texts: Energy Absorption By Series Resistance During Cap Charging

texts:
This question formed while trying to size a NTC thermistor to limit the inrush current to a capacitor. Assume the schematic below (with a fixed resistance):

simulate this circuit – Schematic created using CircuitLab

The total energy \$ E \$ provided by the inrush current to the capacitor is given by:

$$ E = \frac{1}{2} C V_{in}^2 $$

where:
\$ C \$ = the downstream capacitance, in Farads
\$ V_{in} \$ = the input voltage, in Volts

Many sources (http://powerelectronics.com/community/how-do-you-choose-right-type-ntc-thermistor-limit-inrush-current-capacitive-applications, http://www.ametherm.com/inrush-current/) use this equation to work out how much energy the NTC thermistor will absorb at turn on (when SW1 is closed).

This is where I am confused. I thought this equation tells you how much energy flows through the thermistor and is delivered to the capacitor. The NTC thermistor will absorb some amount of energy additional to this as determined by the integral of the voltage drop across the thermistor and current through it during the turn on period (both of these are changing dynamically).

Assuming those sources are correct, can anyone explain why the energy stored in the capacitor is equal to the energy dissipated through the resistor?


texts:
I found about the nRF24LE1 chips a while ago and they seem perfect for really small applications that require RF since they are the same as the well-known nRF 24L01 but include an 8051 MCU and memory.

But I can't seem to find much information on how to develop software for them. What I found was:

nRFgo SDK: This is the official SDK from Nordic, but it seems it's very Keil-oriented, and licensing is very, very expensive (about USD 5000).
DeanCording's version of the SDK: This seems to be an adaptation or complete rewrite (I'm not quite sure) of the SDK, and more friendly with SDCC. But this version hasn't been updated in 4 years, so the project seems to have been abandoned.

The Keil option is completely off the table for me.

There are guides on how to run SDCC with Eclipse, with the eclipseSDCC plugin. I haven't had much luck with these. On Windows, I get a NullPointerException when trying to run the "MCS51 Project" that the plugin adds, and on Linux (Ubuntu) the plugin seems to do nothing. It's worth noting that the plugin last release dates from 2006.

Has anyone been able to develop software for this device using free tools lately?

I was able to set up an SDCC toolchain on a Windows PC and manually compile example code from the libraries. But this is not practical for me and I'd really prefer to have an IDE instead of just a text editor.


texts: Circuit that would meet this requirement

texts:
A radio needs to be tuned to a range of values between 526.5 -
1606.5 kHz. Choose a combination of inductor and variable
capacitor values within a tuned circuit that would meet this
requirement. Choose practical components from standard vendor
web sites (e.g. Maplin/RS) if possible and provide full item
description.

I have done the working out but I keep getting a different answer.

$$L = 100\mu H$$

$$X_L = 6.28*526.5*10^3Hz*100*10^{-6}H = 330.642 \Omega = X_C $$

$$ C = \frac{1}{6 .28*F*Xc} = \frac{1}{6.28*526.5*10^3Hz*330.642 \Omega} = 91pF $$

$$ X_L = 6.28*1606.5*10^3Hz*100*10^{-6}H = 1,009.4 \Omega = X_C$$

$$ C = \frac{1}{6 .28*F*Xc} = \frac{1}{6.28*1606.5*10^3Hz*100*10^{-6}} = 990pF $$

C = 91 pF to 990 pF.
Closest standard values


texts:
I am using STM32L433CCT6 and I am programming it with eclipse and code genereted by STM32CubeMX.

I would like to ask you, if is possible to add iterrupt that will be called, if i press two (or more) buttons.

I mean something like this interrupt

void EXTI2_IRQHandler(void) {
    HAL_NVIC_ClearPendingIRQ(EXTI2_IRQn);
    HAL_GPIO_EXTI_IRQHandler(GPIO_PIN_2);
    {
        /* EXTI line interrupt detected*/
        if (__HAL_GPIO_EXTI_GET_IT(GPIO_PIN_2) != SET) {

            //what I would like to do when is detected rising/falling edge

            __HAL_GPIO_EXTI_CLEAR_IT(GPIO_PIN_2);
            HAL_GPIO_EXTI_Callback(GPIO_PIN_2);

        }
    }
}

but it will be called when I detect 2 pressed buttons, instead of rising or falling edge.

Thank you for your reply.


texts: Not able to read SPI signal with digital oscilloscope

texts:
I'm trying to connect my beagle board xm rev. C to an external SPI device. Before doing this, I want to study SPI signal coming out from SIMO pin when running the spidev_test program (included in the Linux kernel source tree under Documentation/spi/spidev_test.c).

The problem is that I cannot see any signal coming out from pin 19 (McSPI3_SIMO), although spidev_test is working fine. In fact, if I short-circuit pin 19 and pin 17 (McSPI3_SOMI), I can see a bunch of bytes going out and coming back. I'm new to oscilloscope so I'm doing something wrong for sure in setting the scope.

My scope is a Siglent SDS1000DL. It is new and it is working fine, since I tested it with other simple signals.

Reading the BB xm rev. C SRM (http://beagleboard.org/static/BBxMSRM_latest.pdf) I know the voltage levels on the expansion header are 1.8V. From what I understood this means that when I transmit an hex digit on the wire, for example '0xA' (in binary it is '1010', decimal '10'), I should see on the scope an impulse whose amplitude is 1.8V (the first logical '1'), then the signal should fall down to 0V (the second binary '0'), then again an impulse at 1.8V (the third logical '1') and in conclusion the last '0'.

For this reason, I set the Volt/div parameter to 1.8V, in order to have a logical '1' on the wire displayed as high as a single screen vertical division.

Regarding Sec/div parameter, it don't know the best value to set. The clock frequency of the SPI test signal is 500 kHz. I know this because it is an information printed on stdout when running the spidev_test program. 500 kHz is a period of 2 µs. I am wondering if setting sec/div to 2 µs has sense. My screen has 15 horizontal divisions.

For the physical setup I hooked up the probe to pin 19 (SIMO) and the probe alligator clip to pin 27 (GND). You can read which signals come out from which pin on the bb xm SRM, page 108.

Finally, I don't know what's the best probe setting, 1X or 10X (I have only these two options).

So I would like to ask to who already tried this kind of measurements; What are the best scope settings in order to capture and display SPI signals?


texts: "What power supply do i need to power 60 1.5v dc motors that draw about 200ma?"

texts:
We're trying to rig 6 bundles of 10 motors at a time, so 60 motors in total on the same power supply.
Each one normally is directly powered with 1.5v aa battery.
We read the current as 200ma per motor.

PS. I am dyslexic, and have severe learning disabilities. Forgive any grammar and punctuation issues.


texts: Scattering Matrix with Power Waves and Voltage Waves

texts:
I read that for a given N-port network there are two different conventions about  defining the incident and reflected waves.

This is the first convention:

This is the second convention (we see that there is a normalization with respect to the characteristic impedance of each line connected to each port; in general we assume that these lines do not have the same characteristic impedance):

In both cases Scattering parameters are defined in this way:

My question is this: is the Scattering Matrix the same for both conventions, or should we find it in both cases? If it is different, when we see S parameters in devices datasheets, which is the convention used?


texts: Ground loop isolation of a USB-powered device

texts:
I have a device (Device 1) that is bus-powered via Full-Speed USB and that is drawing up to 400 mA from a laptop.

Device 1 has a DAC that can output an analog voltage to another device (Device 2) through a jack connector, Device 2 being powered externally.

The problem is that if the laptop connected to Device 1 and Device 2 are connected to a different outlet, it creates a ground loop and its characteristic "hum". If the laptop runs on battery, there is no issue.

edit : The ground loop occurs when both devices are connected to the same laptop

I first thought about using a USB isolator such as the ADuM4160 which works great. Unfortunately it is too expensive for my application. Another solution that works fine is to use a USB Y cable, splitting data lines and power lines. However, I would prefer a solution that is fully transparent for the user.

As there is no problem with the USB Y cable when the USB data lines are not isolated, I was wondering if it was possible to use a similar principle used in ADuM4160 ((1:1) transformer) to isolate only the power lines from USB, leaving the data lines untouched. I haven't found such a component so I'm not sure about this.

I also had other ideas to perform an isolation at another place (i.e. between the DAC and the output) but it does not look convenient at first sight.

Do you have any recommandation or any other solution to avoid ground loops in this kind of setup ?


texts:
I'm trying to find out how "good" 5V power adapters can be with respect to power consumption if:

there's no attached power consumer, and/or
the consumer takes very little power, such as an ESP32 in one of its low-power sleep modes

Are there particular circuits that are known to be particularly good? And how would I hunt for products that implement those?

Clarification: I'm not meaning to ask about the state of the art in what's sold in the mass market market. Instead, I'm asking "what are the best circuits known", even if they are for very specialized niche markets, or aren't available in commercial products at all. E.g. -- just a wild guess -- could it be possible to build something that has essentially two separate circuits for different load situations and dynamically switches between them? Where the low-power one is made to produce, say, 10 micro-amps at 20% efficiency for the sleep states of the processor, and the high-power one is a "normal" one that is kept disconnected during the sleep state?


texts:
Hello for homework assignment I have to design an electric circuit which takes input from a light sensor and finds if the brightness is bigger than some value.
This is what I have done so far:

simulate this circuit – Schematic created using CircuitLab
Is the circuit working as expected?


texts:
So I want to make my own version of the iCade Any thoughts on how I go about doing the hardware side? Has anyone done an unofficial version of this? I'm thinking a combination of:

Concave Button
Arcade Joystick
PodBreakout
Arduino Mega

Any suggestions would be greatly appreciated!


texts: Qualitatively assessing time domain characteristics from bode plot

texts:
Given a bode diagram of loop transmission function, I have heard that it's possible to qualitatively assess the behavior of the system in time domain. These characteristics include delay time, settling time, overshoot and steady state error. My question is how?

For example, I know that the delay time in general increases when the relative degree of the system is increased. Are there any shortcuts like this that I can infer from bode plots? What parts in particular should I look for in a bode diagram?


texts:
I've got a little problem with a board I designed. What I tried to achieve is to control some LEDs with a microcontroller featuring an Arduino bootloader so that you can program it with the Arduino IDE.

As you can see on the picture, I've used an ATmega32U4, and flashed the Arduino Leonardo bootloader (Caterina-Leonardo) onto it, but it wasn't recognized as USB-device when I connected it to my PC (neither under Windows nor under Linux, nor was it recognized at all). Note that some caps between +5V and GND near the microcontroller as well as a cap between VBUS and GND are not shown on the picture but present on the board.

Flashing went without any problems, and the fuses were set just like another project featuring an ATmega32U4 I found on the Internet:

So when I measured D+ and D- of the USB-Socket, my oscilloscope showed the following:

So obviously something is not working right. By activating the CKOUT-fuse I was able to measure the clock on PIN7, so it seems that the chip does at least something. I then flashed a small example program onto it to set some pins to HIGH, but no matter what pins I choose I always get the following output:

Does anyone have any idea what is wrong or what I could do? I hope the chip is not dead after all. I also measured the +5V rail but it was very clean, much less noise than a "USB-5V".

I hope I didn't forget something important!


texts: How is it that powered speakers appear to deliver more power than they take?

texts:
As just one example, this spec of a JBL 15 G2 says:

  300 watts low-frequency and 100 watts high-frequency (bi-amplified) -
  actual power delivered to the drivers.

and also says:

  110 - 230 VAC, 50 - 60 Hz., 175 watts

I can only imagine that these ratings are being measured differently.  But I can't figure how.

(just to make sure it wasn't simply a typo, I found another example : 500W RMS speaker power, 130W power supply)


texts:
I've a circuit that have one input pin that should go LOW if one of two conditions is accomplished:

USB is connected;
Button OR Switch is pressed/slided;

If USB is connected Button or Switch is ignored and input pin is always LOW.

Button may be permanent or momentary. Switch is a standard 3 pin switch.

Input pin voltage rate is indifferent, so 3v3 and 5v it's ok.

The button/slicer need to be debounced.

The only debouncer and ON/OFF switcher ICs I've found(with low power consume and small package) are:

LTC2950
MAX16054
MAX6816

Initial state of input pin should be always 1 even if I reinitializate deboucers ICs.

I prefer a momentary button(if the name is right) if is possible, but if not switch it's also ok.

My main problem is that this pin should go LOW when USB is connected even if switch output is 1.

Can you advice me a solution?


texts:
So I soldered for the first time today and when I burp I can taste the smoke in my mouth and smell it in the air.

I only soldered for about 10-15 minutes at most.

Is there anything bad that can happen to me?


texts:
I want to create a circuit that will power my Raspberry Pi using Lithium Polymer. My knowledge of LiPo is rather low and I believe they can get dangerous if used incorrectly so I turn here.

THe intention is to create a LiPo battery (of two cells) that I can charge with a LiPo charge circuit chip of suitable type, that part I'm ok with.

Then I hope to use something like the LM2676 3A switching regulator to get the 5V out that I require.

My main question is, do I need any sort of circuitry when running the LiPo cells for protection, for example to ensure they don't get discharged too much?


texts:
I am getting these errors while running simulation in proteous.
[SPICE] transient GMIN stepping at time=7.87403e-006
[SPICE] TRAN:  Timestep too small; timestep = 1.25e-019: trouble with node #00004.
Please help me out....


texts: A basic question about amps, watts, and charging batteries

texts:
Why do we speak of watts (and not amps) when we refer, for example, to the "7.5W Wireless Charger for iPhones," but when we talk about cord-based USB charging, the specs typically refer to amps (and not watts). For example, one page explains that the "USB spec is 500 mA maximum current. The charger provided with your iPhone can provide up to 1000 mA."

The difference between amps, watts, and volts is something I have struggled to understand since high school, which was a long time ago for me. I've re-read your standard references like Wikipedia, but I'm still not getting it.

Can someone help me understand these concepts by demonstrating how I would apply them to understand how to compare the difference, in performance, between a 7.5W wireless iPhone charger and a 1000 mA corded USB charger?

Thanks in advance for your help and patience.


texts: How does flyback diode decrease the response time of a solenoid valve

texts:
Dear all StackExchange users,

I want to make a circuit consisting of 8 valves. Each valve has 55mH and 33 ohm. I want to control them with an Arduino board and a proper MOSFET. Valves reaction time is 0.05ms and I want to drive them about 10 times per second, 5 times off and 5 times on. Valves are 12Vdc. The battery is also 12 Vdc.

I know that I have to add a sort of flyback diode to protect the MOSFET from high voltage while I switch each of the valves off. I know how a single flyback diode, flyback diode + resistor and a Zener & diode can protect it.

Also I know that Zener is much faster than a single diode.

My main problem is that I don't know which part of I-t or V-t signal I should look to see the valve is turned off. I am using LTSpice. So I'd be thankful if you could guide me through this.  In other words, When the valves are off after 5vdc is gone?!

Also in the simulation when I generate the 5vdc to MOSFET I see that the Voltage of the line that goes to ground is going from 12VDC to 0VDC. I really don't understand what's happening. Because when I connect the 12VDC directly to the coil and the coil to the ground, it remains 12VDC and doesn't go from 12VDC to zero!!

It is about 10 years since I passed electronics course in my bachelor years... so please forgive me if I am asking for the obvious.

Also I am coming from here "Can a Zener diode that protects a switch against inductance when the switch opens, affect turn on speed of the valve while you close it again?"
Isn't the energy dissipation normal?

UPDATE: I checked the response time experimentally: 70v Zener = 8ms, with simple Diode 25ms.


texts:
I bought this USB programmer: USBasp USBISP 3.3V / 5V AVR Programmer USB ATMEGA8 .

But I can't understand how to connect it. This picture has got 9 circle inputs and 1 square input but all the inputs are square in my item. Can anyone help me step by step because I am a beginner.


texts: Arduino with L298N Motor Driver and external Power

texts:
I would like to control a slave clock which requires 24v applied for approx 1/2 second in alternating directions once every minute and have bought a Arduino Uno to control the pulses.  The Arduino is synchronised to radio time via a DCF77 module.

In order to drive the clock (which is an inductive load) I propose to use a L298N module as this has an H-bridge to easily reverse the polarity of the pulses.

So far so good.

I have bought myself a cheap 24v power supply and when manually directly connecting the power one way and then the other to the clock the minute hand advances correctly.

My question relates to wiring these three components together whilst at the same time developing the required software from my PC.

The UNO is powered from the USB port of my PC, which is also used for serial communication during programming and serial I/O during operation of my sketch.

The L298N will additionally require power from the 24v adapter.

In order for the circuit to operate I understand that I will need a common ground between the Arduino and the L298N.  This seems to imply that I need a common ground between my 24v cheap adapter and the ground side of the USB coming out of my PC.

Is this a safe configuration?  Or is there a worry that the ground side the my PC's USB port and the outer sleeve of the 24v power supply are at different potential and that this is dangerous?

Advice appreciated before I plug it in!  Thanks!


texts: Safe shutdown/restart Raspberry Pi due to a power loss

texts:
I am a total beginner in electronics so I need your advice. Does this simple circuit provide for a safe shutdown, with two super caps of 10F?

(Original image)


texts: Is the peripheral mapped I/O different from what is known as port-mapped I/O or simply known as I/O mapped I/O? I don't see the usage of the term "peripheral mapped I/O" around much. Was it only relevant to 8085 microprocessor?


texts: connecting an LED to a (sideglow) fiber cable

texts:
For one of my projects I need to glue a (sideglow) fiber cable to an LED.

I have never done something like this before, therefore I wanted to know if you have any experience on how to do that and how not to do that.

I would use (transparent) epoxy glue. Is this a good choice?

Is a 3mm LED big enough for a cable with 3 mm diameter?

Should I "pretreat" the LED somehow (maybe drill a hole or cut the "cap" to make it flat) or is it possible to fill the gap with epoxy?

Some of my further considerations that I have arrived at are as follows:

Whatever kind of glue one uses, it will never transport light as good as air. This is why I think it would be the best option to use a tube and put the led and the fiber cable inside. I would then glue the fiber and the led to the tube (and probably use hot glue, but epoxy may be even better).

[edit]

Don't want to have this question unanswered at all, therefore I share some of my further considerations:

Whatever kind of glue one uses, it will never transport light as good as air. This is why I think it would be the best option to use a tube and put the led and the fiber cable inside. I would then glue the fiber and the led to the tube (and probably use hot glue, but epoxy may be even better).


texts: Compact thermostat for VCO temperature stability

texts:
So I have a voltage controlled oscillator with an exponential input made using the THAT2181 VCA IC. The schematic is shown below - the THAT2181 IC is used to change the C4 capacitor charging current and, therefore, the output frequency depending on the LOWCV input.

The problem is the thermal stability of such a solution - THAT2181 has a 3300ppm temperature dependance and for precise audio it is unacceptable - with the same input the schematic will output 807 and 837 Hz signal at 25 and 35 degrees Celsius respectively.

A typical solution for this problem is adding a 3300ppm NTC thermistor divider at the input, but those are hard to find, not exactly precise anyways and manufacturers today move towards "IC heating solutions" in transistor array ICs using one of the transistors in it as a heater.

So, my question is: what will be the most compact, yet cheap solution for THAT2181 IC heating in my schematic? I've looked at the PTC heaters, but the minimal transition temperature of them is about 60-70 degrees Celsius, which is way too hot (I am looking for about 40 degrees) and adding a microcontroller feels like an overkill.


texts:
This is my diagram:

I'm running a breadboard with a NodeMCU powered by a USB 5V say from my laptop.

From the NodeMCU, I'm taking a 3.3v out to the VCC of the Relay and GND to GND of the relay with a D4 or D6 as my data pin to IN1 on the relay.

On the other side, I'm running a twisted wire pair from an AC strip to the relay and from there to the bulb.

I've stripped one wire and run it into the NC port and the same one comes from the COM back to the bulb.

My question is, is this okay and am I gonna blow something? I've not used resistors or the like. Also, can I run the bulb also through a DC source like a 9V battery instead of pluggin into the AC mains?

Update: I'm a nOOb to electronics so to clarify certain things,
1) The "lamp" is a 3W LED in a normal bulb holder. The bulb is rated at 220-240VAC at 50Hz
2) It is very possible I got the diagram wrong. It is my understanding of how the relay circuit works.
3) The relay is actually a 4-relay board with an opto-coupler etc (Refer to image)

Relay Board link: REES52 Relay with Optocoupler

Imgur link to actual photos of my setup


texts: System Identification in a closed-loop feedback system

texts:
I have an unstable system that doesn't have a useable output when open-loop excitation is applied.

Subsequently I've used a controller to control its output. I want to use the system identification tool on MATLAB, but don't know how to calculate the open-loop input to the plant for a closed-loop system.

All the reading material is advanced and theoretical and has largely gone over my head.
Can anyone explain how this open-loop plant input can be derived from known parameters of the controller and the plant output?


texts: How does freezing temperature affect electronic equipment?

texts:
What happens if you put a simple circuit like a timer with a 555 IC and, let's say, a DC motor, including 3 AAA batteries in a freezer (around -15 centigrade) in a working state?

If it does harm the IC or DC motor or batteries, is it just because of the freezing temperature or the moisture - or both?

Is there any way to avoid damaging the equipment, like a vacuum or foam (as insulation) or a little heater?


texts: Common Emitter amplifier Bias Circuit Simplification

texts:
This is a slide from one of my semiconductor devices lectures. I understand how the bias circuit works and how to calculate the resistor values however I do not understand how this simplification works.

I see that the capacitors and Vcc source has been removed however I cant understand how the two circuits are equivalent as wouldnt current I1 (from R1) and Ic (from Rc) be different when connected to the AC source?

Thevenin simplification comes to mind but maybe i'm not on the right track!

Any help appreciated.

Andy


texts: Is it possible to make a footprint off an assembly of pads in a gEDA PCB layout?

texts:
I have spent hours carefully assembling a couple of pads to form the footprint of a Bourns PEC11S rotary encoder. Now I'm stuck in the procedure I know, i.e. «Cut to buffer», «Split buffer elements into pieces». Of course, the procedure assumes we're starting with an existing footprint but in my case I've opted to layout pads on a PCB... in the hope I could get away with it — the reason behind is making SMD footprints from scratch is a complete nightmare in gEDA since pads are converted back to tracks, which are rounded. That's very, very disturbing. To me at least.

So I created SMD footprint files for rectangular pads of given dimensions and I've placed them as if they were components on a PCB. I've tried to combine all the tricks I know but in vain: I either get an empty buffer or no footprint at all. I think the reason is all my pads are still viewed as separate components and I'd like to merge all pads in a single component, keeping all the relative distances.

Here's the pad layout:

Is there a way to quickly convert the assembly of pads into a footprint?


texts:
I am building an electronic tachometer for an old motorbike (a moped).

For RPM monitoring I have come up with a solution of painting part of magnet black and using a TCRT5000 reflective sensor which is fed to a LM393 comparator which finally drives an interrupt pin on an ESP32. A DAC pin from ESP32 is used to set the LM393 threshold as a means for sensitivity control. There is about 100 - 150 cm of cable which needs to be routed more or less near the spark plug wire to the handlebar. The circuit has its own power and is isolated from the motorbike. For completeness: the motorbike has an induction coil and contact breaker. The spark plug cable is strained copper about 20 cm long.

The problem is that when the engine runs there is so much EMI from the spark plug and its cable that it causes countless interrupt firings. The interrupts happen only when the cable is connected to the pin. I am using a 3 x 0.08 mm microphone type cable with the shield connected to ESP32 ground and not used for communication.

So far I made the following improvements with limited success:

a low pass filter at 300 Hz (R = 5.1k, C = 0.1uF) at the
microcontroller side
changed 10k pull up at the comparator output to 1k
added two 1N5819 Schottky suppression diodes at the microcontroller side
wrapped the spark plug wire with household aluminium foil, connected to motorbike chassis (this to my surprise helped quite a
bit)

I am looking for practical solutions to my problem: preventing EMI propagation at the spark plug wire and shielding at the data cable. The space inside the motorbike compartment (where the sensor is located) is very limited so a more complex circuit cannot be put there (like a differential driver). Also, the spark plug cable cannot be changed nor relocated. Any other idea is basically doable. What are the best practices, which type of cable is to be used, etc. I am not an expert in electronics so I would be happy if answers included sources to allow me to further study the matter.

For the record: the setup is tested on the bench with an electro motor and at around 8k RPM still works as intended. I am unfortunately unable to include an oscilloscope measurement image as I do not own one. I hope an expert in the field can guess pretty well what is happening inside the cable.

Thank you in advance!

Suppression diode idea taken from here:
https://www.digikey.com/en/articles/techzone/2012/apr/protecting-inputs-in-digital-electronics

Motorbike's technical book with electrical scheme (unfortunately Slovene):
https://www.google.si/url?sa=t&rct=j&q=&esrc=s&source=web&cd=10&ved=2ahUKEwjH7fXeg6PhAhVx-ioKHXaoDZQQFjAJegQIARAC&url=http%3A%2F%2Fwww.obnovi-si.si%2FSlike%2Fkatalogi%2FKatalog%2520rezervnih%2520delov%2520Tomos%2520Apn%25204.pdf&usg=AOvVaw2RTRIM5KcCoMEm13dPCL8S

Cable (unfortunately German):
http://www.produktinfo.conrad.com/datenblaetter/600000-624999/608065-da-01-de-MIKROFONKABEL_3_X_0_08_MM2.pdf

Edit 09/04/2019:

I was finally able to measure what is happening within the cable with a cheap usb scope. I am surprised that the signal going to the comparator is actually very clean, yet the interrupts fire randomly. The picture shows the non inverting input on the comparator.


texts: How does being exposed to strong radiations effect nanosatellite electronics equipment?

texts: I'm on paper designing a nanosatellite power system. The satellite would be orbiting in LEO. And I am wondering how and what type of radiation would affect its electronics. The system has a microcontroller, a few inductors, a few transistors, capacitors and some op-amps. How does one actually shield a nanosatellite from radiation? Does the metal box of the power system help? Or should the nanosatellite be made of some particular material to protect the subsystems from radiation?


texts: Driving MOSFET/IGBT - Why Miller Plateau is a plateau?

texts:
I'm currently trying to understand what the Miller plateau is: what the different parameters that influence the Miller plateau are, when it begins, and when it ends. I'm reading document "Fundamentals of MOSFET and IGBT gate Driver circuit" from Texas Instrument, but it misses some details for my understanding.

Miller plateau seems to begins when the diode (consider a buck converter) stops conducting. Then the drain voltage is now not clamped to Vout by the diode and the source to drain voltage can diminish. The Cgd capacitor previously charged between Vgate and the drain voltage which was equal to Vout must release some charge as the drain voltage diminish! So some current is flowing from the driver to the drain "through" Cgd capacitor. Here is the question: why is the current steady? If the driver output current is able to source more current than the Cgd capacitor is able to discharge itself, the current should not be a plateau and inversely, why this plateau is so long? Did I make a mistake?


texts: Does anyone here know anything about ce marking? If I want to design a new electronic product and sell to europe I have to include the ce marking in the pcb. I have found many informations about the design rules for the EMC derictive, but i didn't find much about the Low Voltage Derictive and the Machinery Derictive. I'd like to find some guidelines for the design for these two Derictives.


texts: Quick digital receiver for Manchester encoded data?

texts:
I want to implement a digital Manchester encoded data receiver. The application is not dissimilar to the KeeLoq system. That is, there is no time for long link training - I want the receiver to recover the clock and parse the data from a single packet, without relying on anything before or after it. Since this is a digital receiver, the receiver has 100s of samples worth of history to re-process to allow it to do this.

I am finding clock recovery harder than expected. Averaging the number of samples between each transition and taking this as the half-bit period works in many cases, but simple simulations show that with certain payloads (i.e. those with lots of transitions) this average is pushed too high. In any case, skewing of the estimated half-bit period due to these, even when it still works, will surely mean the receiver is less robust than it could be. I have a preamble which facilitates clock recovery, but I can see (with simulation) in some cases it will not be long enough and the average is skewed too much by the full-bit periods in the payload. My application is unusual in that the underlying line rate is very low, so efficiency and latency is important.

There must be some way to take advantage of the bimodal nature of the period distribution to make a very reliable estimator, but I can't think how to do it efficiently.

What is a good approach to a digital Manchester receiver, with very low latency link establishment?

By efficiently, I mean computationally - I can probably do a brute-force search comparing the differences between normalised histograms, but I wondered if there was a better way.

EDIT:
It occurred to me just now that I don't need to match a distribution to a histogram, because the Manchester encoding by nature applies another constraint: the distance between the peaks is related to the peak bin itself. So all I have to do is find the highest peak in the histogram, and then determine whether I have found the half or full width interval, by looking at the bin values x2 above or 1/2x below.
I will prototype this and see if it works, but of course leave the question open for better ideas!


texts: Why is this power adapter transformerless?

texts:
I saw a battery charger that converts 220V AC to 6V DC without a transformer.

Now I am wondering why many (if not all) power adapters are using a transformer, is it about efficiency or about drifting over time?

Update:
This circuit is inside of this torch


texts: Minimum wiring for remote ST7735R SPI TFT display

texts:
Figure 1. ST7735R 1.8" TFT colour LCD. Image source: eBay.
I have an ST7735R working on an Arduino Nano as shown below.

Figure 2. Current setup.
I want to try mounting the display remotely (< 1 m) from the micro-controller.

I'll need separate wires for Vcc, GND, DIN (SDA) and CLK (SCK). That's four.
BL (backlight) can be wired locally.
I won't be using the SD card functionality.

Does anyone know if any of the RST, CS and D/C pins can be permanently grounded or connected to Vcc (via the 3.3 V / 5 V resistors) or are they required in boot or during operation? Any documentation I've read doesn't mention it and any pointers would save me some time figuring it out by trial and error.
Links:

UCGLIB library.


texts: Driving laser modules with MCP23017 and MOSFETs

texts:
I would like to make a PCB to switch 16 laser modules on and off.

The laser module in question is this one: https://www.sparkfun.com/products/9906

I believe the module already has a driver included (there's an IC on it), so I shouldn't be too worried about directly controlling the laser diode, instead I will just need to power it.

The maximum power draw is 300mA but Sparkfun was able to boost it to 400mA.

So I thought of using an IO expander like the MCP23017 since the ESP32 board that I'm using doesn't have too many digital pins left over.

The IO expander then is connected to the gate of an N-channel MOSFET: the MMBF170LT1G. This has a continuous drain current of 500mA, so it should be enough.

To get the power required for 16 lasers I'm including a couple of SKM10B-03's from MeanWell. These convert incoming 24VDC from an external power supply to 3.3V. To drive 16 lasers at 1W each I'll use two of them.

Is my schematic below correct (just showing one laser for simplicity)? Do I need a resistor between the gate of the MOSFET and the pin of the MCP23017? I first considered using a transistor array instead of individual MOSFETs but I'm not sure they can stand continuous operation of all lasers, since often they share a common ground pin?

Note: The ESP32-PoE-ISO by Olimex already has pull-up resistors for I2C. I also put a 10k resistor on the trim control of the SKM10B, this is to trim the voltage up if needed. I probably won't include the resistor and leave the trim free floating.


texts: How does a fiber optic receiver converts the optical signal to an electrical signal

texts:
A fiber optic receiver needs to convert the incoming optical signal to an electrical signal so it can be sampled. How is this achieved in practice?

I believe a photodiode is used, but would a photodiode not have the problem that the frequency of the incoming optical signal is too high? Such high frequencies cannot propagate through the conductors.

This is what Wikipedia says:

  Coherent receivers use a local oscillator laser in combination with a pair of hybrid couplers and four photodetectors per polarization, followed by high speed ADCs and digital signal processing to recover data modulated with QPSK, QAM, or OFDM.

If I am not mistaken, this implies that you interfere the incoming signal with one of a plurality of coherent optical reference signals such that each of said reference signals is equal to one possible received signal. This way you can detect whether the input signal is one of the expected values given the interference pattern. Another possibility is to have each reference signal be such that it destructively interferes with the incoming signal. But wouldn’t that limit the modulation schemes you can use? Can you use frequency modulation over fiber optics?

Any references, block diagrams etc. will be greatly appreciated.


texts:
I am wondering what the voltage ratings on passive scope probes really mean.

Suppose there is an inductive spike that exceeds the rating.  Will this damage the probe?  Will it damage the scope?  Is it a safety hazard to the operator?

My current thinking is that the shunt capacitor in the probe might fail short-circuit, removing the attenuating properties of the probe, and then exposing the scope to the same problematic voltages.  If this is the case, then I would think the probe should be rated against the worst-case inductive spike (which is both large, and difficult to predict), unless the scope itself has some protective circuitry against those voltages (does it?).


texts:
Here is a band reject filter with its transfer function and bode plot. I don't understand how the pole frequencies and zero frequencies are drawn on the bode plot. Even with the pole and zero frequencies given, the math in the transfer function didn't come out to be correct.
According to definition, a pole is when the denominator is zero and the transfer function approaches to infinity, and a zero is when the numerator is zero where the function approaches to zero. So to determine the frequencies for poles, I set the denominator to 0:
\$ 2\big(1+{\tau s \over 0.44}\big)\big(1+{\tau s \over 4.56}\big) = (2.0064-\tau^2\omega) + (5\tau \omega \hat j)\$ =0
where the first bracket is real and the other bracket is imaginary. There is not one frequency that can possibly make both the real and imaginary part of the algebra to be zero!
The book gives pole frequencies at \$ 0.44 \over \tau \$ and \$ 4.56 \over \tau \$. If I choose \$ 0.44 \over \tau \$ and plug that into the denominator, then what is in the bracket of \$ \big( 1+ {\tau s \over 0.44} \big) \$ will just be \$ (1+1\hat j) \$, not a zero either.
And for zeros, if I plug in \$ \omega = {1 \over \tau} \$ to the nominator, I'll end up with \$ (1+\hat j)(1+ \hat j) = 2 \hat j\$ and that's not taking the transfer function to approach zero either.
So how do \$ 0.44 \over \tau \$ and \$ 4.56 \over \tau \$ come out to be the pole frequencies, and why is \$ 1 \over \tau \$ the zero frequency? None of these frequencies take the transfer function to infinity or zero.


texts: Why high impedance source in ADC input causes error?

texts:
Recently, I had a problem with two sensors (LDR and LM35), when I tried to read them in Arduino ADC, both measures were totally wrong. Searching in the internet, the answers are related with high impedance of voltage divider provides to analog pin of ADC. So, I used a op-amp to provides a low impedance and result was great, but the doubt is still in my head.
The sample and hold of arduino have a tiny leakage current (0.1 uA), i'd like to know how the high impedance source affects the ADC.


texts:
I'm using HAL to use I2C and somemtimes I'm getting HAL_BUSY flag, I read STM32F103 errata and added BUSY flag clear according this,
i2c busy flag clear
But I changed error handling little bit and is it right?
do
{
   status = HAL_I2C_Mem_Write(eeprom_handler.instance, (uint16_t)device_address, mem_addr_masked,
                             I2C_MEMADD_SIZE_8BIT, src, bytes_to_write, 1000);
   if (HAL_OK == status)
   {
       bytes_written = bytes_to_write;
   }
   else if (HAL_BUSY == status)
   {
       I2C_ClearBusyFlagErratum(&eeprom_handler, 1000);
   }
   else // if HAL_ERROR, or HAL_TIEMOUT
   {
       return;
   }
}
while(status != S_OK);

in other words, try to write until status will be HAL_OK, because without do while loop, the write procedure will be skipped.
So is this do while  loop the correct way to handle Write/Read functions?


texts: Transformer vs Inductor for lighting a bulb or any other appliance

texts:
There was a question in my school physics exam which is as follows:

  Consider a 100W bulb which operates at 50V dc. John wants to light this bulb by a 200V ac source. What component should he use, also give its specifications.

The answer to the question is an inductor, with which I have got no issues.
But in the exam, I wrote my answer to be a step-down transformer, which I have myself used for such applications. In the explanation I wrote the following:

A step-down transformer shall be used for this purpose. The specifications would be : 200V/50V (rms). The 50V rms voltage will dissipate the same power as 50V dc in one cycle, so irrespective of the current required, supplying the required voltage will achieve the same results. The winding of the primary and the secondary coils will be in the ratio 4:1 (assuming lossless transmission)

My teacher didn't accept this answer and neither did she give any explanations for why my answer was wrong.
Despite having used it myself for the same purpose (powering my ac motors which operate at lower voltages - 12V), my answer was marked incorrect.
Why is it so, or is it incorrect at all (since the question was ambiguous, I chose to write transformer as my answer)?


texts: I plan to use http://www.nordicsemi.com/eng/Products/Bluetooth-R-low-energy/nRF51822  to develop some products. I plan to get a breakout board made but even if I do have it made I was curious as to how I could actually get the code on the device. I guess I will have to use an external debugger. The recommended one is the J-Link segger but will something cheaper which I found like http://www.ebay.com/itm/J-link-V8-ARM-Emulator-ARM7-ARM9-ARM11-Cortex-M3-ADS-IAR-STM32-JTAG-Interface-/310747521001?pt=LH_DefaultDomain_0&hash=item4859fedfe9 work. If not are there are other alternatives for me?


texts: What is the difference between a 2 and a 3 solder terminals socket (coaxial jack dc)

texts:
I'm not pro with electronics and electricity and I want to replace my notebook socket so I'm looking for a coaxial jack dc socket but, as I only have two cables (a positive and a negative one) to solder to the socket, I can't see the purpose of a third solder terminal.

Is it for the grounding or something like that ? Can I use such a socket without using the third terminal ? (If that's the case, which one am I supposed not to use ?).

I know that I could directly buy one with two terminals but that's not the question.

 (two terminals)

 (three terminals)


texts: Sampled offset voltage data and its uncertainty

texts:
In a measurement process sometimes contant voltage output of a for example force transducer is logged as offset as a bias to be subtracted later from the dynamic measurement. When the sensor is at rest, this offset is sampled at a specific sampling rate and specific duration.

If we have the sampled data in time series of this offset how can we calculate the uncertainty of the mean value of the offset?

I mean what is the uncertainty of the mean value of the offset due to random noise? Is it the standard deviation or standard error? I want to be able to say “This is the mean value of the offset with this standard uncertainty”


texts: Regenerative braking on an electric bicycle

texts:
I'm currently trying to build myself an electric bicycle with a regenerative braking system.

I am however stuck on the regenerative breaking part.
The bike will include a simple DC motor, powered by two 12 Volts batteries connected in series. The motor will ALWAYS be connected to the wheel via a chain.

From there, there are 3 possible scenarios:

I want to accelerate using the motor, in which case the batteries will simply be connected to the motor, which in turn will rotate and apply some extra torque on the wheel and thus the bike will accelerate.
I don't want to accelrate nor brake (using the electric bicycle as any other normal man-powered bicycle), in which case the batteries will simply be disconnected from the motor via a switch.
I want to brake, using the regenerative breaking system.

Now this 3rd scenario is where I need help. The idea I have is that the motor will be driven by the wheel which will be rotating quite fast. The motor would then be used as a generator, used to re-charge the batteries. However, I have trouble figuring out how to do this/what circuit to use.
Am i right in assuming that the generator (the motor driven by the wheel) will never produce more than the 24 V of the batteries, and I thus need to find a way to reduce the P.D. of the batteries, if I was to simply inverse the circuit?


texts: How can I easiest (cheapest) I'm within EMC regulations?

texts:
I'm a hobbyist that's currently developing a simple clock and hoping to make it into a small scale sellable product. It's a simple 5V USB clock with a ATTiny84 8MHz clock, a RTC-module and some WS2813 LED's. It's simply powered by a USB-cable and no power regulation is done on the chip.

Current regulations in Europe require it to be CE certified since it has MCU with a clock-speed of >9kHz. So if it didn't have the ATTiny84, it would not even be required for certification.

But now since I need to certify it, I want to do some testing to make sure everything is alright. However I want to do it in the easiest and cheapest way possible.

What would minimum testing be?
It it enough to do it with some standard in-house testing equipment
(spectrum analyser, H-probe, LISN etc)?
Pre-compliance testing?
Or do I not have any other choice than to pay for a full compliance
testing?


texts: Microchip 48LM01 memory secure read operation CRC and STM32 hardware CRC

texts:
I'm trying to use STM32 hardware CRC calculation mechanism to get CRC value from this data (3 byte address and 128 bytes of data):
// address
0x00 0x00 0x00

// data read
0x00 0x01 0x02 0x03 0x04 0x05 0x06 0x07 0x08 0x09 0x0a 0x0b 0x0c 0x0d 0x0e 0x0f
0x10 0x11 0x12 0x13 0x14 0x15 0x16 0x17 0x18 0x19 0x1a 0x1b 0x1c 0x1d 0x1e 0x1f
0x20 0x21 0x22 0x23 0x24 0x25 0x26 0x27 0x28 0x29 0x2a 0x2b 0x2c 0x2d 0x2e 0x2f
0x30 0x31 0x32 0x33 0x34 0x35 0x36 0x37 0x38 0x39 0x3a 0x3b 0x3c 0x3d 0x3e 0x3f
0x40 0x41 0x42 0x43 0x44 0x45 0x46 0x47 0x48 0x49 0x4a 0x4b 0x4c 0x4d 0x4e 0x4f
0x50 0x51 0x52 0x53 0x54 0x55 0x56 0x57 0x58 0x59 0x5a 0x5b 0x5c 0x5d 0x5e 0x5f
0x60 0x61 0x62 0x63 0x64 0x65 0x66 0x67 0x68 0x69 0x6a 0x6b 0x6c 0x6d 0x6e 0x6f
0x70 0x71 0x72 0x73 0x74 0x75 0x76 0x77 0x78 0x79 0x7a 0x7b 0x7c 0x7d 0x7e 0x7f

When I send SECURE READ opcode, and 0x000000 address to 48LM01 chip it responds with 128 bytes (above) and CRC value: 0x9D3D.
Datasheet says, that this chip uses x^16+x^12+x^5+1 polynomial and initial value is 0xFFFF.
This is my (wrong?) CRC configuration in STM32CubeIDE:

And here is my code:
#define TEST_DATA_LEN 128
#define EERAM_ADDRESS_BYTES 3

typedef struct {
    uint8_t address[EERAM_ADDRESS_BYTES];
    uint8_t data[TEST_DATA_LEN];
    uint8_t crc[2];
} buffer_t;

// (...)

buffer_t buffer;
buffer.address[0] = 0;
buffer.address[1] = 0;
buffer.address[2] = 0;

// fill buffer with test data from 0 to 127
for (uint8_t i = 0; i < TEST_DATA_LEN; i++)
{
    buffer.data[i] = i;
}

uint32_t computed_crc = HAL_CRC_Calculate(pCrc, (uint8_t*)(&buffer.address), TEST_DATA_LEN + EERAM_ADDRESS_BYTES);

// memory contains data from 0 to 127 starting from 0 address
// my function reads it correctly and reads also 2 bytes of CRC
buffer_t readBuffer;
EERAM_SecureRead(0, &readBuffer.data);

// readBuffer at this point contains correct data and 0x9D3D CRC

After many tries (with inverted byte order, inverted data/address positions) I can't get 0x9D3D CRC.
I have found some page (link to crccalc.com) with many CRC type calculations, but none of them returns 0x9D3D.
What is wrong with my CRC calculation?


texts: Simple soft power latching circuit for a microcontroller

texts:
I'm building a simple device with a microcontroller and I'd like to be able to turn it on and off using the "hold a pushbutton for 2 seconds" trick that is found on so many consumer devices nowadays (bluetooth headset, USB powerbank, smartphone.. come to mind). This feature seems to be called "soft power latching" but all the schematics I can find to implement it have drawbacks that make them impractical for such application, such as :

overly complicated, too many components for a small PCB such as found in a bluetooth hand-free headset
sometimes erratic behaviour in some borderline use cases such as a peak of current draw
need two separate buttons for on and off, or act as immediate response and do not allow for a 2-second-ish delay
a non-negligeable amount of current is consumed either at the on or off state, or both.

I thought such feature would easily be found implemented in a small IC for such applications, for example one with a pulled-up input for the push button, an external resistor/capacitor to configure the delay, and an open-drain output to control a pass-transistor or an EN pin. A Clear input pin to allow a software shutdown, a way to be able to use the pushbutton by the microcontroller as a user input, and a way to detect an imminent shutdown to perform a cleanup routine, would also be necessary in my case. However I fail to find such chip (granted I might not be using the right keywords). The closest I've found is the MAX16054 but it is a bit expensive for such feature and doesn't allow for the 2-second-hold delay (adding a capacitor beside the button seems a bit hacky because it would rely on the activation voltage of the IN pin).

I've therefore imagined a simpler/smaller/cheaper circuit that looks like it would match all the requirements but I'd like an external opinion on it, because it doesn't feel right that I can't find anything similar documented anywhere for such a useful and widespread feature :

It works like this :

the LDO's EN is pulled low by R3 and Q1 is pulled in a blocking state by R2, ensuring the LDO is off by default
when the button is pressed Q1's grid is pulled low, making it conductive and pulling EN high, which powers on the microcontroller
the MCU waits for two seconds then ouputs a low state on its PIN0 to permanently enable the LDO even if the button is released, allowing the delayed-latching behaviour (if the button is released before the delay, there is no latching : the LDO is disabled immediately)
the voltage across the button is pulled high again by R1 and made independent from Q1's grid by D1, allowing it to be used by the MCU through PIN1
the software is responsible for implementing the turn-off behaviour as required by reading PIN1 and releasing PIN0 to shutdown itself after doing the required clean-up

My questions are therefore :

would this circuit work and are there drawbacks I'm not thinking of?
why this kind of simple and useful IC doesn't exist and how is it implemented in consumer devices? (or alternatively, am I bad at searching?)

Edit : the circuit above will not work because the ESD diodes in the microcontroller will pull the lines low when the LDO is disabled (thanks @ElliotAlderson for pointing it out). Here is an updated version which should address the issue :


texts: Small low power circuit power domains inrush

texts:
I have a battery powered circuit using a MCU and several peripherial circuits (eg. an SD Card slot, small audio amplifier).

The peripherials are rarely used, but the MCU is constantly running. So the peripherials are switched on and off by low side FETs to stop them draining the batteries.

However, the inrush current from switching a SD-Card or audio amplifier creates a temporary voltage drop, that causes the MCU to restart by brownout / blackout detection.

I don't like to add capacitance to the main circuit, as it's leakage would drain the batteries while the peripherials are off.

So what else can I do?

Experimentally adding resistors to the peripherial power lines do stop MCU resets, but I don't want to risk flaky behaviour / incompatibilities of the SD-Cards of course, or audio distortions.


texts: Why would you want a SMPS to be PWM under light load?

texts:
I am looking at the datesheet for a buck regulator AP6320x. There is one variant the AP63201 that states,

Pulse Width Modulation (PWM) Regardless of Output Load
o AP63201
Supports Pulse Frequency Modulation (PFM)
o AP63200, AP63203, and AP63205
o Up to 80% Efficiency at 1mA Light Load
o Up to 88% Efficiency at 5mA Light Loads

I am wondering in what circumstance you would want to choose the AP63201, given the part price is the same. Why would you want continuous conduction mode at low load, and what are the trade offs/benefits of it vs switching to PFM?
There is the following text on page 10,

... As the load current approaches zero, the AP63200, AP63203, and
AP63205 enter Pulse Frequency Modulation (PFM) to increase the
converter power efficiency at light load conditions. The AP63201
remains in continuous conduction mode at light load conditions. When
the inductor current decreases to zero, zero-cross detection circuitry
on the low-side power MOSFET, Q2, forces it off until the beginning of
the next switching cycle. The buck converter does not sink current
from the output when the output load is light and while the device is
in PFM. Because the AP63200, AP63203, and AP63205 work in PFM during
light load conditions, they can achieve power efficiency of up to 88%
at a 5mA load condition

datasheet


texts: Digital/Analog voltage conversion and switching

texts:
What circuit topology should I use for digital high voltage (20v-30v) to low voltage (3.3v-5v) conversion (for MCU input) and vice-versa? I can think about the following topology:

Voltage divider based
Power MOSFET based switching with NMOS gate drive

Further to this question, what topology should I use for analog voltage and current input from high side (20-30v) to MCU side (3.3v-5v) for ADC input? I can think about the following topology:

Non-inverting Op-amp amplifier
Voltage controlled current amplifier

Reference: I wanted to integrate the solution into my existing embedded system and the particular product feature I am looking for can be referred from this link: http://www.phidgets.com/products.php?category=0&product_id=1012_2


texts: TIP120 Transistor + Solenoid Failing Randomly

texts:
I am using TIP120 transistors (controlled by 74HC595 shift registers) to control 12VDC, normally closed solenoid valves. Everything is working in short-time tests however when left overnight, some solenoids will open by themselves. The shift register is locked overnight with all pins low, and all the solenoids should remain unpowered - however, some are getting power and opening during this time. I suspect a hardware issue since this occurs both when the control program is running and when it's not. Could this be an issue with the TIP120s closing their circuits after prolonged charge on the collector? Should I perhaps be using MOSFETs in this circuit instead?

Please see the full schematic and a simplified, close up schematic below as well as images of the front and back of my perfboard.

Here are the specs for the two types of solenoids I am using. Both are showing the same behaviour. https://www.canadarobotix.com/products/1642?variant=14423744086065 , https://www.canadarobotix.com/products/1643?variant=14423744118833


texts: When Intel / AMD choose their Nanometer Processes, why were the specific numbers, 5, 7, 10, 14, 22, 32, 45, etc chosen?

texts:
When looking at the roadmaps for the CPU manufacturing process
https://wccftech.com/intel-expects-launch-10nm-2017/

10 µm – 1971
6 µm – 1974
3 µm – 1977
1.5 µm – 1981
1 µm – 1984
800 nm – 1987
600 nm – 1990
350 nm – 1993
250 nm – 1996
180 nm – 1999
130 nm – 2001
90 nm – 2003
65 nm – 2005
45 nm – 2007
32 nm – 2009
22 nm – 2012
14 nm – 2014
10 nm – 2016
7 nm – 2018
5 nm – 2020
3 nm – ~2022

Why are these numbers chosen specifically? I have looked around, and there are deviations, such as:

Samsung Electronics began mass production of 64 Gb NAND flash memory chips using a 20 nm process in 2010.[114]

TSMC first began 16 nm FinFET chip production in 2013.[115]

And many others.
and so on. Yet as far as Intel and AMD are concerned, they are both in lockstep. Is there something to these numbers that lends themselves to the manufacturing process? Or is the selection completely arbitrary?


texts:
Let's assume that a panel has an efficiency of 15%.
What will be the output at STC, will it be -
P = 15% * 1000 W/m2 = 150 W/m2
or will there be an adjustment for the air mass of 1.5?
Basically, does the 1000 W/m2 already factor in the air mass?


texts: Off-the-shelf electromagnet with deterministic pole

texts:
I looking to buy an electromagnet (12v) and there are a lot of them out there on amazon and ebay in all kinds of size and shapes -some are round, some are rectangle, etc.  However, in my application, it's important that I have a positive side of the magnet facing out when the current runs through the electromagnet. In my application, I'm utilizing the repel effect of two magnets where another piece has a permanent magnet with positive side facing out.  So the goal here is that when the electromagnet is energized, we have a force that pushes the two magnets away from each other.

For example, in this picture with this DC electromagnet, is it as easy as changing the polarity of positive and negative to get, say the positive side on its face?  The specs that I ready don't mention anything about that.  Thanks in advance.


texts: Values for calculating PN2222A Base Resistor

texts:
I know that there are several posts in regard to calculating the base resistor of the PN2222A Transistor. Calculating the value in particular should not be a problem. My problem is in regard to finding the values for hFE, Vbe and Vce.

The resistor is part of a small 12V circuit whith the purpose of turning on a regular light bulb. That bulb has a resistance of 75 Ohms. Ergo it will drain 160mA. The base of the transistor will be connected to an 5V digital pin of an Arduino.

Looking at https://www.onsemi.com/pub/Collateral/PN2222-D.PDF, I have no clue which values I should select for hFE, Vbe and Vce. I know that they must be the saturation values, but that's how far I got.


texts: How to use FG ground on a meanwell buck DC\DC power supply

texts:
I would like to know how to safely connect a 48V 200A battery to a step-down converter. The step-down converter is this. SO the step-down converter is to be used inside a forklift to drop the 48V DC to 24V DC.
The block diagram for this power supply is:

The mechanical specs are:

I know that the positive (red wire) from the battery of goes to V+ of the power supply and the negative (black wire) from the battery goes to V- of the power supply.
However, how do I connect the FG (floating ground) pin (pin 3)? Does this get screwed into the metal frame of the forklift?
Manual


texts: Unstable diesel generator output voltages causing irregular behaviour in uninterupted power supply (UPS) units

texts:
I am a technician for a security and access control systems company, and we are experiencing a strange interaction between the clients diesel generator and the UPS unit we installed to act as a handover supply to the clients CCTV system during power outages.
The issue to our best understanding is that when the mains supply is lost, the UPS takes over the supply to the equipment while the generator switches on, with the generator supplying the power, the UPS hands the equipment off to it.
With the addition of the equipment, the load on the generator supply increases causing a voltage drop, which cause the UPS to take over the supply again, the generators supply stabilizes, the UPS hands off again and the cycle repeats. This switching between supplies causes our CCTV equipment to reboot constantly, which is an issue because we are not monitoring or recording footage.
Another theory we have is that the output of the generator is just unstable and fluctuates enough between cycles that it cause the UPS to take over the supply, though we are not entirely sure on this.
So, how exactly would we go about fixing this issue?
We have "loadshedding" which results in the municipal supply being cut for 6 to 8 hours at a time, as often as every day, so the CCTV equipment has to run on the generator, and because it is CCTV we have to have the UPS in place to prevent any downtime.
If anyone can suggest a fix, or a piece of equipment we could put in place, that would be great.


texts: Is state variable analysis used much in circuit analysis these days?

texts:
I am an older EE and I have used the old tried and true methods of circuit analysis like KVL, KCL and some Signal Flow Graph methods. Recently I have been reading about methods that were originally used for solving larger circuit analysis problems by computer methods using "state variable analysis".

I was reading in the textbook "Computer methods for circuit analysis and design" by Vlach, that "Since the disadvantages of state variable formulation far outweigh its advantages, it is no longer used in computer applicatons".

Is the above really true with respect to circuit analysis?

Before you say "just use pspice, etc" please remember that spice methods provide an answer to a specific problem without providing much "insight" into the circuit in question. Of course I have used spice for years after I have gained a fundamental understanding of what I really want the circuit to accomplish and how I need to implement it.

Thank You
Tom


texts: Altium: Hierarchical Design not connecting properly?

texts:
So I've been meaning to design a board that has many repeated components; basically making the user of the board able to create a state machine with discretely implemented ands for next state logic, ors to combine them, and then well, the D-Flipflops.
The structure of that looks like this:

The problem I'm having however, is that Altium shows an "only one pin connected" error when I try to update my PCB from here, for all of the pins that were connected in this manner.

The Documentation on Repeat() is fairly lackluster, so I couldn't really find a solution by myself.
For clarification: all the and outs (a single one per instance) should go into all the or ins; the D outputs should all go into the flipflop_output block. The documentation page does it similarly, however there, the net names are uniform across the signal paths. Might that be the source of my problems?
My problem's solved as soon as those connections get recognized by Altium.


texts: How does 2-ff synchronizer ensure proper synchonization?

texts:
Using 2-ff synchronizers has been a standard for a signal to cross clock boundaries. And there are lots of paper/figures illustrating the mechanism, such as this one:

It seems bclk can only sample the pulse of adat once (at the second rising edge of bclk), which causes output metastability on bq1_dat. How can bq1_dat be sampled "high" on the next active clock edge?

In addition to my question, I'd like to add what I think for a signal to go through safely to another clock domain (suppose 2-FF is enough to satisfy MTBF requirement). Please correct me if any mistakes.

ps: Metastable state does not display "wandering around" waveform, but a level that is neither '1' nor '0'. The following figure shows an example of metastable output.

The original figure came from Lecture notes for EE108A, Lecture 13: Metastability and Synchronization Failure (ow When Good Flip-Flops go Bad) by W. J. Dally.


texts:
I do not want to include a dedicated power supply for the operation of a low current demanding microcontroller chip in one of my projects. Instead I wish to use something which would just work fine. I couldn't think anything simpler than this circuit.

Though it may seem a very silly circuit and may fail at higher current requirement, but I guess it can power a microcontroller and a few LEDs(2 or 3) which will require just few milliAmps of current. Also, I can prevent the resetting of the IC due to minute voltage irregularities by adding some ceramic cap near the it.

This is what I can see as of now. Is this feasible to make and use such a circuit for practical purposes. What could go wrong?


texts: Estimating battery life from capacity and varying load

texts:
I'm having some troubles trying to estimate battery life.
I have a device that consumes 50mA under IDLE time, 650mA under transmission, and 100uA in Sleep mode.
I have a battery with 1.7Ah of capacity, the times are:

IDLE = 5s
Transmission = 10s
Sleep = 86,385s

I don't know how to calculate the average of the currents with the times of the various states, I need some help with this.


texts:
I have a question regarding the distortion I see at the transition of bit '0' and '1' in an FSK, I have the receiver connected to a sensing circuit at two frequencies, because my input is current limited at the sensing frequencies I would like the impedance to be as large as possible in order to get a good voltage range for sensing. I thought I might update the components with their respective parasitic resistance, because I am not sure whether the damping solely was the cause of it.

The response of the circuit looks something like this

However, when I actually test the circuit together with the receiver, I see some distortions between transitions

another example

and if I run an FFT this is the result I get, offsetting the window doesn't help either, so it's not because I am slicing into part of the previous bit.

I know the frequencies are all slightly different in these cases, it's because I had to tune my circuit a bit for 24 kHz and 32 kHz, but I don't think that would have changed the behaviour I observed so I hope the problem is still valid.
Basically, if I send a series of '010101010101....' and have a sliding window of baudrate (so say for example frequency 1 is 24 kHz, frequency 2 is 32 kHz and the baudrate is 4 kHz), instead of clearly seeing a tone at frequency 1 and frequency 2 for bit 0 and 1 for each bit, I essentially see a mix of two frequencies with similar amplitudes, and there is never a clean signal.
greatly appreciate any pointer!


texts: Kickstarter electronics and local regulations

texts:
There are some electronics projects on Kickstarter. For being successfull, they offer buying the product worldwide.

I wonder how they are able to comply with all the local regulations, for example CE, FCC, ETL, CSA and so on...

For a small team of founders, it seems to be impossible to know all the regulations of all countries they sell the product to. I have not seen any Kickstarter project that restrict the states they are selling the product to.

Do they just ignore some local regulations? Is there a legal way to do it?


texts: Mobile Phone Signal Flash Light 3-12V - not working. Circuit viable?

texts:
Another ebay-heist that does not work as adverstised. I build it, and tested with some normal g3 cellphones, but no dice. My antenna at J2 is an 8cm long wire (not really lambda/4 of anything, but i piecemeal snipped it down from 18cm to see whether there was some sort of resonance sweet spot) that i slightly coiled. The DIY inductance L1 was very loosely specified ("5 to 10 turns") so i did 6 turns at 3mm diameter.
It's supposed to take 3-12V, and blink whenever a mobile phone in the vicinity gets a call.

I'd love to know whether the circuit itself is viable, what needs to change, and a short intro to what is supposed to be happening.
(I guess Q3 needs to go active for the LED to blink, so Q2 would have to stop being active as it otherwise pulls the base of Q3 to ground. So i guess the oscillation in C1/L1 somehow wiggles C2 and intermittently quenches Q2 ... or something?)
Thanks!


texts:
I have a weighing scale project using a 200kg load cell with a rated output of 1mV/V. I used 5V as excitation voltage and an Ad620 in-amp for my amplifier. I only need atleast the 0-100kg so I only want to amplify the 0 - 2.5mV part of my output which I believe corresponds to the 0 - 100kg load.

On choosing the gain, I have read the AD620 datasheet: http://users.ece.utexas.edu/~valvano/Datasheets/AD620.pdf which says that the output swing at overtemp(worst case) is -Vs + 1.6 to +Vs - 1.5 which is equal to 1.6V to 3.5V at my case because i'm only using 5V single supply. So i have targeted my output on that part and settled with a gain of 381 or Rg = 130 ohms. So using 2.5V as my reference voltage, I will have an expected output swing of 2.5V to 3.4525V which is within the safe range I assumed.

But the problem is, I don't get an output of 2.5V at zero load even my reference voltage is at half the supply or 2.5V. I only get about 2.47V which is only near it by 30mV or something. According to the book I have read and according to this simulation by analog devices: http://designtools.analog.com/dt/inamp/inamp.html?inamp=AD620, the output at no load or zero differential voltage must be (V+ - (V-)) + Vref. So the V+ and V- will be cancelled out leaving the Vref as my output voltage which must be 2.5V at my case.

This is my preliminary circuit:

What could be the problem? Any help would be appreciated. thanks!


texts: I have a flex-PCB that is acting as a sensor bus for one of my projects. I started getting some wonky readings from one of the sensors, but I found that if I removed the sensor from the bus (with minimal heat) the sensor was working fine. Before applying the heat to the fPCB, I noticed that the solder mask above the ground and signal traces had begun to deteriorate. I feel like I have two pieces of a puzzle, but I just don't know how to put them together. Does anyone have any idea what else is worth my investigating?


texts:
What happens to the gain sensitivity of negative feedback system due to fractional change in open loop gain  when feedback gain His about 0.01-0.05.
Here's my work:


texts: Voltage output across purely capacitive voltage divider when PWM/Square wave signal is applied?

texts:
Having some trouble with understanding the voltage output in time domain across a capacitive voltage divider when applying a square wave from 0 to 5V? It can be assumed that the capacitors have some small series resistance.

I plotted the following circuit to better to see what would happen:

The below graph shows the time domain response of two capacitors in series. The brown curve represents voltage across C2 and the yellow curve represents voltage across C3.Note - C2 and C3 have a ESR of 5 ohms.

How and why does the the voltage across C3 become negative like that?


texts: How can I power a SCSI hard drive without a motherboard/scsi card?

texts:
While this is possibly more of a Super-User question, I chose to put it in EE because I'm looking for information about power assignments on SCSI cables, and understanding how to send power ONLY (not data transmission) to a SCSI drive via it's ribbon cable or some other method. I figured that's going to involve schematics and likely some soldering...hence, EE.  :)

I`m building a DIY gyro-stabilizer for a camera, and have determined through a few experiments with long ribbon cables that two 10000rpm SCSI drives offer just the right amount of resistance for the device I'm stabilizing. Once I'm disconnected from the computer/SCSI card, though, I have no power to the drive. For an IDE drvie, I'd just solder a battery holder to a molex connector and be done with it. All I need is for the drive to spin.

This SCSI Ultra160 (16-bit, if it matters) connector is what I'm working with, but I can't seem to find any pin-out information that tells me which of the pins/cables supplies power to the drive. I'm also interested to know if there are any hardware mechanisms in SCSI that would cause the hard drive to stop spinning. For instance, there may be a 3V connector somewhere that causes a standby mode if I don't connect that as well. I'm not sure if there's anything like that hidden in the ribbon cable of which I need to be aware.

Can anyone help? Does anyone have experience doing this?


texts:
I refer to a 2N3055 power transistor, the spec. sheet gives the following:

Max. current 15A, Max. Voltage 50V,  Power rating is 115 Watts.

What is the power rating calculated on?
If it is E*I then the power would be 750 Watts, this is of course incorrect, so how is it calculated please.?


texts: Connect load to collector or emitter of transistor

texts:
When setting up a transistor as a switch is there any difference between putting the load on the collector or emitter?

As far as I can see the only difference is in calculating the Vbe i.e. calculating what voltage is required to turn the transistor to saturation because of the voltage drop across the load


texts:
I have a PIC16F1828. I am using PWM in order to control brightness of bunch of LEDs. My goal is to dim those LEDs to the maximum point. Currently they are not dim enough.

System clock runs at 32Mhz.
Period register is set to 255.
The Timer prescaler associated to this PWM is set to 1.
When I set duty cycle to only 1 the LEDs still feel somewhat bright. Can I somehow decrease pulse width even more from the software?


texts: Parts identification: Y-cap, MOV or NTC?

texts:
I am having problems identifying whether a component is an Y-capacitor or a MOV.
They are from my parts bin so I do not know beforehand what they are.

Is there a simple way to know the difference without searching for the part number or measuring them? If measurement is required, what is the capacitance usually for a "standard" MOV?

Two examples of the components I'm talking about.

Resistance: inf

Resistance: inf

EDIT
Some more...things that are probably different things but it a similar package:

Resistance from top left:
inf, inf , 11 Ohm, 5 Ohm, 55 Ohm

I think the middle one is a transient-voltage-supression-something but i don't know about the others.


texts: Running a Peltier water cooler from a battery

texts:
I'm planning on using this unit:
12V Peltier water cooler

for a portable heater/cooler. As such, I would need to run it off a battery. Based on what I've been reading, the best choice is a deep-cycle battery. Problem is, these are quite bulky and heavy for my application.

My questions are:

Is there a more efficient way to run a peltier module off a battery?
Given this module is 180W, I plan on running it off a 12V supply, this gives a 15A draw. If I was to plug it to a 4AH battery, would that mean the system would only run for about 20 min or would it damage the battery?
What kind of safety margin should I apply when trying to size the battery? E.g. 10%?

Thanks in advance for your help.


texts:
Hello i need help with the Remappable UART communication on pic18f45j50.

so here is my code compiled using Mikroc Pro for pic

 //Set Analog pins as digital...
 ADCON1=0X0F;
 ///////////////////////////////

 //Initialize UART2 module with Peripheral Pin Select
 Unlock_IOLOCK();
 PPS_Mapping_NoLock(0, _INPUT, _RX2_DT2);
 PPS_Mapping_NoLock(1, _OUTPUT, _TX2_CK2);
 Lock_IOLOCK();
 delay_ms(100);
 UART_Remappable_Init(9600);
 ////////////////////////////////////////////////////

 //Initialize UART1 module
 delay_ms(100);
 UART1_Init(9600);
 Delay_ms(300);
 /////////////////////////

 //Infinite Loop...
 while (1)
 {
     if (UART_Remappable_Data_Ready()==1)
     {
     UART_Remappable_Read_Text(output, "OK", 15);
     UART_Remappable_write_Text(output);
     delay_ms(100);
     }
 }//loop ends......

connected the RP0 and RP1 to the usb-uart module. but it seems only tx is working on the microcontroller..

it means only microcontroller can send data but cannot receive data?

BTW.. RP0 and RP1 represent pin 19 and 20 resp.. which is RB0 and RB1 normally.. so is there i'm missing?


texts:
I am looking at a few IC's for full-duplex RS485 communication.

Are there any recommendations?

The current options I am looking at are:

SP490
SN75179
LTC490

The first two are well priced for my project but I am just interested in what other people are using.

Added details:

The project is for hobby use only. It will connect 2 Atmel MCU's via UART that can be between 1-10 meters apart. I opted for Full-Duplex RS485, allowing users to connect the two units without any firmware changes.(3rd party firmware involved that I would like to interface to but can't make changes to)

The ADM2582 has a bunch of extra features that are on my wish list but its price puts it out of reach as I will need at least 2 units.


texts:
In the following inverter a pure inductive load is applied, then from where the starting current will start? (from 0 or -I(peak)). I want to draw the waveform of current through the inductor and find its peak value.

f = 50 Hz and inverter mode is 180.


texts: Can I directly connect a wifi-antenna to an NRF24L01 chip without SMA-connector?

texts:
I have an NRF24L01 wireless communication chip with an onboard, copper trace antenna. I saw a guide on soldering a wire to the end of the copper trace in order to extend the signal/reception.
I happen to have an antenna with SMA-connector from an old wifi-router laying around. Would it work to connect this to the PCB-antenna copper trace via just soldering a wire to the PCB and stuffing the other end in the antenna SMA connector? Or do you need to consider grounding/power output etc?


texts: PIC18F4520 failed using internal oscillator at 1MHz

texts:
I am wishing to use the internal oscillator of the pic18f4520 at a frequency of 1Mhz , what I wish to achieve in the end is to use to control a servo.

#include p18cxxx.h
#include pwm.h
#include timers.h
#include adc.h

#pragma config OSC = INTIO1
#pragma config MCLRE = ON           /* Set Master Clear */
#pragma config WDT = OFF            /* set watchdog timer off */
#pragma config LVP = OFF            /* Low Voltage Programming Off */
#pragma config DEBUG = OFF          /* Compile without extra Debug compile Code */
#pragma config PBADEN = OFF         /* Disable Analogue on PORTB */

void main() {
    OSCCON = 0x42;
    TRISC = 0X00;
    PR2=152;  // period
    T2CON = 0x06;  //prescale to 16
    OpenADC(ADC_FOSC_32 & ADC_RIGHT_JUST & ADC_20_TAD,ADC_CH0 & ADC_INT_OFF & ADC_VREFPLUS_VDD & ADC_VREFMINUS_VSS, 0b1011);
    SetChanADC(ADC_CH0);
    ConvertADC( );
    while(BusyADC( )); /* wait for completion */
    CCP1CONbits.CCP1M = 0x0C;    //make the pin an output
    CCPR1L = (ReadADC()/4);   // duty cycle
    CCP1CONbits.DC1B=0;
}

When I use an external oscillator, the pwm works fine but I can't get a 50Hz signal with a 20Mhz external oscillator, I want to use the PWM without the external oscillator just because it seems like a sweet trick to know.

I am very new to micro controllers and I apologize if I don't follow any protocols to explaining my problem but to repeat, the issue is setting up the internal oscillator to 1MHz, I read the data sheet and assigned OSSCON register the necessary value and to turn on the internal oscillator and to set it to 1MHZ.

The code doesn't compile and seems to be a bit iffy about me configuring the OSC to INTIO1 even though thats what the data sheet says to do when desiring to use the microcontroller's internal oscillator capabilities.

The program is in c18 compiler

For some reason the site blanks out words with "< > " and capitalizes anything in front of the "#" sign so please assume that everything is correct except in the include and pragma's except the pragma config OSC=INTIO1 which as mentioned did not allow successfull build.


texts:
This circuit is from an Elenco AM/FM Radio kit.
How does this circuit start working when the 9 VDC power, at the top right of the schematic, is applied?
Specifically, what puzzles me is the "chicken or egg" conundrum of the first current flows. It appears to me that Q13 has to be on in order for current to flow out of its collector so the base of Q10 is energized in order for Q10 to turned-on.  With Q10 on current will flow from the 9 VDC source through D5, R49, Q10, and R48 to ground and thus turn-on Q11, which would in turn turn-on Q13.  But, I have assumed that Q13 is already on in order for Q10 to be turned on.
Do very small leakage current play a role here is getting things going?


texts:
Hey I took apart a joystick and I found some pretty neat parts. I found multiple of these knobs; I think that's what they're called.

Characteristics of Component

Turns
Three wires

**Picture **

My question(s)

What is this switch called?
How do I connect it to an LED(Connect it in general)


texts: How to connect to common ground when using the TB6612FNG

texts:
Instructions for the SparkFun TB6612FNG indicate that the ground connections for the voltage driving the motors and the logic voltage must be connected together.  For motor voltage, I am using a model TE-5305 bench power supply as shown, with a green middle post for GND:

I am assuming that I would make the ground connection for the power supply at that post.  What I am confused about is the ground connection for the Arduino board.  Connecting the grounds of a device like the power supply and the tiny Arduino board seem "disproportionate" in some way.  Am I OK?

Also, should I connect the black negative post of the power supply to its own ground post, as suggested by some sources online?  If I don't connect them together, where would I connect the negative post in the circuit?

PS: I did read about ground loops in this answer here: https://electronics.stackexchange.com/a/56130/27163
However, I am still lost with the specifics for the case at hand.


texts: shorting a remote control pushbutton with GPIO and a transistor

texts:
I'm trying to control my garage door remote with a GPIO pin from my Raspberry Pi.  Instead of driving a relay, it would be much easier to just short the pushbutton on the remote.  Is this how I should do it?  Do I need a protection diode and if so, where should it go?

Does it matter that the 3.3V GPIO pin is referenced to a different ground (Raspberry Pi ground) than the remote ground?

Would also appreciate guidance on transistor to use and resistor value.

UPDATE; More info from comments by OP:
After checking, you're right, the pushbutton simply shorts the circuitry to the return path of the 9V battery. My main concern is the 3.3V being referenced to GND while everything on the remote is floating.


texts: Embedded Development Support plugin does not generate CMake files in CLion on Ubuntu 19.10

texts:
I can build, run and debug my old projects.
But when I try to import new STM32CubeMX project, nothing happens. No CMakeLists.txt file created. Pressing 'update CMake project with STM32CubeMX' from menu Tools -> CMake has no effect.
My system is Ubuntu 19.10, CLion 2019.3.3, openjdk version "14-ea".


texts:
I am using a simple pre-amplifier circuit for an electret microphone.
Here's the schematic and the AC transfer function:

The output is connected to a 3.5mm audio jack through a couple of half a meter wires. I tested the circuit on a breadboard and was able to ensure that the circuit works. I used an oscilloscope to view the output as I was speaking to the microphone.
Here comes the problem:
When I tried to connect the audio jack to my phone and record a voice I noticed a lot of noise picked up on my recorded voice. To come up with an explanation for this I believe the audio jack itself would act like an antenna and pick up some high frequency signals lying all around.
To verify this I connected the probe to the output while kept everything quiet. I observed some 20mV peak-to-peak noise signals with frequencies ranging between 40-80kHz.
So it seems I'm right. If so, what should I do to remove the unwanted noise? Should I use a low pass filter right before the audio jack is connected to the phone?
EDIT
Here's my setup. I have not used any decoupling capacitors on power supply yet. I will update the question after using a decoupling cap to see where it goes. Also note that I used a UA741 not Op07.


texts:
I'm using bunch of LEDs with red, blue and yellow colors in a product for sign indication. the product has total around 150 LEDs of all three different colors.

As these LEDs are purchased in bulk, there are some faulty LEDs which are sorted on either side or both side. Currently, I check each LED with multimeter in forward bias and reverse bias mode. If LED is OK, then I solder it to PCB. These method works but it is time consuming. is there any fast method to check bunch of LEDs?

Another question is, there are some LEDs on PCB, which become faulty after some use. Some are sorted on either one side or both side. So, is there any circuit that I could integrate in my PCB which will detect LED failure?

Below image is the LED driving part of circuit. Is there any problem in my circuit to cause some LEDs to become faulty after I install them on PCB?

The L1, L2, L3 are connected to AVR microcontroller with 3.3V operating voltage. 74HC595 is supplied with +5V and controlled by AVR. Circuit shows only three LEDs, but there are a bunch of LEDs in column not shown in circuit for sake of clarity. Does this circuit have any problems?

EDIT:

I want to mention that only one LED will glow at time out of all 150 LEDs. So, No over-current problem in this case. I have tested voltage drops for each color type and according to that resistor R1 is set to 200 ohms which is maximum resistor value required by three color types(The brightness level may be low for 2 out of 3 color types, but that is OK for me). I am thinking to create a test program that will run on on-board AVR microcontroller and test each LED. is it possible to test LED from its current and applied voltage value by program ? Any idea how it can be possible ?

EDIT-2:

Suppose if any channel (guess here QA) is off(at 0V) in 74HC595 IC and L1 is at 0V then, LED D1 gets 5V at cathode side and 0V at anode side. Is it cause failure due to reverse breakdown of LED? Can i omit R62, R65 and R68 pull-up resistors ?


texts: Driving a proportional solenoid from PWM via NPN/MOSFET

texts:
I'm very new to electronics and just want to get some feedback on a circuit + hopefully some explanation about a couple of points:

I have a digital pulse (PWM from controller ranging from ~0-300Hz) which needs to control a proportional solenoid (inductive load/coil) (the base resistor R2 would be hooked to a PWM pin on a microcontroller by the way not directly to the +24 I was just doing it in a simulation)

I'm used to using NPN as a switch and believe I need to use a MOSFET due to the 2A rating of the coil so think I should do something like the :

You'll probably note that

i) I have schemed the coil as a resistor (R3) - if the coil is 24v I assume that it's load is calculated from its coild resistance? (confused on this)

ii) I have put another resistor R1 which I think I don't need as a current limiting resistor - does R3(the coil) do this on it's own?

iii) The NPN should almost certainly be a mosfet as it is switching +2000mA - correct?

iv) I have put in a flyback diode - ignore if polarity is wrong I do understand the concept.

What else should I do? Any advice?


texts: How does a 90 watt fan consume power from a 500 watt solar panel?

texts: I have a ceiling fan that consumes 90-watt energy. If I have a solar panel that generates 500-watt energy, then how does a 90-watt fan consumes only what it requires from a 500-watt solar panel.?


texts: Hole for the disc type knob potentiometer

texts:
I am going to use this potentiometer:

and looking for advice on the best practice for the hole for the disc.
The panel is having flat inner and outer surfaces, and the thickness of the panel is 2 mm. The datasheet only gives the dimension of the protruding disc part is 2 mm, exactly the thickness of the panel of the device.

To allow users rotate the knob, it, logically, must protrude the panel. The obvious starting height of the hole for the knob is ~1 mm so that knob itself would fit into the hole.
I have two ideas on my mind:

in addition to the hole for knob, cut another 1.5 mm height of the panel from the inside, so that the front (top on the diagram above) fit into this additional space; then knob will be visible ~ 1 mm above the panel and properly operated. The con is that panel becomes thinner in the location of this additional cutting;
instead of cutting from the inside, cut it outside making oval-like cavity; while the knob will not protrude out of the panel, the user, pressing the finger into the cavity, will be able to rotate the knob. The cons are that plastic of the panel, if being machined, has different structure inside, and the cativy itself will not look ergonomically and the plastic will deteriorate with the time. In addition, this is a place for dirt;
a combination of the two above.

What is your recommendation? Is there any best practice applying such potentiometers?


texts: Fan does not spin when controlled by PWM

texts:
I am using the following fan : ME70201V1-000U-A99, which should be supplied at 12 V and consumes about 150 mA.
My schematics is as follows :

Than fan is connected to X3. PWM_VENTILO is the PWM output of a microcontroller.
If PWM_VENTILO is a simple high GPIO output, it spins at full speed.
But if I try to control its speed with the PWM, it does not spin.
I have tried different frequencies (some Hz to 20 kHz) and different duty cycles, I always have the same result : it gets stuck and never spins. At low frequency, it kinda works, but the spin is irregular. The MOSFET transistor accepts voltages and current which are necessary.
Is there something I am doing wrong ?
Thanks


texts: Why place inline capacitors on PCIe traces?

texts: What does a series capacitor on a PCIe signal trace do, and how does it work? I've read that a series capacitor smooths out ripple in a power line, but this is a signal trace, and I'd like to know what its purpose is.


texts: What is a sufficient way to ground my 2 layer low frequency PCB inside a housing?

texts:
I'm designing a simple PCB for GPS signal control. The frequency is below 5Hz, supply voltage is 9V and converted to 5V.
This print will be screwed in a plastic housing with four M3 mounting holes at the corner which can be see in the picture.
I have tried to route most of the trace on the Top signal layer.

My question is:

Is it a good idea to pour the entire bottom layer as GND? Or it can be on the Top layer too?
Should I connect the GND pour with the mounting holes? I saw a term called Chassis Grounding which makes use of screw for external grounding connection. I don't really understand this technique clearly, so I would like to have some advice on it.

Thank you!

Top layer

Bottom layer


texts:
I had purchased an ATMEGA 16 microcontroller and chaged its fuse bits settings and used internal caliberated RC clock with 1000000.
Changes done in make file and F_CPU. But it do nothing.

Programme for LED Blinking

#define F_CPU 1000000UL
int main(void)
 {
   DDRC=0xFF;

  while(1)
       {
        PORTC=0xFF;
   _delay_ms(1000);
    PORTC=0x00;
    _delay_ms(1000);

    }
 }

At the same time the following programme works fine.Can somebody helps me out please its urgent.....Did I forgot something to do.....
These problems are same while using external 16Mhz crystal.
  Programme for LED Glowing.

#define F_CPU 1000000UL

int main(void)
 {
   DDRC=0xFF;

  while(1)
       {
        PORTC=0xFF;
   }
 }


texts: Flyback converter Transformer design- N87-etd29

texts:
I have designed a Flyback using UC3845, PCB and components assembling are done. But I have some problem in transformer. My primary winding is 40 turns ( 2 paralell 0.40mm), and secondary winding is 9 turns(3 paralell 0.65mm).
When I apply around 100kHz square wave in primary windings and observe secondary, the results are in shown below in picture. It is saturated? Can any body comment this issue? It can some problem?

Thanks


texts: Does voltage cause current or does current cause voltage?

texts:
So as the question asks, say you have a circuit with a battery connected to a resistor to form a complete circuit in this case does voltage cause current through the resistor? or does the voltage across cause the current?

I feel like there are so many explanations of various electronic circuits and devices in which people say that current cause a voltage to appear and in other cases the other way round which one is it?

As far as I know based on basic physics of voltage and electric fields once a circuit is completed the charge separation between the two ends of a battery cause an electric field through the entire metal, resister/capacitor etc this causes the electron cloud to drift one way or the other am I wrong? how can current cause a voltage drop?


texts:
I am in the process of designing an RF signal generator, as many of my other projects require analysis up to several GHz. My hope was to receive some verification regarding the intended design. Nothing too detailed at this point, primarily just theory. Ideally, the design will achieve the "optimal requirements" listed in the table below, however, I would still be satisfied with the minimal requirements for a first design.

Design Approach

Referencing this article from Analog Devices, a signal generator design was presented, but no where near the frequency I require. Instead of using the AD9834C as they list (schematic below), I intend to use the AD9102 DAC/DDS. This will provide a frequency up to 180 MHz, then, utilizing a wideband synthesizer and mixer, I intend to upconvert the signal. The LMX2592 has a frequency range of 20 MHz to 9.8 GHz, and the VGA in the schematic below is limited to 18 MHz, so theoretically my maximum frequency will be:

$$f_{o_{max}} = 9800 + 18 = 9.818 \text{ GHz}$$

This is close enough, but I could also choose a higher frequency synthesizer or wider bandwidth VGA. It should also be noted that some variable bandpass filtering will be required on the output.

Primary Concern

In order to achieve 40 Vpp output at higher frequencies, given a 50 ohm load, that means the output power must be 36 dBm:

$$P_O = 10\cdot \log_{10}\left(\frac{40 / 2\sqrt{2}}{50} \cdot 1\times 10^3\right) = 36 \text{ dBm}$$

The reference design provided by Analog Devices demonstrates P1dB at 36 dBm, so this should theoretically be possible to achieve that output power when upconverted - although the mixer will have a conversion loss (~6 dB). This suggests an output power of +30 dBm at higher frequencies, thus yielding 20 Vpp output. Again, although this is not optimal, I would still be satisfied given the frequency range trade-off.

The board will most likely be etched or purchased from Oshpark, including proper transmission lines (coplanar waveguide with ground). I'm worried that given the wide bandwidth, multiple transmission lines and RF switches would be necessary for different regions of the band (e.g. 0 to 1 GHz, 1 to 5 GHz, 5 GHz to 10 GHz) to avoid significant losses?

Final Thoughts

I primarily wanted to check my thought process against some of you who are more experienced! Any thoughts would be appreciated. It is quite possible this frequency range and output voltage is a castle in the sky, as they say?


texts: Convert AC/DC power supply to current source for battery charging

texts:
I have an AC/DC power supply unit (400W) with the controlled output voltage (40V...60V). It would be great to use such a power supply as a current source to implement a dual step current changer. The charger is for four 12V 12Ah lead-acid batteries in series.

The algorithm for dual step current charging is below:

Questions:

1) How is it possible to implement the dual step current charger with the aforementioned power supply unit?

2) Is there any better algorithm for charging four 12V 12Ah lead-acid batteries in series?


texts: Another DIY Led Question (Complete Newcomer)...sorry

texts:
I have 10 Bridgelux leds (forward voltage 3.5 to 4.5v, drawing 750ma max).  I also have a 36v Mean Well HLG Driver, offering 1.12a.  It seems to me that trying to run all 10 leds (in series) is cutting it a pit fine re: Voltage, and therefore I should look to run just 8 leds. I cannot find one of those graph things for these lights, so cannot guess as to which would be brightest (10 lower powered or 8 higher powered). 2 paralell circuits would not work as there aren't enough amps available.

Maybe, though, I am talking complete crap.

Which of the options would you take?  Is there a secret option C (modifying the driver?) Also, do you know of any good reading materials, so as I can actually understand your answer?

At the end of the day, this is just for a fish tank.  I would like to learn, though...


texts:
Im trying to calculate the output of an opamp, the data is

Closed loop gain = \$20dB\$
CMRR= \$90dB\$
Common signal applyed = \$-60dBV\$
so the idea is to use the next equation
\$v_{o}=A(v_{id}+\frac{A_{cm}v_{ic}}{A})=A(v_{id}+\frac{v_{ic}}{CMRR})\$
or

\$CMRR=20log\frac{A}{A_{cm}}\$
I undestand that \$A=10\$
but I dont know how to calculate the differential voltage and the common voltage.
Someone can clarify this, so the problem can be set right?
Update
if it is used
\$CMRR=20log\frac{A}{A_{cm}}\$
\$90=20log\frac{10}{A_{cm}}\$
It is supposed to find the common mode gain, but then what?