texts: How to calculate RMS current from the rated current? Are they the same in a stepper motor?

texts:
I want to use the TMC2130 driver with the stepper motor I show below. This driver has these main features amongst others:

Integrated power MOSFETs handle motor currents up to 1.2A RMS (QFN package) / 1.4A RMS (TQFP) or 2.5A short time peak current per
coil.
Range of Vref values:

default: 1V (±0.2);
MAX: 2.4V;
MIN: 0V;

Stepper motor current

I have these motor specifications, I know the rated current that the motor can use

I need to set the parameter X_CURRENT in the Marlin firmware that is the maximum that the stepper driver TMC2130 should give:

#if AXIS_IS_TMC(X)
    #define X_CURRENT        800           // (mA) RMS current. Multiply by 1.414 for peak current
    #define X_CURRENT_HOME   X_CURRENT     // (mA) RMS current for sensorless homing
    #define X_MICROSTEPS     16            // 0..256
    #define X_RSENSE         0.11
    #define X_CHAIN_POS      -1            // <=0 : Not chained. 1 : MCU MOSI connected. 2 : Next in chain, ...
#endif

The line comment says I need to multiply RMS current x 1.41 and set the value. But I am not sure if the rated current I saw in the motor specificatios is the same as this RMS current.

I have also read here that the current can be written in many forms in the motor specifications:

  Stepmotor-current ratings come in many forms such as amps/phase, amps RMS, average current, and even amps peak current.

  Labels on motors and motor data sheets typically list an amps/ phase rating. amps/phase specifies how much average current each winding or phase can handle without burning out the motor. It should be obvious that this value is the same as the amps RMS rating.

  To help with the calculation, assume the current for each phase is 1 A when both phases are powered, and 1.41 A when only one phase has power.

How to calculate RMS?

If I take into account all of the information above I could get the value in different ways:

X_CURRENT = RMS current * 1.41 = 1.3 * 1.41 = 1833 mA

// or

RMS current = Max current / 1.41 = 1.3 / 1.41 = 0.92 A
X_CURRENT = RMS current * 1.41 = 0.92 * 1.41 = 1300 mA

Which is the right one?

Get the X_CURRENT from the Vref

I have seen this video from Teaching Tech where the guy apply these formulas:

RMS current = Max current / sqrt(2)
Vref = (RMS current * 2.25) / 1.77
Using 90% Vref is safer

For some reason, the guy also says that in his case the Vref concide with the value that he should write in the X_CURRENT parameter

Vref = 0.76 V  =>  0.76 A = 760 mA

So taking into account this, I would get another different value:

RMS current = 1.3 A
Vref = (RMS current * 2.25) / 1.77 = 1.65 V
90% Vref = 1.49 V  =>  1.49 A = 1490 mA

Although I did not find the formulae for the Vref in the TMC2130 Datasheet

Doubts

Is the guy of Teaching Tech assuming that the resistance is 0 to convert the V to A directly?
Are some of these parameters the same thing?: Rated current =? RMS current,  Max current = Peak current. How to calculate the RMS current if they are not the same?
What I should write in the X_CURRENT parameter?
What Vref should I use?

Note: I am going to plug the stepper driver to a Ramps 1.6+ board with 12V DC if that changes something.


texts:
I want to implement a driver circuit for a (sensored) motor that I am purchasing which has the characteristics (on the shopping website):

Max Amps: 16
Max Power: 350W
ESC: 35A
KV: 1900

The name/title of the motor contains the word: "17.5T"

What MOSFETs should I purchase? I see name/titles such as: "30V 60A", "12A 500V", "100V 5A", etc.

My current guess is to choose one >= 16A, however the ESC spec says 35A. I have even lesser confidence regaring the "V" of the MOSFET. The spec says max power: 350W, and I feel that simply dividing 350W/16A = ~22V might be too low. On the other hand I know that the power is dissipated over multiple MOSFETs (3 or 6?) in which case 22V might be overkill.

I did skim through various tutorials I found but they aren't in the context of the commercial specs of motors.


texts:
I've gone through the complete datasheet, searched SE and on google, but I cant seem to find this information:
Whats the output Voltage of QA..QH just after power-up when G (Output enable) is pulled low, but no data have been clocked into the shift register?


texts: PCB board to board connector with thin footprint

texts:
I am trying to design a small PCB that goes into a bigger PCB.
My small PCB is mounting a very sensitive fragile sensor on the top surface that has to be wire bonded to the PCB, so I am trying to design a smaller PCB that can be surface mounted to the bigger PCB.
The smaller PCB will mount the sensor on top and using vias all the connections will be taken to the bottom plane of the PCB.
I am looking for some kind of a footprint that I can use for interconnecting the two PCB boards. I am looking for a very thin footprint and very low noise.
Any ideas that can help are appreciated.


texts: Is there a maximum switching frequency for solar cells ?

texts:
I'm wondering what the frequency response of a solar cell is.
Does a solar cell behave like a low pass filter e.g if i switch a load at 1 MHz, 10 MHz, 100 MHz ? Does the output power decrease if the frequency is too high ?

I'm asking because there exists a Maximum Power Point Tracking Method which is called "Pertub and Observe" . I'm wondering how fast you can change the load and measure the voltage at the load (e.g with a high speed adc) and still get accurate readings.

Will i have problems regarding the frequency response of a solar cell if I change the load 1 Million Times(e.g with a appropriate Transistor) and read the result with a high speed ADC, let's say with 1 Mega Samples per Second.


texts: Is it possible to use the status output of a GENIE 08 microcontroller as a digital output as well?

texts:
I have a GENIE 08 microcontroller, and am running low on available pins to use. Currently I am using pin 7 solely for status output, which is connected to the download socket. It can also be used for a digital output, so  would it be possible to connect an LED to it while the download socket is still in place? When I come to upload new code would it be an issue that the LED is drawing current from the pin?

Any help would be greatly appriciated.


texts:
I'm new to electronics (outside of twiddling with Arduino and a basic college course - I'm more of a software guy) and I'm attempting to build a custom, extremely low-powered, extremely thin, laptop.

The ideal is a keyboard, a microcontroller or some chip running command-line Linux distribution (potentially uClinux) and an LCD display. It could potentially run on double A batteries for the time being. It would also need wifi access.

My current biggest question is what kind of microcontroller (or other device) I should look for as the brain of the device. I've considered just sticking in a Raspberry Pi, but that's actually much larger than I would like, so I'm willing to attempt a custom-soldered solution. Are there sufficient ones which already have Linux installed? Are there some which have enough input pins / proper inputs for a keyboard / LCD display?

I'm also willing to write a driver or two for the keyboard, LCD, etc. as necessary, FYI.


texts:
As I understand a buffer gate is the opposite of a NOT gate and does not change the input:

However I sometimes see buffer gate ICs used in circuits and to an inexperienced eye they seem to do nothing at all. For example recently I've seen a non-inverting buffer gate used at the output of an emitter follower, roughly something like this:

So when would one require to use a buffer IC in their circuit? What could be the purpose of the gate in the aforementioned schematic?


texts: I have a 10kW, 72 V golden motor motor and motor controller. When regeneration occurs, the battery terminal voltage increases to more than 72 V. Is there any way to capture this energy to a separate capacitor bank?


texts: Is it dangerous not to connect ground to a 12v power supply

texts: Alright, so I realize that this probably is a very foolish question but I'm new to electronics and how they work. Basically I have a 12v regulated power supply that I use for a car audio amplifier in my home and I only have it hooked up with a cord that has a Line and a Neutral, no ground. Could this be dangerous or cause any other issues? It's been working fine so far and I don't get a shock when i touch the case of the power supply.


texts:
I've been looking for a solution to provide solid-state overcurrent protection for automotive loads such as small water pumps (0.6A continuous), fans (3.5A continuous) and fuel pump (8A continuous).

Initially I looked into integrated high side switches such as the following: https://www.mouser.com/datasheet/2/389/vnd7004ay-973698.pdf

Recently, I found something from Texas Instruments which they call an E-Fuse. It performs essentially the same functionality as the high side MOSFET switch linked above, but integrates a lot more features like inrush current blanking, programmable current limitation with auto retry, high accuracy current sense at <15A etc. It does this all while having a lower Rds than the automotive switch.

Link: http://www.ti.com/lit/ds/symlink/tps25982.pdf

I have not been able to find an "automotive" high side switch with similar functionality (especially accurate current sense combined with low Rds). My question is, would there be an issue with using the TI part, which is intended for servers and computing applications, in a one-off automotive application?


texts: I am having a doubt in why are the transmission lines are sent at a very high voltages? I also  went through quite a few sources which said that it is to decrease the losses in the lines. BUt I am not quite satisfied with the solutions, can somebody please let me the answer for this in detail. Your help is much appreciated.


texts: Is it possible to flash an Atmel SAM E70 through a CAN bus without a JTAG?

texts: My circuit board needs to have both a MCU and a CAN connection so it would be nice to be able to cut down on some of the components.


texts:
I have read this article about protecting input pins.

One thing is still unclear to me — why is the protection needed at all with such a high resistance on the input pin inside of the microcontroller? The current would be really small and the heat dissipation will be little as well.


texts:
In the following image:

Why can't current flow across the following wire?
It's a simple question, but I've kind off always wondered.

Thanks!


texts: Soldering guidelines for freezer applications?

texts:
I'd like to do a home project where I take temperatures inside of my freezer and inside liquids.  Liquid-compatibility aside, I'm mostly curious about whether or not anyone can recommend some best practices for the board design.  I haven't found any resources online that explain what will happen in applications that are intended for 0C temperatures.  I assume the solder joints will contract due to the cold, but does this mean that a surface-mount design will inherently fail?  Therefore, should I limit my temperature (and possibly microcontroller) selections to through-hole parts?  Is there a better solder formulation to go with, i.e. lead-free or not?  Should the pads or through-holes be larger than what's normally found on the IC data sheets in the footprint section?

Any advice or insight would be really appreciated.  I'm more than willing to experiment and learn from my mistakes, but if I could get a better head start, that would be nice.  :)


texts: Half wave rectifier input voltage and current waveforms

texts:
ok so i am having a problem in power electronics in my book there is a circuit for a single phase half wave rectifier as shown below and also its related waveforms

and then its performance parameters are discussed and then they show some waveforms which i have also shown here along with the text related to these waveforms

so my questions are:
Q1)why the current waveform is a square wave?
Q2)how can the current (is) can go negative in the second picture i included in my question where as the same current (is) waveform in the first picture(third waveform from the top) is only positive and is a pulse sinusoid instead of a square wave
Q3) referring to the second picture why there is a phase difference between the fundamental component of current and the instantaneous current


texts: What is the name/type of the connector on the 28byj-48 stepper motors?

texts:
These are very useful inexpensive motors however I haven't been able to identify what type of plug is on them to make custom driver boards. Here is a picture:

Thanks
Andy


texts: Use of connecting capacitor in I to V converter

texts:
This is the suggested circuit for Trans impedance amplifier for 7721.

I will be using this as current to voltage converter. I wish to know why the capacitor Cf is connected in parallel with the feedback resistor though the textbooks give circuit diagram of I-V converter with feedback resistor only? And why generally we put capacitors with the power supplies?


texts: Is it safe to use an "18v ~ 20v" power brick/adapter for a device that originally had an 18v adapter?

texts:
We have a device that uses an 18v adapter/power brick, unfortunately the adapter broke. As a replacement, we are considering an adapter that has a "18v ~ 20v" rating printed on its back. There is no switch whatsoever on the power brick to adjust the output voltage. The person selling the item says that the voltage will basically adjust itself based on the device being powered.
Question: Can I use a power brick labeled "18v ~ 20v" for a device that originally had an 18v adapter? Or will this be harmful to my device? Could the self adjusting voltage statement be true?
I understand that for voltages, it is necessary to look for an exact match, while for the amps, we just need to match the minimum. It's just that it's the first time I saw a "~" in the voltage indicator of a power brick. I'm really hoping to be able to use this, since other available options are 19v.
EDIT:
About the device being powered:
This is the machine meant to be powered by the adapter: https://cricut.com/en_us/machines/cricut-explore-air-2.html
A video of it in action: https://www.youtube.com/watch?v=LdkyoMDQ5Pw
As can be deduced, it has several stepper motors and several circuit boards.
Image of what the main board with the DC input looks like
Another image of the main board
A photo of one of the motors
A troubleshooting video showing the DC board among other parts: https://youtu.be/aNqq-6n_vqs?t=836
A teardown video: https://www.youtube.com/watch?v=ergcvPaaVwk


texts: Does it exist: Latching Relay with Manual Switch

texts:
I'm looking for a latching relay (so I can control its state remotely) with a manual switch (preferably with a rocker style switch, so I can control its state locally).

Do these exist as I'm struggling to find one?

Thanks


texts: Precision amplitude 600kHz square wave generator

texts:
I'm looking for a circuit that creates a precision amplitude square wave of 600kHz (50% duty cycle).  The amplitude of the square wave needs to be 3Vpk-pk +/-10mV, but can be DC offset.  The output of the circuit must be able to supply 100mA.  The whole circuit is powered from a single sided 5-6VDC supply.  The circuit is for a small sensor and would like to have consistency between them (i.e. 3Vpk-pk +/-10mV amplitude on each board).
My initial idea was

generate a 3V precision power rail.
Use a 555 timer circuit to generate the base square wave at 600kHz
Feed the raw 600kHz square wave into a unity buffer rail-to-rail op amp circuit which has power rails of 0V and the precision 3V rail.
The output should be a buffered square wave signal with 3Vpk-pk amplitude.
My concern is that the rail-to-rail op amps still have some voltage drop between the supply rail voltage and the output voltage when it is at the rails and it could vary between boards/chips (I need consistency between multiple boards).

My second thought was to use a voltage limiting circuit (with 5V supply) and set the voltage limit levels to 1V (from precision reference) and 4V (from precision reference).  Feed the 5Vpk-pk 600kHz square wave oscillator signal from the 555 timer into the voltage limiting circuit to get the 3Vpk-pk output at 600kHz.
Does anyone have any other thoughts or issue with these approaches, or perhaps better ideas for circuits to consider.


texts: Is a subwoofers RMS/peak wattage rating subject to the enclosure type?

texts:
The RMS and peak wattage rating of a subwoofer (or any speaker) show afaik how much power it can safely handle without damaging it. But is this true for both sealed and ported enclosures? (assuming the boxes are build to the recommended dimensions)

There are several ways to damage a subwoofer, but the one I'm concerned about is exceeding the maximum excursion. When you have a subwoofer in a sealed box, the air inside the box acts as a spring, resisting movement from the speaker cone. With a ported box, this effect is much less, resulting in a larger excursion for the same amount of work.

I have a Hifonics mxz12d2 http://www.audiodesign.de/downloads/datasheets/Hifonics/MXZ12D2.pdf with an amp more then capable to deliver 1000 watts RMS. My plan is to use a sine wave, attach an (true rms) amp meter around one speaker wire and a volt meter over the two amp connection points. Then I  increase the amp gain until I see the speaker uses close to 1000 Watts rms. But is this a safe way of setting the gain for this subwoofer if it's in a ported box?


texts: Need help in using a solid-state relay with Arduino

texts:
Disclaimer: I'm a newbie in electronics, so please pardon my lack of knowledge.

I'm trying to automate my water tank filling system with an Arduino Uno. The part I need help with is picking the correct solid-state relay for the task.

The pump is a 3 HP submersible pump. As for the schematic, an MCB is connected to a box which has analog volt and amp meters and a switch. The process to turn on the pump is as follows:

Turn on the MCB.
Turn on the switch on the box.

My intention is to insert a solid-state relay between the MCB and the box, which would be controlled by the Arduino to turn the connection on and off. Now, could someone help me pick the relay with the appropriate specifications?

I'm aware of the following specifications of the pump:
Full load current: 6.3 amps,
load voltage: 200 volts.

P.S. My residential voltage is 230 volts at 50 Hz.


texts:
I need to check the low power consumption of a microcontroller in the range of picoamperes. I only have a multimeter capable of measuring milliamperes and as such it shows 0.

Is there an easy and precise way to measure picoamperes?


texts: Analysing performance of Sub-1 GHz 433 Band

texts:
I am required to analyse the performance of my 6LOWpan network working on Sub-1 400MHz band for criteria such as throughput, range, packet delay, PER etc.

My system uses CC1125 (Sub-1 modulator) + CC1190 amplifier by TI.

I intend to produce graphical content from analysis results, however I do not know tools I can sue to analyze this network.

I do not mind buying support equipment such as spectrum analyzer to look into range and received power etc. But I cannot afford one that are beyond 300$.

My network consists about 100 Sub-1 nodes working in the 400 MHz band. Application is deployed in a rural/ foresty area.

I would appreciate your help a lot.


texts: How much voltage/amperage can a NPN transistor take?

texts: I got the MakerShed Ultimate Microcontroller Pack and it came with a "Transistor NPN". I want to use it (or probably buy something else) as an electronically controlled switch so that on arduino I set a digital output to "HIGH" and it allows 12 volts though or set the pin to "LOW" so that it turns the 12 volts off. This is much harder to explain than it was in my head. Anyway, is that possible? Or do I need a bigger, better, transistor or some other special purpose circuit for this?


texts: Looking for confirmation of a BLDC project

texts:
I’d like to use a BLDC motor & control on a drill press.  I’ll explain what I think I can do…  and you can tell me where I’ve gone wrong.

It appears 1/2 HP is quite enough for most drill press operations.  Thus a 400 watt motor & controller should do the job. The DC power supply would need to supply the motor’s voltage (12,24,48, etc) at, minimum - 400 watts. I'm also thinking a 3-phase motor with Hall should be easy to setup and run

The desired speed range is 100 to 3000 rpm.

If I used a 400 watt BLDC with a max speed of 12,000 rpm, and used 4:1 timing pulleys to get the 3000 top end - would I get the expected torque increase?  I’m mostly concerned about the low-speed torque and I understand BLDC’s are good at sustaining this.

It all looks to simple - I just get the the 400w motor, power supply, controller and pulleys, and I’d be good to go - basically.  Essentially I’m tinker-toying a system together... So now I need a reality check to see what is REALLY needed!


texts: Working with a cathode-based LED seven-segment display

texts:
I have recently purchased an Arduino micro and am using it to learn more about electronics and embedded systems. I have a numeric LED display HDSP-H101 with the following circuit diagram, and I am trying to figure out how I can use the digital I/O pins on the Arduino to activate different segments of the display.

simulate this circuit – Schematic created using CircuitLab

If the diodes were oriented the opposite way, it would be a simple matter of connecting the output pins (and a resistive load) to each of the pins and the cathode to ground and then when the pin was set to HIGH a forward-bias voltage would be applied across the LED and it would light up. However, in this case a reverse-bias voltage would be applied and therefore I am unsure of the best way to selectively light each segment?


texts: Using IP connected arduinos to trigger cameras

texts:
I am looking to build a 5 DSLR camera triggering system using arduinos over our network.

Currently we have physical trigger cables so that we can trigger each DLSR camera without delay. Even though all the cameras are on the network and running Nikon capture pro, there is a small delay from hitting the "shoot button" in the software, and the camera actually capturing the image. The physical trigger is instantaneous.

Basically I'd like to eliminate the need to run dedicated triggering cable to the cameras, as all I want to run is power, and a couple of ethernet to each camera. I want to have the ability to trigger, and intelligently change camera timings through an arduino or similar ip connectible device, sometimes we may have a single trigger, but slight delays to each shot, like, take one immediately, then two slightly later....

The triggering needs to be done physically, but may be done via sensor, so having an arduino with each camera will give us lots of options.

In the control room we want to be able to trigger any of the cameras with physical buttons, much like you'd see in industrial applications, something that can really take a beating. So from these buttons I would expect to run them all into an arduino, and then that arduino communicates with the others to trigger them.

Signal flow is like this

Button in control room > arduino > internet > arduino > Nikon external trigger cable > Nikon Camera.

Some cameras will trigger at the same time, others with delays.

So my key question is: What is the latency of one ip connected arduino, triggering another?


texts: Why use a tantalum instead of a ceramic capacitor?

texts:
On page 72 of the AD7124-4 datasheet it says:

Decouple AVDD with a 1 μF tantalum capacitor in parallel with a 0.1 μF capacitor to AVSS on each pin.

Why would this capacitor be specified to be a tantalum?
At this low capacitance a ceramic MLCC is cheaper and has superior ESL and ESR.
Is there a reason for this?


texts: How do I know if it's safe to connect the common grounds of the input signals of two garage door openers?

texts:
I have two Hormann ProMatic garage door openers, identical ones, both have a pair of built-in input connectors where anyone can use an external switch to trigger the garage doors to open/close.
My question is, how can I know whether it's safe for me to join the two minuses into one joint in order to use a wall switch like this to operate the two door openers independently?

According to the manual it uses a 24V DC for the signal, however, it's unclear to me whether this connectors are "potential free", there is no clue whatsoever in the user's manual.


texts:
I am finalizing my design which connects a USB Controller (FT601) with the FPGA (MachXO2). There is last thing I am not particularly happy about and I would like your feedback on that.

In the following image, the two vias connect 2 supply sources (3.3V and 1.0V respectively) to the IC while the surrounding traces are LVCMOS33 data lines.

The PCB is 4 layer stackup, second plane is ground plane. The data traces are 8 mil wide with an impedance of approximately 54Ω. The lines are bidirectional, and both ICs output at 50Ω impedance, so they are matches. Rise/Fall time is 0.8 to 1.2 ns.

The power lines are 7 mil wide. I made them 1 mil shorter to gain a little bit more space between them and the data lines. They are properly decoupled, since I have put the necessary caps exactly on the opposite side. Their length is around 200 mil.

Question: Is there a strong possibility that the power supply will affect the data lines or vice versa, resulting in an instability of the IC?

Simulation in Altium with a proper IBIS file reveals a small fluctuation of 30-40 mV of the power lines affected by the data lines.

In case you are wondering I did not place the supply internally of the footprint because is a QFN with a large pad connected to ground so I cannot risk a short-circuit. Thanks in advance.


texts: Does a microcontroller fetch instructions in blocks?

texts:
It seems that the flash memory on most microcontrollers that stores the assembly code is NAND flash, which is only accessible on a per-block basis. Does the CPU has to fetch an entire block to execute the code, or am I mistaken and is it made of NOR flash that is byte accessible?

The datasheet of the ATmega 186 says the following:

  This is the basic pipelining concept to obtain up to 1 MIPS
  per MHz with the corresponding unique results for functions per cost, functions per clocks, and functions per
  power-unit.

The datasheet is not very clear what the technology is behind this "flash", but is seems to be different from the EEPROM that is used for the data, that has 10 times as many write cycles.

Edit: the possible suggested duplicate question and answers are about pipelining, not about the storage technology.


texts: What components do I need to add to the power circuit for this ESP8266 project?

texts:
I'm planning to make some controllers for each of the electrical heaters in my house. The heaters use a pilot wire to control their mode of operation:

I'm following this project to control the pilot wire: https://web.archive.org/web/20180607082257/http://www.homautomation.org/2015/11/28/pilot-wire-for-electrical-heaters/

I decided to use a Wemos D1 Mini instead of an Arduino because of size and ease of communicating. Here's my circuit diagram from Fritzing:

Because the ESP8266 has 3.3V DIO instead of 5V I changed the triacs to MOC3042-M and the resistors to 330 ohms, based on my understanding of their datasheet: https://www.onsemi.com/pub/Collateral/MOC3043M-D.pdf. This isn't the main reason I'm posting, but have I correctly understood this?

My heaters don't have convenient power sockets next to them to be able to power these controllers from a 5V micro-USB charger so I would like to add a 230AC to 3.3VDC converter to the controller which will receive AC power in parallel to the heater. For your info, the heaters only have live and neutral connections, no earth connection. For the AC/DC converter I intend to use a Mean Well IRM-01-3.3 (https://www.meanwell.com/Upload/PDF/IRM-01/IRM-01-SPEC.PDF), Hi-Link HLK-PM03 (http://www.hlktech.net/product_detail.php?ProId=59) or similar - does anyone have any recommendations?

I've read that the ESP8266 can be happily powered directly on the 3.3V pin but I don't know if additional components are needed on the AC or DC side to compensate for noise, surge, etc. I've added a 1A fuse on the live line but I don't know if this is too large or too small. I've read that a varistor should be added to cope with inrush current but I've no idea about size. I read that the Hi-Link converter (actually the 5V version) is very noisy and found a circuit diagram with lots of capacitors and inductors on the AC side to bring the noise down to tolerable levels (https://skippy.org.uk/revisiting-the-hlk-pm01/) is this a suitable/necessary filter for any AC/DC converter I could use?

On the DC side, I've assumed I don't need anything, is this okay?

I will install all the components in a suitable box, probably IP66. These controllers need to be reliable (run for at least two weeks without intervention) and safe (I'm primarily concerned about fire but I also want to preserve what I've made). If anyone spots something I can improve in this regard please tell me.

You can see I've also added a temperature and humidity sensor but that's not relevant to the topic AFAIK. (and FYI it will be mounted outside the box, not inside).

Thanks in advance for your help :)

PS - to give you the full picture, I plan to run Mozilla's webthing-arduino (https://github.com/mozilla-iot/webthing-arduino) on the ESP8266 and have Raspberry Pi running Mozilla's Things Gateway so I can control the heating when I'm out of the house, e.g. turn it on in advance of me returning.


texts: How can I calculate the inductance of the primary of a transformer given a specific load on the secondary?

texts: Inductance in the primary of a transformer decreases as the load on the secondary increases. How can I calculate the inductance of the primary coil? What if it was step up or one to one ratio?


texts:
Update: I have read more about this and what I can conclude is that the phy IC is not initialized correctly. Still no able to figure out how to initialize phy device. Please go through the code and strap configurations and let me know where the error is.

I am using the K60DN512 device with 8720A PHY IC. I have written a simple program to communicate with the PHY IC. I have checked it on logic analyser and I am not getting any response from the PHY device. What can be possible causes?

Configuration of PHY device straps.

PHYAD[0]: Pulled low.

MODE[2:0] : 011 100Base-TX Full Duplex. Auto-negotiation disabled. CRS is active during Receive.

MDIO : Pulled high.

MDC: 1 Mhz.

I am using the processor expert generated code. So in that case there shouldn't be any error. What can be the possible reason for communication failure? The value is either 0 or 0xFFFF.

main(){
    MAChandler = mac_Init(NULL);
    Bit1_Init(NULL);

    uint16_t id = 0;
    uint16_t value = 0;
    uint16_t timeout = 0;
    uint16_t count = 0;
    uint8_t sfr = 0;

    const uint8_t netifLINK_DELAY = 3;
    do {
        mii_read(id, PHY_PHYIDR1, &value);
        count++;
    } while (value == 0xffff);

    do {
        value = 0xffff;
        mii_read(id, sfr, &value);
        if (value != 0xffff)
            sfr++;
        count++;
    } while (sfr <= 0x1F);

    uint16 config;
    do {
        config = 0x2200;
        mii_write(id, PHY_BMCR, config);
        uint16_t i, j;
        for (i = 0; i < 0xFF; i++)
            for (j = 0; j < 0xFFFF; j++)
                ;
        mii_read(id, PHY_BMCR, &value);
        count++;
    } while (value != config);
}

int mii_write(int phy_addr, int reg_addr, uint16_t data) {
    int timeout;

    /* Clear the MII interrupt bit */ENET_EIR /*(ch)*/= ENET_EIR_MII_MASK;
    /* Initiatate the MII Management write */ENET_MMFR /*(ch)*/=
            0 | ENET_MMFR_ST(0x01) | ENET_MMFR_OP(0x01) | ENET_MMFR_PA(phy_addr)
                    | ENET_MMFR_RA(reg_addr) | ENET_MMFR_TA(0x02)
                    | ENET_MMFR_DATA(data);

    /* Poll for the MII interrupt (interrupt should be masked) */
    for (timeout = 0; timeout < MII_TIMEOUT; timeout++) {
        if (ENET_EIR /*(ch)*/& ENET_EIR_MII_MASK)
            break;
    }

    if (timeout == MII_TIMEOUT)
        return 1;
    /* Clear the MII interrupt bit */ENET_EIR /*(ch)*/= ENET_EIR_MII_MASK;
    return 0;
}

/********************************************************************/
/*!
 * \brief   Read a value from a PHY's MII register.
 * \param   phy_addr    Address of the PHY
 * \param   reg_addr    Address of the register in the PHY
 * \param   data        Pointer to location were read data will be stored
 * \return  0 if write is successful; 1 if write times out
 *
 * mii_read() polls for the FEC's MII interrupt event (which should
 * be masked from the interrupt handler) and clears it. If after a
 * suitable amount of time the event isn't triggered, a non-zero value
 * is returned.
 */

int mii_read(int phy_addr, int reg_addr, uint16_t *data) {
    int timeout;
    /* Clear the MII interrupt bit */ENET_EIR /*(ch)*/= ENET_EIR_MII_MASK;
    Bit1_SetVal(NULL); // Indication that the MDIO transfer is about to begin.
    /* Initiatate the MII Management read */ENET_MMFR /*(ch)*/= 0
            | ENET_MMFR_ST(0x01) | ENET_MMFR_OP(0x2) | ENET_MMFR_PA(phy_addr)
            | ENET_MMFR_RA(reg_addr) | ENET_MMFR_TA(0x02);

    /* Poll for the MII interrupt (interrupt should be masked) */
    for (timeout = 0; timeout < MII_TIMEOUT; timeout++) {
        if (ENET_EIR /*(ch)*/& ENET_EIR_MII_MASK){
            Bit1_ClrVal(NULL); // Indication that the MDIO transfer is complete.
            break;
        }
    }
    if (timeout == MII_TIMEOUT)
        return 1;

    /* Clear the MII interrupt bit */ENET_EIR /*(ch)*/= ENET_EIR_MII_MASK;
    uint16_t test = ENET_MMFR /*(ch)*/& 0x0000FFFF;
    *data = ENET_MMFR /*(ch)*/& 0x0000FFFF;
    return 0;
}


texts: Low power dual edge detector using too much power

texts:
I am creating a hobby circuit which transfer signal to edge triggered pulses. I created circuit like this:

But I have issue with power consumption. XOR gate need power which take 8mA which is really lot because it is powered from battery.

Does anybody know how to create circuit which does not require so much power? For my circuit is necessary create pulse on edge in meantime is turned off.


texts:
Novice question, sorry if it has been asked. I couldn't find it.

I'm currently working on a project and I'll be powering 2 LED strips connected together. They each require 12V (24W, 2 amps).

I need wires to run about 15 feet. In my research I'm finding AWG charts are all pretty conflicting. Some are trying to tell me 20 AWG would do the job, others are saying I should use 12 AWG, 14 AWG... etc...

As someone who sincerely doesn't want to start a fire, is there some trust-worthy source for this information?

Thanks in advance.


texts: soldering 3M MDR (Mini Delta Ribbon) connectors?

texts:
3M MDR connectors (see here for details) seem to be a pretty common interconnect system. Has anyone tried making a few cables and boxes with these without buying the 3M tooling kit? Since the kit is $2000 (from e.g. Digikey) it would be nice not to have to buy this if I'm only hooking up a few things.

Specifically, I'm looking at their 50-pin connector with this cable. Is it feasible to connect these with nothing more than a decent soldering iron?


texts: How can I calculate the current flowing through this diode?

texts:
I know this is a basic question, but I'm just not good at solving diodes in parallel circuits.
I tried applying the current divider rule to get the current flowing through the diode, such that:


texts: Error (209015): Can't configure device. Expected JTAG ID code 0x020B10DD for device 1, but found JTAG ID code 0x000210DD

texts:
I bought from ebay Altera Cyclone II EP2C5T144 development board. It came with USB Blaster. I'm using Quartus II 13.0sp1.
FPGA is programmed with default settings as it should be (flashing onboard LEDs).

It seems like there is a byte missing in the ID. Does someone know what that is and how to fix it? Also, where is this JTAG ID from: FPGA or programmer?

I don't know if it's the same problem but when I try to Auto Detect. I get

Error (209053): Unexpected error in JTAG server -- error code 2

Looks like it was a typical power problem. When I connected external power to FPGA programming was successfully completed. But Auto Detect still returns the same error.


texts:
I have the problem that I need to locate the sim-card about 8 meters from the device in which it would normally be installed. As far as I am aware, the devices communicate with the sim card with a serial protocol.

Would it thus be possible to design a extension cable, i.e. with additional line driver on both ends if necessary?

Does anybody have a good (accessible) reference on the signalling and electrical standards of GSM cards?


texts: I've looked at a couple of posts on this topic, but I can't really get a feel to them. Does the LUT have an input where the logic address is given, or does the LUT read from the D Latch? If anyone has a picture that describes this, it would be very helpful, since in most pictures I found online, all the logic cell pictures had a LUT with no inputs, which confused me since there was no way for it to read logic. Thank you for your help!


texts: Does anyone know what the nitrogen gas on this telephone pole is for?

texts: I saw this out walking. The tank had a sticker saying it is nitrogen. I followed the brown hose up to the cylinder on the what looks like a power wire. I would think it is a non-air "bath" to prevent arcing. I don't know what the cylinder is. Seems like something someone would steal, but the tank was left there in the open secured with an easily cuttable steel chain. So it must be worth it to have it there.


texts:
I am fixing an old regulated load dummy that I use in my workspace. It was a mess and I want to modify its regulator side.

My question is: will the circuit showed in the image work properly? If you have any hints about possible upgrades, I would be grateful. I want to keep it simple as possible.

The regulation of load current is in range of 0-24 A.

I am aware, that this is not a modern design, but as I said I'm only fixing it and modified it a little bit. I need to keep these two NPNs there.

Also, there will be cooling fan control and temperature shutdown protection. Also fuse and protection diode. My question is only about the functional part.

Thank you.


texts: Necessary things in LPC1343 basic development board

texts:
I have finished my LPC1343 basic development board,just based on specs from datasheet and some referred from microbuilders.eu.  I'm unsure if the board design is good or not so I've attached my schematics.  Some things I'm concerned about are:

1.Power supply

2.D+ and D- from usb through 33 ohm resistor to chip and additional usb softconnect if necessary

3.Testing LED.

4.Separate switches for RESET and USB ftoggle.

5.12MHz crystal oscillator with 16 pF caps.

My question: Is the board design is good enough to work or will it go wrong? If something is wrong, what is wrong with it?

]3
[]4


texts: Transmitting Data over USB Port Intended for Flash Drive

texts:
I have a device that allows one to transfer program files for execution via a USB flash drive.

I'm interested in directly connecting this device to a PC, and writing drivers such that a given folder in my PC "looks like" the contents of an attached flash drive to my device. This way, I can execute programs without having to go through an unplug/ plug process.

Is this possible, or are there solutions to this problem already?

In general, given that my PC expects to see a USB data interface and the attached device expects to see flash memory, what happens when I connect the two?


texts: I have a power supply with 36V 1.8A, and I need to reduce this for my drill, which uses a 18V 1.2A battery. How can I lower the 36V from the power supply to the 18V that the drill accepts?


texts: Addition in verilog: simulation doesn't match synthesis

texts:
I come from very predominant background in VHDL and have recently been doing a lot more coding in SystemVerilog. I've noticed a couple of strange behaviours that I don't entirely understand.

Summary

In the following example, I am performing an addition of several signals. I know that this is particularly inefficient (and probably bad style), but I am using it to demonstrate the type of issue I've run into recently.

// Main add (inside synchronous process)
// all signals are 32b logic or reg (except for 64, which is a `define)
dma_ins.dest    <= sdram_addr + slice_address + slice_offset - 64;
                   0x3800 0000  0x0001 0000     0x0000 0050

When I run this add in simulation, I get the correct result. In synthesis, it's incorrect.

Simulation: 0x38010010
Synthesis:  0x38008008

The synthesis value is one shift to the right (0x8008 instead of 0x10010).

In order to determine the synthesis value, I am writing all four signals to debug registers. The DMA also ends up at the wrong address in the SDRAM in hardware.

In order to fix this issue, I did the following:

dma_ins.dest        <= sdram_addr;
dma_ins.dest[26:15] <= queue_prop_new[0].contig_head; // non-shifted versions of slice address
dma_ins.dest[14:4]  <= queue_prop_new[0].contig_hoffset - 4; // and slice offset

I'm probably missing something in regards to the SystemVerilog type definitions, but I'm not sure what. I've added some details below.

Detail

The signals being added together are defined as follows:

// SDRAM ADDR (synchronus process, 32b reg)
sdram_addr <= 32'h38000000

// SLICE ADDRESS (asynchronus combinitorial assign)
// slice address: 32b logic
// queue_prop_new[0].contig_head: 12b logic: value of 0x02
// 32768 is a `define that has been substituted.
assign slice_address = (queue_prop_new[0].contig_head <<($clog2(32768)-1));
// (slice_address = 0x02 << 15 = 0x10000)

// SLICE OFFSET
// slice_offset: 32b logic
// queue_prop_new[0].contig_hoffset:  11b logic: value of 0x05
// 16 is a substituted `define
assign slice_offset = (queue_prop_new[0].contig_hoffset<<($clog2(16)-1));
// (slice_offset = 0x05 << 4 = 0x50)


texts: What is voltage gain of a transistor amplifier and how is it affected by frequency?

texts:
I'm actually concerned about the frequency response of a bipolar transistor.

I searched online for an answer to this question but there was not a simple answer for a high school student to understand. So I would like a simple answer.


texts: How to get maximum damping factor from this system?

texts:
I have a system with a transfer function as
$$
\frac{(s+3)(s+10)}{s(s^2+4s+5)(s+10)+K_Ts(s+10)(s+3)+600(s+3)}
$$
Which has the characteristic equation:
$$
1+K_T\frac{s(s+3)(s+10)}{s(s^2+4s+5)(s+10)+600(s+3)}
$$
And I know that the poles and zeros of this are:
$$
z_1=0 , z_2=-3,z_3=-10 , p_1=-3.1786 , p_2=-13.2478 , p_{3 , 4}=1.213_-^+6.42j
$$
Here is the root locus that comes from said function:

I have been asked to find the maximum damping factor of the complex roots - I am afraid I don't know what this means or how to go about it - I have had a search on the web but am more confused as to how to solve this. Any help / guidance would be greatly appreciated.
Forgive me if this is more of a Mathematics question - it's just part of an Electronic Engineering degree hence asking here.


texts: How should chips with pins on bottom be drawn?

texts:
When you are drawing a schematic for an IC, and there are pins in the bottom center (in my case I am drawing for the BGM13S32F512GA-V2R), how should they be drawn?

I have looked into some beginner tutorials, but everything I've found uses ICs with pins along the side only. I am using OrCAD Capture.

I have also heard a debate between whether you draw the schematic based on the datasheet, or you draw it based on how the pins are used (GND on bottom, VCC on top, everything else on sides... or however).


texts:
I actually have an  Arduino Due board, with everything working on it, using the ADC and the DAC.
For my input for the ADC I need to have a signal 0-2.2V but my signal is actually between -5V to +5V.
My idea is first to reduce it to be between -0.5V and +0.5 V, than add on offset of +0.5V to have it 0 - 1 V and then add a gain.

The first step is to reduce it but i don't know how to reduce a signal....

If someone has any idea everything can help me


texts:
I don't understand what the following paragraph is trying to tell:

I know how PMMC works. But why does the text say PMMC cannot be used to measure AC? It says action of iron varies with frequency. Which iron? Why is error introduced? I'm completely lost. I would be glad if someone could explain what mean here in a plain way.

And what are these resistors for?

Here is another text:

Why does the text say measurement of ac is not possible with PMMC?

Edit:

I think the reason of rectifying AC to pulsating DC is given by the above paragraph:

  Due to the inertia of the movable coil, the meter indicates a steady
  deflection

(?)


texts:
I have 100Mhz system clock and I would like to have a 200Hz Enable signal for enabling the state machine. I need a clock divider for this process and thought about this :

clkdiv : process (clk)
begin
    if (clk'event and clk = '1') then     -- rising clock edge
        -- default value
        EN <= '0';

        clkcntr <= clkcntr - 1;
        if clkcntr = 0 then
            clkcntr   <= X"7A120"; -- 500000 decimal value
            EN <= '1';
        end if;

    end if;
end process clkdiv;

I have seen other implementations on the internet they always start first dividing with 100Mhz to 2. In my case I should decrement 250000 time to match this, is this because clk is 1-0-1-0-1-0-1-0, since we are interested on the rising edge we should also consider the falling edge times? I would be glad if someone can demonstate a proper clock divider.
Then when I am done I would like to go into the state machine with an if condition

if EN = '1' then

 go into the state machine

end if;

In the end I would like the duration of my output signal from the FSM be 200Hz long, would this be correct? Are there other ways for implementing this?


texts: How to create a "multi bit pin" for a schematic symbol in Eagle PCB?

texts:
Here is the part for which I am making an Eagle part.

Now it is completely possible that I draw the schematic symbol looking like thie exactly. It is how I have seen things done often. However, I am curious to find out that is it possible that I have a single pin in the schematic symbol like R[0..7] which covers all R0,R1,R2... upto R7? And then this single multi bit pin in the schematic symbol shall map tp 8 pins in the package. Is it possible to do this in Eagle?


texts: Raspberry Pi 3 SPI speed and ADC sampling rate

texts:
I have been working on a project where I am collecting data from an AD8232 ECG sensor in my Raspberry Pi 3.

The raw signal is so distorted and I am guessing I may have an issue with SPI speed and sampling frequency set up. While testing, I actually checked SPI speed from 2 kHz to 20 MHz. The sampling rate is 200 Hz. I am not getting how to fix this.

Anyone can suggest what may be a possible issue and fixes? FYI, I need a sampling rate of 200 Hz. I am using MCP3008 with my Pi as an ADC converter as the sensor is an analog sensor.


texts: Why old PMOS/NMOS logic needed multiple voltages?

texts:
Why does old PMOS/NMOS logic needed multiple voltages like  +5, -5, and +12 volts?
For example, old Intel 8080 processors, old DRAMs, e.t.c...

I'm interested in the causes on the physical/layout level.  What was the purpose of these additional voltages?

Yes, this question is about stuff which was used 35 years ago.


texts: Using logic level fet in switching application?

texts:
I want to create dc boost convertro based on microcontroller.
If I only use low-side switch, can I just use logiclevel NFET instead of using gate-driver?
I've planed to replace ir2110 + IRF540 with IRLZ44NPBF with 5V 64kHz 8-bit PWM.


texts: Use of virtual ground to split ground loops?

texts:
So I have a "broadband" signal (DC-5MHz) which I'd like to send over coax cable to two other circuits referenced to the same ground.  Simply floating the other two circuits is not an option for various reasons.  EDIT: sorry I should mention that the circuit shown below is only one signal sent to one receiver.  Another similar part of the circuit (not shown) sends a different signal over a different coax cable to the other receiver.

The two receivers are currently single-ended, but could be upgraded to differential in the future.  So I thought it might be simple and clever to wire things up so that the driver could be jumpered up to run differential.  As you can see, the negative half of the signal can be replaced with a buffered ground to make it "single-ended" when R23 and R21 are removed.  It made me a little nervous to short the follower completely, so I put 0.1Ohm output impedance there.

The question:

Does a virtual ground really cut ground loops?  It seems like the Thevenin equivalent impedance looking "backwards" into the follower would be almost zero anyways?  Or perhaps the output impedance of the op-amp is enough to "break" the loop?  I am interested in getting rid of pickup and cancelling out the effect of the differences in the references of the three circuits.  So in this case mains hum (50Hz) and residual rf (20MHz, 40MHz).  EDIT: according to the data sheet the output impedance at 20MHz is about 50ohm.  At 50Hz it's below 0.1 Ohm.  So if I'm interpreting things correctly, this doesn't seem like a very strong "break" of the ground loop at 50Hz.

The followup question:

Is there a downside to changing the output impedance resistor of the positive signal (R24) to zero and the negative one (R26) to 49.9 in order to cut the loop the "low-tech" way?  (series resistance)  EDIT: The cable has 50 Ohm characteristic impedance and will be terminated with 50 Ohms.

Thanks for reading.


texts: LM339 Comparator IC is not responding to any input

texts:
I came into Electronics through Arduino, so pardon me if my knowledge about non-Arduino circuits is somewhat silly. I am preparing a small electronics project for my school with LDRs to detect light levels. With, an Arduino I could easily detect light levels and when they go down a threshold, I turn on a relay.

But, I wanted to make this without an Arduino, so I though of using an LM339 Comparator. I connected pin 3 of IC to Vcc and pin 12 to Ground. Pin 4 has an input lower than the input on pin 5 which receives input from Vcc. Lastly, I had the output 1 from pin 2 connected to an LED.

This circuit is only to test the comparator. If it works I am going to change the reference voltage and in place of the LED place a transistor. Here is a quick circuit Diagram I created:

But, the LED does not glow. Even if I switch the inupts, the LED does not glow. I tested this in circuits.io, the online simulator. It works perfect there. But, the problem persists on the breadboard.

How do I get the LED to glow in my circuit on the bench?

UPDATE: I just got the LED glowing with the help of Raj, but how can I connect the base of a transistor in place of the LED.


texts:
Background:

I am designing a small Arduino-driven circuit to control a ~3/4 hp AC hoist motor. The hoist motor includes a starter-capacitor. The Arduino drives a transistor which in turn drives a power relay that switches the motor on and off. I am not an electrical engineer, so I'm using a Factor of Safety of 2 or higher throughout the circuit to avoid component damage/burnout.

The particular relay I had in mind is supposed to be capable of handling up to 30A sustained (more than 4 times the max-load current of my motor) at double the nominal operating voltage. My intent is to run two of them in series for safety (to handle one failed-closed relay) and for wear-leveling of the contacts.

Consulting an ampacity chart, it looks to me like I need 10AWG copper wire (about 5.3mm^2 conductor area) to handle 30A. But as you can see from the relay datasheet, the load pins are ridiculously tiny: each is roughly equivalent to 17AWG (1.6mm^2). Unfortunately Digikey does not carry a socket with solder cups or terminal lugs for this particular relay, and I'm having a very hard time soldering 10AWG wire to a 17AWG pin.

Questions:

How can the relay pins carry so much current with such a tiny conductor?
Is 10AWG really the right size of wire to carry 7A AC with an inductive load?
How should I go about wiring this relay to the rest of my circuit?


texts: Can AC in-rush cause problems for other devices on same circuit?

texts:
I'm working with a system that is encountering hardware faults in the field (micro-controller circuits appear to be damaged in some non-visible way); the symptoms are such that it's likely some condition at the site is causing damage to the hardware, since replacing electronics fixes the issue, it doesn't fail when operated away from the site, then fails again within a week or two of returning to the site.

Is it possible that AC power conditioning issues could damage electrical components in the system?  One device of note at the site is a centrifuge that can pull a 100A in-rush current (at 220V) for up to 1 second, followed by continuous operation at up to 30A.  I've heard of power surges causing issues with electronics, so is it possible that a 100A in-rush on the AC power supply circuit could cause damaging surges to other components on the same supply circuit?  I would think that the AC-to-DC power supply for the electronics would protect against this?


texts:
I want to generate 2 PWM on PC6 & PC7 on an STM32f10x , it work fine but , the problem that I have is that I want to make them phase shifted to each other , say 45° and I really don't how to do that, since the PWM started  at the same time. any idea how tihis could be made.

thanks for any hint


texts: What is the meaning of the first gain in the block diagram?

texts: I have do design a circuit based on the block diagram below. I know how to design the PID part but I don't understand what the K=2 is. For the PID I have made the following:


texts: Versatile input termination / translation for reference clock?

texts:
I've got a microcontroller I want to clock from an external 10 MHz reference. I'd like the reference input to be as versatile as possible. At the moment, my reference is an LVCMOS square wave, but other folks have various levels of sine wave references.

I'm going to use a 74LVC1G17 to condition the input, fed with 3.3 volts (the microcontroller runs at 5v, but I've already tested that it will accept a 3.3v clock).

The remaining question is how best to terminate and/or condition the input, and what range of input signals it will accept (assuming regular, stable, 10 MHz, 50% duty cycle input).

I've googled around and learned about AC parallel termination and Thevenin termination, but in simulating them in circuitlab, I don't see the transitions lining up the way I'd expect.

In particular, a series cap feeding a voltage divider on the input doesn't give me a square wave centered on Vcc/2 like I'd expect.

simulate this circuit – Schematic created using CircuitLab


texts: Howto use/shield NFC/RFID Sticker on back of iPhone 5?

texts:
I want to stick a RFID sticker on the back of an iPhone 5 (between a case and the iPhones back to be precise). The sticker is an Mifare DESFire EV1 sticker, in case that matters.

Problem is, the tag never gets read when it's so close to the iphone. Therefore I'm wondering what kind of material (perferable very thin) I could use to shield the sticker so it can be read properly?


texts: Pinout of microwave motion sensor FC1816

texts:
Please, help to figure out the pinout of microwave motion sensor FC1816.

The seller "doesn't understand" what it is required on queries to provide the pinout for the module. The module is the smallest microwave motion sensor I found, so it's very welcomed to run it.

I followed traces to find the function of 4 pins of 5. Please, help me to understand last pin. UPD: This question solved. Other question arose below...

From left to right:

Pin 1: Out, connected to pin 2 of BISS0001.
Pin 2: Vcc, connected to pin 8 of BISS0001.
Pin 3: Enable, connected to pin 9 of BISS0001. Short it to GND should run the BISS.
Pin 4: Gnd, connected to pin 7 of BISS0001.
Pin 5: UPD: Vcc of microwave generator.

I have tried to connect both Vcc together to +5V, Enable to Vcc via 2k resistor (pullup), ground as regular.
The out gives always logical 1.

What voltage should be supplied? BISS0001 supports up to 5V.


texts: Frequency compensation and feedback capacitance

texts:
I was reading the chapter of Microelectronic Circuits (Sedra Smith) about negative feedback systems, and it shows an example of Miller frequency compensation with the capacitance Cf shown in the following scheme (a common emitter amplifier which is part of a cascade of amplifiers):

It shows how that capacitance moves a pole in the s plane, and this allows us to make the closed loop total system stable:

I have a basic doubt: if you see Cf, it is in the same place of the BJT common - emitter parasitic capacitance (or, in case of MOSFETS, gate - drain capacitance), i.e. a capacitance between output and input.

But sometimes I have read that these parasitic capacitances are terrible regarding stability, and that problem was important also for old vacuum tubes. In "the design of CMOS radiofrequency electronic circuits" (Lee) for instance it is shown as Cgd of a MOS amplifier may determine an input admittance with negative real part, which means that the system is not stable.

So I do not understand why I read both that a Miller feedback capacitance may be useful to get frequency compensation and to get the stability, and also that a parasitic capacitance included exactly in the same position in the circuit may provoke unstability.


texts: How does a boost converter power the oscillating circuit and load at the same time?

texts:
so I've put together a boost converter circuit of my own and I have a problem, I want my boost converter to output reasonably high current but whenever I connect a high current load - the astable multiple vibrator I'm using to switch the boost circuit on and off gets cut off from the power supply, which is a 3.7v battery, my goal is to achieve 5v at 4 amps max... Please help me, and please ask me to specify anything you need me to. Thank you
It's a 26650 Li-ion cell - 3.7v 5000mah


texts:
I am having trouble understanding some PID code on an FPGA that is posted on github, by David Paquette.
I will paste it in at the bottom of the post.
It looks very compact and neat, an I understand the concept behind it, but I don't understand why the Kp, Ki and Kd constants are negative numbers. Kp as -300 and Ki as -2 for example.
Suppose I have two questions regarding this:

Why the negative numbers? I am thinking it gives a broader spectrum to work with error values, as the output is capped at zero if the output calculates as a negative.

I am assuming the hardware requires integers of 100, i.e. whatever sensor or motor pwm frequency, but what would the reasoning be behind the 1000 and 10000 integer sizes for the variables?

----------------------------------------------------------------------------------
-- Company:
-- Engineer: David Paquette
--
-- Create Date:    16:49:31 11/19/2015
-- Design Name:
-- Module Name:    PIDController - Behavioral
-- Project Name:
-- Target Devices:
-- Tool versions:
-- Description:
--
-- Dependencies:
--
-- Revision:
-- Revision 0.01 - File Created
-- Additional Comments:
--
----------------------------------------------------------------------------------
library IEEE;
use IEEE.STD_LOGIC_1164.ALL;
use IEEE.numeric_std.all;

-- Uncomment the following library declaration if using
-- arithmetic functions with Signed or Unsigned values
--use IEEE.NUMERIC_STD.ALL;

-- Uncomment the following library declaration if instantiating
-- any Xilinx primitives in this code.
--library UNISIM;
--use UNISIM.VComponents.all;

entity PIDController is
    Port (  samplingRateClock : in std_logic;
                reset : in std_logic;
                setpoint: in integer range 0 to 100;
                sensorFeedbackValue : in integer range 0 to 100;
                controlOutput : out integer range 0 to 100
        );
end PIDController;

architecture Behavioral of PIDController is
    signal controllerOutput : integer range 0 to 100:=0;
    constant kp : integer range -1000 to 0:=-300;
    constant ki : integer range -1000 to 0:=-2;
    constant kd : integer range -1000 to 0:=0;
begin
    process(samplingRateClock, reset)
        variable error :  integer range -1000 to 1000:=0;
        variable previousError : integer range -1000 to 1000:=0;
        variable errorSum:  integer range -100000 to 100000:=0;
        variable errorChange:  integer range -1000 to 1000:=0;
        variable output:  integer range -1000 to 1000:=0;
    begin
        if(reset='0') then
            error:=0;
            previousError:=0;
            errorSum:=0;
            errorChange:=0;
            output:=0;
            controllerOutput<= 0;
        elsif(samplingRateClock'event and samplingRateClock='1') then
            error := (setpoint - sensorFeedbackValue);
            errorSum    := errorSum + error;
            if(errorSum > 10000) then
                errorSum := 10000;
            elsif(errorSum < -10000) then
                errorSum := -10000;
            end if;
            errorChange := error - previousError;
            output := (kp*error + ki*errorSum + kd*errorChange)/100;
            previousError := error;
            if(output>100) then
                output := 100;
            elsif(output<0)then
                output:=0;
            end if;
            controllerOutput<= output;
        end if;
    end process;

    controlOutput<=controllerOutput;

end Behavioral;

```


texts: What happens when Amperes hour (Ah) and voltage regulation go together to the party?

texts:
This is the first time I ask on the Electrical Engineering site of Stack Exchange, please feel free to dismember my question.

Please take into account: I am thinking about the hypothetical ideal case (100% efficiency, no energy loss) and the voltages and currents stated here are hypothetical values. If there are implications on the specific voltages (like types of batteries, or anything else) I would really appreciate if you let me know in your answer.

Let's say I have the following requirements regarding power for an electrical application that I am developing:

2.5V DC
1000A (all the time, not peak).
Portable. Duration of the battery: 1 hour

In an ideal world I would buy a 2.5V 1000Ah battery and it would be fine. However, imagine that I found a 5V 500Ah battery (and can provide 500A continuously). My assumption is, if I downregulate the voltage to 1V, it will be able to provide higher amperage at the outside of the regulating circuit (while not surpassing the previous power output which was 5V*500A = 2500 W).

My doubts are:

How would you regulate the voltage? I am pretty sure a voltage divider won't do the trick, and I guess a voltage regulator would work, but with such high amperage I am not sure about the limitations, I have little experience with power supply circuits.
With that solution, if the voltage is halved, would the amperage at the output of the regulating circuit be doubled? (that means, I could use the 5V 500Ah voltage source). Again, on "ideal" components. I understand there would be energy loss.

Thanks in advance!


texts: Kinetis KE16 not coming out of reset without debugger 3V3 and GND connected

texts:
I have a project based on the MKE16F256VLH16 MCU. The processor won't run unless the 3V3 and GND are connected to the debugger (a LPC Link2 board), even if the LPC Link2 is unplugged from USB and left floating.
I've measured the 3V3 line (without the debugger connected) and it's 3.45V, another weird thing, since it should be PSU IC is a fixed 3V3 one.
PS: Have checked and U1 is indeed marked N3XF, which means it's the 3V3 fixed output one.


texts: Is this voltage division equation correct?

texts:
I am trying to study the significance of resister divider feedback circuit in buck regulator.
This is the TI document I am referring to.
As per TI doc, voltage at the feedback pin is as follows,

When I try to estimate the same feedback voltage, I feel the drop at the R1 resistor (value in the red box) should be omitted from the equation. What is the information I am missing here.


texts: Current drain of a power amplifier LM1876

texts:
I'm designing a power amplifier based on the TI's LM1876 and I need to know how much current it will drain in order to order a transformer with such current capacity. It'll have a 500mV@1KHZ on its input, from a RIAA pre-amp and it will power a pair of 8ohms speakers. As it is an AB class type amplifier, the maximum theoretical efficiency is 78.5%, acording to the table below. So, I thought of assuming it has a 60% efficiency and will fed it with +-24VDC. The gain will be 21x, the datasheet sugested circuit, and so, it will produce about 14W@1KHZ/channel (13.78W to be exact) over a load of 8ohms. Considering an efficiency of 60%, it'll be needed aprox. 23.4W/ch, 14/0.6 = 23.333W.
If I am right, can I consider there is 48VDC (+24VDC and -24VDC) powering it and therefore it will drain  0.5A/ch, 23.4/48 = 0.4875A?
Is my assumption of 60% efficiency good in this case?
Can those same estimatives be done for a NE5532 based RIAA pre-amp?


texts: extracting DC from audio signal for biasing

texts:
I've been wondering if there is a simple means of extracting a DC signal from an AC+DC signal for the purpose of providing a small DC supply to a CMOS device.

Essentially the signal I'm considering is a DC microphone bias supplied to an electret microphone. The electret mic will add its own small signal AC, and this will pass through some circuit that requires the DC bias only, leaving the microphone AC undistorted to be passed to another part of the circuit uneffected. The rest of the audio chain is passive, and no external supply is available other than the 2.5V - 5.0V DC microphone bias superimposed with audio AC.

I'd like to add a small CMOS comparator (or similar) that requires a DC supply, and the microphone bias is the only DC source available for the CMOS device supply. Usually removing the DC from a signal is straight forward with a DC block capacitor, but any thoughts how to do this DC extraction simply without effecting the audio signal ??

Cheers, Mike


texts: Crystal oscillator not giving true square wave

texts:
I just purchased an oscilloscope and I was testing it on a 10MHz crystal oscillator (OSC-25CMN 10.00000MHz SIWARD 6C).

I noticed that the signal is very distorted (see pic). I also tested a 40MHz cystal oscillator and it gave kind-of a sine wave instead of square wave, but I guess it's the reading of the oscillator as it's not the best quality (KKmoon 5012H).

Is the oscillator faulty? Or is that what's supposed to happen?

As you can see the "0" state jumps to 1V in the middle which caused my binary counter to trigger a count when it's not supposed to...

Is there any way I can "smooth" the signal?

Thanks

EDIT:

Additional photos of the board


texts:
I'm planning to use a TL084 JFET quad op-amp with each op-amp configured as a voltage follower (datasheet). Some questions:

Does Vcc+ have to equal -Vcc-? i.e. can I set them to Vcc+=15V, Vcc-=-8V?
I'm planning to run the op-amp in a non-inverting follower configuration with the input V+ between -4V and 12V. The input common-mode voltage range says -12,15 V. Does this mean I can output any voltage between -4V and 12V in this configuration?
The output short-circuit current is listed at 60 mA. Can I safely assume that my voltage follower can source ~60 mA of current?
Should I be adding any passive components to this circuit to make sure it is stable?


texts: Why does 1-bit predictor miss on first iteration of inner loop next time around?

texts:
My computer organization and architecture claims that with 1-bit predictor, there are 2 mispredicts.

The first miss is when mistaken on last iteration of inner loop.

The second one is as not taken on first iteration of inner loop next time around.

I can't get why the second one occurred.


texts: The resistance between the 1.2V rail and GND is 40 Ohms, is it safe?

texts:
I have a power supply board that supplies a DSP, FPGA, CPLD and other components of a system. When I measure the resistance between power rails and GND using a multimeter I get the following readings:

Between 12V and GND: Infinite
Between 5V and GND: Infinite
Between 3.3V and GND: 250 Ohms
Between 1.2V and GND: 40 Ohms

The 3.3V and 1.2V rails have many decoupling caps around power supply pins of the DSP and FPGA, are they the only cause for this much reduced isolation between these voltages and ground?

Is it safe for the long run to work with these specs? The system is now running perfectly.

Also how can I avoid this issue in future designs?

Edit #1

In a project I'm currently working on, one of the tests that will be done on the product will be isolation tests. The customer will measure the resistance between supply rails and Chassis ground and want it to be greater than 10 Mega Ohms, that's why I want to avoid these low resistance values. Is there a device used to measure isolation? or it's done with a normal ohmmeter?

Edit #2

These measurements are done when the system is powered OFF.


texts: One led is blinking too frequently using the hardware timer (stm32f103vdh6)

texts:
i recently started my internship using embedded C and i'm having some trouble with one of the tasks: Two leds should be blinking at 1Hz, one using the hardware timer, and the other one using the RTX RTOS os_dly_wait() function. The led using the RTX RTOS task is working fine, meanwhile the other led is blinking at a higher frequency (i estimate around every ~0.9 seconds). The microcontroller is operating at 72 MHz, so i'm using the prescaler value of 7200 and using a period of 10000. I'm using the TIM2 timer. I will also include a Clock tree of the microcontroller. What could be causing this?

#include <RTL.h>
#include "stm32f10x.h"
#include "stm32f10x_gpio.h"
#include <rtl.h>

#define     GPS_LED_PIN  GPIO_Pin_9
#define     NAV_LED_PIN  GPIO_Pin_2

__task void task1 (void);
__task void task3 (void);

void InitLED(void) {
    GPIO_InitTypeDef  GPIO_InitStructure;

    RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOE | RCC_APB2Periph_GPIOB
                            | RCC_APB2Periph_GPIOD, ENABLE);
    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_Out_PP;
    GPIO_InitStructure.GPIO_Speed = GPIO_Speed_10MHz;
    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_2;
    GPIO_Init(GPIOD, &GPIO_InitStructure);
    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_2;
    GPIO_Init(GPIOE, &GPIO_InitStructure);
    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_9;
    GPIO_Init(GPIOB, &GPIO_InitStructure);
    GPIO_SetBits(GPIOE, GPIO_Pin_2);
}

void TurnOnLeds (void) {
    GPIO_SetBits(GPIOD, NAV_LED_PIN);
    GPIO_ResetBits(GPIOB, GPS_LED_PIN);
}
void InitializeTimer()
{
        TIM_TimeBaseInitTypeDef timerInitStructure;
    RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM2, ENABLE);
    timerInitStructure.TIM_Prescaler = 7200;
    timerInitStructure.TIM_CounterMode = TIM_CounterMode_Up;
    timerInitStructure.TIM_Period = 10000;
    timerInitStructure.TIM_ClockDivision = TIM_CKD_DIV1;
    timerInitStructure.TIM_RepetitionCounter = 0;
    TIM_TimeBaseInit(TIM2, &timerInitStructure);
    TIM_Cmd(TIM2, ENABLE);
        TIM_ITConfig(TIM2, TIM_IT_Update, ENABLE);
}
__task void task1 (void) {
    os_tsk_create(task3, 1);
    for (;;) {
        os_dly_wait(5);
        GPIO_SetBits(GPIOB, GPS_LED_PIN);
        os_dly_wait(95);
        GPIO_ResetBits(GPIOB, GPS_LED_PIN);
  }
}
__task void task3 (void) {
    for(;;)
    {
        int timerValue = TIM_GetCounter(TIM2);
       if (timerValue == 0)
             GPIO_SetBits(GPIOD, NAV_LED_PIN);
       else if (timerValue == 1000)
          GPIO_ResetBits(GPIOD, NAV_LED_PIN);
    }
}
/*-----------------------------MAIN---------------------------------------------*/
int main(void) {

    InitLED();
    TurnOnLeds();
    InitializeTimer();
    os_sys_init (task1);
}


texts: Is the Raspberry Pi a microcontroller or a motherboard?

texts:
I had quick question regarding Raspberry Pi: is it a microcontroller or a motherboard?

It looks like a motherboard, but considering that it has its own dedicated memory and processor, it should be a microcontroller.


texts: What the purpose of a diode in parallel with a power switch

texts:
I've come across a circuit that has a diode in parallel with a power switch that's controlling a BLDC motor circuit.  I was told that it's a flyback diode to prevent voltage spikes from an inductive load, but that doesn't really make sense to me.  I've always seen a flyback diode placed in parallel with an inductive load, like with a relay coil, or in a buck converter.  The two ways I understand it are that:

a) the diode provides a path for the current in the inductive load to continue to flow

b) when the current though the inductive load is suddenly stopped, the voltage, which is V=L*di/dt is a very large negative number, so V_LOAD goes negative.  However the diode is then forward biased, so it clamps V_LOAD at the forward voltage of the diode

With the circuit in question, neither of those conditions hold true.  The current could have to instantly change direction for the diode to conduct (which would probably cause a lot of other issues), and V_LOAD would have to increase in voltage in order for diode to be forward biased.

Has anyone seen this before and know what the purpose of this diode is?  It kind of seems like someone didn't know what they were doing by putting the diode in that position, but I might be missing something super obvious.


texts: Switch mode power supply connected to the diesel generator makes bad voltage oscillation

texts:
GEKO diesel generator has 60 kVA electric power. Our switch mode power supply connected to this generator via passive filter DL-50EA3 and 6-pulse bridge rectifier (see the schematic). In this configuration we suffering from the filter excitation:

(yellow - input voltage divided by 10 = 200V/div, blue - current 5Amps/Volt = 25A/div)

If the power supply connected to the regular electric network - everything is OK.

Schematic:

The equipment connected to the generator suffers from this parasitic oscillation and we need to suppress it as we can.

One possible solution is to put additional filter between generator and rest equipment in the following configuration:

Can anyone suggest the filter? Or maybe we miss some extra solution.


texts:
i am writing as essay evaulating accuracy of smart phone gnsss for GIS data collection

for part of the essay i thougt it appropriate to mention DGNSS and Assisted GNSS. So far i understand Assited gnss is using cell towers to send over sateltie information and DGNSS is using basestations to do the same thing.

Is this accurate and are their benefits of one over the other


texts: If a battery gives me a 5V terminal and a 0V terminal I calculate power by multiplying total current of the circuit by 5V. What if the battery has a +12V and -12V terminal I'm using to power my circuit? What value do I multiply current by to give me Watts?


texts:
I have to do a connector adapter, that has to handle 5A current, from a pwm motor driving circuit(power mosfet), to the motor.
I have not found the current rating for dupont connectors

It is possibile to use them for a prototype connection or it is dangerous?
Thanks


texts: How to create automatic dual battery changeover/switching circuit for uninterruptible power?

texts:
I've search for a solution to my problem both on this site and on Google but I did not find a complete and adequate response.

I need a circuit that switches two 12v sources (one that comes from a lead-acid battery powered by a solar panel and the other source comes from the output of a 220-12v switching power supply) without the final power output being interrupted during switching (this is very important!).

Notes:
 - The final power output will be used to power 12v devices (30 Ampere maximum).
 - The sources voltage range is 11-14.7v

How can I switch between two 12V sources?


texts: PCIe high speed signal TX and RX routing with via

texts:
I am working on 4-layer pcb design with PCIe connector and golden finger. I asked a question about power planes before:Necessary to put all power planes together for 4-layer pcb?

Now I have a follow-up question about the most significant signals TX and RX on the board.

Here is my pcb layout,

What I am now worried about is the place in the blue rectangular. These vias may cause problems on the high-speed signals. But I am not sure how serious that could be.

Thank you!


texts: DDS/AD9106/20kHz burst amplitude modulated

texts:
I am looking for some guidance on how to implement amplitude modulation on a 20kHz, AC signal, ±0.5Vp2p.

It is being generated by an AD9106 with a 2MHz clock. I have it generated a 20kHz sine wave and it is amplitude modulated.

However I am finding it is for some reason it is limited to a length of 6ms. Even though the SRAM has 4096 positions, and 2MHz clock would take ~2ms to go through it.

That unknown issue aside my primary question is - if I turn off the amplitude modulation and make the output of the AD9106 back to a 'normal' 20kHz burst with constant amplitude. Is there anyway to add a PASSIVE circuit to the output of the AD9106 that could slowly ramp up the amplitude? If so, are there any recommendations on parts, part numbers or other?

I am not really an analog engineer..

Secondly does anyone know how I could extend the period length on the output of this with the registers or the IC settings?


texts:
I am building a 8 channel 50MHz PC based logic analyzer to learn a bit about digital design. I am currently having trouble at the trigger portion of it, more precisely generating the signal that will "clock" SRAM and binary counters.

simulate this circuit – Schematic created using CircuitLab

Signals come into CH1-CH8 inputs, with MASK1-MASK8 I can set channels for triggering. AND gate is for positive edge, NOR is for negative edge. At the end of this triggering circuit I had in mind a D flip-flop which will detect a rising edge and generate 15-20ns wide signal that is needed to "clock" SRAM and binary counters.

The problem is I cant find a way to combine 8 signals into 1 and then detect rising/falling edges to generate a pulse. I cant seem to do it (according to LTspice) with XOR-ing them. If for example, signals on CH1 and CH2 are same, but CH1 leads CH2 for 4ns and propagation delay of XOR is 6ns the output of it will always be 0. I am wondering if this is the correct behaviour and if so why (shouldn't there be at least a spike at the output)?

So I am thinking, for the first positive edge that some circuit sees, it should generate a 15-20ns pulse and somehow "locks" all other signals from generating this same pulse. And "unlock" them at the end. Again I could do this with D flip-flop, but it has a 7ns propagation delay from CLR to OUTPUT.

I am looking for suggestions on how to implement this logic. I have 200-250MHz clock avaliable if it helps.


texts: Will my circuit interfere with ATtiny25 in system programming?

texts:
I've got a simple circuit with an ATtiny25 on which I indend to do in system programming. I'm wondering, will the rest of my circuit interfere with the SPI programming?

So the data sheet says:

PB0 = MOSI, this is used as an output so should be fine
PB1 = MISO, this is used as an output so should be fine
PB2 = SCK, this is used an input, connected to a voltage divider. So the 442 ohm resistor will cause a 7.4/11.3 mA current at 3.3/5 V, respectively.

Am I screwed here, is that too much?

Edit: I'm planning to use the Atmel-ICE programmer, but can't find any docs on how much current that can source.


texts:
I am creating a library component for KiCAD using a convenient online app at: http://kicad.rohrbacher.net/quicklib.php. The component I am making is the Microchip PIC24EP512GU814 in LQFP http://www.microchip.com/wwwproducts/Devices.aspx?dDocName=en554337.

The app asks me to assign a type to each pin. The types avilable are:

Input
Output
Bidir
Tri-state
Passive
Unspecified
Power Input
Power Output
Open Collector
Open Emitter

I must now assign one of these types to the VDD and VSS pins.

My best guess is that VDD should be assigned as Power Input. Would VSS also be considered as a power input?

Perhaps since VDD is analogous to VCC (and VSS to VEE), I could classify VDD as an Open Collector (and VSS as Open Emitter). However I'm not sure if VDD and VSS can be considered as "open" for an IC.

What should VDD and VSS be mapped to?


texts: DC Blocking capacitors - What value to choose

texts:
I am in the progress of ordering parts for a LNA board (2.4GHz, based around the broadcom/avago MGA-635P8). I was following the manufacturer's component list in the datasheet for their evaluation board.

They use a 1000pF DC blocking capacitor. I was wondering why one would use such a large value in a 50Ω system, when the operating frequency is 2.3GHz up to 4 GHz. Wouldn't using a smaller value improve the noise power, since the bandwidth of the system is decreased? Is there some other reason why I would choose such a high value of capacitance?


texts: Standalone Barcode Reader that checks against file

texts:
What I'm looking for is a standalone barcode reader device that checks a barcode against a list of numbers stored on the device and returns the status (valid/not valid/...) associated with the specific code.

Is there any available device that does this or will i have to make something myself with a microprocessor, sd card reader / storage addon and barcode scanning engine?


texts:
Why are the capacitors on the image being used with the DC motor?

For my arduino aplication with L298n is ok to keep or remove them?


texts: Voltage Difference Between Machine Laminations

texts: Given a lamination stack that is exposed to a transient magnetic field, how can the potential difference between the individual laminations be determined?  is there a rough rule of thumb that can be used?


texts: What happpens to the Vgs in the Miller plateau region during MOSFET turn-ON?

texts: During my mosfet switching power dissipation I went through the Vgs curves of the MOSFET during its turn-ON state.Here i found that the Vgs curve remains flat during the miller plateau region. Why is it so? What exactly is happening to the Vgs growth here? Could somebody give clear cut explanation here?


texts: Connect to LIN bus with logic level shifter as transceiver

texts:
Is it good idea to connect my microcontroller to LIN bus with logic level shifter (5 <=> 12 V) instead of factory LIN transceiver (MCP2003, TJA1020, etc.)?

As I understand, LIN transceiver just converts logic level UART signal to 12V LIN bus and vise versa. The same thing is possible to do with logic level shifter or voltage divider on resistors. Are there any gaps in these approaches?


texts: Is it bad practice to always have a MOSFET on?

texts:
I am designing a circuit where I have a microcontroller driving
a four-channel logic level N MOSFET module. The simplest way for my circuit to work is to have the microcontroller run "HIGH" on the MOSFET gate for extended period of time (1 hour on for every 10 seconds off). Assuming the heat dissipation is within specifications, is it generally "acceptable" to have a MOSFET on this long? Or would an experienced circuit designer find a way to accomplish the same thing by inverting the logic?
For reference, I am designing an LED neon sign. One of the MOSFETs is meant to "flicker" the entire light. Turning the MOSFET off briefly cuts the power supply. Turning it back on reestablishes the power. The other MOSFETs turn on/off different parts of the light. I only have N channel MOSFETs, I am trying to avoid breadboards/resistors, etc. I believe I am able to dissipate enough heat to avoid a heat sink.
Here is a circuit below. The 100 ohm resistors are just placeholders. The bottom three 3.3 V are the microcontroller I/O pins. The top 12 V is the LED power supply. I will add pull-down resistors to keep the I/O pins and MOSFET gates low.


texts: Should I use a Dual 4-channel analog multiplexer/demultiplexer for powering up 4 sensors and getting their readings?

texts:
74LV4052
Dual 4-channel analog multiplexer/demultiplexer

I currently am using a multiplexor to connected to one analog channel from my Arduino. The multiplexor is connected to 4 pressure sensors that draw approximately 100mA while in use.

Because I don't want to keep my pressure sensors powered on all the time, I want to use a NPN transistor to complete the circuit.

However I want to complete the circuit by using the same combinations of GPIO's high and low that I am using for the multiplexor.

My current design is using a demux to help me bring the proper transistors high or low. I would tie in the same GPIO's that I use for the multiplexor to keep the sensors powered on and readings acquired in sync.

I just stumbled upon a IC that is a multiplexor/demultiplexer (dual)

I am not familiar with the component, would I be able to simplify my project by using the component listed above?

I understand I need the transistors to complete the circuit because I can not achieve enough current with the demultiplexer.

I appreciate your help in advanced, please let me know if you would like further clarification.

Thanks!


texts: sensor to detect rope position, as it nears the end of the line retreval

texts:
I have built a winch for a 4wd, to race with. I would like suggestions on a sensor to detect rope position as it nears the end of the line retrieval. Not at the drum end, as that may vary. Something along the lines of a short piece of trace wire, inserted inside the winch cable, a few meters from the hook end, to turn a light on as it passed by a sensor? Is there something like this? Application would be in water and dirt, 12v power supply. Thank you for any help.
Great feed back, thanks. see the winch here.https://www.youtube.com/watch?v=vgx1hc5GikU
FYI I want some kind of warning system, for when the hook is attached to the front of the truck, and we are winding the loose rope back onto the drum, and you cannot see how near the rope is to stopping as it pulls tight.


texts: Replace magnetic sensor - help identify 3-pin IC marked "W10" and "1095"

texts:
We have an instant gas hot water system that is not initiating.
I've traced it to the water flow sensor not signalling when water is flowing. After inspecting the housing, the magnet is spinning freely and easily, free of debris.
I checked the sensor readings and it seems faulty. It's a 3 wire sensor, likely a hall effect sensor of some sort. Voltage across black and red is 5.01V and across black and white is also 5.01V (so I'm guessing its normally closed / NPN).
If I understand it correctly, I should see a change in voltage on the load wire (black + white) when the magnet spins across the sensor, but I'm not seeing any movement of voltage in either black+white or black+red.
Unfortunately the supplier has no more replacement flow sensors and the model it's used in is discontinued.
Naturally, I pulled apart the flow sensor (see photo below), cleaned off the potting agent and see it's a 3-pin IC marked with "W10" and "1095" below.
BUT, my Googling for hall effect and those numbers doesn't pop anything. I was hoping I could replace it and get back to having nice warm showers again :-]
Does anyone know of an equivalent IC or how I can identify / order that IC?
Much appreciated.


texts: Is it normal to feel shocks on corner of laptop

texts:
When working on my laptop connected to power and lightly touching the right corner with my forearm, I can feel small shocks which are uncomfortable, almost painful. Is this normal?

It happens under all these conditions:

an HP Envy laptop
Macbook Pro 2017
Macbook Air around 2014
3 different flats in Hong Kong + office


texts: What is a good resistor value for my circuit?

texts:
I'm trying to tap into my car's brake circuit to switch between receiving a wireless camera signal and powering my device. For this purpose, I connected a relay to the circuit via a fuse tap. It should connect the phone to the receiver (displaying the camera feed) when the brakes are applied and charge the phone otherwise. Unfortunately, I'm having some difficulty figuring out how to get the relay to switch properly.

I wired the relay to the circuit in the fuse box that powers the car's instrument lights and the brake lights. The current draw for the instrument lights (which are always on) is 0.7 amps. The brake lights draw 1.15 amps. Without adding additional resistance between the car battery and relay the constant 0.7 amp draw will always keep the relay in the ON position (connecting phone and receiver). Hence, the need for additional resistor between battery and relay. The relay's coil draw is .5 amps.

simulate this circuit – Schematic created using CircuitLab

Here is my most likely flawed resistor calculation. Please point out any errors.

First I calculate the internal circuit resistance

V=IxR
12 = .7xR
R = 17.143 ohms // with the brake lights off

12 = 1.15xR
R = 10.169 // with brake lights on

To keep relay in OFF position, I need to supply a current less than the relay's coil draw (.5 amps). Adding an 8 ohm resistor should do the trick:

R = 17.143 + 8 = 25.143 //brake lights off
I = V/R
I = 12/25.143
I = .477 < 0.5 // relay switch in off position

R = 10.169 + 8 = 18.169 // brake lights on
I = 12/18.169
I = .66 > 0.5 // relay switch in on position

It seems like 8 ohms is enough to keep switch OFF with 0.7 amp draw, but my relay always stays in the ON position, even after I increase resistance to 16 ohms. So what gives?


texts: Looking for a quad low side power driver IC

texts: We have been using the Allegro UDQ2559LB. This is a quad (4 channel) low side power driver (used to drive relay and lamp loads) with about 0.5 amp per channel capability and overload, short circuit, and over temperature protection. Allegro is shutting their fab and discontinuing this part. Any one have suggestions for a good replacement? 4 channels would be ideal and the part must be surface mount.


texts: MOSFET finite output resistance in saturation mode

texts:
Since MOSFET has finite output resistance in saturation/active mode, the slope of unsignificanlty rising drain current is defined by Ua and slope parameter as lambda:

This parameter (as I know) is not given in any MOSFET datasheet.

Question: Is there any other way to get slope parameter out of the equation? For example with transconductance it can be done but I don't really know how to get it out of it (so this parameter can be defined with other already given variable of parameter).


texts: Why does writing to a read-only register increase current consumption?

texts:
Looking at the datasheet of the MSP430, it says writing to read-only registers results in increased current consumption.

Why is that? What is happening when trying to write to a read-only section of memory that increases current consumption?
For reference, here is the family datasheet for the MPS430.

Edit: Further, are there other devices that exhibit similar behavior? It seems like I've seen this in datasheets before, but maybe not.


texts: networking platform to meet the IEC61850 sampled value requirements

texts: I've developed a linux based simulator of the IEC 61850 sampled value publisher, even with RT linux I still can't meet the requirement to publish a message with MTU =-1500, every 1uS on a PC platform. Someone suggested DSP chips, I really a fish out of water in the field, can someone suggest a DSP chip that can run linux and be able to meet the processing and network requirements.


texts: System Verilog Coverpoint Bin for everything else that is counted towards coverage calculations

texts: Setting a bin to default grabs everything else in the coverpoint, but the default bin is ignored in coverage calcuations. Is there anything similar to default that I can use for syntax that will generate a bin to cover "everything else" in a coverpoint but code in coverage calculations? Alternatively is there way I can tag the default bin so that it will be counted in code coverage calculations?


texts: How can I test microprocessor / microcontroller?

texts:
Possible Duplicate:
  Is it feasible to test microprocessor/microcontroller?

As far as I know the manufacturers do it before shipment.
How they test microprocessor / microcontroller?
However, if I want to test  microprocessor / microcontroller by myself, how can I do it?


texts: AD7705 - current drawn by reference input for operation with LM4041

texts:
I want to use an LM4041 shunt reference voltage to generate 1.225V, as demanded in the AD7705's datasheet for a 3V supply voltage. However, to calculate the required impedance before the shunt I need to know the maximum current drawn by the load (in this case the AD7705). This is not given in the datasheet, though. If I assume it to be much smaller than the minimum current drawn by the shunt (45µA) and neglect it I get a value of:

R = ( V_supply,min - V_ref ) / ( I_ref,min + I_load,max )
  = (3.3V - 1.225V) / 0.000045A
  = 46111 Ohm

However, with a 46k and even with a 30k resistor I measure an output voltage in the range of 3.25V so what would be a better assumption or how is the regular procedure for dimensioning shunt voltage references?

Regards,
Dominik


texts:
I've got a few questions regarding the power transformer used in typical linear power supplies (with full-bridge rectifier, filter capacitor, and voltage regulator).

A typical transformer datasheet will specify a full-load voltage, which is the RMS secondary voltage measured when the secondary is delivering its rated RMS current. Is it correct to assume that this VA rating only applies when the secondary voltage and current are both sinusoidal? For instance, if the bridge rectifier causes the current draw in the secondary to be pulsed (but the RMS value of the pulsed current is still equal to the transformer's rated value), then can I expect the secondary voltage to be sinusoidal at its rated value? In other words, how does the shape of the current waveform affect the transformer V-I ratings?
How would one go about determining the proper current rating for a linear power supply transformer? My immediate thought would be to approximate the current through the filter capacitor as a periodic sawtooth pulse and find the RMS value of the pulse waveform, then add maybe 50% to account for the fact that the transformer supplies current to the load while the diode is conducting and also to provide a decent safety factor. Is there a better way of doing this?
If you draw, say, 5 A of peak current on the transformer secondary, then for a 10:1 transformer, you'd be drawing 50 A of peak current on the primary. How is standard grid power able to handle such high repetitive peak current spikes without blowing a breaker?


texts: Explanation request of a circuit involving contactors, transformer and a 3-phase motor

texts:
I found this circuit in a machine, I removed it and installed a VFD instead.
 This is how it works:
when current arrives, the motor starts rotating, and the contactors K2 K3 and K4 close one after another with a 2-second delay.
There is a continuity between each set of wires and the wires in the other side.

I have 3 questions to understand it:

1. What is the purpose of this transformer?

2. what is the science behind it?

3. Can you explain to me the numbers in the transformer?

[![enter image description here][3]][3]

[3]: https://i.stack.imgur.com/DSYje.jpg


texts: Searching for electronics components in mouser.com

texts:
I'm trying to get into electronics and read that mouser is a good place.
I wanted to buy a couple of leds, just like this one.
But searching for "led" or "simple led" yields pages and pages of results.
How do I search for components in this kind of store? Do I need to be super specific to get right results or am i doing something wrong?


texts: Wiring 2 ac to DC power adapters together

texts: I have a mini amp and several powe adapters. Can I wire 2 6 volt DC power supplies together for the required 12v DC the amp needs? If so, how? And it suggests 2 amps. Are amps cumulative, and does it matter if they are different? the only relevant video i could find on you tube didnt quite fit my situation and i ended with more questuins than answers


texts: Getting different FFT results in LTspice comparing to MATLAB and Python

texts:
I have a 10 seconds of sampled data. Sampling rate is 1kHz. I uploaded the text file which is a two column time vs voltage data; it can be downloaded here.

I performed FFT in MATLAB, Python and LTspice. MATLAB and Python agrees when I plot but I get different result in LTspice.

Here below is the code I use and the plot with MATLAB:

ts = 0.001; %sampling interval (sec)
Fs = 1./ts;    %sampling frequency (Hz)
L = length(y); %number of samples
complex = fft(y)/L; % complex signals
f = 0 : Fs/L : Fs/2; % frequency bins
amplitude = 2*abs(complex(1:L/2+1)); % amplitudes
pow = (amplitude).^2/2*(L/Fs); % power
semilogx(f,20*log10(amplitude),'-b');
grid on;
xlabel('Frequency [Hz]')
ylabel('dB')

Below is the code I use and the plot with Python:

plt.figure()
y = v_in
T = 1/sampling_rate
N = len(y)
yf = scipy.fftpack.fft(y)
xf = np.linspace(0.0, 1.0/(2.0*T), N/2)
amplitude = 2.0/N * np.abs(yf[:N//2])
pow = (N/sampling_rate)*amplitude*amplitude/2
plt.semilogx(xf, 20*np.log10(amplitude),'b')
plt.grid()
plt.xlabel('Frequency [Hz]')
plt.ylabel('dB')

And finally I fed the signal from the text file to the signal generator in LTspice(by using PWL file option) and performed FFT and I get the following plot:

MATLAB and Python both show the max db point as -46.2dB but Ltspice shows this point as -49.3dB. This is not a very small difference.

What could be the reason for this difference? Am I doing something wrong in MATLAB and Python when evaluating FFT or LTspice is wrong?