texts:
I'm learning how to use an Attiny84. I've generated a fast pwm signal. I managed to understand how to do this:

#include <avr/io.h>

int main(void)
{
  // setup timer0
  TCCR0B |= _BV(CS00);  // use clk_i/O without prescalers as clock source.
                        // also enables TIMER0

  // set fast PWM mode
  TCCR0A |= _BV(WGM01) | _BV(WGM00);  // Mode 3
  TCCR0A |= _BV(COM0A1) | _BV(COM0A0);  // set OC0A on compare match, clear on BOTTOM

  OCR0A = 0xff / 2;  // 50% PWM

  // set PB2 as output. This should enable OC0A
  DDRB |= _BV(PB2);

  for (;;) {
  }
}

However, I don't understand why I got only ~30kHz on the scope. I disabled the CKDIV8 fuse and sets my CKSEL to "Calibrated Internal RC Oscillator 8MHz".

I though I could have at least 8MHz PWM frequency. I can't find in the documentation how clk_i/o and clk_cpu are related. Is there any way to gain a higher PWM frequency ?

N.B.: I don't need to have a particular PWM frequency, I'm just testing the chip and trying to understand its boundaries.


texts: How is binary converted to electrical signals?

texts:
I'm just starting off in electronics and am already fascinated. Having played with an Arduino these past few days I'm aware that binary is a representation of different voltages - such as +5V representing 1 and GND representing 0.

I've been trying to discover how, at a physical level,  the microcontroller converts the binary to these voltages. I cant seem to find a description anywhere. Can anyone share their knowledge or point me to a place/good book that describes how this works?


texts: The voltage drops measured across very high value resistors do not add up - why is that?

texts:
I have a very simple series circuit which I originally built hoping to measure voltage from an Arduino, but while calibrating realized an irregularity, so stripped it down to its basic parts.

simulate this circuit – Schematic created using CircuitLab

The circuit now consists of a lithium-ion battery (unknown Ri), a 10Mohm resistor, and a 1Mohm resistor. When measuring the voltage drops across these resistors, the voltage does not add up.

Unlike in previously asked questions, I am not referring to a small margin of error around 5-10%. Instead, the voltage when measured across both resistors is 3.68V. R1 has a measured voltage of 1.78V across it, and R2 has a voltage of 0.17V across it. This does not add up by a very large margin, and I have no idea what could be causing it.

I have considered possible bad connections across the wires and in the breadboard, and have not been able to find any significant voltage drops to make up for the 1.7V difference.
I'm at a loss for what could be causing what appears to be a violation of KVL and would appreciate any explanation for this.


texts:
When I was reading through the RECOM book of knowledge DC-DC, I found out that the SEPIC converter has more chance of having resonance feedback than the ZETA converter. They mention that the SEPIC has 4-pole feedback. Doesn't the ZETA has 4-pole feedback aswell? Why has the ZETA a more stable feedback function?

Both images can be found in the RECOM book of knowledge DC-DC.


texts: Is there any notification system that can turn on a LED pulse?

texts:
I have an idea, and I searched if it exists and didn't find anything.

I'm a live sound Engineer, and many times my musicians want to call for my attention, and I'm distracted with other sound things. I need a system where they step into a pedal with a single button, and the button will trigger a LED that will pulse in my end. I need a button to turn off (reset) the LED when I want, and I need a switch that I'll plug many pedals into it so I can have as many pedals in the stage as I need.

Is there any notification system like this? Can I implement it myself? I'm not a master but I feel I can implement it, and resources are not scarce.


texts: Linear voltage regulator current source high side/low side regulation

texts:
My application requires a constant current source for driving LEDs across a large voltage range (60-300VDC), and also the possibility to do this on both the high side and low side of the LEDs.
Microchip AN-H40 shows the LR8 linear voltage regulator being used as a constant current LED driver, much like similar arrangements for the LM317 or other linear regulators. In this configuration the device looks a lot like the Diodes AL5890, except with the addition of a capacitor.

Is it possible to use this configuration on both the high side and low side of LEDs, as shown in this circuit?
In theory the current drawn on both sides will on average be the same, but it had occurred to me that without C1 there would be larger ripples on the input side than the output side. Are the capacitors needed at all for a 1mA source?


texts: Single conductor connecting two parts of a circuit vs two separate circuits

texts:
In a textbook exercise, this circuit appears

simulate this circuit – Schematic created using CircuitLab
Solving it was no problem, but checking the answer it stated that i0 must be 0 as no current can flow in a single conductor connecting two parts of a circuit. The consequences raised some questions:

Does that mean that the connection between A and B is unnecessary?
That the diagram you get by removing this connection is equivalent to the original?

With no current flowing, must the voltage between A and B be 0? If these were two separate circuits,
couldn't the voltage be anything? If the voltage is non zero, why won't the current flow?

From a practical perspective, how can the voltage controlled current source know the value of v0 if there is no connection between the parts. Is there some real world hidden connection in such current sources that are abstracted away in diagrams?

Thanks, from someone just starting out with simple hobby electronics.


texts: Current/power consumption of an H11L1 optocoupler

texts:
Looking at the datasheet of H11L1 Datasheet, for the Total Device, the power dissipation is 250 mW, does this mean that assuming I put 5V (Arduino) on it, it uses 250 mW / 5 V = 50 mA ?

I think it's quite a lot (assuming I need 3 or 4 in my enclosure), that alone is already 150-200 mA.

(Also I'm wondering if very basic components like diodes, capacitors between GND/5V of ICs etc), pullup/down resistors also uses a lot of power?


texts: Identifying an IC with markings: 0270000 DCP1227 0601

texts:
I have a chip on one of my boards, and I cannot identify it. I tried differnet variations of search patterns but I cannot find it anywhere. The marking on the chip are in three rows as following:
0270000
DCP1227
0601

It seems to be 12 pins total, in groups of three pins in each corner.

I am wondering if the reason I cannot find this chip is because the manufacturer was bought out or went out of business?

I suspect this to be a DC/DC converter from Burr-Brown (bought by TI back in 2000). But I could not find any information about the markings in any online document. I wonder if anyone has an old catalog with a table of product numbers and markings of BB?


texts: Controlling DC motor without Arduino motor shield

texts: I am trying to make a line follower with the help of this tutorial. In the tutorial they have used Arduino motor shield. I want to know, is there any way to control the motors without using Ardumoto?


texts:
When an ac voltage source is applied to a resistor, current and voltage are in phase in the circuit.

When an ac voltage is applied to a pure inductor, voltage  leads the current in the circuit by 90 degree.

But

When we apply ac voltage to a circuit where both resistor and inductor are in series, voltage leads the current not by 90 degree but by another angle.

My question is that when resistor is alone in circuit it  doesnt effect the phase angle, then how can it causes change in phase angle of the overall current when it is with an inductor?


texts:
The cut-off frequency of an RL circuit is described by the following equation:
$$f = \frac{R}{2\pi L}$$ where R is the resistance of the circuit and L is the inductance. Applying this equation to a straight length of RG-58/U coax cable (no resistors or inductors in the circuit) with the following specs: $$Length = 5m$$
$$OD = 5mm$$
$$ID = 0.81mm$$
$$L = 0.00000159H$$
$$R = 0.163\Omega$$
yields a cut-off frequency of 16.32KHz. I know the cable is good for at least a few GHz. What's going on here? Does the formula not work for distributed inductances?


texts: arduino best serial communication solution

texts:
During the last two days I was googling and searching about serial communication tools for Arduino.

I found a lot of tools like :

Node.js through node-serialport
Python through pyserial
Javascript through breakoutkjs using Frimata

So from your experience which is the best one of these and why ?


texts:
I am trying to make a bunch of LEDs fade out when they are turned off. The task is quite simple for a single LED by using a 1000uF capacitor to produce a time delay as in the following circuit:

The other possibility is using Arduino analogWrite() function and get my work done but I don't want to use any microcontroller.

When I try to make it work for like 25 LED in parallel. The capacitance needed grows quadratically to store that much energy. Is there any other way of getting this effect to work which does not involve the usage of a lot of capacitors and neither a giant one.

Note: Please add tags to this question that are more relevant as I could not find many.


texts: What will be mode of operation for BJT in figure?

texts: The value of Vbe active is .7V. Also give reason.


texts: Why do some devices use electrolytic capacitors instead of ceramics for small value components?

texts:
I've recently run into a number of consumer-grade devices that use 50v, 0.22uF electrolytic capacitors, as well as other similarly rated parts, all below about 10uF. In use, the voltages on them are far less than the rating, usually around ~15-25V maximum, and they seem to be used in op-amp filters or as rail bypass caps.

My question is this: Why on earth would you ever want to use an electrolytic in that kind of a situation? I get that ceramics de-rate as the voltage increases, but surely a 1uF 50-250V ceramic would be better for device lifetime and would be cheaper to boot?

(And yes, I have read Ceramic caps vs electrolytic. What are the tangible differences in use?, but it doesn't quite answer my question.)


texts:
I have six 12V WS2815 that I would like to connect in a series and control with WLED running on an nodeMCU board. I have the 5m x 30LED/m = 150 LED strips.
I'm struggling to figure out the proper way to power these strips. The specifications say that the 30 LED/m strips use 9 W/m, so that's 45 W per strip. At 12V, that's 3.75A per strip, or 22.5A for all six.
I assume that I can't just hook up a 25A 12V power supply to one end of the series of strips and call it a day, that's way too much power flowing along the entire length of the strips and something will go poof.
How many of these can I safely power together from a single end?
What gauge wire do I need to supply power?
Should I keep all the power lines connected across all the strips, and inject power at certain intervals, or is it better to just keep the data lines connected and power each strip or set of strips independently?


texts:
I recently received NUCLEO-L433RC-P, which I want to start using with the Keil application. I installed the STM32L4xx_DFP package, but I can't select the board under the "Manage Run-Time Environment" settings.

Would anybody know, what I'm missing?

Thanks.


texts: Three phase motors in parallel - possible?

texts:
Is it allowable to connect some (a group) of three phase fan motors with Dahlander wiring inside in parallel? The whole group will be used for low and high speed according to request. Equal load on each motor. Maybe someone has such an experience? Common fuses for the whole group, not individual (know it is bad).
The same power all of them.


texts: Why do we need many complex voltage references when a zener can do the job

texts: There is a huge variety of Zeners that exist. They have varying breakdown pd among other things. Why then do we need voltage references that are more complex and made up of many components?


texts:
I designed a simple circuit:

that I would like to put components on - the point of the circuit is to light the LED when the voltage source is above 4 volts (it won't be more than 5), so I am looking for a transistor which would have a sharp on/off state at a fixed voltage (say .7 volts, so I can put in some numbers)

at 5 volts, I will put a 330 ohm resistor for R3 to limit the current to 5v (max) /330 = 15ma across the LED (rated for 20mA)

at 4 volts, I want the voltage for the transistor to be .7V, so I will choose R1/R2 = (4-.7)/.7 = 47:10, or 47k for R1 and 10k for R2, which at 4v would give me roughly 70uA for the transistor (if this is not enough, I can increase it by lowering the resistance values)

all of the above can be tweaked, but now I am not sure how to choose a transistor such that this would work - I can go with either pnp or npn transistors by re-organizing the components, but I don't know what else to look for or how to go from here

P.S. if anyone wants to edit the schematic, it's available here


texts:
BMI088 has 4 interrupt pins, 2 for ACC, 2 for GYRO. I've been scanning through the datasheet and can't seem to understand:

Why does ACC/Gyro have 2 interrupt pins that do the same thing?
INT1~INT4 can be configured as input or output - what do those pins do if configured as input?


texts:
I don't really know what is with those stacked dimensions 5.00/4.90/4.80
on the ADP1708 package drawing.


texts: Talking to the Cortex M3 (Stellaris EKS-LM3S1968) under linux

texts:
I've searched around quite a lot, but haven't found an easy(ish) way to load programs onto the Cortex M3 using Linux.

I have tried using the summon-arm-toolchain https://github.com/esden/summon-arm-toolchain/ but it was having problems downloading one of its dependencies.

Does anyone know of any other options?


texts: Arduino reset with FTDI breakout question

texts:
How do you get the SparkFun FTDI Basic Breakout board to auto reset?

I still have to hit the reset button for any Arduino clones when I use the breakout board. I have tried connecting to the DTR pin and other methods of trial and error but I am just not getting it.


texts: What is the maximum safe voltage for 1.5V and 3.7V gadgets of consumer electronics?

texts:
I know that most electronics for 1xAA battery accept at least 1.1-2V and for li-ion 3.5-4.3V. But what is probable safe maximum? Can I use li-ion with 20ohm resistor or even without it for supply 1xAA gadget or 5V for li-ion without noisy DC-DC converters?
Possible easy solution is for example use LED/zener 2V, lm317, some IC current limiters but maybe it is redundant and internal gadgets PSU have it and do it more efficient way due impulse power use of circuits?


texts:
I have basic undestanding of electronics, but I never build anything more then simple one element logic boards. I know how transistor, resistors, and LEDs works, but I having trouble figuring out proper specs for each one. Here at home, I'm trying to build simple IR detector with 2 indicator LEDs, it suppose to lid one of red or green if object inside IR detector.

Here is principal schematics attached. IR led (D3) connected with photodiode (PD2), signal from photodiode go to transistor (B139_2) base and which suppose to get open and allow red LED to lid, same signal go to second transistor (BD139_3) base and close it (reversed using lowering resistor), leads to off green LED. And wise-verse to open red and close green.

How to find proper values for transistor (model) and resistor values to make schematics works?

Photodiode BL-L3522PD working on 5V gives output 0.35V when lid, then I need to find proper transistor which opens on 0.35V. And I guess should keep in mind all internal resistance of all elements, like LEDS and transistors. I suppose transistor has to be MOSFET sine I'm not using current to control transistor, but only voltage.

Second attempt.

Almost working. If I connect 5V to the BC547 base it switch the LED's (green / red) just fine. But, for some reason, If I connect PD2 to the BC547 base it turn's the green LED and RED at the same time. Still the same question: how to find correct transistors (not by guessing or googling for similar schematics), and how to get correct resistor values. (I already blew up one transistor, so, be save, it actually blow, ohh!)

EDIT: D3 goes with 220ohm resistor. replacing PD1 with L-7113P3C makes this schematics works. Check youtube link below.

https://youtu.be/e1UOlpuMJP4 (now I'm thinking about this solution, and I can't explain how it works, looks like miracle to me).

Third attempt.

Using phototransistor L-7113P3C. Using two BC547 transistor's in pair to switch red and green led's.


texts:
I am trying to build a phase shift RC circuit as shown below. I want the output frequency to be 100Khz at a 5V input and  I want to be able to lower the output frequency as I lower the input voltage. So far I have looked into RC phase shift oscillators and used the following equations to determine my cap values.
I verified the the DC bias point of the transistor to be operating but for some reason the oscillations don't show up. Below is my circuit built on LT spice. Any tips to help me achieve a variable RC phase shift oscillator?


texts: Requirements for microcontroller programming of an RFID project

texts:
I am new to microelectronic.But I have a little knowledge in some hobby circuits etc.

I want to make a fully automated circuit for my vehicle,by using a short range RFID sensor for detecting the unique person(Driver) for driving a vehicle,-So as to avoid anyone driving my vehicle..

My idea is..

program description

When the owner sit on his vehicle and put the key on vehicle.
RFID sensor start detecting necessary tags.
If necessary tag found detected, vehicle will turn on
If no necessary tags found,inform the owner with some voice alert

Advantage is that

no one can ride our bike without necessary RFID tag(Because No one knows about our personal RFID tag).

This is the first step.

Is it possible to create a micro-controller program using high-level programs like JAVA or VB etc and convert to hexadecimal codes,for my MC??.

Thanks in advance..


texts:
I am using AD8347(0.8 GHz to 2.7 GHz Direct Conversion Quadrature Demodulator) to demodulate a BPSK modulated carrier wave. There is no intermediate frequency used.

By feeding the signal into this chip, I was able to get 4 outputs: IOPP, IOPN, QOPP, QOPN (I signal output positive, I signal output negative, Q signal output positive and Q signal output negative).

The source data is 115200 baud BPSK modulated to a 2.4GHz carrier wave. How do I analyze the 4 outputs to retrieve the original data? I understand that BPSK modulation meant that only the IOPP and IOPN signals are useful.


texts: What does a transistor look like in the Intel 4004 microchip?

texts: Could anyone show a picture of what the transistor looks like in the Intel 4004 microchip? There are 2300 transistors in that microchip.


texts:
I'm porting a code from c in the Arduino platform (I'm using an Arduino Leonardo). I wanto to remote control a camera with an IR LED. The info about the remote control want to emulate here. The code, here.

The Burst frequency to drive the IR LED is 32700 Hz, and i'm trying to make Arduino runs at this frequency.

I've not an engeneering background so i don't really know what to do. I think i need some kind of delay to make Arduino run at that frequency, there is a note on the frequency in the second link i gave:

  Before compilation, the microcontroller clock frequency must be
  specified [...]

  In case the IR light is visible and the camera not responding: [...]
  check the program timing. The _delay_us() routines in the code need a
  proper setting of the F_CPU variable.

EDIT: i'm posting because i have tried the code in here but it seems to be some communication problem with the IR signal emitted: not every time the LED blink (i have tested with a cellphone cam and it blinks at specified times) the camera is shooting.


texts:
For a pet project I want to run a motor and also be able to reverse the direction. I found this motor and pasted the information table below. As far as I know a DC motor needs to be brushed for it to be able to reverse the direction, but I can't find if this motor is brushed or brushless.

Am I missing something? Does anybody know if I will be able to reverse this motor? All tips are welcome!


texts: How to calculate capacitor to fix a brownout

texts:
I have connected an ESP32 to a 3v3 voltage regulator as seen in the picture below.
Essentially: Unregulated voltage ----[4.7uF]---LDO---[4.7uF]--[0.1uF]--

Then at the ESP32 at the VIN i have [10uF]--[0.1uF]---ESP3V3 [Where all the caps are connected between LDO and ground].
The LDO datasheet https://www.digikey.com/en/datasheets/diodes-incorporated/diodes-incorporated-ap7361c

After connecting it the ESP during wifi boot detects a brownout and constantly resets.
The brown out can be seen below. The duration is aprox 1ms

And the voltage drop is around 1V

At the input side of regulator this is the brownout

How do i calculate the capacitors needed to avoid the brownout.
How would you go around this problem?

I think the problem is that the capacitors i used are simply too slow (have big internal resistance?) to provide the current needed fast enough.


texts: Wake up a PIC from sleep using Timer1 Interrupt

texts:
I tried to wake up a PIC (16F88) from sleep using Timer1 Interrupt with external crystal. But it doesn't work. I tested it using watch dog timer and it works. But I want to use Timer1 Interrupt. It doesn't wake up. My code is here.
I used PIC 16F88, (checked also 12F683) and 4MHz Crystal.

unsigned short cnt;
 void interrupt() {
  if (TMR1IF_bit) {
    T1CON.TMR1ON = 0;
    cnt++;
    TMR1H = 0x00;
    TMR1L = 0x00;
    T1CON.TMR1ON = 1;
    TMR1IF_bit = 0; // clear TMR0IF
    }
}

void main() {
  ANSEL = 0; // Configure AN pins as digital
  TRISA = 0x00;
  PORTA = 0x00;
  TRISB = 0;
  PORTB = 0x00;
  cnt=0;
  T1CON = 0b10110101; // Timer1 settings, No Sync with internal oscillator
  TMR1IF_bit = 0; // clear TMR1IF
  T1CON.TMR1ON = 0;
  TMR1H = 0x00; // Initialize Timer1 values again
  TMR1L = 0x00;
  T1CON.TMR1ON = 1;
  TMR1IE_bit = 1; // enable Timer1 interrupt
  INTCON = 0xC0; // Set GIE, PEIE
  //OSCCON.IDLEN = 0;
  do {
    asm SLEEP
    asm nop
    //asm nop
    if (cnt>=1) {
      PORTB=~PORTB;
      cnt=0;
    }
  } while (1);
}

I tested it changing T1CON as 0b00110111. Doesn't works. What is wrong in my codes?
Please help me.
Thanks.


texts: High voltage dielectric breakdown & layering insulators

texts:
I’m going to use 230 kV as the reference voltage for the example below;
I know if I put a piece of metal too close to a 230 kV source it will breakdown the air and jump to the piece of metal causing a visible spark, even if the piece of metal is floating in air and not completing a visible circuit.
I also know that when a dielectric breaks down it drastically reduces its resistive properties and can act like a conductor.
Let’s say the dielectric breakdown of air in 230 kV is 7 inches.
If I put a grounded piece of metal 8 inches away from the source then nothing will happen other than negligible small currents from capacitive induction.
If I put a floating ungrounded piece of metal 4 inches away from the source then it will breakdown the air and cause a visible spark, energizing the piece of metal.
Now what if I put one ungrounded floating piece of metal (piece “A”) 4 inches from the source and another grounded piece of metal (piece “B”) 4 inches from the previous piece A. Together the total distance piece B is from the source is 8 inches. Would the 230 kV breakdown the air from the source to piece A (visible spark), causing piece A to become energized and then breakdown the air from piece A to piece B (visible spark) causing piece B to be energized at 230 kV and causing a fault?
Can this cycle continue if I were to put another floating ungrounded plate (piece “C”) 4 inches from A then put B 4 inches from C? (Source <-4”-> A <-4”->  C  <-4”->  B) Then air to A would breakdown then air to C would breakdown then air to B would breakdown causing B to be energized and a fault?
If the above is true then here’s my following question;
If I have rubber gloves rated for 20 kV and dielectric boots rated for 20 kV, does that combine to make a total rating of 40 kV safe to touch?
Or if I had say a 35 kV source would the voltage breakdown my gloves destroying their dielectric properties and then break down my boots as well? Meaning the total rated voltage safe to touch would be 20 kV since that’s the highest of any single dielectric.
I understand if we were to build a circuit with capacitors acting as insulators there would be a voltage drop across each capacitor causing the layering effect to work, making the gloves and boots a total rated voltage of 40 kV when worn together. But this does not incorporate the concept of dielectric breakdown of the insulators causing a significant change in its resistivity.
Thanks for the help, please provide details and reasons for why your answer is what it is and if possible please explain the theory behind it.
Thanks!


texts: High accuracy (0.1°C) digital temperature sensor

texts: What kind of digital temperature sensor can provide a high accuracy (0.1°C)? Especially, 1-wire. I want to use it in medical thermometer.


texts: What is the difference between IF data and IQ data? How we can read IF data in SDR?

texts:
How to read IF data in  GNU SDR?

As i had tried a lot to read IF data in SDR but it can be readable in MATLAB but not in SDR..


texts: How does this overcurrent indication circuit work?

texts: Can anyone explain how the overcurrent (OVC pin) circuit below works? I am lost in all these transistors. I only get that it will output +5V on the OVC pin in the event of an overcurrent condition on either the VPP or the VDD line, but have no idea how it actually does so.


texts: Can the FTDI Tx and Rx tension level be different that it's VCC?

texts:
I'm building my own FT232RL to convert a UART signal to USB.

The source of power will be the USB 5V, but for reasons of the circuit i already have it would be easier to let more of the circuit keep working at 3V3 (i use a DC DC from the 5V to 3V).

The FT232RL needs its VCC at more than +4V so it uses its internal oscillator.

From the datasheet i'm having trouble to understand if i can have its VCC at a voltage level and then receiving the signal on Tx and Rx at a different level, let's say 3V3.

What shall i look on the datasheet?

This is the circuit in question:

On the datasheet on page 26 there is an example where it shows we can connect VCCIO to the 5V from USB or the 3V3OUT of FT232RL, this is another question i have, instead of 3V3OUT can we use another 3V3? The reason is i don't think 3V3OUT provides enough current for all my circuit. (hope this doesn't cause a problem)

"The VCCIO pin is either supplied with +5V from the USB bus (jumper pins1 and 2 connected), or from the +3.3V output from the FT232R 3V3OUT pin"


texts:
I would like to find out the internal resistance Ron of this IGBT device :
http://www.infineon.com/dgdl/Infineon-IHW50N65R5-DS-v02_04-EN.pdf?fileId=5546d461464245d30146ae23713f0115

The Ron resistance is not included in the datasheet.

Is there a way to export Ron from the charts that are included ?

Thanks in advance


texts: Which formula is correct for a Digital-Analog-Converter?

texts:
I am looking for the formula for an ideal DAC: a device that takes in a digital code and returns an analog value

rfwireless-world.com claims

$$V_{out} = D\cdot V_{ref}/(2^N-1)$$

where D is the digital code and N is the resolution of the DAC.

However, sciencedirect.com claims it is

$$V_{out} = D \cdot V_{ref}/2^N$$

Which is correct? The second equation seems to imply that \$V_{out}\$ will never equal \$V_{ref}\$ since the highest value \$D\$ can take is \$D_{max} = 2^N-1\$


texts: What are the pcb routing standards that I have to follow for routing STANAG video signals on my pcb? Specifically, what are the impedance requirements? Is it better to route as a stripline or microstripline transmission line? Can I can use vias on my board?


texts:
Suppose I want to measure individual cell voltage of a 12-serial-cell battery pack, what would be my most economical options?

Single cell voltage is 3V-4.2V but the stack can be between 2-12 cells high.

I am looking for a solution to be attached to a microcontroller running at 3V3. Update rate requirement is modest in the range of 10Hz for the whole stack.

My first bet would be a instrumentation amplifier with sufficiently high common mode range multiplexed to the respective junctions between the cells. This however requires both a sufficiently high rated amplifier and multiplexer. Can someone suggest suitable parts or suggest a better approach?

By the way, the cell voltage of course needs to be sampled by an ADC but resolution needs to be modest 8-bit at most.


texts: How to identify high side switch or low side switch? Is the circuit a high side or low side switch? Why?

texts:
I am in progress of analyzing a schematic.  I have a major doubt and confusion.

The below circuit is for measuring the current and if the current reaches the threshold value the Mosfet will get switched off so it will cut the power between battery and the vehicle for protection.  In this circuit they have used two MOSFETS for switching.

Are the below Mosfets connected as high side switches or low side switches?

I searched on Google and I got many results. I understood the concept but when I compare it with the circuit I am getting confused because both the sources are connected together.

Please explain which type and why when it comes to two mosfets.

Please tell me if it is high side or low side and why and also how to identify it.


texts: How does the current travel in Bipolar Junction Transistor (BJT)?

texts:
I am completely unable to understand the current direction in npn transistor.

in figure 1, the red arrow indicates the electron flow(which is from emitter terminal to collector terminal). thus according to the convention, the current flow is just opposite to the direction of electron flow. therefore the current must flow from collector terminal to emitter in npn trnasistor.

but nothing like that happens. instead, the current flows from emitter terminal to collector terminal(that is in the same direction of electron flow). why is it so? why does this happen?


texts: What is the purpose of a PCB with no copper tracks, but only unconnected copper rings?

texts:
I have a PCB which has the perfect size for a project of mine, so I would like to use it if possible. However, the copper plating on the back side of PCB only surrounds the individual holes (that is, no holes are interconnected). See picture right here:

I find this strange. How can this be useful? I would definitely need some copper tracks with interconnected holes in there because some components need to be connected to each other. Am I supposed to make my own tracks somehow?

I saw some stuff online about people who would insert multiple wires in the same hole to make interconnections, but this seems undesirable. I'd rather avoid that if there is some way to make tracks.


texts:
I got a Motherboard of a Notebook that has three identical capacitor damaged. But I can't find this model, I think its a smd electrolytic 390uF 2.5v. But its so hard to find one that match with that specifications.

Can someone confirm that? Or just tell me what is the Real Model of it?


texts:
I've got a phone line on the blue pair, and VDSL on the brown pair. Leaving the orange and green pairs available.

But when I try and connect a router in one room, and a laptop in the other room, I don't get a connection and also the phone line goes off. VDSL stays on.

Why is it even touching the blue pair? I thought Ethernet only used the green and orange pairs. Or have I got something wired incorrectly? I haven't seen any indication that I have.


texts: OpAmp/Comparator for AC current detector circuit

texts:
I am trying to complete schematic for current detector. This is addition on How to build AC current sensor circuit for ESP-01 GPIO.
By googling and researching I came with following schematic which I try to simulate in LTSpice:

For a simplicity I used V1 which is voltage representation of a current that will be flown through current transformer i.e. burden resistor.
LM358 should work as comparator, while D1/C2/R4 are used as peak detector to maintain high enough voltage for mosfet to turn on when current flow is present.
But as you can see on transient response above, LM358 obviously is not a good choice for this task.
Output from LM358 provides significant voltage drop and it ends on around 1.7-1.8V which is too low for mosfet to reliable conducts.
As far I understand some explanations on the net, LM358 is not rail to rail op amp, on my surprise it really behaves according to this model and doesn't fit for this purpose.
Seems like LM324 behaves in a same way.
I try to use few comparators as an alternative, for example LM393.
Problem I found with comparators is that some of them requires negative voltage source V- along with V+ - they didn't work by grounding V-.
Second problem I found out is that some of them requires external pull-up resistor at the output to work properly. But this can't work properly for this circuit, at least I don't know how to do it.
Once I finally found one comparator that fits this purpose - TLV3501 I noticed that my local electronic shop doesn't have it. Alternative, LT1720 that worked in simulation also is not available for me. Some of them are expensive for simple design like this.
Do I need to change the circuit or get a better opamp? Do I need a reason to rail op amp?
Input voltage should be 50Hz sine, with amplitude not lower that 100mV.The only restriction for this component that I can see is that should be rail to rail i.e. output voltage close to V+.


texts: How to add a low pass filter to this non-inverting amplifier circuit?

texts: I've come up with this simple circuit as an amplifier before an 8bit ADC which receives audio signals. R2 is actually a variable resistor (pot.) of 100k. The circuit also biases the signal to VCC/2 and uses large resistors to set the input impedance is pretty high all over the working audio frequency range. This works well for my application, however I would like to add a single low pass filter stage to this amplifier so I can remove some high freq. content that I would not be able to sample. How to approach this without having to use another op-amp and without changing the characteristics of the circuit in the spectrum I would like to pass?


texts: Why should a fuse be installed in live instead of neutral?

texts:
I understand why it should be installed in positive instead of negative side in DC, but this is AC. Direction of current reverses half of the time.

It is said that installing a fuse in neutral causes a high potential difference between live and the fuse. However, isnt it the same if you install it in live? Since it is AC, the potential difference between the fuse and neutral will be negatively high, which causes equal amount of damage in a ground fault.


texts: 180 degree motion servo that can take a hit

texts:
I was looking into servos and I need some help choosing the proper one. I need a servo that has complete 180 degree motion but it's going to get hit by dogs a lot so it needs to hold it's position against a good deal of force. My biggest problem with this however is the fact that it needs to be tiny. I was thinking I might have to go with a locking gear system what do you recommend.

I am attempting to make self adjusting weave poles like these:

The problem is dogs will be hitting them constantly and there is very little room for these servos. Especially with the fact that they will have to be operated using rechargeable batteries. In order to ensure that they are properly adjustable, they need to hold shape. Also I am designing a GUI that will allow them to be remote controlled so they can be set to different angles depending on the dogs skill level. Anyone have some ideas?


texts:
Sorry for my  obvious  question, but  I am not from the field of electronics and electric  engineering.

I was reading this article:
The first sentence in the introduction says: " All solid dielectrics exhibit the propensity to accumulate electrical charges under electrical stress beyond an electric field threshold. "

First question, is dielectric polarization the same as saying dielectric accumulate electric charges ?

I would like also  to  ask about the diadvantages of  accumulation of  electric charges in dielectrics, can some one give a me a real example from daily life problems?

I read somewhere that   this can cause cables to be damaged, how this occurs?

Thank you in advance.


texts: Is it Possible to control LED with arudino pins combined with PWM from IC?

texts:
What I'm looking to make is a multiplexed 16x16 LED grid with  with 2-bits of brightness (aka 4 levels of brightness). There might be a better way to do this.

I've built a prototype 8x8 grid with an Arduino Nano, it works great. I have 8 pins to connect the anodes and 8 pins to the cathodes. I'm using 3v 20ma 5mm LEDs

But, since arduino only has 6 PWM pins, i can't get the resolution I want. I'm looking to get more pwm pins

I'm looking at the ADAFRUIT 24-CHANNEL 12-BIT PWM LED DRIVER, which gives 24 pins of PWM over SPI. While 8x8 I can do on the board, if I wanted to do a 16x16 matrix while connected to the Arduino. Is it possible to use pins from the LED driver to run the anodes (16 of the 24 pins) with PWM while using 16 GPIO pins on the arduino to run the cathodes (to get more pins for multiplexing)? From my experiments, only the anode needs PWM while the cathode just needs to be high or low for multiplexing. Would the VCC for the Driver need to come from a power supply?

Thanks!


texts: Measuring Peak Output Power for Frequency Hopping Transmitter (915MHz) for FCC Section 15.247

texts:
I've been looking at building a ~900MHz frequency hopping transmitter that conforms to FCC Section 15.247.

See section 3.2.1 Frequency Hopping Spread Spectrum Requirements in the Semtech document below.

Semtech's write up on FCC Section 15.247

There are all kinds of channel separation measurements, and whatnot in the regulation, but I am wondering how do you ACTUALLY measure the peak conducted output power that goes up to 1 watt (+30 dBm) according to 15.247?

I've got an EMI testing antenna with known antenna factors, and conduct 3 meter readings in my office for field strength measurements; however, I've never encountered this kind of measurement?  For whatever regulatory reason, the FCC doesn't specify a field strength measurement for these systems.

Is measuring the conducted output power, simply just hooking up a coax pigtail to your TX IC output line (or using an SMA / UMCC connector, etc.) and running the TX IC output into your spectrum analyzer?

If it is -- one word of caution is that +30 dBm would blow-up the front end of my signal analyzer which is rated for up to +20 dBm; so you might want to look at an attenuator.


texts:
I've read most of the datasheet, but have not found a solution. Why is PORTB on my PIC18F2550 only accepting a maximum value 3? My code is:

;Configure PORTA e PORTB
MOVLW   0x0F ; Configure A/D
MOVWF   ADCON1 ; for digital inputs

;Enable the pull-up resistor
MOVLW   0X00
MOVWF   INTCON2

;Set all the pins of TRISB as input, except for <R0:R1> that are outputs
MOVLW   b'11111100'
MOVWF   TRISB

;Clean up registers
CLRF    LATB
CLRF    PORTB

The LATB can store 11111111, but only stores 00000011 PORTB, why?


texts: I designed a PCB where I have a local oscillator Input to an IC. The LO signal (2.48 GHz) has a power of -20 dBm. I put a cut SMA cable on the ground plane and measured a signal level of -60dBm. Is this normal?


texts: Controlling two devices with the same push button

texts:
Currently, I have a push button (SW) controlling a device (DEV1). What I would like is to another device with the same push button (SW). I measured the voltage on DEV1's and DEV2's push button inputs, and I got 5v and 2.45v respectively.
Is it possible to have a single push button controlling both devices? What should I do with respect to the difference of voltage between DEV1 and DEV2?

The devices are two swing gate motorizations. They both have push button input in the form of 2 screw connectors as shown below. Both devices are looking for dry contact.

Furthermore, my ultimate setup will be replacing the single button with an output signal from Meross RSG100 WiFi garage opener kit as follows:


texts: Does iphone shock transfer AC or DC current to body?

texts: Suppose an iphone gave a little jolt when pressing the power button. Is that AC or DC current? The phone was connected to a laptop which was connected to a power outlet.


texts: active current protection with diode instead of shunt resistor

texts:
Is this current protection technique going to work?
I came up with this because I want to make a current protection circuit and I do not have a shunt resistor at hand. I think the circuit should work in the following way: Initially, at power up, the voltage across the diode D1 is almost zero, so the output of the op amp OA1 is less than the non-inverting input of OA2 (formed with a voltage divider from a 9v power source), hence the output of OA2 will close the N mosfet Q1. This in consequence will close the P channel mosfet Q2. The 10 V zener diode Z1 will have a voltage drop of 10 v and the rest of 30 v will create a current of I_z =30/500 = 0.06A which is assumed to be lower than the maximum rated current of Z1. Therefore the mosfet Q2 is conducting.

However, if the current through R_load is increasing too much, say to create a voltage drop greater than 1v over the diode D1, (this means less than 50 A through diode, according to this), then the output of OA1 will be greater than that of the voltage divider, and the output of OA2 then will be low, opening Q1, which in turn will open Q2.

Is this how it will work? Feel free to comment on this design ... Which are the possible problems?


texts:
PCO/ADC/PCINT8 is pin mapping for pin 23 of ATmega 168.Which of these mappings should be included in LiquidCrystal lcd(0, 1, 2, 3, 4, 6); when interfacing ATmega 168 to 16*2 lcd?
Can someone assist me on which parameters of ATmega 168's pin mapping should be used to initialize the library(LiquidCrystal lcd(0, 1, 2, 3, 4, 6)) using arduino IDE especilly for Proteus Simulation meaning Arduino Programmer is not available?


texts:
Despite my Computer Systems Engineering degree, I haven't played with electronics for over a decade, and I'd like to get back into it.

I have a project idea, and I think I've got all the design leg work done. However before I commit money to this project, I would like a second opinion. My assumption is that I'm completely out of touch and no longer know what I am doing, so please take a look.

I believe the digital parts of the project to mostly be a nonissue. My biggest problem is powering 2048 LEDs that require that I deliver 640W over 5V, so a 128A current draw.

I've written up what I intend to do (and how I came upon the Idea) here.

In short, and in terms of power supply: I intend to have 512 LEDs, each drawing max. 60mA in parallel. Thus a total of 32A @ 5V. I will then connect 4 of these these in series. Thus 32A @ 20V achieving my 640W supply for 2048 LEDs. Thus avoiding DC-DC converters and yet more heat.

I plan to deal with connecting the logic parts of the circuit to the floating grounds using some form of Digital Isolator IC.

I need to ensure that each of the floating 5V power rails stay at 5V. Remember each LED has its own PWM and so current draw will fluctuate very rapidly. After some searching I landed on the idea of using a Zener diode to provide the base current to a power transistors . I need to look at possible transistors. I think I will probably pepper more then one across each rail to keep current and heat (in any one area) down.

Some capacitors would probably also help.

Is this a reasonable solution? Or is there a better way?
Should I arrange the circuit differently somehow? e.g. dividing through 40V (8 x 256 LED strips) to keep the current down even further? Can I get 40V from a ATX PSU or will I have to use some other supply?


texts: 500mw laser diode: What's the point of a driver and will it need a lens to focus?

texts:
For a hobby project I recently bought a laser diode with the following specs:

Mitsubishi 645-655nm 350-500mw High-Power Red Laser Diode LPC-836

Power output: CW 380mW
Pulse Power: 570mW
Working Current: <340mA
Working Voltage: 2.2-3.0V
Sealed method: TO18 (5.6mm)

Naturally, the first thing I did when it arrived in the mail was to power it up using 3V DC. What I observed was a bright red light, but it was very spread out. Thus I have a few questions:

Will the diode likely be destroyed with just DC current from two 1.5V batteries and no driver?
Is the point of the driver to only provide a steady current? Could not a suitable resistor do the same trick?
What is the point of the third pin on the laser diode?
Is the light supposed to be spread out like that from a laser diode? I also bought a bag of cheapo 5mw laser diodes, that are mounted in a small brass housing and appear to have a simple driver attached. Would this housing be enough to focus the beam?
Finally, in the case that I do need a driver to set this up correctly, would something like this do the trick?


texts: Influence routing on power consumption in FPGA

texts:
What does influence of routing in static/dynamic power consumption  in FPGA design?

I want to know that, different routing results different power consumption?


texts: How can Qsys component configuration be accessed in software?

texts:
I'm designing a Qsys component which I want to be user-configurable. It has config parameters which are defined in the TCL file. For example, for a GPIO bank component I would write:

add_parameter GPIO_OUTPUTS_COUNT POSITIVE 8 "Number of GPIO pins"
set_parameter_property GPIO_OUTPUTS_COUNT DEFAULT_VALUE 8
set_parameter_property GPIO_OUTPUTS_COUNT ALLOWED_RANGES 1:32
set_parameter_property GPIO_OUTPUTS_COUNT HDL_PARAMETER true

The value of this parameter can be accesses in HDL code easily:

module gpio
(
...
);

parameter GPIO_OUTPUTS_COUNT; // gets the value assigned by user

Now, I would also like to have this value in my driver's C code, e.g. to check for errors where the user is trying to access non-existing pins:

int gpio_write(pin, level) {
    if(pin >= GPIO_OUTPUTS_COUNT) return -1; // No such pin

    ...

    return 0; // Success
}

How can I get GPIO_OUTPUTS_COUNT name defined in my C code?


texts:
I am interested in developing a generic 8-channel 4-wire PT100 interface for RaspberryPi. Needed accuracy must be better than 1degC and range from 0-200 degC. Additionally i need lead wire compensation. Here is the plan:
1) Use constant current source using TL431 and a 2N2222 transistor. I am guessing this should work:

2) Then route this 1mA current through a CD4051 multiplexer to the power wire of each of 8 PT100s. Additionally, get the return signals through another two CD4051 multiplexers into an ADC as follows: :

3) Finally use ADS1115 ADC to A) find potential drop across the lead wires 1-2 of the 4-wire pt100. Then B) measure voltage drop across PT100.

Now my problems are:
1) I can at best procure 1% resistors for the constant current source. So the current may not be that constant. I will hand pick the resistors but what about temperature compensation? In general how much current variation can i expect?

2) Is the scheme of interfacing 8 PT100s OK or can there be better ways to do the same? As i have read in distributed posts here as well as in some papers(eg. here or here), this is a common method. But i could never find how they practically implemented this or if its performance suffered and so on.

3) How can i measure leads wire resistance without getting the Rds(on) of CD4051 in the effect? This is so because 1mA is passing through the 1st MUX.

Kindly let me know if there are any mistakes or improvements in the above scheme. I am a novice (mechanical eng.) but i am OK to learn, so kindly pardon me if i am off somewhere. Thanks!

------------------------------ EDIT ---------------------------------------

I am only now interested in 3-wire PT100 sensors as these are what available locally at affordable prices. All the rest of the requirements remain the same. So the problem is clearer now: How do i measure the sensor lead resistance while avoiding the Rds(on) of CD/HC4051*? A possible solution:

In this figure, the first wire of pt100 is supplied by 1mA current through a HC4051(see footnote). Since i need to make a differential measurement between the first two leads of the pt100 while avoiding rds(on) of HC4051, i attached A0 of the ADC directly to the first wire through a schottky diode. The diode prevents the activation of other PT100 channels not activated by HC4051. The 0.3v drop due to this diode can be incorporated into calculations to get lead resistance. Am i wrong or OK in this regard? Is leakage current going to be a problem?

I have also included a resistance (2.5k) between the third wire set of PT100 and ground. This i presume will help make a better differential measurement at the ADC (A2 and A3) while avoiding any current passage through HC4051. Does this make sense?

Thanks a lot for responding so far.

*(I accept the suggestions given that CD4051 is not the best for this case. I will take @Sephro's suggestion of HC4051.)


texts: Need help driving N FET gate from LM393 comparator output

texts:
I am working on a charge controller circuit idea I had. The circuit
'works' meaning it achieved desired output voltage but the fet doesn't
seem to be turning all the way on so lots of heat is generated.

I am using an LM393 dual comparator to measure the voltage at the
junction of the zener and series resistor R1, compare it to the voltage
at the - pin of the capacitor, and switch the enhancement mode
FET on and off accordingly. I built the circuit on a breadboard and
was elated when I measured the output and was able to connect
a solar panel and battery. The fet needs about 5v at the gate. For some
reason i only measure 2 or 3 v at the gate. Can you drive this FET
direct from the output pin of the LM393 directly or will I have to
amplify the output somehow to make sure the fet turns all the way
off and on? Also, I am powering the LM393 directly from the input.
I wonder if that could be a problem. Am I going about this all wrong?
Any help would be much appreciated. It 'works' but wastes power
by the fet presenting resistance. Please take a look.

Input is 16.5 v PV panel
zener is 12V
output is 12v lead acid battery
R1 is 1k, R2 has been 3k and 10k
The FET is a typical enhancement mode N channel, RL2203N or RFP50N06


texts: Circuit to save one battery when another battery is present

texts:
I have a battery powered system and I want to preserve the test batteries during setup and calibration.  I want the system to use the setup batteries if they are present and use the test batteries if not.

The test batteries are either LiOn (nominally 7.2V) or NiMh (nominally 6.0V) and the setup batteries are NiMh (nominally 6.0V).  I'd prefer a simple system, and also one that doesn't necessarily depend on the exact voltages and charge levels (as it's possible the setup batteries could be higher voltage than the test batteries in some cases).

I'm guessing the following PMOS circuit would work, provided that the Vgs(th) is higher than the max difference between Vtest and Vsetup.  Getting a PMOS FET with Vgs(th) of about 4V seems about right.

simulate this circuit – Schematic created using CircuitLab

There are a few other SO topics about undervoltage and undervoltage cutoff that use voltage dividers, opamps and PMOS FETs, and another using an SCR, but I'm hoping for something simpler.

It seems like a JFET circuit might work here too (but I've never used a JFET yet).

Will my circuit work?  Is there a better way?


texts: What is this symbol circled in green in the image? Is related to that induction motor, and I guess it is a french project (if that helps).


texts: LDO - DC Accuracy Error Calculation (Datasheet vs Theoretical question)

texts:
I'm looking at calculating the DC Accuracy of a couple LDOs and came across some good resources - but I'm having trouble linking their example calculations to the "real world."
[TI LDO] https://www.ti.com/lit/an/slva072/slva072.pdf
[Analog LDO] https://www.analog.com/en/analog-dialogue/articles/understand-ldo-concepts.html
The example (interestingly, the exact same example in both articles) uses the parameters:
3.3V LDO over 0 to 125C temperature span
±100 ppm/°C resistor temperature coefficient
±0.25% sampling resistor tolerance
±10 mV output voltage change due to load regulation
±5 mV output voltage change due to line regulation
1% reference accuracy

I get that the sampling resistor parameters come right from the resistor datasheet.

The Line/Load regulation errors (I imagine) come from my system? If I'm supplying voltage with a USB port it would be the variation in the USB port voltage supplied, and if my load is a couple LEDs the amount of voltage variation over those LEDs?

The reference accuracy - I figured that comes from the LDO datasheet, but I'm not sure exactly which parameter it refers to. Is it just the "Fixed Output Voltage Accuracy" or is there another parameter I haven't connected?
[ADM7172] https://www.analog.com/media/en/technical-documentation/data-sheets/ADM7172.pdf

Thanks so much for any guidance, and/or additional resources.


texts: 5 pin push button switch with LED AC wiring question

texts:
Thank you in advance for any help you can give.  This is really my first project like this.  I built a shelf in my house based on this picture.

and I'm integrating an Eddison bulb lamp into the project for some lighting.  I've decided I want the light to be operated by a switch and I was looking to purchase a small push button that could be screwed into the piping I'm using for the shelving and I could run all the wiring in the pipes to "hide it".

I'm looking to use this  Switch (for sale on Amazon) which has the following properties, wiring diagram, and an integrated LED to operate the on/off function of the Eddison bulb.
(Switch Properties)
Switch rating:5A/250VAC
Switch combination:1NO1NC
Operation types:Self-locking

I did some preliminary digging to find a compatible wiring diagram for the switch but cannot find the voltage/amperage settings for the switch's integrated LED.  Similar switches from the manufacturer with integrated LEDs I have seen have the LED rated at (LED voltage: 12V).  I'm assuming this is 12v DC but i guess i'm only 99.99% certain.

I guess my questions are as follows:

(1) can anyone tell me if the LED is likely 12v DC (is this a stupid question?) and if so, suggest a way to wire in a converter or how I should wire in the LED so that I can fit into the shelf piping and wire it into the same line powering the Edison bulb?  I'm just confused as to how a switch rated for 5a/250v ac would have a 12v (presumably dc) LED on it and how to wire or integrate it into the wiring for the switch itself if I have 120v running through the switch.

(2) is it possible to wire the LED light in such a way that when the Eddison bulb is on, the integrated LED is off and vice versa?

(3) if the amperage coming off the wall is 15/20A as most sockets are, do I need to wire in a resistor to the switch to make sure it's not damaged or will it be okay?


texts:
I want to use a ESD Diode against Vehicle Battery which is rated @ 36V max. I have selected below Diode :-

http://www.nxp.com/documents/data_sheet/PESD36VS1UL.pdf

Now, I am okay with working voltage which is 36V & peak pulse current which is 2.5A. But I could not find any information on continuous current rating. Can someone please explain?


texts: Power Density parameter in Ultra Low Power (ULP) devices

texts:
I'm doing a bit of research on ULP processors.

In a few papers (e.g. "Energy-Efficient Near-Threshold Parallel Computing: The PULPv2 Cluster") I found a figure of merit called "power density" and defined as Pdens = uW/MHz, so basically it is energy.

The thing is I don't understand what it means, I'm not sure when this would be useful either.

From my understanding:

A circuit consuming 10 W @ 25 MHz has a Pdens1 = 10/25 W/MHz = 0.4 W/MHz. If it was running @ 50 MHz but still consuming 10 W then it would be Pdens2 = 0.2 W/MHz.

To me, Pdens2 is better than Pdens1 since the goal is to minimize power consumption.

Any hints? Or good introductions books/article to ULP which better explains figure of merit like this and Energy Efficiency (MOPS/mw), for example.


texts: unstable / distorted / glitchy digital line signal

texts:
Is there a proper word that describes what the MISO line does in English language ?

And secondly how would I debug this hardware issue? I should say that the SPI device that I am trying to communicate with has already been replaced with a new one. Same behaviour.

Update in response to comments: no analog oscilloscope available, circuit's clock is set to 2 MHz, logic analyzer samples at 16 MHz, the (one and only) SPI slave is a RFM43 ISM TRANSMITTER Module, no schematic - just wired an arduino to the SPI slave.


texts:
I'm trying to build a Radio wave penetration device that register the RSSI on the RX module.
There are two 433 transceivers one is the RX and the other TX - I want to place between them different types of walls to measure the penetration of the radio wave.

To avoid other signals to interfere and to assure maximum penetration I want to use for the both a directional antenna. The catch is it must be as small as possible I've googled for hours trying to find small designs but no luck - I'm not going to transmit any data I just want a link and a RSSI read. any Ideas? I need it ( the antenna ) to fit a 12X12 cm box.

Thanks


texts: Zener voltage regulator circuit question

texts:
I'm repairing a power supply, which has the following circuit:

It looks like a Zener regulator but have this strange 1K resistor in red. Does anyone knows what is the purpose of this?
I'm also trying to figure out the zener value, it measured inconsistently values, i guess it has failed.
Vout must be 15v.


texts:
I found in the schematics of Arduino DUE some polarized capacitor but in the board I can see NO polarized capacitor.

Somebody to know why ?

I guess the capacitor on board is like a capacitor 50v like Capacitor Murata


texts: Voltage across and current through the LED load

texts: Assume that an LED of rating 3V and 20mA is connected in series with a resistance and a supply voltage of 9V is applied across it. For the required ratings of LED, I chosen a resistance value of 300 Ohms (Theoretical Value). Now, when I increased the supply voltage upto 12V by taking current 10mA~70mA, What will be the voltage across that LED and also the current through it? Actually the 3V LED will burnout but what will be the theoretical current and voltage across it when supply voltage is 12V?


texts:
I'm designing a voltage measurement device and I i'm testing it and the front end voltage divider and it has a much lower voltage than expected. Circuit is below.

simulate this circuit – Schematic created using CircuitLab

So I put in 5V (real world) input across R1 (10Meg) and R2 (10Meg) I only see 384.6mV between them?? I expect to see 2.5V. What have I done wrong and how do I fix it?

p.s dont simulate the schematic its just representation

UPDATE---------

Thank you for the input, I have found the issue and its a novice mistake which took me awhile to find. I've updated the schematic. See im using R2 and R9 to attenuate the input voltage, but I did not take into account the OFF resistance of M1 and M2, which I have measured to be 0.9Mohm, so obviously most of my voltage is being dropped in R9 and M2.


texts: Possibility of effectively under sampling a band pass signal?

texts:
For a university project we have been tasked with implementing a digital signal processing system on an STM32 discovery board in which we must model the AM channel  to measure and graphically display the channel characteristics of the AM band (526.5 – 1606.5 kHz with 9kHz channel spacing in my country). The user should be able to select which channel (at 9kHz intervals) they would like to see and we'll have to use digital filtering techniques to display the FFT of that 'chosen channel' in addition to producing the demodulated output signal using the boards DAC.

I thought a good place to begin would be with an anti-aliasing filter to limit the input signal within the band between 526.5 – 1606.5, which is a band of 1.08MHz. According to Nyquist's theory I should sample at twice the highest frequency content of the signal which is 1.6065MHz, so sample at 3.2MHz. For the boards ADCs this is pretty demanding. I'd like to know if it would be possible to shift this range back to baseband such that the highest frequency component is \$1606.5kHz - 526.5kHz = 1080kHz\$ and then I would only need to sample at twice this frequency which is 2.16MHz.

I wondered if someone could tell me if this would be possible and point me in the right direction of how to do so.

edit: I've read about so called "bandpass undersampling techniques". Given a bandpass signal, if the bandedge frequencies, \$f_L\$ and \$f_H\$, are integer multiples of the signal bandwidth, then the signal can be sampled at a theoretical minimum rate of 2B without aliasing:

\$F_s(min) = 2B\$

The equation above is valid provided the ratios of the lower bandedge to the signal bandwidth and/or the upper band edge to the signal bandwidth are integers:

\$n = \frac{f_H}{B}\$ or \$n=\frac{f_L}{B}\$

If the signal band is not integer positioned, the band edge frequencies can be extended such that the band becomes integer positioned.

In my case I have

\$n = \frac{f_H}{B} = \frac{1606.5kHz}{1.08MHz} = 1.4875\$

It is possible to reduce the lower band edge frequency to a new given value by choosing the nearest integer value of n through the formula:

\$f_L' = (\frac{n-1}{n})f_H\$

but in my case if I choose n=1 then this makes the new lower band edge frequency 0Hz? Then the new bandwidth becomes 1606.5kHz - 0 and Fs is 3.2MHz, so this hasn't made any difference.


texts:
I have noticed that professionally done board always fill top and bottom with GROUND planes. As i have been making PCB board myself i find that having the top layer POWER fill and bottom layer a GROUND fill.On 2 Layer PCB what are differences between using POWER and GROUND fills as opposed to GROUND and GROUND fills?

Further more for Multi-Layer PCBs I have noticed that the stacked seems to be like SIGNAL GROUND POWER SIGNAL. why is that? wont filling the outer most layer with ground/power protect the signal traces more?


texts: I need help understanding how this stepper motor circuit works

texts: This is my first time working with stepper motors. The motor in question is a Portescap 55M048D1B (source: http://www.digikey.com/product-detail/en/55M048D1B/403-1016-ND/417823). I am having trouble understanding the wiring diagram for the motor. Would anyone be kind enough to enlighten me on what role the inductor and transistors play in the circuit and how the circuit rotates the shaft. And how does a unipolar differ from a bipolar.


texts: Modern capacitor replacement for tube audio

texts:
I have a Dynaco PAS 3 pre amplifier from the early 1960s that has been in storage for years.

I have been led to believe I should replace the capacitors in a couple of the boards.
 I have read your information on hype vs performance.

I have a list of what I need. They tend to be 400 V 0.002 to 1.0 mF capacitors but there are others too.

What type of modern capacitor would I use if I wanted the correct capacitance in the circuits?

My major concern is  with value and durability. I have very little interest in esoterics, I just want the thing to work.


texts: Why do some power plugs have holes in them?

texts:
I've just learned that electrical chargers with pins with holes in them are illegal in Australia. Here's what I'm talking about (ignore the one second from the left):

What's the purpose of these holes?


texts: Determining current draw and Ah requirements from a multi-component system

texts:
If component one draws 300ma in a steady state, and component two draws 150ma in a steady state, and component three draws 25ma in a steady state, that is a total nominal draw of 475ma while the system is in a steady state (user defined of course).

The question is, if you ignore transient changes in current, off/sleep state, temperature, or any myriad of nuanced considerations that must be made,
 1) is this a rough, first pass way to determine total current draw from multiple sources being run by a single power source, and
 2) determine battery capacity for a desired run time? aka, 4.75Ah capacity for 10 hours in this scenario.


texts: 2.4 ghz RF radio and antenna - nrf24 underneath a 7-segment display

texts:
I have this tiny nrf24 module that I want to use underneath a 7-segment display.
How much will this affect the range and the quality of the radio signal?

I have done a lot of research and testing on this other similar nrf24 module. Mostly about modifying the antenna to get a better signal/range, but unfortunately, none of those mods really do anything. Since then I went back, read more and found out that the antenna design in these nrf24 module are called Meandered Inverted-F Antenna (MIFA), which means it is the already a good design and trying to modify it is a bad idea? After done my own homework, I am able to get twice the range than before, and I am pretty happy about it, but longer is always better.


texts: Modbus RS485 - Voltage greater than 12V?

texts:
I have a boiler (Immergas Eolo Star) which has 2 pins where you can connect either a normal thermostat or a "remote control unit" which can also give more detailed information (self-diagnosis) about the boiler. This made me think that it has implemented some communication protocol over RS485, maybe Modbus and I could connect to it via a RS485 adapter and have fun. Today I got the time to have fun with it but to my surprise the voltage on those pins is (measured) 31.8V DC / 7mA. This confuses me a little since as far as I know, RS485 operates at max 12V.

Do you have any ideas, should I add something between the adapter and the pins so the voltage level should be lower? If so, what should I put there?

Thank you,

P.S.:

Why do I think is working on RS485?

The fact that the "remote control unit" can be connected via the same 2 pin interface as a normal thermostat; also, I've checked that make of boilers and for other boiler family the "remote unit" had clearly specified that it's working on RS485. For mine this is not clearly written somewhere unfortunately.

From the manual I get only this:

"Digital Remote Control Device with climate
chronothermostat function (Fig. 1.6). In addition
to the functions described in the previous
point, the Digital Remote Control panel enables
the user to control all the important information
regarding operation of the appliance and
the heating system with the opportunity of easily intervening on the previously set parameters
without having to go to the place where
the appliance is installed. The Digital Remote
Control panel is provided with self-diagnosis to
display any boiler functioning anomalies. The
climate chronothermostat incorporated into
the remote panel enables the system delivery
temperature to be adjusted to the actual needs
of the room being heated, in order to obtain
the desired room temperature with extreme
precision and therefore with evident saving in
running costs. The chronothermostat is fed
directly by the boiler by means of the same 2
wires used for the transmission of data between
boiler and chronothermostat."

As per installing the remote control unit:
"Digital Remote Control or On/Off chronothermostat
electrical connections (Optional). The
operations described below must be performed after
having removed the voltage from the appliance.
Any thermostat or On/Off environment chronothermostat
must be connected to clamps 40
and 41 eliminating jumper X40 (Fig. 3-2). Make
sure that the On/Off thermostat contact is of the
“clean” type, i.e. independent of the mains supply;
otherwise the electronic adjustment card would
be damaged. The Digital Remote Control must be
connected to clamps 40 e 41 eliminating jumper
X40 on the P.C.B. (in the boiler), (Fig. 3-2)."

Here's the wiring diagram:
http://imgur.com/GC8i9Nx


texts: Adding small AC signal to a DC current using inductive coupling

texts:
Is it possible to add a small AC current on to a DC current in a wire using inductive coupling from an external source. Or if there is another way, I want to add AC ripples to a DC current.

simulate this circuit – Schematic created using CircuitLab


texts: How to measure power (5-500 mW) consumed by low-voltage, low-current device?

texts:
I want to compare power consumption of two devices powered by 9V batteries. One uses a buck converter and the other uses a linear regulator. Depending on their modes, these can draw between ~5-500 mW (~0.56-56 mA).

The way I would normally think to do this is to put a small resistor (~1 ohm) in series with the device's power supply and measure the voltage across that to determine current. Then, power would be found by multiplying current by supply voltage.

My concern is that the small resistor could potentially change the power consumption of the devices. I figure this effect would be tiny at low current draw but possibly significant at ~50 mA.

Plus, it's tricky for me to measure low voltages precisely: my multimeter has mV precision (ok at ~50 mA draw, not so good at 1 mA).

Is there a good way to measure power that I'm missing? Ideally, something accessible to a small lab without expensive equipment?


texts: Need Help with PWM Motor Speed Controller Circuit

texts:
I am using the following circuit to make my PWM Motor Speed controller. I just replaced the MOSFET IRF510 with IRF540 and LM555 with NE555. I found the schematic on the web.

My motor is 12V rated and draws approx 200mA current when on full speed. But the motor was not receiving the required duration of current to start running. And finally, it didn't work. So, I tried increasing the C2 to 1uF (electrolytic) and it started rotating. Well, but with 1uF, the highest frequency of PWM could rotate it at half of its max speed. I want to increase the speed of the motor. Should I keep increasing the Capacitor? Would it actually destroy the purpose of controlling motor speed with PWM?

What I certainly did not understand is the purpose of R2. What does R2 do? Would the speed of the motor be impacted by changing this resistor value?


texts: Is it possible for a Teensy 3.1 microcontroller to receive USB keyboard input?

texts: As I've read, it is possible to have the teensy act as a keyboard for a computer.  I would like to know if the opposite is possible - can I collect keystrokes through the USB port on the teensy.  If this is not possible, can you explain why?


texts: Why does my input current inverter is high?

texts: I have a problem with input current in my inverter is high. My inverter will use for solar panel and using boost converter to convert dc voltage 12-18 Volt to 24 volt. I'm using P channel mosfet IRF9540 and N channel mosfer IRF540 as switching to convert dc to ac and using optocoupler pc817 as driver mosfet. And i use sine pulse width modulation arduino program. So the problem is when i give input voltage less than 12 volt, the input current is high 5 ampere. Is there something wrong in my inverter circuit?


texts: Can a Nordic Semiconductor nRF24L01+ be powered by 5V?

texts:
When I look at the nRF24L01+ datasheet, I'm confused by two apparently conflicting details.

"1.9 to 3.6V supply range" (page 1, Key Features)
5.25V maximum input voltage Vi (page 12, "absolute maximum ratings")

So, two parts of my question:

practically, can I power this chip from a regulated Vcc of 5V?
what is the difference of "supply range" and "maximum input voltage" ?


texts: This is a differential VCO which produces a sine waveform at the output taken across the drains of the MOSFETs. How should I interpret the drain current waveform at that point? Will it be a proper sine wave like the voltage or somewhat distorted?


texts: Different 'connection types' between components

texts:
Is there a name for the different types of connections between components? For example in the following:

Point A is connected between two components -- a battery and resistor -- and so is in series.
Point B is connected between > two components, and so is in parallel.
Point C is connected between three components (though I believe "Ground" is not really a component so it disappears into the negative terminal?).

Are there formal names for the types of 'junctions' or what they'd be called to differentiate the connection points (nodes/vertices in graph theory).


texts: Coiled wire around connector terminal, what do I call this, and how do you do it?

texts:
Please consider the following image:

I randomly wandered into the telecom room at work a while ago, and I noticed these strange looking terminals. How do you terminate a wire like this? Is there a certain tool to create the coil around the terminal? What do I call this sort of terminal?


texts:
I have a 3.3V PWM signal form microcontroller and i want to increase its voltage and current driving capability (at least 10mA source-sink current).
I have designed circuit like on the pic, but a am not quite satisfied how it's works.
To convert voltage level from 3.3V to 10V i have used a simple CS stage. Basing on simulation results i decided to use mos-based push-pull as a output stage (it had much better voltage levels than a bipolar push-pull).
But this design has some flaws:

During PWM state change i am getting a short between 10V and GND. For a short period of time both transistors are half open. It is a result of poor slew rate of a CS stage. I could improve it a bit by reducing a R3 resistance value but it would increase power consumption.

I am not sure if uP can drive a MOS gate. I could add resistor in series with gate, but it would increase a transition time even further and hence a power rail shorts time.

So, im looking for more handy solution or tips how could i improve my design. Maybe IC drivers exists for such a job?


texts: Raspberry Pi Piezoelectric Compatability

texts:
I am looking to control two piezoelectric actuators using a raspberry pi. I am looking at these piezoelectrics. I have read on the internet that it is difficult/impossible to use piezoelectric actuators with a raspberry pi due to the piezoelectric's necessary voltage input. Will this be doable? I can be more specific about the project if need be. If you have any links to someone who has done a project like this before I would greatly appreciate them.

Edit:  I am realizing that piezoelectric actuators may not be the best idea because of the voltage demand. I am looking for some type of actuator that can move at a fairly high frequency (>10-20 hz) along one axis with a travel distance of around .1 - .5 mm. Any suggestions would be welcome. I have been looking at linear actuators but the ones I have been seeing seem to move too slowly for my application.


texts: How is the output voltage adjusted on this schematic?

texts:
This is a schematic of TI's reference design for a 65-W USB Type-C high density active clamp flyback with GaN (PMP21639), which can be found from this reference design page.
The page claims that the design has a maximum power rating of 65W at 20V output, but is "adjustable for 20V/15V/9V/5V" output voltage and 3A.
How does this circuit adjust the output voltage? For instance, what if I need a fixed 15V/3A output from this design?
Thanks in advance.


texts:
I see numerous references to ESP32-WROOM.
Does "WROOM" have a meaning, or is it just a marketing term for a particular version of the ESP32?


texts:
I'm experimenting with trying to reflow a 0.8mm BGA myself for prototypes/repairs.

I've solved the main problem: alignment. I've used my 3D printer to print custom board guides that align on large through-hole pads and guide the BGAs into place. So far, I'm 100% on alignment for the 4 BGAs I've done so far.

Now, I'm trying to reflow it with my hot air system. I've got a BGA tip that fits over the part, and I have followed some general advice from a tech who told me to set it to 450 degC and put the BGA head down just about on the PCB totally covering the BGA for no more than 20 seconds.

I'm noticing that even the outer row of pads (All I can examine) are not shiny. They've reflowed beautifully, but all the flux has not burned off. I notice that paste pads that have been under the hot air long enough go completely shiny, and many other pads never quite burn off the flux (I assume) and remain somewhat dull. Is this fine, or does that indicate it didn't reflow properly?

How well does the air from these hot air BGA heads penetrate to the inner pads of a medium sized (14mm square) BGA?  Should I bump up to my maximum 480 degC and/or heat it longer...  ?

After noticing the dull pads on my first board, I attempted to reflow it for a longer period (40 sec) and pretty much burned the board. So, I know how far NOT to take it.

Any advice on the actual reflow of these?

EDIT:  I forgot to mention I am using an IR preheating unit. (I actually use the hot air gun with the board on the preheating unit) I leave the preheating unit at about 250 degC for a couple minutes before starting.

I am seeing some videos online showing the use of a hot air gun and sort of following a real reflow oven profile at lower temperatures. Should I be doing that? I was thinking the hot air was not going to be as efficient and needed to be somewhat higher.

EDIT 2: I've tried following a profile used on a Youtube video for reflowing an XBox chipset, and even the paste on the surface of the board doesn't reflow. I guess if I really want to do this right I need to get some thermocouples and measure this directly. I re-ran the Youtube profile with 460C instead of 360C, and it looks good visually. I'll complete that board and see if it works.

EDIT 3: It works! An i.MX283 ARM processor running full Linux @ 454Mhz. 0.5-1 watt w/Ethernet. I'll get these 6 BGAs (3 boards, 2 BGAs each) X-rayed and see how I did.


texts: Film/TV question: How to build Foam Cutter from only household items

texts:
I'm writing a scene for television and I need to make a foam/rope cutter from household items. I've watched several videos, including this one: https://www.youtube.com/watch?v=cM0lP2WCzY0, and determined that I need two sticks (can be anything), two copper wires (for electrical conductivity), a battery to power them, and a "blade" to heat.

Since nichrome wire is not readily found, I'm thinking of using a sharp-edge belt buckle or coiled earring. What material could be a reasonable substitute?

Also, since this cutter is homemade (to use when there are no other options), the copper wires would not have sheath coverings. Would the user be able to handle the device and related shocks, or would this be unrealistic to handle unprotected?

Thank you for your feedback. This is my first post, and we may be looking to work with science advisers on future gadgets, I am happy to discuss further privately.

EDIT: I wasn't expecting so many great suggestions, and I am aware that my question wasn't precise. I will correct in the future. Thank you all.


texts: Does leaving empty PCB holes filled with solder matter?

texts:
If I was soldering and I accidentally filled an unnecessary hole on my PCB with solder, is that a problem or can I just leave it filled?

Thank you for answering this ! All help is appreciated!

(And yes, I do know this is a beginner question. That's because I'm a beginner.)


texts: Control 5v relay through 3.3v GPIO using NPN transistor

texts:
I'm not very pratical as I just started learning electronics and I'm planning to make some experiment with Raspberry Pi.

I'm trying to control a 5v relay board that, I think, is made for Arduino, as Raspberry only has 3.3v GPIO.

It's active low, as GPIO.LOW activates the relay, and the 3.3v keep it active too, so I think I'll need exactly 5v to turn it off.

So, basically I think I'll need a transistor, with the base controlled by my GPIO, that will activate a 5v line to Input line of the relay switch.

I have thought about these schematics, but I've been told it will burn my transistor as I need a resistor between 5v and the transistor collector.

My question is certainly basic, but... WHY?

When no current flow through base there will be no problem, when the transistor gets activated isn't my load the relay board? Why do I need other resistors?

Thanks in advance.

This is the relay board I bought, I couldn't find schemas, so I can't provide more.


texts:
Is there a standard for the sizes of PCB traces?

That is are some 25 mil and others 10 mil or is can you choose your own?

I plan to run 400mA through some thicker traces, but less than 30mA for all other traces. About what size would I need?


texts: Wiring two LDOs in parallel with only one diode between

texts:
i know the traditional wiring of two power sources with two diodes. But can it also work only with one?

Please take a look at the attached schematic:

The TPS706 pmos LDOs have build in reverse current protection so no current can flow from output to input. In my system i have three power sources:

1) Battery 3.6V

2) LiPo 3.7V (which can also be charged by the sources under 3)

3) 4.5V-6V external Supply (e.g. USB or solar panel for charging the LiPo)

If the power-good signal (#PG, meaning external supply > 4.5V) is asserted i want to disconnect the battery (1) and power the system (VCC) via the external supply while (eventually) charging the LiPo. The same becomes true even if PG is not asserted but i instruct my lipo charger (MCP73871, CE pin high) to connect the LiPO to Vout.

My question:

Is this schematic smart if one of the two jumpers in the upper right corner is closed. I want to implement this way some sort of power supply priority. But this approch leads to have two LDOs connected with only one of it isolated by a diode...Iam not quite sure if this is too clever ;-) Or is it possible to connect both LDO directly together? Have some doubts about the control loops inside...

Thank you for any comments!


texts: Generate a 4.25 GHz using 50 MHz crystal/oscillator and PLL

texts:
I want to generate a 4.25 GHz using a PLL and 50 MHz crystal/oscillator.

I am confused as to what I need to look for in a PLL. In a integer-N PLL, the prescalers are 16/17, 32/33, 64/65, etc. So, my understanding is that these PLLs take in the reference 50 MHz signal and then multiply it by the prescaler to generate 800/850 MHz, 1600/1650 MHz, 3200/3250 MHz, etc respectively. Most integer-N PLLs have a prescaler upto 64/65 only and hence I am limited to 3200/3250 MHz. So, I wont be able to generate a 4.25 GHz signal using 50 MHz crystal.

So, is my understanding correct? If not, can someone guide me as to what the mistake is.

If I am correct, do I need to use a higher frequency crystal or are there other PLLs available which can be used to generate the desired frequency using 50 MHz crystal?

Note: I have taken the data of prescalers from the Analog Devices ICs


texts: Mosfet as a switch (on/off) and ground isolation

texts:
my question is simple (I hope)

So I have DC in.
 On both + and ground line I have 2 mosfets (one for each line) (driven externally)

When I switch off both Mosfets , can I claim "full galvanic isolation" ?

Is there any leakage current or high frequency noise passing through a switched off mosfet ?


texts: Help Identifying a Component in a Power Supply

texts:
I had a component in a sizable power supply open up, but I haven't had any luck identifying it. The PCB is marked with this symbol under the component: (two terminals, one on on each side)

I never saw this thing before it failed, but it looked exactly like a failed MOV after it failed (burnt up gray disk with leads flat on each side).

However, the component is wired in series with the AC line input, on the opposite AC line from a fuse. I've never seen any varistor used like this.

The power supply does not work with this component open, but I tried jumping across the two leads, and the power supply came right up, so it was clearly carrying current before.

So what is this?

Edit: Here is how it appears in the circuit:


texts:
Firstly, I've always wondered how do engineers calculate the right parameters of components (caps, resistors, inductors, ...) in big projects, such as mobile motherboards and etc.

It feels rather complicated and very time consuming, let alone error sensitivity - one mistake and oops.

If it's all about several ICs – all the passive components around it – do they just follow reference sheets of these ICs?

Also, looking to the boards with SMDs, I usually see the components tremendously aligned. Obviously, it's all about space efficiency – let's look at iPhone XR motherboard.

If one zooms in the A12 chip, the long row of components (perhaps capacitors) might be found just above it:

And generally pretty much every component is aligned elegantly with the others, no unused space.

The question is:

How do they do that?

Is the board multilayered to make it possible?

If so, that's odd because no vias can be spotted in here.

Or what other kind of techniques are used to design such complicated boards?

Do they align the components by themselves or is it done by software?

For instance, designing a PCB in Eagle involves a manual component distribution, which is surely possible when the PCB is not complicated, but what about the other ones? I doubt they do it by hand...

Summing up the foregoing:

How to design a PCB this complicated?


texts: I'm trying to create a 2s3p battery pack for a robot. I have 6x Eastshine e35 cells (which is a protected version of LG MJ1 cells). Is a 2s3p pack out of protected cells used with a balance/smart charger the same as a 2s3p cell with a BMS system? Is it going to be equivalent in terms of safety and performance ?


texts: Is it possible to model a single-phase phase-shifting transformer in LTspice/Multisim/PSpice?

texts:
As you know, three-phase two-winding transformers can produce a phase-shift between the line-to-line or line-to-neutral phasor voltages of one side and the respective line-to-line or line-to-neutral phasor voltages of the other side. This is taken into account as explained in the standard IEC 60076-1 by indicating the vector groups of the transformer.
As may also know, we can analyze balanced three-phase circuits using single-phase (or per-phase) equivalent circuits, whether using per-unit values or real values. In such single-phase circuits, we substitute the three-phase transformer with a single-phase transformer. How is the phase-shift taken into account? At least on the popular textbooks by Grainger & Stevenson and by Glover & Sarma, the authors use a "complex turns ratio". For example, using per-unit values, below are shown per-phase circuits:

Figure 1. Taken from Glover & Sarma's textbook.

Figure 2. Taken from Grainger & Stevenson's textbook.
This is fine, I understand it. But suppose I want to simulate a per-phase circuit (using real values) in a simulator such as Multisim, PSpice, LTspice, etc. and use the AC Analysis mode (which solves for phasor voltages and currents). Is there a way to model the single-phase transformer to include the phase shift (e.g. with a complex turns ratio)?
First attempt
I read the Supported Mathematical Functions, Operators and Constants in Multisim but it looks like there's no support for the imaginary unit, which I'd use to model the complex turns ratio.
I also read the Available Complex Functions in Multisim, but it says the imaginary unit is available only in the Postprocessor. Now, according to this page the postprocessor (and thus the imaginary unt) can be used only after a simulation is run, which is useless in my case.
Second attempt
As you may know, it is possible to model an ideal single-phase transformer using dependent sources. But in such case, to include the phase shift of the three-phase transformer (i.e. the complex turns ratio), I'd need a "complex gain" for the dependent sources. Since Multisim doesn't support the imaginary unit, I can't use a complex gain.

Of course, if it's not possible to model the phase shift of the three-phase transformer in the single-phase transformer, instead of simulating the equivalent single-phase circuit I could simply simulate the actual three-phase circuit. The downside is it'd take more time for me to set up the whole power system.


texts: I have a very simple question. I have an array of AC to DC converters from well known companies such as Meanwell, Delta Electronics, Recom Power, XP Power etc. They take my 230V 50Hz AC mains and convert it to a DC output (24V, 100W in my case). However, when I use an AC voltage tester on the DC lines, I detect the presence of AC voltage. In my case I get an AC voltage of 90-100V (RMS) on the voltmeter when I measure the AC voltage of the DC ground/ 24V with respect to the neutral. Is this because of poor AC mains or is the AC-DC converter not good enough in the sense that it does not filter AC mains well enough from the DC lines? Or am I missing something quite obvious?


texts: The role of internal voltage source resistance in pulsed operation

texts:
I have a question regarding the role of the internal voltage source resistance in pulsed vs DC operation. Here is a sketch of the situation I imagine:

simulate this circuit – Schematic created using CircuitLab

DC operation:
The voltage at point at the voltage source output (node 1) will be determined by a voltage divider between the internal resistance of the voltage source and the transmission line, therefore:
\$ V_1=\frac{R_2}{R_{source}+R_2}  V_{source}\$

Pulsed operation:
Assume that the voltage source launches a rectangular pulse of amplitude \$V_0\$ and duration \$\tau\$. Now, I assume that the resistor \$R_2\$ is a long transmission line, with a travelling time \$t\$ much longer than the pulse duration \$t >> \tau\$.

Also, it should be matched to the generator, such that no reflections occur at node 1.

Question: After the voltage pulse travelled through the source resistor \$R_{source}\$, will it be completely contained in \$R_2\$ and the voltage amplitude inside the line will be \$V_0\$ (and not a voltage divided value)?


texts: Step by step explanation of voltage regulator

texts:
Let's consider this basic scheme of voltage regulator (here the reference):

I wanted to verify that a sudden variation of the output voltage is compensated by the circuit. Suppose that the output voltage Uout increases, what happens to the current through Rv and the base current of the transistor? Can you explain me what happens step by step?

If its aim is that of generating a stable output voltage signal, the transistor should react in order to decrease Uout.


texts:
Silicon chips are made by slicing up wafers; in general, the fewer transistors a design needs, the smaller the area it needs, so the more chips you get out of a wafer, and the lower the cost per chip.

But there must be some limit to this. Maybe you can have a chip of one square millimeter area, but it seems unlikely that you could have a chip of one square micron area.

What is the minimum... To be specific, I'm not asking what is the minimum physically possible area, but what is the minimum area below which chips stop getting cheaper? The point at which you stop trying to shrink your design, because fewer transistors will no longer save money?

And has this remained roughly constant over the decades, or has it changed with iterations of process technology, and if so, in which direction?


texts:
I have some systemverilog codes built by other colleagues and running in hardware without problem.

I can see there are some connections for two modules have no local signal declaration like this:

module module_top (
  input clk,
  input rst,
  output result
);

logic[255:0] data;  // connector for data
logic[4:0]   empty; // connector for empty
// there are no connectors for vld, sop and eop signals

module_to to (
.clk(clk),
.rst(rst),
.in_vld(vld),
.in_sop(sop),
.in_eop(eop),
.in_data(data),
.in_empty(empty),
);

module_from from (
.clk(clk),
.rst(rst),
.out_vld(vld),
.out_sop(sop),
.out_eop(eop),
.out_data(data),
.out_empty(empty),
);

endmodule

The code above can be compiled without error and running smooth in hardware.

I tried to remove the data[255:0] declaration. It doesn't work in hardware. So, please advise the theory behind it.


texts: Can I use a 150w 12v 775 DC motor with an old 800w PC PSU?

texts:
Is it possible to use a 150W 12V motor with a PC PSU?

I know that it means that motor will draw a current of 12.5A from the PSU. The PSU can supply 20Amps in total on the +12V rail. As soon as connect the motor to pc PSU it will short and trip the supply( overcorrect protection is triggered).
I know that PC PSU hasn't been designed for motors but is there anyway to make them work together?


texts: common mode choke - symbol and orientation

texts:
I was wondering why there are different symbols for common mode chokes and if/how they affect the way I have to connect them.

(upper image incorrect but left for understanding the comment from @Felthry)

Most often I see type 1 and there is no doubt on how to use them. But with types 2 and 3 I'm not so sure. They must have different meanings as I saw them simultaneously in one circuit. Can anyone enlighten me or refer me to a decent source on what the difference is?

Thank you!


texts: Inrush current from DC motors causing Arduino to reset

texts:
I've got an Arduino controlling a relay.  The relay controls two small DC motors.  All of these components are powered through a 9v power regulator.  I need the power regulator because the power source is a 16 volt battery, which would fry the motors and arduino if I connected them directly.

When the Arduino powers on the relay is initially open so the motors are powered off.  The problem comes when the Arduino switches on the relay and motors start.  The inrush current overloads the regulator and as a result, the Arduino loses voltage and resets.  I have determined from experimentation that the regulator has enough ampacity to handle the DC motors at steady state, it's just the inrush that is the problem.

I am very inexperienced in this area, so it's not clear to me how to solve this problem.  Might I use a capacitor to provide power to the arduino during the inrush period?  Or maybe a capacitor could be charged up and provide power to motors on startup?  Or maybe capacitors aren't the answer?

Using a voltmeter (on amp mode) it looked like the DC motors pulled about 1.5 amps on startup, and then went down to 0.5 amps on steady state.

Whatever the answer, a detailed explanation of wiring would be helpful, as well as what numbers I need to consider when picking out a capacitor or whatever it is I need to buy.


texts:
Having a LDO output that is connected to digital circuitry, I would like to know the best way on how to place the bypass capacitors in this network.
Is it better to place higher capacitance ones near the chip and low capacitance ones further away?


texts:
I'm stuck on this problem I'm working on:

With the following questions:

So my approach:

Well to start with there is two cases: t<0 and t>0, so I  thought that I would start to find IL(0), the initial value.

And I redrew the circuit like this:

I was thinking that the inductor conducts current and that it doesn't change which leads to the voltage over the inductor to be 0 V and that makes the inductor behave like a short circuit when the switch is closed.

Now what is a little bit hard for me to understand is the case with the R2 resistor. I don't understand if I should consider it in my calculations or not? Should I do a Rtotal = 100kohm x 1kohm / 100khom + 1kohm?


texts: Calculating the Thévenin Voltage (Vt) and Thévenin Resistance (Rt) equivalent of the circuit below

texts: How would one calculate the Thévenin voltage and Thévenin resistance for the circuit above?


texts: What does changing the volume on a Bluetooth audio device really do?

texts: For example, when playing audio from a smartphone through car speakers, you can change the volume on both the phone and the car. It makes sense that when changing the volume on the audio controls in the car, the car’s audio system will send more electricity to the speakers to create louder sound. But how does changing the volume from the phone work? Is there some sort of metadata that the phone sends along with the data of the audio playing that tells the car’s audio system how loud to play it? In this situation, none of the electrical energy from the phone is being used to physically influence the car speakers to produce sound. How would the phone be able to influence how loud the music is playing?


texts: Question after my first attempt with reflow soldering

texts:
I have a couple of questions, plus I'd invite any comments/feedback/suggestions to improve my results.

I used solder paste Chipquik SMD291AX10 (Sn 63 / Pb 37) on the pads and also flux  (Chipquik SMD291NL) on the pins/pads of the components.  I wonder if this is the recommended practice, or whether the solder paste already has the necessary flux in the mix?

Notice that there is this "amber" touch around the components, and I believe it is the "cooked/possibly-burned" flux.  Here is the link to a couple of pictures I took, plus the temperature profile:

https://cal-linux.com/tmp/

My other question is:  could it be that the temperature profile (in particular, how slowly it went) is negatively affecting the results?  The image above shows the plot of the profile, as captured by a thermocouple some 5 cm away from the actual board inside the toaster-oven.

What I did is:  set the oven to max.  When the thermocouple temperature reaches 90 °C, I unplug and leave it unplugged for one minute.  Then, when the temperature reaches 185 °C, I unplug it for good.  Then, when the temperature passes through 200 on its way down, then I open the oven door to speed up the cooling down.

Does the above make sense to those of you with more experience on this?

Thanks!
Cal-linux