made but I have no way of looking inside - it's sealed.


texts: How do I calculate KVA and KW to fill out this load sheet ?

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I'm in the process of trying to build a small hobby farm from scratch. One of the initial steps is to get temp service on the property, and to do so I have to fill out an electric load form. I will mostly be operating pumps, table saws, etc. Single phase, and most of the time not at the same time. Part of the sheet requires you to fill in the KVA and the KW of the different electric loads. I've done a fail amount of electrical work, but honestly these are metrics that I'm not familiar with. Can someone provide a little guidance on how one would fill this out? I vaguely recall from engineering school that the difference between KVA and KW is one is absolute and one is apparent power, but what that means within this context I'm not sure.

Thanks for the help


texts: I am very new to LTspice. I would like to ask "How can I add a photodiode in the Ltspice?" Is ideal photodiode (or any specific) model already included in the LTspice or do I need to create third party model for photodiode? If it is already included, under with categories it is included in library ? Or If it is not included, how can I make one? Do I need to create the spice model of photodiode which will consist (roughly) of a current source, capacitor and resistor then refer back to the photodiode? Or if there is another way around can you please share your knowledge?


texts: How important is impedance matching in audio applications?

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How much will reflected signals matter in audio applications (say between an amp and a speaker, or a pre-amp and an amp)?  Mostly with regards to fidelity and not power transfer.

What are the different options of matching the impedance and their pro's/cons? This can be on the output terminal, input terminal, or modifying the cable?


texts:
I realize that there is along history to mica capacitors; however, I've been unable to determine if there any modern equivalents that have the same static electronic characteristics. The short list of types that seem like they'd have similar behavior and properties over time are silicon capacitors, ceramic capacitors, film capacitors; however, I've not found a rigorous comparison anywhere.

I'm trying to redo an old amplifier with modern parts as the original parts are no longer available.


texts: How to use an ADC with a non zero lower reference voltage input

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I need to convert, linearly, a voltage in the range of about 1v to 2v into the range 0 to 1v for input to an ADC.

This is the background: I fiddle with electronics and programming as a hobby to give me interesting and challenging projects -- but on this one I am stumped.

I have built a power supply to give me 0 to 1 amp, approx, and want to add an ammeter to it. I will use a Sparkfun ACS712 Low Current Sensor Breakout board which I can adjust to give a voltage output range from 1.000 to 2.024 volts over the input range of 0 - 1024 mA, so that a 10 bit ADC with these as its lower and upper reference voltages will give me a nice 1mV per mA per bit output. I will be happy with a 1% or so accuracy.

I intend, if I can, to use a Microchip PIC12F675 to do this conversion, but it allows adjustment of only the upper reference value. To display the current reading I will use an I2C link to a Sparkfun 7-Segment Serial Display COM-11442.

So my question is: please, how do I convert the 1.000 to 2.024 voltage range into 0.000 to 1.024 to suit the ADC?

As an alternative, is there a different small PIC that I could use, which has an ADC with a variable lower Vref to a  10 bit ADC, and also an I2C serial module? I have looked on Microchip's website, but the needle, if it is there, is in a bewilderingly impenetrable haystack of data.

I want to use a PIC because I can program them easily in Assembler, which is a process I view with somewhere between enjoyment and love, and I have the software and hardware to do it.

This is a specific question, please don't suggest other ways I can sample the current, I can do that myself. Thank you.


texts: Is it possible to code an animation into hardware?

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First off, I am a total illiterate in electronics. (Well, I did my Electronics for my Computer Engineering degree but that seems ages ago)

I am considering creating a set of video displays playing a small loop of video in HD, as in a photo exhibition that instead of photos has HD video loops that look like photos but move ever so slightly, so you can only notice if you stare for a while.

In order to make this installation less power-comsuming and less bulky, I'd like to know if the animation can be "coded" to a chip or whatever that could fit in the same flat screen, so it would be just a screen with a power cord.

Thank you.


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I'm working through an old Popular Electronics article, trying to apply and learn some of the math behind the project. Math for the clock pulse generator frequency has me stumped; wondering if anyone can provide a hint or might know what I'm doing wrong.

According to the description, the clock pulse generator should generate a square wave with a period of 8.1 microseconds or 122.8 khz. It uses part of a 4049 CMOS hex inverter, and the project runs on 9VDC; this feeds a counter chain which provides other multiples of the clock. In the diagram below, C1 is 100pf, R1 is 100k, R2 is 15K, and R24 5K variable/pot. Datasheets and other online discussion points to the formula as freq = 1 / 2.2RC, which I find gives me about twice the frequency I'm expecting here (2.2 x 17.5k x (100 x 10^-12)?). Am I trying to apply the wrong formula? Thanks.

Edit: I have not built the project, just working on paper.


texts: I need a power source for my DBD (Dielectric Barrier Discharge)

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I need to make a circuit which gives me ac voltage in the range of 5-20 kV and frequency above 1 khz. The ac voltage which my lab gets is 50 hz 240 v. I need to somehow step up the voltage and frequency for my project.
Is their any lab equipment that can be used to do this?
One more thing, I know how to make a voltage multiplier using a battery but I dont know wether it increases the frequency as well.

Thank you for your help.


texts: Truth Table does not exhaust all combination. Can it be translated to a circuit? Is it ill-pose?

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Step|A|B|C
----------
1   |0|0|1
2   |1|0|1
3   |1|1|0
4   |1|0|0

From the truth table above, I can not find the equivalent boolean expression hence I can not create the logic circuit. Does it have any?


texts: Setting pins as output Code - micro-controller

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So i am using the MSP432 and i am confused on how the code for setting pin to desired function works.

so for example from the manual i have found that:

  PxIE = 0b // means that x pin is dsiabled
  PxIE = 1b// means that x pin is enabled

now if we have the code shown below:

  P1IE |= 0x02 // what does this code do

i understand that | means or and that 0x02 is hexadecimal for 0b10 so how does that make the pin 1 enabled?


texts: Converting 0.6V 20A DC to AC (frequency ~ 240 Hz)

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I will be driving ~1600 linear resonant actuators (LRA) in parallel (each requiring 0.6V @ 19 mA AC). As the buck regulator, I will be using TPS546C23 synchronous buck converter from TI to convert 5V 4A DC supply from battery bank to 0.6V 20A DC. To control so many LRA using only 4 pins of an MK20DX256 ARM Cortex 4 MCU, I will be using several daisy-chained TLC5940 LED Driver to control gates of 2N7000 MOSFETs (each LRA will have its own MOSFET) via PWM signals. I tested the setup with a smaller number of ERM motors (which are similar to LRA but works with DC voltage) and it works just fine.
The problem is converting the 0.6V 20A DC to AC for the LRA. I did not find any suitable IC or circuit diagram to do DC/AC conversion of such low voltage and high current. I tried to look for individual chips that could possibly do DC/AC conversion of 0.6V 19mA DC to AC but failed to find anything. Most inverter circuits use 555 timers and I don't think those circuits can work with such low voltages. Also, LRAs are normally driven with haptic drivers but it severely limits how many LRAs I can connect to the MCU, unlike the setup I designed.
Any suggestion would be appreciated.


texts:
Can I know which component senses heat or acts as heat sensor in the following circuit?
In the given diagram, it is said that the 1N4148 diode acts as the sensor. But basically it is a zener diode and I don't think that it is able to sense temperature shift. This circuit provides a working model but the sensor remains as a mystery for me. Can you please help it for me?


texts: Should I connect ground for differential measurement with oscilliscope?

texts: Suppose I need to view voltage between two arbitrary points of a circuit with an oscilloscope. For that I can use two probes and A-B math, but should I connect the ground lead to the circuit? How to maximize CMRR?


texts: How do I wire Solid State Relays to a linear actuator

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Sorry for the dumb question, but I only know enough to get myself in trouble..  I've searched through previous questions and haven't found an answer that dumbs it down enough for me.

I'm trying to activate a 12vDC 12amp linear actuator  (https://www.progressiveautomations.com/linear-actuator-ip66#ig_lightbox2[gal]/0/) to travel in/out using 2 solid state relays. (https://www.automationdirect.com/adc/Shopping/Catalog/Relays_-z-_Timers/Solid_State_Relays/Panel_Mount_Relays,_Hockey_Puck_Style,10A_-75A(AD-SSR6_Series)/AD-SSR6M12-DC-200D)

Ultimately an Arduino will control the relays, but for now I'm manually activating them with a 9v transformer for testing purposes.  Currently it works fine with 1 relay attached, but when I attach the 2nd it short circuits.  I believe the issue is my ground connecting to both leads on the linear actuator, but I'm not certain on how to rewire.  Do I need a relay for both positive and negative leads? (4 total)

Revised for changeover relay and diodes:


texts: PCB Single 90 Degree Connectors for More Secure and Removable Connection

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I am building lithium battery packs and want to connect the power lines securely to each pad on the printed circuit board of the battery monitoring system (BMS) board. I am using braided wires with silicon sheathing to connect to each pad.

The wires need to be removable so that field servicing the batteries is possible without the need to solder/unsolder each wire.

I'd like suggestions on possible connector solutions - I've been digging through Digikey but no joy. Here are views of the BMS card. Thanks!


texts: In an induction cooktop, what happens to the coils resistance when there is no pot? Does it vary between pots? How does the appliance respond?

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An induction cooktop (or an induction rice cooker) uses a copper coil with a high-frequency alternating current going though.  The magnetic flux heats any iron-alloy pot placed above.

But what happens to the coil's impedance when there is no pot (or any piece of iron)?
My guess is that it would become a short circuit. As I understand, the magnetic core of a transformer/inductor is what gives it impedance (makes it resist alternating current), and I figure this would be no different.

How do they overcome the obvious problem of the coil being a short circuit?  My guess is that it's current-regulated rather than voltage-regulated.  An increase in resistance causes a decrease in wattage if the voltage is constant, but it causes an increase in wattage if the current is constant.  Therefore, the coil would have low power usage when there is no pot and the resistance (or in this case, impedance) is low.

How does the choice of pot affect the coils impedance, and ultimately the power draw and heat output?  Do bigger pots, or more ferromagnetic pots cause more impedance (in the coil)?  Additionally; I realize that the heating of the pot comes from it's own electrical resistance, but how does this resistance affect the copper coils impedance?

EDIT: An earlier version of this question mistakenly stated that increasing resistance with constant voltage causes increased wattage, but decreases wattage with constant current.  This was a mistake I failed to detect during proofreading (not a misunderstanding of Ohm's law), so I corrected it to what I intended in the first place.
Some uses of "resistance" have been changed to "impedance" to accurately communicate the intended question. The question would be silly if it referred to true resistance.


texts:
Power Efficiency is defined as output power/input power, right?

And there are a little bit different definition of power efficiency ...output power/(output power+power loss).

Is these mean same thing? If so, why?

In voltage doubler(or think about just 1-stage Dickson charge pump,), output voltage is twice of input voltage. And if there a current source on its load, VDD provides same(or very similar) current with load's current source. Hence, output power is LARGER than input power! I know it is truely and utterly NONSENSE. Then how can i calculate/simulate the power efficiency?


texts: Confused about exponential equation in First Order Integrator Circuit

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I have a problem above, where the question goes as such:

I have a Miller Integrator Circuit as such:

Now, I pass in a square wave pulse of 1V height and 1ms Width

Now, I have a resistor of Rf = 1M ohm connected across C as shown above. According to book that I read, I can't seem to understand how the time constant or the exponential equation is derived as shown below:


texts:
If I was to make an antenna for BLE for an ESP32-pico-D4 by just making a wide cobber trace (as on the esp32).
How long and how thick would it have to be?


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I'm recycling some spare parts of an old treadmill for a new project. I have the motor with its driver board, the elevator piston and the controller board. All works out of the box, but I need to replace the controller board with my own PIC-based since the former uC firmware cannot be modified, nor read (pretty obvious).

The controller schematic is pretty straight-forward, CON1 comes from the driver board, PIN1 is 19v, PIN2 is GND and the other two pins are connected as follow to the uC.

I measured the voltage at pins 3 and 4 with different speed/inclination  combinations obtaining always the same value (even stopped), around 4.8v on PIN3 and around 1v on PIN4. Unfortunately I don't have an oscilloscope so I can't see what's really going on there. I've had a look to the uC datasheet and the connected pins are just TTL output ports (it's a really old basic uC).

I've searched around the internet but I haven't found any similar board, so yeah, I'm wondering if someone has ever found/worked with this kind of driver.


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I am using a ferrite core to remove video noise in an NTSC video system. I am using the ferrite core on the video and video GND lines.

I am merely winding the video and video GND lines on the ferrite core. The core used is - this.

The impedance charachteristics is as shown below -

Now, analog video consists of a base-band signal of approx 5Mhz. I was connecting 2 different video sources to the same connector on my board. The video signals come to the connector as shown below -

.

Now, I kept observing a lot of roll noise on both my video signals. Now,I coiled the 2 video lines (and their respective GNDs) over 2 independent ferrite cores. This absolutely removed the roll noise and made the video very clean. I gave about 8 turns on the torroid. How did that happen ? How does a ferrite core work ?

Also, can I acheive the same impedance charachteristics using passives ?


texts: How should I connect four resistors to double the capacity with the same resistor?

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I know that putting two resistors in parallel will double the wattage from the input to output, but only with half the resistance.

Example Parallel Circuit:

simulate this circuit – Schematic created using CircuitLab

I know that putting two resistors in series will double the resistance, with the same wattage.

simulate this circuit

However: I need to double the wattage without the affecting resistance. Would this work?:

simulate this circuit


texts: Why are Alkaline, NiMH, and Li-ion AA measured differently (mAh, mWh, etc)?

texts:
Looking around Amazon, it seems that different types of batteries are measured differently:

Does anyone know why?

Li-ion are measured in mWh

1200mWh ALTIZURE (Cheap-Os)
3200mWh Deleepow
3000mWh AmpTorrent

NiMH are measured in mAh

2000mAh Eneloop
2800mAh EBL

Alkalines are typically not measured

"Long Lasting" Duracell
"Longest Lasting" Energizer

I assume that Alkalines are not measured for some sort of historical reason with marketing departments?

... or is it that alkalines so mystical and unreliable that giving them a measurement is too aggressive? Or that switching to non-toxic / non-mercury was such a bad move in performance that measurements had to be removed in the 90s so people wouldn't know?

Perhaps NiMH are measured in mAh because the voltage can very so greatly and mWh doesn't make sense?

Are Li-ion measured in mWh because that's more consistent with non-battery measurements and they do deliver reliable voltage?


texts: Why we need blind or buried vias in our layout ,What is the difference between microvias?

texts:
I have a 6 layers board with blind vias from 2-3-4-5 and micro vias (size:.004")
While it isn't a high density circuit with conductor width 6 mil and pads.02")
Can anybody share some tips on these,Why we need put blind vias in our design.What function it will achieve?


texts: I released the smoke from oscillosope probes, how to repair?

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I discovered that while my Siglent SDS1052DL oscilloscope has about a megohm of input impedance, the ground of each channel is actually common.

I accidentally connected a 12 volt, 25 amp power supply across through the ground of the scopes channels. The smoke came out of the ground clip on the oscilloscope probes. Both got hot enough to melt the insulation off the wire. The cable that leads out to the probe was not even warm to the touch. The rest of the probe appears fine.

I tested the oscilloscope against its 1 khz source that is on the front and both channels seem to work still. I am assuming whatever current path it took through the inside of the scope is actually very large in terms of conductor size, so the scope is probably fine.

Can I just heatshrink the wires on the probe ground clip to repair them?


texts: Altium update from schematic - delete and add component constantly

texts: When I issue an engineering change order to update my PCB from the schematic window, 2 components are always deleted and added every time.  How can I stop this?


texts: Switch a differential I²C bus section, controlled via I²C

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I want to separate a section of an I²C bus, controlled via an I²C message. (Similar to an I²C bus switch/multiplexer like e.g. PCA9540.)

Indeed the I²C bus to switch isn't a plain vanilla I²C bus, but rather a 4 wire differential bus. I wanted to save myself from converting to and from plain I²C before and after a PCA9540, so I got the idea to use a quad SPDT (rather a 4PDT) to select between connection and separation (with termination) (e.g. (74)CBT3257).

Problem: Usual I²C-IO devices update their IOs during the acknowledge phase, but not after stop condition. So controlling the 4PDT by any of them leads to bus separation while SDA and SCL are both low, ending up in a race condition of both now separated I²C lines pulled up simultaneously.

Does anybody know of an I²C-IO with IO-update delayed until stop condition?
Is there a simple possibility to use a I²C multiplexer (which usually are delayed until stop condition, of course) to control the 4PDT?
Any other ideas?


texts: I am trying to build an inverter without a transformer. I want to use a 12V battery connected to a boost converter which will boost the 12V to 120V, then simply attach an H-bridge to the 120V boost converter output to create an AC voltage. Is this going to work?


texts:
This is a very basic question. I hope it won't offend you.

One my prof in college, while giving us assignments, asked us to consider channel length of all the mosfets in the design to consider same. like L=200nm.

My question is it a good idea to set channel length (L) of all transistors same.

Also, I heard that if we vary channel length of transistors (like to get hight output resistance we may increase L)  then there may be problem while making layout of the design. Can you please confirm this whether this is followed in practical analog design like in analog companies.


texts: Instant signal frequency change on amplifier

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I was wondering what happens to an amplifier when the frequency is suddenly changed from (in my case) 2401 MHz to 2479 MHz. Would the amplifier somehow oscillate at the beginning or would it be steady?

The amplifier ranges from 2300 MHz to 2500 MHz.


texts: USB Full Speed driver with MCU in DIP package

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I desire to apply a USB driver with a MCU that has a DIP package.
The device should communicate in Full Speed (12 Mbps).
To your experience, is that possible?
Taking into consideration the physical phenomenons of a high frequency communication.
I should clarify that the MCU's GPIO pins would be connected (not directly) to the D+ and D- pins of the USB port (through a resistor as the USB protocol requires etc.)

Edit (01 July, 09:14 UTC):
I'm looking to implement something like this:

The implementation should be possible with any MCU, it doesn't have to be ATTiny2313.
I thought of adding a Parallel-in Serial-out (PISO) shift register in order to lower the load on the MCU.


texts:
I am studying about CMOS inverter and in my book provided the transfer characteristic as follows (actually i simulated it):

and then I changed the parameters and I got something like this:

I found later case interesting because it got two flat regions on curve.

Now in the first case I entered the \$V_{T_{N}}=1 V\$ , \$V_{T_{P}}=-1 V\$ and in second case \$V_{T_{N}}=3 V\$ , \$V_{T_{P}}=-3 V\$. In the first case there is only one region where gain is huge in between about \$1.5V\$ to \$2.5V\$ but in second case there are two such regions one is at \$1.3V\$ and another is just after \$3V\$. I am curious to know what causing this kind of behavior?


texts: How to reduce voltage from shift register to ESP32 MISO pin?

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In this circuit I have sensors that are  rated for a minimum of 6V connected to a 74HC165 which passes its output to the MISO pin of an ESP32. I was hoping a simple divider to convert the 6V from the shift register to 3.3V for the ESP32 would work ... but no.

The ESP32 is unable to process the input consistently, delivering erratic output results. Interestingly, it all works perfectly if I remove the resistors for the voltage divider and power it all with 5V. The sensors can apparently handle the lower voltage fine ... but they need to be operated at 6V minimum.

Should I use a linear regulator or switching regulator instead of a voltage divider? Or is there something else I'm missing?

Much thanks,


texts: Accurate RF voltage magnitude measurement

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How would you measure the magnitude of a RF sinewave in the KV, MHz  ballpark?

The frequency is known and the sinewave is very pure, does this help?

Can you devise a method that would give millivolt precision in a kilovolt?

Its also very desirable not to load the circuit too much.

How would your proposed precision method drift with temperature?


texts: Lithium Coin Cell CR2032 battery specifications

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I am using a CR2032 battery module to operate a BLE 4.1 module. The BLE radio for communication takes around 3.5ma to 5ma of current. But when I look at the datasheet of the battery (https://cdn-shop.adafruit.com/datasheets/maxell_cr2032_datasheet.pdf) it shows the nominal discharge current is 0.2mA.

My question is: during BLE communication, when current is about 5mA, will this battery be able to provide this current? Also for what purpose are nominal discharge current values shown?


texts: CMOS vs BiCMOS technology nodes comparison

texts:
I am trying to make a comparison between several technology nodes. More specifically I want to compare 28nm, 40nm, 65nm CMOS and BiCMOS processes. However I cannot find papers that compare some of these processes or at least several papers that present individually information for these nodes. Am I searching in a wrong way? Can someone guide me to the rigth way? I would like for example to compare the \$f_t\$, \$f_{max}\$, noise figures, intrisic gain etc

Thank you in advance


texts: Does anyone know why BLE Tx power is 4dBm maximum?  Does it have anything to do with coin cell battery peak current limit (15mA?)


texts:
I would like to use some color coding in our experimental rig (microscope). All BNC cables so far are black 50 Ohm, and I'd like to use some yellow, red or any other very-not-black colors. I can't find these cables.

Are there are any special search keywords, apart from "Red 50 Ohm BNC", that I might use? Price at this point is not a real issue, if most BNCs are connected to BNC patch panel, they can be all black. But I'd like to highlight any non-BNC-patch-panel connected cables (temporary cables) so that they can be replaced later.


texts: Help Me to Identify what is the Cause for MOSFET Heating with this Battery Backup System Circuit

texts:
I have created a circuit as a hobby project for my router. With this Project I want to power my two 9V routers in case of a Power Failure.

Two routers combine uses around 600mA.

I’m using two 18650 batteries in series as backup power and 2A 9V SMPS power supply to power two routers.

Also I’m using Atmega328P chip to monitor battery voltage and ACS712 Current Sensor to keep track battery capacity.

Problem I’m having with this circuit is that when power goes out MOSFET getting very hot and routers getting reboot. After few seconds routers get power and works normally.

Also if I pull the wall power supply from circuit to stage a power failure, circuit switches to battery instantly and MOSFET doesn’t get hot.

MOSFET I’m using in this circuit is IRF9530.

MOSFET getting hot and not switching to battery instantly because when a power failure happen power adapter doesn’t go to 0V instantly?

Any help to identify and solve this problem appreciated.


texts: Timer1 remap cause debug crash on STM32F103

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I build a Keil project for my STM32F103 MCU with STM32CubeMx.

My goal is use the TIM1 channel 2 for control a Buzzer.
I want to generate a PWM at 4KHz through TIM1 channel 2.
I configured, with STM32CubeMx, the TIM1_Channel2 as "PWM Generator CH2".

The problem regards the debug session. In particular, when I start the debug session and when the MCU executes the macro "__HAL_AFIO_REMAP_TIM1_ENABLE()" the debug session crash.

This is the timer initialisation code generated by STM32CubeMx:

void HAL_TIM_MspPostInit(TIM_HandleTypeDef* htim)
{

  GPIO_InitTypeDef GPIO_InitStruct;
  if(htim->Instance==TIM1)
  {
  /* USER CODE BEGIN TIM1_MspPostInit 0 */

  /* USER CODE END TIM1_MspPostInit 0 */

    /**TIM1 GPIO Configuration
    PE11     ------> TIM1_CH2
    */
    GPIO_InitStruct.Pin = GPIO_PIN_11;
    GPIO_InitStruct.Mode = GPIO_MODE_AF_PP;
    GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_LOW;
    HAL_GPIO_Init(GPIOE, &GPIO_InitStruct);

    __HAL_AFIO_REMAP_TIM1_ENABLE();

  /* USER CODE BEGIN TIM1_MspPostInit 1 */

  /* USER CODE END TIM1_MspPostInit 1 */
  }

}

This issue is related to Timer1 pin full remap.

Anyone have the same issue?

Thanks!

=== UPDATE ===

Finally I found some time to test the solution proposed by @SamGibson an it works! And thanks to @Rafiq Rahman for his code!

Thanks guys for your time!

This is the code that I used to remap the TIM1 and maintain the ability to generate the code with the Stm32CubeMX.

if(htim->Instance==TIM1)
{
  /* USER CODE BEGIN TIM1_MspPostInit 0 */
  #undef __HAL_AFIO_REMAP_TIM1_ENABLE
  #define __HAL_AFIO_REMAP_TIM1_ENABLE()  (0)
  /* USER CODE END TIM1_MspPostInit 0 */

    /**TIM1 GPIO Configuration
    PE11     ------> TIM1_CH2
    */
    GPIO_InitStruct.Pin = GPIO_PIN_11;
    GPIO_InitStruct.Mode = GPIO_MODE_AF_PP;
    GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_LOW;
    HAL_GPIO_Init(GPIOE, &GPIO_InitStruct);

    __HAL_AFIO_REMAP_TIM1_ENABLE();

  /* USER CODE BEGIN TIM1_MspPostInit 1 */
  /* Make a copy of AFIO register */
  volatile uint32_t afioRegisterCopy = AFIO->MAPR;

  /* Clear Timer1 remap bits and + JTAG/SWD bits */
  afioRegisterCopy &= ~((7 << 24) + (3 << 6));

  /* To perform a full remap Timer1, bit 6-7 of
     AFIO->MAPR must be set. Mask is 3 (11b)    */
  afioRegisterCopy |= (3 << 6);

  /* Apply the new register configuration*/
  AFIO->MAPR = afioRegisterCopy;
  /* USER CODE END TIM1_MspPostInit 1 */
}


texts: Can I improve serial data signal using reversed output on a twisted pair?

texts:
This is a serial data communication with one or several transmitters and one or several receivers.

From the transmitter I have one serial data output (D+) and a second, reversed serial data output (D-).

On D+ "1" is 5V, "0" is 0V.

On D- "1" is 0V, "0" is 5V.

Both line will be output by a 3-state buffer of this type:
http://www.ti.com/lit/ds/symlink/sn74lvc2g241.pdf

On the receiver side, I need to use D- (the reversed signal) but it doesn't cost me anything to use D+ and an inverter schmitt trigger ("NOT1" on the schematic) because I plan to use a shcmitt trigger anyway.
I think it's better to use the standard signal for compatibility, if someone else wants to connect its own system to the receiver.

D+ and D- will be carried on a twisted pair of a CAT5 or 6 cable. As far as I know, this helps reducing noise and interference.

The question is: If I use the D+ line, can I do something with the D- line to improve the signal on the receiver?

Is using the D- line as in this schematic would make any sens? Or should I leave the D- line unconnected? Suggestion?

The goal is the to be able a cable as long as possible (100 or 200 meters for example) and as many nodes as possible (10, 20 etc). There is no requirement. Just making the best.
Imagine that there can be several identical receivers. (not visible on the schematic) and several transmitters too.

The resistors and the zener diodes are there for elementary protection.

Speed can be low or very low. As low as I want. It's synchrone communication.

This is still in development.

simulate this circuit – Schematic created using CircuitLab

Edito:
The idea would be this:


texts:
I have 3 different working motors ranging from 1kw to 2 kw (on 220V AC, 1 phase), they all use running capacitors.
I tried 2 different AC ammeters on them and I get bad readings between 0 to 1 amp, when I should read at least 5 amps.

I cant figure out what's going on, but I guess it has to do with the running capacitors, in one instance when the motor has the running capacitor disconnected ( and therefore the motor cant spin) I get a realistic 6 amp reading.

So do you know what's messing up the AC amp readings and how could I measure the amps that the motors use ?


texts: Setting up and controlling loads of LEDs

texts:
I need some input as I am a bit electronically challenged :) I know a few things but I am actually a programmer.
I am trying to find out how to do something like this:
http://bit.ly/1gx8Cc8

I was searching this forums and it led me to Peggy 2  from evil mad scientist.

So, I think the idea is the same, except I will not be able to use a flat circuit board- It will be inside of a big globe, as in the video.

I was thinking to use the following RGB LED lights, (as they say it uses less power, is more bright) .. http://bit.ly/19mBhds
It is the same ones used in the LED strips.

As in the video, i want to be able to have some animations going and setup my own. I was thinking Arduino.

I will probably end up with more than a 625 (25*25) LEDs.

Should I use Peggy 2 as a baseline and principles?
Should i use a flexible circuit board or any other suggestions - because it is inside a globe, it wont be on a big flat surface?

Any input will be really appreciated :) Just collecting some knowledge.


texts: Trouble understanding KVL for discharging RC circuit

texts:
I am trying to derive the equation for the charge in an RC circuit with respect to time.
I have drawn the circuit as follows:

simulate this circuit – Schematic created using CircuitLab
Using a KVL, I determine the following:
\$iR - \frac{q}{C} = 0\$
\$\frac{dq}{dt} * R = \frac{q}{C}\$
Solve for q and t:
\$q = q(0)\exp(\frac{t}{RC})\$
This indicates exponential growth and not decay, which doesn't make sense. However, it is evident to me that the first line must potentially be this instead:
\$iR + \frac{q}{C} = 0\$
...which will solve my problems. But I do not understand why. Could someone help explain to me please?


texts:
Can a current transformer be damaged with an open secondary coil even if it is powered with an extremely low current?

e.g a small spark gap is made, though no plasma stream is created due to the small current the coil is fed.  This results in an open secondary, but will it damage the coil?


texts: How do I look at all the footprints in a KiCAD library?

texts:
In the KiCAD PCBnew layout editor,
is there some way to see what a footprint looks like before I place it?
Or am I forced to select a footprint that has a plausible-sounding (ASCII text) name,
place it, and then afterwards delete it and start over ... until I find the right one?

How do I look at all the footprints in a footprint library
without laboriously selecting one, placing it,
going "That's not what I wanted", through the whole list?

I would be happy with any one of

a quick way generate .pdf of all the footprints in the library
a quick way to generate a "dummy PCB" with every footprint in the library
somehow show each footprints one by one, with at most a single arrow-key to get to the next one (like the KiCAD EESchema schematic editor, when I place a schematic symbol I can see what it looks like before I place it.)


texts: Estimating current draw from alternator (14.4v?) to 12v DC

texts:
I'm wiring my caravan into my car this weekend. In order to keep the caravan's leisure battery charged the cars alternator provides a current to the caravan for this purpose.

I need to figure out what gauge wire and fuse I need for this.

Unfortunately my multimeter can only measure up to 10amps DC and I don't want to kill it in the process of measuring the current from the car. I intend to let the leisure battery drop to 12v (about 50% full) at most. I think the voltage from the car is about 14.4v for charging the leisure battery, or around that.

I'm not sure how to calculate a current draw between two voltages.. I suppose a lot of it has to do with the fact these are lead acid batteries?

Some guidance would be very much appreciated. I couldn't find the answer on google.


texts: FPGA "physical view" visualiser with Verilog simulation

texts:
I find the 'Physical View' provided with most FPGA tools somewhat mesmerizing for a complex design. Tens of thousands of switchboxes, LUTs, latches and multiplexers all configured from the HDL. It would be great to combine a logic simulator with the post-P&R layout to animate the physical view with 1/0 signals rippling through the design as stimulus is presented. This would also provide a "visual check" that the trace tools are actually making valid measurements of the timing. A slow motion view could show the clock/data race through the design so you can see the longest path lose the setup race against the clock.

It would make an educational video for teaching timing. So, why isn't this done? Other than the tools are fiendishly complicated already and functional correctness is difficult enough without worrying about animation?


texts: What transistor to use in place of QVE11223 opto

texts:
In the circuit below, I'm trying to replace the physical switch on the 'flipper opto switch board' (and 'power driver board') with a transistor, controlled by Arduino.

My understanding (please correct where I am wrong, learner here) is that I should be able to use a NPN transistor, with Collector tied to the 12v feed from the fliptronics board. The transistor needs to be able to pass 12V at ~12ma

I have tried using a 2n4401 that I have stock of, and I believe this has a hfe of 80, so I run the 5v arduino output through a 2k resistor, which should pass around 0.25ma to the base? (And be enough to switch the transistor 'on', dragging the 12v feed to the LM339 down to below 5v)

But nothing happens.

Entirely likely I'm making a fundamental error here, but I'm not sure what it is. Any help appreciated.


texts: Modifying switching power supply to produce any voltage(s)

texts:
I have few units of 24V 3A output smps power bricks. I'm planning to mod one of this to generate 12V at least at 5A for my LED strips.

My idea is to tap two wires from the secondary winding of the 24V unit chopper transformer. This should give me high frequency AC which I can feed into another self made transformer, wound on ferrite toroid. The secondary of this transformer should have half number of turns but at least doubled wire diameter (compared to the primary) to generate 12V at 5 Amps.

After rectify and smoothed the 12V, regulation loop can be closed by sending the correct DC portion to the controller of the 24V smps brick so that it remain stable.

This scheme, if viable, will give me the freedom to wind required turns for any voltage I need for all my other projects.

My question is, how do I determine the wire diameter and number of turns for the primary of the toroidal transformer which I intend to built?


texts: So far the most RAM laden MCU I have found in a hobbyist friendly DIP package is a dsPIC33FJ128GP802, which has 16KB, and the Parallax Propeller, which has 32KB. But does anyone know of chips with more memory in said packages? This is only for prototyping, I also need surface mount chips for production.


texts:
What does the variable "k" mean in the solenoid equation in the picture attached?
Many thanks for the help.

Source: Theory & Practice of Electromagnetic Design of DC Motors & Actuators
George P. Gogue & Joseph J. Stupak, Jr.


texts:
I'm curious as to how fast I can communicate between multiple sensors. I have a board with an adxl345 digital accelerometer and an itg3200 3-axis MEMS gyro on I2C. I'm trying to build an IMU which requires fast polling of both sensors. The faster I try to poll, the more error codes I get. How can I calculate the optimal delay required for simultaneous communication? Also how fast can I2C really communicate between multiple sensors?

PS.
Im on an atmega128 chip @16MHz.


texts: What does non-combinational area represent in synopsys design compiler

texts:
I have designed a ripple adder using full adders. In order to find delay incurred to perform this addition I included a clock in each full adder module. In my main code I instantiated these modules to construct the ripple adder. When I synthesised the ripple adder code and found the area the result was something like :

combinational area=54
non-combinational area=204;

I want to know if this non-combinational area is due to overhead of including clock in each module. Is there any way to reduce this non-combinational area.


texts:
Apologies if this is a very low-level question, but I have no experience in this field and don't know where to start. I'm looking to borrow an accurate pressure gauge from GE:

https://www.gemeasurement.com/sensors-probes-transducers/pressure-transducerstransmitters/unik-5000-silicon-pressure-sensor

It looks like it takes a 4-20mA signal, and I was wondering if there a way I could use one of these units, which I already own, to log the data:

http://www.onsetcomp.com/files/manual_pdfs/11196-B-MAN-U10-003.pdf

How does the 4-20mA signal work when transmitting pressure or temperature data? Is there a way you can 'translate' a temperature readout back to a pressure readout on a computer? Or do you need a dedicated pressure signal logger/digital display to accurately translate the signal?

Also, how standardised are the 4-20mA signals? Can I use a gauge from one brand and get a digital display from another and expect correct results?

Thanks


texts: Relationship between volts and Mechanical Energy

texts:
I am studying Electrical Engineering and I came across one definition of the volt being defined as follows:

V = J / C

Where "V" is voltage measured in "volts", "J" is energy measured in "joules" and "C" is charge measured in "coulombs". If this definition is correct, it would appear that a 10 V battery should be able to produce 10 joules of energy per coulomb of charge. My question is, what is the relationship between volts and Mechanical Energy?

The reason I bring this up, is because if we assume that the acceleration due to gravity is 10 m/s², the amount of energy required to move 1 kg of water a distance of 1 meter vertically is equivalent to 10 joules. I used the following formula:

F = m * a = (1 kg) * (10  m/s²) = 10 newtons.

W = F * d = (10 N) * (1 m) = 10 joules.

Does this mean that using a 10 V battery, I should be able to create a device that is able to move 1 kg of water a distance of 1 meter up in the air? I am trying to better understand the relationship of volts as a difference in Electrical Potential between two points in space and somehow using this potential to move objects with a certain mass a certain distance. Perhaps I am mixing different physics concepts together. Any insight into this would be appreciated. Cheers.


texts: Wireless Sensor Network Lifetime Estimation

texts:
I am attempting to replicate a calculation for estimating the lifetime of a wireless sensor network based on the measured energy draw of each operation.  These values are given in a table which I have screenshot-ed and attached below.

There are two types of motes and two configurations.  The first type of mote is a weather sensing mote that has all of the subsystems in the table but the occupancy sensing subsystem.  There is also a burrow mote that has every subsystem.  The weather mote has a single 2.8V 860mAhr battery.  The burrow mote has a single 3.6V 1Ahr battery.  Both motes can be in either a single hop or multihop configuration.  Energy draw based on overhearing or packet forwarding is ignored.

The period in the table is how often the activity occurs in seconds.  So the single-hop configuration climate senses and occupancy senses every 300 seconds.  The multihop senses every 1200 seconds.

I am attempting to determine how the 140, 127, 90 and 80 day lifetime estimates were reached.

My reason for asking is that I am producing a model of sensor network, and I want to put the measured energy estimates into the model.  After I have filled in the energy estimates, I want to write a program that can evaluate the model to determine the expected lifetime.

More or less I need the formula for determining the expected lifetime.  I hope I have provided enough information but I am not familiar with electric units of measurement.  If any needed details are missing, I'll edit the question to provide.

Thanks.


texts: High power IR transmitter circuit for ESP8266

texts:
Currently I am using this IR transmitter circuit for an ESP8266:

It works, the reception is not bad, but I need a little bit higher power to control my AC unit. The AC unit is ca. 10 meter away from the transmitter. From about 5 meter it is working nicely.

Do you have any idea how to get more power through the diodes?


texts: How to Calculate the Impedance of the Capacitor T network?

texts: I guess Capacitor T network used in the schematics is for Impedance matching, if yes how to calculate the impedance of the same circuit?


texts: Altera Cyclone IV memory block Verilog module

texts:
This document explains the various characteristics of the Altera Cyclone IV memory blocks (known as "M9K").

However, there is no mention as to how these modules should be instantiated in Verilog. Where can I find the M9K memory block Verilog module documentation? Does Altera provide example code?


texts: Unity Gain Phase Splitter- Why outputs have different voltages

texts:
I’m trying to calculate the values of the biasing resistors for this phase splitter circuit. (I know the actual values of the resistors, but I just wanted to manually work it out).

When I made the circuit on a Multisim, I realised that Vc=11.25V and Ve=3.75V. I’ve been looking around the web to see why this is the case, but I can’t seem to find anything. I understand the outputs are different polarities, but why are these voltages like this?


texts: SMD IC mounted upside-down inside a drill hole for extreme low-profile requirements

texts:
I don't know if the title is descriptive enough, but I came across this PCB and could stop to wonder about its brilliant design. It is an aftermarket trigger controller for an airsoft gun that works linear Hall sensors, such that you may glue tiny neodymium magnets to the different moving parts (not shown in the picture) to detect their position.

Notice the Hall sensor at the very left. It's buried within the PCB! And it even looks like it has some exposed vias to aid with soldering. This way the designers could place the sensor right between the shell and one of the moving gears (removed in the picture). Beautiful!

Is this common practice? And how difficult would it be to use on my own designs? Are there any references or guidelines I could read? This design really impressed me, and gave me many many new ideas for future projects I would like to try out.

UPDATE: As discussed in the comments and in some of the answers, it seems that the cost of manufacturing this PCB will increase because these components must be hand-soldered. I would like to clarify that this is no issue for me. I produce only very low quantity PCB's for prototypes (which I usually solder myself). But still, thank you for bringing this extra cost to my attention. I didn't account for it because of this same reason :)

About the accepted answer: Sadly I can only accept one answer, though I find all of them very useful and insightful. I now know that this type of assembly is not common practice, but can be done if one is willing to pay for the extra cost (or solder oneself by hand). However, I've accepted the answer that gave me the key concept, namely  castellated holes, plus the idea of doing the milling right at the edge of the board (just as in the attached screenshot). Thank you all again for helping me out on this, and I'm glad this question lead to a healthy discussion on the pros and cons of z-milling.


texts: Solar/battery powered LEDs circuit - Arduino controlled

texts:
First the battery is not connected directly but over protection IC logic.

Question:

Current circuit works as follows:

When solar cell voltage is higher than 0.7V , LED is OFF (sort off day/night sensor).
When solar voltage is lower than 0,7V, LED is shining with low intensity

What is the the correct way to connect arduino pin D2 to take control over above described default behavior? (disconnect SW4 and remove R9)?

Question:

Which voltage measurement technique (internal reference or reference to regulated Vcc voltage) should  i use to meassure Lipo voltage?
What are correct/recommended resistor value for optimal battery utilization.

Should this reference be used: https://github.com/rlogiacco/BatterySense

3.Question:

Is arduino pin D2 connect properly?
It control two level LED intensity:

pin HIGH - LED glows with HIGH intensity (between led+ and led- is ~4V)
pin LOW
LED glows with LOW intensity (between led+ and led- is ~2,5V)

Thanks for help and recommendations


texts:
I'm trying to print a PDF to put my PCB design on copper, and I get the PDF document and everything seems to be alright but when I print my design the pads are filled in black.

PDF Output

And this is the result:

So then, how can I get the holes in the printed PDF?


texts: How is powering an LED with a 9 volt battery possible without burning the LED?

texts: I used a 220 ohm resistor with a 9V battery and the LED works fine. However, most sources say the forward voltage in a red LED is typically only ~2 volts. Going by this logic, the LED should have burned out, as resistors only limit current not voltage. If this is a stupid question, I’m sorry. I’m relatively new at electronics.


texts: LED Controller + LED Panel with common cathode

texts:
I have a 3-CH DMX controller (5-24V, 5A/ch, common anode) from amazon (don't know if links are desired here) and a 12V 100W MCPCB LED panel, which unfortunately has a common cathode. The panel is equipped with 200pcs 3.0V 0.5W LEDs and has two different LED types (bi-color). So I would connect to the panel with two channels from the controller to change the brightness for each channel of the panel. Because of the common cathode wiring of the LED panel both channels are up, when changing brightness on either channel.

I would like to modify the DMX controller outputs so that it can handle this panel. Can you recommend which MOSFETs I should use and how I wire them? Or another solution that is suitable for this project. Per channel I have 4.16A in the line.

Thanks a lot!

Edit: I'm attaching an image and pinout of the controller (for the led panel board i don't have schematics, but the manufacturer confirmed that this panel has common cathode wiring):


texts: Irll024N logic level mosfet + atmega 2560 problem

texts:
We're designed a circuit based on an atmega2560 and wanted to turn on or off some parts of our pcb.

So we've installed an logic level mosfet (IRLL024N) that was supposed to act as a switch on our 5V line.

The mosfet is controlled by a digital pin of the atmega set to high or low to turn on or off the rest of the circuit.

The problem is that we are experiencing a huge voltage drop on the mosfet when it's turned on.

The source voltage is 4.93V the gate is 4.89V but the drain voltage  is only 3.02V

Why is this happening?

Below is our  schematic


texts: Modifying brushless alternator for external regulator

texts:
I'd like to modify a Delco Remy 38si or 40si brushless alternator for use with an external voltage regulator.  For a brushed alternator, I'd just need to pull the field out external to the case.  My expectation is that the same would work for any brushless alternator.

Are there issues here I'm not seeing?

Can someone speak directly to these specific alternators and the possibility for removing the voltage regulator (obviously possible) and pulling the field out to an external terminal?


texts:
When writing Verilog, I use a variety of "linters" that will give errors and warnings. These are my simulator (ModelSim), my compiler (Quartus II), along with a linter (Verilator). Together, I have good coverage for common pitfalls, such as bus size mismatches and inferred latches.

Unfortunately, none of the three tools detects registers which are not being reset. To see what I mean, consider the following.

reg a;
reg b;

always @(posedge clk_i or posedge rst_i) begin
  if(rst_i) begin
    a <= 1'b0; // Reset a
    // Ooops, forgot to reset b
  end else begin
    // Do stuff with a and b
  end
end

How can I have my tools automatically detect registers which are not being reset?


texts:
I have two DG sets which are to be synchronized on to the same AC bus and needless to say, they must share load. I have gathered some parametric data which I felt would decide how well these can work as part of single bus. But I am not sure, and would like to know what the experts feel about these two DG sets getting synced easily.

DG-1

Engine Data:

1200KW
50Hz
Power Factor (Cos Phi): 0.7

Generator Data:

3 Phase - 6 Wire
X Wye Delta,
X Series Parallel
600 Volts
1828 Amps
1714KVA
Sub Transient X"D : 0.133 per unit 0.028 Ohms
Transient X"D : 0.197 per unit 0.043 Ohms

Excitation Data:

31 Volts, 7.1 Amps
Separately Excited

Frame:
 - 826 Frame
 - 1500 Rev/Min

DG-2

Engine Data:

1330KW    - KW is specified at a higher PF here
50Hz
Power Factor (Cos Phi): 0.8

Generator Data:

3 Phase - 6 Wire
KH734E Wye
P7 Series
600 Volts
1492 Amps - So Amps is much lesser than DG-1
1662.5KVA - So KVA is slightly less than DG-1
Sub Transient X"D : 0.101 per unit 0.092 Ohms
Transient X"D : 0.581 per unit 0.21 Ohms

Excitation Data:

45 Volts, 3.5 Amps - Excitation power is also much lesser than DG-1
Separately Excited

Frame:
 - Steel Frame
 - 1500 Rev/Min

Any kind of help shall be highly appreciated.

Best Regards,

Vishal


texts: CMOS inverter: circular reasoning to understand it?

texts:
I am confused by a litte detail with CMOS inverter. Note that I am really a beginner in CMOS "theory". Here is the electrical circuit:

At "first view", I understand the principle. If \$V_{in}\$ is high (\$V_{in}=V_{DD}\$), then the PMOS will be open and the NMOS closed. Thus \$V_{out}=0\$.
Reciprocally, \$V_{in}=0\$ implies the PMOS closed and NMOS closed thus \$V_{out}=V_{DD}\$
My question
I have trouble when I look at the details. Let us consider \$V_{in}\$ high for instance. A PMOS will be closed for \$V_{GS} < V_{Tp}<0\$ (threshold voltage), and \$V_{GS} > V_{Tn}>0\$ for NMOS.
But for this I must identify where are source and drain. To identify where is the source and the drain of a transistor, I must find which one has the highest voltage.
But as I do not know \$V_{out}\$ how can I find them ? \$V_{out}\$ is what I try to find so I am not supposed to know it (else the reasoning is circular)...
Is there an implicit assumption that "by design", for CMOS circuit, any voltage in the circuit will verify \$0 < V < V_{DD}\$. Applying this to \$V_{out}\$ I can deduce source and drain for both transistors and solve my issue ?
Because "in principle", I could imagine some negative voltages and because of that identifying what is source and drain is not straightforward here.


texts: Suppose a 3.3 V white (or any colour) LED with a current draw of 20 mA is shone into the lens of a cheap webcam (or any budget camera) at close range (< 3 cm) for a long period of time (24 hrs) or more. Will the CCD/CMOS be damaged by this light?  If the LED blinks, will it cause more/less damage?


texts:
I'm studying optocouplers in general, and in special the 4N25.

I'm applying the optocoupler in a zero crossing circuit, like this one:

I know the CTR is minimum of 20%, but checking the datasheet of 4N25, I'm wondering how to get the aprox. CTR based on IF and ambient temperature:

So, my question is, how to determine if is in saturation mode or not? Which curve could I look?


texts: How deep should we discharge lithium batteries to maximise their lifetime?

texts:
Recently I posted an answer mentioning the very classic "lithium batteries like partial discharges, so design your system for limited depth of discharge". But then I wondered: with partial discharges, the number of charge/discharge cycles increases as well for the same energy delivered, so the gain in available cycles lifetime will decrease. For example, the battery of a cellphone discharged at 50% in the morning, recharged, discharged at 50% in the afternoon and recharged overnight requires twice as many cycles as a cellphone discharged at 100% and recharged once a day to last as long. I thought it would be interesting to look into that.

I went ahead and as usual, I submit my findings for any SE user's approval and welcome anyone to add to it.

I should point out this only covers regularly used batteries, not those sitting on a shelf for periods greater than a few days. Even so, they do tend to age independently on the cycles but I do not have data on that - perhaps experts could shed some light on that.


texts: Motor Control board -replace capacitor with higher voltage?

texts:
I hope that someone may be able to help me with a problem i have-

My good lady wife dusted down her trusty Kenwood mixer last night to get started on the Christmas cake (apparently it must be done this weekend or doom will ensue)
On attempting to use it she found that when switched on the motor would start then stop then slowly start etc etc- generally misbehave.

Here is a short video of the misbehaving motor:

https://youtu.be/7Mmma936F_w

I stripped the beast and checked the brushes- all ok and so took further advise from a "kenwood expert" who says my speed control is likely goosed (a common problem it seems).

He recommended replacing the triac, a couple of 4.7k resistors, a 220uF capacitor and a 150nF resistor.

Although i can't see any obvious signs of distress on the board such as blown / leaking cap's or charred resistors i am not capable of testing the triac with the limited equipment i have so thought it best to go ahead and replace the components suggested by "the Kenwood man"

The control board is actuated by a rotary dial - the spindle passes through the board and the speed control (Potentiometer?) we have a direct mains voltage input, a motor output and a thermistor input (thermistor is attached to the motor to prevent overheat)

Upon turning the dial the motor speed should increase progressively depending on dial position-  The machine also has a function whereby you can turn the dial in the opposite direction for a "pulse" of full power- this full power is applied until you release the dial and it returns to 0 (stop) via some sort of spring action in the potentiometer?

I only have a Maplin in my area and can't seem to find a like for like match on the capacitor which should be a 150nF 275v x2

The only available 150nF capacitor at Maplin is a Wima Polypropylene Metal Foil 1250V 0.15uF Capacitor which is obviously 4.5 x the voltage of the one i want to replace, other than that the closest match i can come up with at Maplin is a 0.1uF 275V X2 RFI Metallised Polypropylene Capacitor.

Can anyone tell me if either of these two capacitors are likely to be acceptable?

I thank everyone in advance for their time, i'm sure you all get fed up with people like me popping up out of nowhere asking for help but it really is appreciated!

Regards,

Rob


texts: Help identifying component on Sainsmart 4-Channel Relay board

texts:
http://www.thesunrain.com/Amazon/4%20relay%20board/4-ch%20relay%20module.pdf

In the Schematic there are 4 Items Labeled U1,U3,U5,U7

They look like small black boxes on the actual boards. I can't really tell what they are, it looks like some sort of LED icon and then a transistor? If so whats their purpose? These are Mechanical Relays btw.


texts: Reducing H-bridge inputs for multiple motors with same direction

texts:
I need to control 5 motors independently from a microcontroller.  At stall these motors only draw around .25A.

What is a circuit I can use for controlling 5 DC motors that draw about .25A max with as few pins as possible, under the condition that they will all be moving in the same direction at the same time (though possibly at different rates).

use a full H-bridge for each one. 10 pins (base case)
use one high-current half-H and 5 regular half-H, one side of motors all in parallel on the half-H. 6 pins
use full-H for each motor, put one side of them in parallel. 6 pins
use some magic IC (which I will find myself) where I can tie a digital direction input together for all chips. 6 pins
use some IC that takes PWM signal and drives DC motor, 5 pins


texts: Understanding the purpose of this D flip flop circuit

texts:
I'm struggling to understand the purpose of this circuit.
As far as I know, this is not an edge-triggered Flip Flop.
Q0 = x
D1 = Q0 and X'
Y = Q1 and X
What I know
So in order to get one in the output, I need to set 1 in the first flip flop and X = 1.
If I set X = 1 when CLK is 1, Q0 will be 1.
If I set X to 0 when CLK = 0 I will have 1 at the D input of the first flip flop
When CLK goes to HIGH I will have Q0 = 0 this will force D to 0.
Problem
So my understanding is that the first flip flop needs to be set before Q0 goes to LOW and X needs to go to HIGH to get 1 at the output.
I did the simulation in Quartus to try to understand but it doesn't matter what I do Y is always 0
My thoughts
Maybe this is an edge-triggered flip flop? If this is the case I can achieve Y = 1 by setting the X to 1 waiting for Q0 = 1, setting X to 0, wait for Q1 = 0, and finally set X back to one to enable the output.
But even if this is the case, I don't see the purpose of the circuit.

Exercise for reference:


texts:
I'm trying to get my head around integer division. I'm entering a decimal number between 100 and 6300 into my program, I then need to scale this number by 100 and output the result as a 6-bit number.

Mathematically what I'm trying to do is:

Output = Input/100

Very simple! But I just can't seem to get this to work in C. I'm using MikroC for a PIC18 MCU.

Example code:

int input;
int output;

void main(){
TRISA = 0x00;
input = 1000;//operator has input 1000
output = input/100.0;//scale input by 100
PORTA = output;//output 6-bit number
}


texts: Looking for a level translator for single duplex serial bus

texts:
I have a 3.3V UART (two pins) plus a direction selector pin (also 3.3V.) I need to talk to and listen on a single duplex serial bus at 5V with 20 mA drive strength. The signaling rate is 3 Mbit/s, although switching directions is allowed to take 4 microseconds.
An automatic bidirectional translator like TXB0102 is not right because it ignores the direction signal.
A 74hct125 (one element going each way) doesn't do level translation.
A simple MOSFET for translation isn't good enough because it's not push/pull and thus doesn't get the drive strength both ways (plus strong pull-ups are bad for this bus.)
Finally, I prefer something in DIP-8 but can go up to DIP-14 if no external components are needed, and I'll break down and use SMDs if there is no other choice.

So, what existing component is there that fulfills these requirements? I've browsed parametric search at Digi-Key but not found anything that his all the requirements above...


texts:
Can anybody identify this package? Looks like a sort of QFN to me but it's not square and I have not been able to find anything like it.

The chip itself is proprietary, no datasheet available for it.

I'd like to make a break-out board + perhaps some pins on such package are "standard"/often used as VCC/GND and similar - so that's why I'm after it.

Chip has 17 contacts on long side, 6 on short side, totaling 46 contacts.

Measures 7.5mm x 3mm.

Pictures of the chip + layout of the package on the PCB below.


texts: Increase gain reduction on op amp filter

texts: The image below features the EQ section of a DJ mixer with -26db gain reduction on each frequency band (hi/mid/low). My goal is to modify this circuit so that the op amp filters are "full kill" (aka isolators) - meaning that when you turn the VR all the way down, it kills the frequency band completely. What can I do to accomplish that (or at least increase the gain reduction beyond -40db)?


texts: Do I need a higher amperage power supply for more stepper motors

texts:
I have a very simple question:
I am trying to power five 28BYJ-48 stepper motors attached to some ULN2003 driving boards but I am confused about the amperage I need. Each of the stepper motors needs 5V and 250mA to run and my driving boards take up to 500mA.
I'm wondering if I need to buy a power supply that's 5V/250mA or 5V/1.25A? If its the latter I'm worried that my driving boards may fry under the high amperage, what should I do about that?
Many thanks to anyone that can help.


texts: How can I simulate a battery's current/voltage characteristics?

texts:
I want to simulate a battery whose behaviour can be controlled by a microcontroller. If the battery is at low charge and there is a high current, the voltage should decrease. Any solution for this issue is good.

My idea was to use a voltage regulator and to change the voltage when required. To simulate the battery, the current would need to be measured constantly. I could simply add a resistor in series and measure the voltage across it. Then, I would have to use a large resistor so that the output voltage still matches the output voltage of the voltage regulator. But then, the maximum voltage at the resistor would be very low and I would have to amplify it.

So my question is whether there is any voltage regulator with integraded current measurement, or you see any alternative solution.


texts: Using a twin secondary in place of centre tapped transformer

texts:
The project I am working on specifies a 12v 0 12v centre tapped transformer. I have a 12v twin secondary left over from a previous project. My plan is to wire the two secondaries in series in order to form a centre tap, as per this thread:

A question about using a dual secondary transformer as a center tapped transformer

My question is, I think this will double the voltage to 24v - is that correct? The project specifies 12v, so would I be better using a 6v twin secondary transformer with the secondaries wired in series?

I am a wee bit confused since a similar question was asked here:

https://www.eevblog.com/forum/beginners/replacing-centre-tap-transformer-with-standard-transformer/msg21738/#msg21738

The advice given was, "If you can't find a 12V centre tapped transformer, use a 12V transformer with twin secondaries and connect them in series"

I would be very grateful if someone could clarify.

Many thanks


texts:
I am attempting to read an HC-SR04 ultrasonic sensor at the same time a couple of servos are running. Having a servo running is messing up the timing of the pulseIn() method.

The distance measurement will be correct for small distances (up to 24 cm or so), but anything larger sometimes read incorrectly. If a server is not attached to D2 or D3, the distance sensor works fine. How can I get both to play together? Maybe a library that doesn't rely on the same timers as a server on D2 and D3? This is on a Mega.

// read the distance sensor
// returns: distance in inches. -1 means out of range
float ReadDistance(int trigPin, int echoPin)
{
  long duration;
  float distance;
  digitalWrite(trigPin, LOW);  // Added this line
  delayMicroseconds(2); // Added this line

  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10); // Added this line
  digitalWrite(trigPin, LOW);
  duration = pulseIn(echoPin, HIGH);
  distance = (duration/2.0) / 29.1 / 2.54;
  if (distance >= 200 || distance <= 0)
    return -1.0;
  else
    return distance;
}


texts: Unit in the exponent for phase modulation

texts:
How does the "unit" per Hertz in behave in the exponent? My specific question is about the calculation of the modulation index \$\eta\$ from a measured spectral density of a phase modulation on a spectrum analyser. For a read value of P in dBc/Hz (for example a noise floor), the modulation index can be calculated by
$$\eta=2\cdot10^{\frac{P~[\text{dBc/Hz}]}{20}}$$
What happens with the per Hertz in the exponent? Is the result of the unit rad/Hz?
I have read several threats about units in exponents not being possible because an exponent can be developed into a power series, just to give two examples:
Exponentation and Units-Exponential.

My guess is the following: Per Hertz is not a unit anyway but a normalisation to the equivalent noise bandwidth. Thus, the outcome would be rad/Hz.

To make the question clearer: Units in exponents cannot exist because exponents can be developed into power series leading to an addition in the from of ()+()^2+()^3+... And Units of different power cannot be added. So how can I deduce a modulation index per Hertz from a noise power per Hertz?


texts: What is the (exact) difference between CLM and DIBL in MOSFET?

texts:
I am wrapping my head around this for a bit and I understand both effects (Channel Length Modulation, Drain Induced Barrier Lowering).

While CLM is usually explained as effective decrease of the channel length due to increased depletion region, DIBL is usually explained as reducing Vth due to the same effect ("drain is a second gate").

However, fundamentally I cannot see a difference between them. Both effectively reduce the channel length due to larger depletion at the drain and hence result in finite ro. Change in Vth is just an alternative interpretation.


texts:
First off, thanks for taking the time to read this and help out.
Here's a quick overview of what I am trying to design. I have a break out box that has 200 female probe inputs. Each input is numbered, and I have to take continuity / resistance measurements across a whole range of potential combinations. Sometimes, the polarity will need to be reversed (ex: pin 34 to 80 and another measurement of pin 80 to 34, high and low side respectively) due to active components inside what I am trying to measure. I would like to automate this process, and compare the resistance of each connection to expected bounds.
In my head, I think a solution looks somethings like this:
200 inputs to header pins -> PCB to route header pins to BGA CPLD -> CPLD has input selectors and routes a selected signal to each output pin accordingly -> the outputs go to a resistor network that acts as an auto-ranging multimeter which is controlled by an Arduino that has the expected measurements inside to compare with. Results will be saved to a CSV file and anomalies will be displayed on an LCD screen.
Will a CPLD be able to route the analog signals to the arduino properly? I'm fairly new at digital / analog design and greatly appreciate all help. Thank you!


texts:
In this circuit, I calculate the current through R1 to be 10mA. What happens if I take into account the electromagnetic radiation in the ideal wire?

simulate this circuit – Schematic created using CircuitLab

edit: This is a pedagogical question, trying to establish that no, an ideal wire does not dissipate energy because that's not a useful definition of "ideal".


texts: pulse charging lead acid battries effects and side effects

texts:
I am developing a solar charger which charges lead acid batteries.I would like to clear a few of doubts on this issue.

I am using IR2110 gate driver for driving 2 n-channel mosfets in an half bridge configuration.
Should the Gate to Source voltage of the high side MOSFET be pulled up to my solar panel   voltage in order to force current to flow through the battery?

Is it possible i can connect the output of the H bridge(which is a high current PWM signal) directly to the batteries. Or should i use some kind of smoothing LC filter to first smooth-en the PWM signal?If its the latter ,any mathematical data on calculating the L and C values would be very helpful.

Edit:
Postd the circuit that i planned.

simulate this circuit – Schematic created using CircuitLab

Diode D3 is for preventing the MOSFET M2 from shorting the battery to ground
Diode D2 is a flyback diode used to ground negative current from the inductor
Thanks


texts: Synchronizing multiplier with adder to form mac

texts:
I have designed an 8-bit multiplier in Verilog which takes a maximum of 8 clock cycles to give the product. I have also coded a 16 bit adder based on combinational logic. I now want to integrate the two to make an 8 bit multiplier accumulator, but can't think of a good way to synchronize all the signals. As in, how do I make my adder wait for 8 clock cycles until the product is given, before it performs addition with the previous result?

The accumulator result has to be first initialized to zero, which then changes every 8 clock cycles as soon as the correct product is available. Also I want the code to be synthesizable. Please suggest a way of doing this.

This is what I have done so far:

    module mac_abacus (result, x, y, clk, reset);
    output [16:1] result;
    input [8:1] x, y;
    input clk, reset;
    wire [16:1] product;
    wire carry, cin;
    reg [16:1] prod_bus, prev_sum;
    wire [16:1] sth;

    ab_mac abmacus (product, x, y, clk, reset); //this is the multiplier
    //when reset=1, prev_sum=0, prod_bus=0,result=0
    //when reset=0, prev_sum=result(i.e the previous result),
    //prod_bus=product(shd change every 8 clock cycles alongwith the product)

    condsum16 csummer (result, carry, prod_bus, prev_sum, cin);//this is the accumulator
    //so, effectively when reset=0, result shd hold its value until 8 clock cycles when the new product appears
    endmodule


texts: LM4871 audio amplifier BTL configuration question

texts:
I am reading the datasheet of LM4871 audio amplifier. The typical application looks like:

The datasheet says it is in BTL configuration. The 1st OPA inverts input signal and the 2nd OPA inverts again so we get a differential pair for driving a loudspeaker at output stage.

My question is:

The path of Vo2 (2 OPA) is obviously longer than Vo1 (1 OPA). Why there is no synchronization problem between them? Are these OPAs fast enough so we can ignore the asynchronous?
I also found an article of wikipedia which describes BTL. It looks like:

Why there are different design of BTL. What is the difference between them?


texts: Configuration in MPLABX compared to MikroC Pro

texts:
I need to modify a C code of an PIC18F4550. I want to use the MPLAB X IDE to do the job because I'm more familiar with it. However, the code that I need to modify is accompanied by an introduction tutorial of programming using the MikroC-Pro. In the tutorial, when it was explaining how to creat a project, it edited the project. So, I noticed a difference between the two IDEs. The MikroC asks for a lot more information like frequency, Oscilator etc...  I didn't find how to make a similar configuration in the MPLAB X's project.

I would like to know, why MPLAB X did not ask this information ? Will I need to add this information in my code, I mean , I will need to type it in the C file using MPLABX ?

Below is the print-screen of the information availabe to edit the project in the MikroC.


texts: Can we get higher internet speeds even with low BW message signals?

texts:
Consider a case where i’m listening to a recorded audio on internet.Basically the useful audio Frequency range lies b/w 40hz to 4khz, which has a BW of 4khz which is pretty low ,does that mean the audio has low data rate? But it loads up pretty quickly.

Another question:-  does higher message signal BW mean  it can accomadate MORE info at a time and lead to fater data rates, as more data is being transferred per second?


texts: Is it possible to "trace" a hall effect sensor on a PCB?

texts:
To my knowledge, a hall effect sensor is just a soft-cored hooped metal (iron?) with some wire wrapped around it a precise number of turns. This surrounds another wire that you wish to measure the intensity of passing current. The coil has a magnetic field inducted into it and thus, current flows through the wire and can be measured without invading the circuit.

I'm trying to measure the varying current on a DC line (5A max @ 15v *ish) without paying too much for an expensive hall effect sensor, or putting a high rated resistor in series. My circuit should only be worried when I'm approaching the max current and I'll probably use a potential divider and a comparator to detect this.

So my idea is; would applying a square trace right next to the current line on a PCB like an antenna, induct any current, and would it be measurable? Could I bypass buying expensive components and tune a comparator to detect the inductance myself work?

Cheers,
Mike


texts:
I doubt if the way I am converting the logical level is correct and if it is the best way to do this.

The PWM_1 signal comes from a STM32F4 microcontroller. When PWM_1 = logic level 1 I have 3.3V. When PWM_1 = logic level 0 I have 0V.

I need PWM_1's 3.3V to be converted to 0V in OUT_1 and PWM_1's 0V to be 5V on OUT_1 output.

As the SN74HC04D logic port is being powered with 5V it only recognizes logic level 1 when it has 3.5V in the input (according to the datasheet). So I need to do the logical conversion from 3.3V to 5V.

I would not want to use an integrated circuit for this, so I thought of that circuit with Mosfet-n.

I wonder if this is the best way to convert logical level without using integrated circuit.


texts: Is it worth it learning how to use 7400 series "jelly bean" logic IC's or are they completely obsolete?

texts: My road map for learning electronics included the 7400 series logic chips. I started in on electronics by following the labs in the "Art of Electronics" lab manual which includes labs with these chips. I ended up building several custom Microchip PIC and Atmel microcontroller boards before doing these particular labs. Now I am eye-balling FPGA's and getting excited to try one of those out. Should I leave the 7400 series behind or is an understanding of them considered fundamental to understanding the more modern programmable logic chips? Are some of the 7400 series still used in new (good) designs for simple stuff? Are there still particularly useful 7400 series chips that get used all the time? I guess it wouldn't take long just to do the 7400 series labs, but, I just wanted a sense of how obsolete they are since I had such a difficult time sourcing the parts. I couldn't find some and I ended up spending way more money than I thought was acceptable.


texts:
I was trying to solve a question from the  2004 GATE IN paper,

I solved it this way,

Now, the book is giving a different solution, I'm pretty sure my way is correct since they pulled the "standard form" out of nowhere. I don't think that formula is applicable here. But please tell me if I am wrong.

Also while I understand that I performed those algebraic manipulations to find how the disturbance and error is related in the frequency domain, I am not comfortable with the fact that I had to assume input R(s) was 0. I mean practically we would care about how the disturbance D affects the output C or error E in the presence of some non zero input R right? If I don't take input to be zero I can't seperate terms and find the transfer function. So I was wondering if the superposition principle is strong enough such that this result is useful even in the case of both D and R bring present?


texts: Frequency demodulation with a spectrum analyzer

texts:
In my university lectures I have generated an FM signal (for instance with carrier frequency of 2GHz, frequency deviation equal to 100kHz, and modulating frequency equal to 100kHz.)

In order to perform the demodulation, my teacher has followed these steps:

Choosing a high resolution bandwidth in order to incorporate all the side bands inside one single peak (obviously it is not good if we want to analyze the spectrum properties.)
Choosing as center frequency a point in the transition between the peak and the "null" part of the spectrum.
Switching to time domain and visualizing the modulating signal.

I have some questions about step 1 and 2:

about 1: Why do we have to choose a so large RBW (for instance 3MHz?)
about 2: Why do we have to choose a point of demodulation which is not the peak of the spectrum?

My professor has said that choosing the peak frequency will lead to a demodulated signal with 0 voltage dynamic.
 Why?


texts: I have an old sony universal remote, the rm-v15. I opened it to get to the pcb, and a strange nasty smell came out of it. Is there anything I should be worried about? Any hazards used in old remotes?


texts: Buffering a constant current source IC to increase maximum voltage rating

texts:
The actual question: Which of these configurations, if any, is the most effective for my goal of increasing the maximum voltage rating of the outputs of a constant-current driver IC?

As established in a previous question, a constant current source IC may specify a maximum voltage rating that refers to the entire voltage across the load rather than the voltage remaining after what the load drops. For example, when the specs for TI's TLC59281 specify VO (voltage applied to output) of 17V, this indicates that a string of LEDs connected to an output must be supplied with no more than 17V, regardless of the voltage drops of the LEDs.

An application circuit I'm presently developing already makes use of the '59281 for a few single- and dual-LED outputs at 20mA. I'd like to add several 10-LED output strings with, say, a 48V supply, but the IC alone isn't rated for such.

One comment on the answer to the original question indicated that a simple buffer—specifically, a common-base NPN buffer—might be all that is necessary to work around the rating. After a little investigation, I've come up with some possible variations on the topology and need some insight as to which might be the most useful.

Pictured are some possible configurations. All transistors pictured are rated for 65V or greater.

(A) The way the driver is expected to be run, unbuffered at less than 17V.
(B) The way the driver would ideally run, unbuffered at more than 17V. As established, this is not supported.
(C) Buffered with NPN common-base buffer, base voltage of 1V. Ideally the driver output sees no higher than about 0.3V. Output current is slightly less than driver current (dependent on hFE of transistor) but this effect is hopefully negligible.
(D) Same as (C) but with base voltage of 5V. Ideally the driver output sees no higher than about 4.3V. Seems to work about the same in Falstad as (C); unsure about any actual advantages/disadvantages.
(E) Mostly wishful thinking—this configuration would have output current roughly equal to input current. However, this doesn't fix the base voltage below 17V, so it's entirely possible that this is ineffective for increasing the maximum voltage rating.

EDIT: As indicated by one answer, the TI application note SLVA280 describes two similar solutions to this very problem. The following is my digest of that app note.

(F) is similar to (D) but uses an N-channel MOSFET. According to the app note, the gate resistor is included to suppress oscillations caused by fast switching (and might even be omitted for a slower FET).
(G) is similar to (D) but includes a base resistor. The resistor is selected to minimize base current while still allowing the full maximum LED current on the collector.

The tradeoff is essentially precision versus cost. The MOSFET in (F) can cost substantially more than the BJT in (G). But (G) is far more sensitive to the value of R and the current gain of the transistor (which itself tends to be rather loosely specified) while (F) appears to be more forgiving.

(By my cursory examination, at voltage ratings of above 60V or so, the differences in price are rather less pronounced, so the MOSFET version is probably the way I'll go.)

For (G), R is defined thus:

\$\frac{\left(V_{CC}-V_{BE}\right)\beta}{I_{LED\_OC}}<R<\frac{\left(V_{CC}-V_{BE}\right)\beta}{I_{LED\_max}}\$

where \$\beta\$ is the current gain of the transistor, \$I_{LED\_max}\$ is the maximum LED current, and \$I_{LED\_OC}\$ is an "overcurrent limit" arbitrarily defined as 1.2 to 1.3 times \$I_{LED\_max}\$.


texts:
I work on simulation of kind of antenna.  How can one interpret this antenna polarization trajectory?

the vertical axis label is 'X'.
If I want to plot polarization like the above figure, what are the elements
I should use in the plot? Ex-Ey or any other component


texts: Using PWM to communicate between ATTiny85s

texts:
Some background: I am putting together a display to teach children about how neural circuits work.  I am making a group of 'blocks' (each of which contains an ATTiny85, an indicator LED, and input/output wires) that can be connected in different configurations to represent different circuit motifs.

The problem: I am trying to use PWM to communicate between the ATTiny85s.  My original idea, simply reading input PWM signals with analogRead and generating a PWM output with analogWrite, worked fine while all the ATTiny85s were running off a 5V power supply from an Arduino.  However, now that I've switched to using a 4.5V battery pack for each ATTiny85, the PWM communication no longer works.

I expected the PWM outputs to change somewhat (given that HIGH is now limited to 4.5V), but what I am finding is that the output values (when read into an Arduino using analogRead OR pulseIn) now jump around hugely (e.g. pulseIn read out between 50 and 15000 from PWM output analogWrite(250)).  Even averaging over up to 1000 pulses doesn't do much to smooth out the value.

Am I missing something?


texts: Is there any correlation between eigen functions and eigen vectors of an LTI system?

texts:
Eigen functions are the origin for Laplace transform while eigen vectors is for state space representation.Can we relate the eigen concept in these two?

The complex exponential functions, are eigen functions of any LTI system. Also there are infinitely many such  linearly independent eigen functions.Then why do we say a second order LTI system has only 2 eigen values/vectors?"
Is it like eigen functions of LTI and eigen vectors of LTI should not be correlated?


texts:
First of, I apologize if this type of question has been answered before (I did have a search).
We are a small startup about to go through manufacturing stage of a product.
I would like to ensure that our design meets FCC & RCM compliance checks. I feel confident (from research) that the product will pass with MCU & Radio checks. We used reference designs that have been approved.
The only gray area is mains. In particular, whether this reference would trouble passing compliance checks:

(source: datasheetdir.com)
Is there someone would have pointers on product compliance with AC? (Regions; EU, AU, USA..)
Thanks


texts: Why are all the DC biasing sources assumed as ground in BJT transistor h-parameter equivalent model?

texts:
For example consider the first image on this schematic:

Source: http://www.zen22142.zen.co.uk/Theory/tr_model.htm.

Vcc is assumed as ground for ac equivalent circuit and thus RB1 and RB2 becomes parallel. And effective input impedance is calculated in this way. Then things like filter capacitor value are calculated using that resultant impedance.

How can this be, as the end of RB1 is not grounded but connected to Vcc? RB1 and RB2 are not really parallel here. Impedance felt by AC input current will be different than RB1 and RB2 parallel, isn't it?


texts: Power supply constant current region and voltage adjustment

texts:
I'm using some Meanwell power supplies and I'm a bit confused about the max output they can handle.
For an example I will mention one of the supplies to understand the logic.
Meanwell HLG-240H-48A
Well, that is an adjustable power supply, offering to adjust voltage and current through potentiometer.
Voltage adjustment range is 44,8 V to 51,2V
Current adjustment range is 2,5A to 5A
Now, it also rates a "constant current region" from 24V - 48V
Rated power is 240W
So here is my doubt. Voltage can be adjusted all the way up to 51,2V, but it rates 24 to 48V for constant current region.
For what I've read, that constant current region would be meaning the voltage the power can handle at full current? 5A being this case? in which max V would be 48V? is this correct?
If it's correct, does this mean I could drive more voltage as adjustment ranges are rated up to 51,2V when running less than full current and going in CV mode?
Going to the point of what I would like to do, given this specs, would it be possible to drive 4,6A at 50,5V? given that this would be in the 44,8V - 51,2V and 2,5A - 5A ranges it rates for adjustment? constant current region means the voltage ranges at full current (5A) when the driver goes in CC mode? (it is both CC and CV)


texts: How to supply electrical current to a motor-powered rotating shaft?

texts: I want to supply electrical current to a motor-powered rotating shaft. The current supplied is of the order of 400-600 amperes (AC or DC). In what ways can it be done? Shaft speed is around 1400 RPM. The voltage applied is 220 volt for AC. For DC, the voltage will be lower. I am on the conceptual stage, so I may be missing on few details. I have a hybrid power source that can supply DC as well as AC as output. So I require this setup so as to work on both as the need arises.


texts: If I plug in a USB wall adapter but don't have a device hooked up, will it use power?

texts: So let's say I have a phone and a USB Wall Adapter. If it is plugged up, but I don't have my phone hooked up, will it use power? And if so, will it be a noticeable amount when left plugged in for extensive periods?


texts: Trying to figure out fuse specs ("3/2 3AG 1A 250V")

texts:
I need to replace a fuse, and I'm trying to get my arms around the specs.  The fuse is stamped "3/2 3AG", then "1A 250V".

What does the 3/2 signify?  Is that related to how fast the fuse is?

Does "3AG" mean the same thing as "AGC"?  Or can I mostly ignore it and just look for fuses that are 1/4 by 1-1/4 inches?

The only other markings are the manufacturer's name (LittelFuse USA) and logo.

What do I need to look for here to replace this safely?


texts:
What are the potential risks when implementing a 12-states ?First of all I will need then 4 flip flops to draw my circuit giving a total of 16 states machines meaning that 4 states will be unused .
What are the problems I might envision in a system that can exist in 4 more states than are actually intended to be used ?


texts: Should I ground an aluminum front panel?

texts: I am building a power supply and it will be housed in a plastic case with a fan. I understand the wisdom of grounding a metal case, but in my case (no pun intended) I have an aluminum front panel. Should I ground it? My feeling is yes, but I want to know if this is correct as I haven't seen metal front panels grounded before.


texts: Voltage regulator and transistor get extremely hot

texts:
I have a 3.3V regulator (L78L33) buffered with a 2N2907A transistor. I am new enough that I might be doing something wrong in hooking up this circuit, so I included both the diagram (copied from the datasheet) and a picture of my breadboard.

When Vout is left floating, I get 3.301v out. But when I hook the output to a rail containing only an STM32F301 that is putting 2.2v out of the DAC. The power estimator says I should be using well below 5mA. However, the regulator voltage drops immediately to about 20mV and both the regulator and the transistor get extremely hot. I can barely touch them for an instant without actually burning myself. This only takes a second or two.

Do I have something wrong in my setup? I had this MCU hooked up to an LM317 before and everything was working fine.

I should also mention that I also tried this circuit with an MJE2955 transistor instead of the 2N2907A since I was sure that I couldn't hit the current ceiling on that. However, that transistor also got nuclear hot - hotter than the other parts, faster if that's possible.

EDIT
Thanks all. After the suggestions I tried without the transistor, same results, then tried adding resistance to see how much the circuit could handle. Turns out the regulator + 2N2907 work great up until around \$100\Omega\$, when the impedance starts getting too close to the input impedance and the voltage starts dropping (but of course I expected this, and the circuit doesn't overheat even down to \$20\Omega\$). So then I thought maybe something happened to the MCU so I hooked it back up like I had it this morning with just the LM317 (at 3.3v output) and sure enough, the LM317 gives the same behavior. So I'm not sure what could have happened in the meantime to cause something like this - the LM317 even causes the system to emit a very high pitched whine... not good.

For completeness I included photos of my scope output from the L78L33 and a picture of my MCU setup, if anyone has any idea why things like this happen (I really hate having to soldier a new MCU to a breakout board :-/). The MCU pins are given here on page 33.

ANOTHER UPDATE
This issue is resolved - there never was a problem. Something (ESD? Voltage jump from a discharging cap? No idea...) blasted my MCU. I have another MCU put in place now and it's working as expected. Thanks everyone for your help - I'm sorry to have wasted your time.

simulate this circuit – Schematic created using CircuitLab


texts:
Hi I have the following problem and data for an optical cavity.
Length \$ L=100 \mu m\$
Reflectivity \$R=0.33\$
Refraction index \$n=3.6\$
Inner losses \$p_i=20 cm^{-1}\$
Now I have to determine the photon lifetime \$ \tau_p\$.
My attempt was to consider the group velocity and then divide it by the length
$$\frac{c}{nL}=8.333 \times10^{11} s^{-1}$$
Taking the inverse of that I get:
$$1.2 ps$$
My question now is how to I relate this time with the actual photon lifetime, and what role do the reflectivity and inner losses play in my expression. Any help is appreciated.


texts:
Suppose I have the following ideal transformer circuit:

According to the textbook that I was reading (Fundamentals of. Electric Circuits by Charles K. Alexander), V1/V2 = 1/n and I1/I2 = n. Does it imply that, for ideal transformers, V1 and V2 are in phase with each other, whereas I1 and I2 are 180 degrees out of phase? If so, can anyone explain why this is the case?

Suppose the load of the secondary circuit is a resistor, then V2 and I2 are in-phase with each other. Since I1 is 90 degrees out of phase with V1 (which is in-phase with V2). Shouldn't this mean that I2 and I1 are 90-out of phase?

The article from http://www.allaboutcircuits.com/textbook/alternating-current/chpt-9/mutual-inductance-and-basic-operation/#02310.png mentioned about 90-degrees and 180-degrees out of phase. However, after reading several dozen times, I still do not understand the exact dynamics of a transformer. Can anyone please explain the basic working principle of a transformer?

Thank you very much.


texts: How can we design a varactor diode in ADS(Advanced Design System)?

texts: I need a varactor. But in ADS I couldn't find it. Some people told me to use sdd1p. If anyone has designed a varactor with sdd1p please help me.


texts: Making mesh sensor networks energy efficient

texts:
SCENARIO:

Say you have a mesh network of sensors that measure something like ambient temperature. The nodes are out of range of the base station; however, there happens to be one intermediate node close enough that can relay their messages to the base. These sensors sample the temperature say every 30min (however they're not in sync) so ideally to conserve energy we'd like to put them in a lower power state the rest of the time. The problem is, if that one intermediate node isn't on then the rest of the nodes messages will either be lost or they'll have to stay on until the intermediate node turns on to sample temperature at which point it could relay other sensors messages if they resend their message before it goes back to sleep.

QUESTION:

Is there some way a node could send out a beacon that excites a component, tuned to a certain frequency, on the other sensors (would this be a tuned antenna?) attached to a wake up interrupt line. This would enable an out of range sensor to wake up the intermediate sensor.


texts: Latching circuits - problem above input voltage

texts:
I'm playing with some latching circuits :

circuit 1 - more details here

circuit 2 - more details here

Latching with these circuits works, but above a given input voltage ( > 30V for circuit 1, > 16V for circuit 2), I can latch ON but I cannot latch OFF.

For circuit 1, I've used :
BC547B bipolar transistor, and FQP27P06 Mosfet P

For circuit 2, I've used :
FQP27P06 Mosfet P and FQP30N06L Mosfet N

For both circuit, load is a DC-DC converter connected to a 5V microcontroller (drawing ~20mA), all components are put on a breadboard. Voltage is provided by a labo power supply. 10K resistors have been replaced by 15K.

Above a given voltage, both circuits cannot latch off. Here is a scope capture when I try to power off circuit 2 :

blue plot : load voltage
yellow plot : P mosfet gate
green plot : N mosfet gate

here is a zoom for circuit 2 :

we can see P channel gate voltage slowly decreasing. When N channel closes, it decreased to Max Value - 1.15V

When voltage is reduced to 7V latching works :

How can we explain this behavior? How can I prevent it?


texts:
I am a little confused on how this W171Dip-7 relay works.  I know 2 is pos 5v and 6 is neg 5v.     Looks like the signal from 1/14 will go to 8 / 7 when closed.  But i cant tell if 13 is tied to 14 or just over lapping. Same with 9/8/7   or is 2 going straight to 13?

Any help would be great!