texts:
I have this ADS6125 adc. In the datasheet it is written that this ADC uses internal decoupling:

"capacitors on-chip eliminates the need for external decoupling" (p.45)
"As ADS612X already includes internal decoupling, minimal external decoupling can be used without loss in performance" (p.55)

It says minimal decoupling is enough. But what is minimal?
In my design I am using 3 decoupling caps for each supply pin. Could I get in trouble for using too many decoupling caps?
ADS6125 datasheet:
https://www.ti.com/lit/ds/symlink/ads6125.pdf?ts=1603138441413&ref_url=https%253A%252F%252Fwww.ti.com%252Fproduct%252FADS6125


texts: Protecting Board form Motor driver Circuitry

texts:
I have the following configuration H Bridge:

I have not added any diodes for kick back protection. I have one 100 uF capacitor across 3 V supply and ground. The Collector of Q1 and Q2 are connected to same 3 V (Not visible in the picture). The DC motor is used to drive a gear in one direction and stopped when stalls. And will be moved back when required. It is not a dynamic to and fro movement. There will by a few 10s of ms of delay between two motor drive inputs.

What are the weak points in the design? Please suggest any improvements towards safeguarding the motor drive circuitry and rest of the board.

Battery is Alkaline, 1.5 V x2 = 3V, 1400 mAh.
I have read article on Diode purpose in H bridge here, but still i have to verify this BJT circuit as well.


texts: Why does this high pass filter behaves like band-pass filter on Multisim AC Sweep simulations?

texts: I have this high-pass filter schematic and its AC Sweep simulation. Until the break through the end, the graph is right but I can't see why the graph breaks on  the right hand side and filter behaves like a band-pass circuit.


texts: Why are five pin XLRs used for long MONO audio connections?

texts:
I understand why a 3 pin XLR would be used for a  balanced single, so what are the additional pins for.

I have read someone that is has to do with capacitance on long cables.

(These days a digital link would normally be used, but is used to be common to send high quality audio over many miles without converting it to digital.)


texts: RS232 to 1-Wire interface - need help understanding the schematic

texts:
There are plenty of projects on RS232 to 1-Wire, each one of them is almost the same, but none of the sources really explain the wiring.

Let's take this one: http://www.instructables.com/id/Temperature-sensor--weatherstation/step2/Build-the-RS232-interface/

I'm trying to figure out why those lines are connected that way.

My basic understanding is that the TXD line is not used, RXD is used as a ground for 1-Wire device, DTR is used for data wire and the DTR cannot exceed 3V9, that's why the Zener diode is there.

My questions are:

TXD line seems not to be used at all, what is that diode and resistor to RXD for?
why doesn't the RS232 GND play the 1-Wire GND role?
What are the diode and 6V2 Zener diode between DTR and RXD for? The Zener provides the  DTR line to be not higher than RXD+6V2, but what for? Why not 3V9 like between DTR and GND?


texts: Convert (-4 to 4v) from sensor to 0-3.3v

texts:
Can you show me how can I make a schematic to convert signal voltage from sensor to ADC module of DSP.

Sensor : -4 to 4 voltage
DSP ADC: 0 to 3.3 voltage.

Thank you,


texts: What parameters effect on voltage regulator's temprature?

texts: What parameters effect on voltage regulator's temperature? Is it current of output or another parameters effect on temperature? For example if a lm7805 is used for current output of 1A and 18 volt input generate temperature like a lm7805 for current of 1A and 7 volt input?


texts: VFD: Regenerative overvoltage trip during deceleration or stop

texts:
I have a Mitsubishi VFD Model: FR-F720.
It shows the error E0u3, which means according to the manual: "If regenerative energy causes the inverter's internal main circuit DC voltage to reach or exceed the specified value, the protective circuit is activated to stop the inverter output. The circuit may also be activated by a surge voltage produced in the power supply system".

This error keeps showing even when there is no motor connected.

I have tried the possible solutions that the manual offers, but they don't seem to work. However, I think, if I certainly need a brake resistor, I am not sure how to place it.

Do you have any suggestion/alternative to this fault?

Thank you.

Manual: http://dl.mitsubishielectric.com/dl/fa/document/manual/inv/ib0600177eng/ib0600177engf.pdf

Technical data:

Input: 48.8A 3PH AC200-220V 50Hz
             3PH AC200-240V 60Hz

Output: 3PH AC200-240Vmax 0.5-400Hz


texts: How to select ADC resolution, considering input signal SNR and digital signal processing?

texts:
What I knew: The ADC resolution selection depends on the ADC inherent noise and input signal SNR.

Our application: Very high precision measurement of signals ranging 1kHz to 10kHz. We want to get as accurate result as possible, even 24-bit result.

The above statement, however, does not take digital signal processing after ADC sampling into consideration.

Since DSP techniques such as FIR, FFT and etc. may reduce the noises greatly, is it possible that increasing ADC resolution may also improve the measurement result when taking DSP techniques into consideration?


texts: Measuring the frequency of a square wave with input capture Atmega328 avr

texts:
I am currently measuring the frequency of a square wave using input capture on the atmega328p. Once it detects the frequency, I have the code lighting up one LED above a certain cutoff (i.e. about 150 hz) and one below.

volatile uint8_t flag;

volatile unsigned int capture1, capture2, CaptOvr;

volatile unsigned long T1Ovs, timer0_ovflow;

volatile  long ticks;
volatile double period;
unsigned long int frequency;
float Ttime;

void timer1_init(void)
{

  // Starting timer 1 in normal mode
//  TCCR1B= 0x00;
  TCCR1A = 0x00;
  // setting interrupt flag register to 0.
  //TIFR1=0x00;
  // timer 1 setup without any pre scalars, and enabling
  //input capture on rising edge
  TCCR1B =  (1<< ICES1);
  TCCR1B |=(1<<CS12)|(1<<CS10);

  // setting the timer/counter i/o locations to 0.
  //TCNT1H=0x00;
  //TCNT1L=0x00;
  // enabling input capture
 TIMSK1|=(1<<ICIE1)|(1<<TOIE1);
  // enabling global interrupt
  sei();
}

ISR (TIMER1_CAPT_vect)
{

 if (flag==0)
 {

    capture1 = ICR1;
    //setting overflow_counter to 0.
   T1Ovs=0;
    //doubleOverflowError=0;
 }
else if (flag==1)
 {
    capture2 = ICR1;

  //saving the value of overflow_counter to total_overflow
   CaptOvr = T1Ovs;
  }
  flag++;
}

ISR(TIMER1_OVF_vect)
{
    T1Ovs++;
}

void setup() {
  // put your setup code here, to run once:
 // initialize timer
  Serial.begin(9600);
    timer1_init();
    //timer0_init();
   DDRD = (1<<PORTD7)|(1<<PORTD6);//|(1<<PORTD5);
   PORTD = (0<<PORTD7)|(0<<PORTD6);//|(0<<PORTD5);
}

void loop() {
  // put your main code here, to run repeatedly:
  //flag = first_capture;

      //while (flag != wait);

   if (flag==2)
      {

      flag=0;

        ticks = (capture2 - capture1) + (CaptOvr * 0x10000L);
       // T1Ovs=0;
       // Ttime= ((256*ticks)/16000000);
          frequency = (16000000/ticks)/1024;
   // frequency= (1/Ttime);

Serial.println ((frequency));

      if ((frequency>=100))
      {
          PORTD = (1<<PORTD7);
          //PORTD=(0<<PORTD6);

      }
    else if ( (frequency<100))
      {
        PORTD = (1<<PORTD6)|(0<<PORTD5);
      //  PORTD=(1<<PORTD6);
        }

      }

}

so now, I want to turn on a 3rd led which will turn on when there isnt any signal being sent to the interrupt pin.( and it will turn off when a signal is being sent). This is the part i am currently stuck on. any suggestion or help would be greatly appreciated.


texts:
My job is to redesign an existing product driving two gauges, currently based on PIC and obsolete Phillips SA5777A air-core gauge driver. I am free to make the design from scratch, but cannot change the two gauges, which are each 4-pin gearless two-coil design with sin+/- and cos+/- pins.

I have browsed the web for many hours for up-to-date and available chip solution, and found only one, Melexis MLX10407. I often base my decisions on stock available at DigiKey, and this Melexis stock is very limited.

My question is, can anyone suggest good source of information how to design this WITHOUT the Melexis chip, using parts which are good for new design?

I do not mind to do it directly from microprocessor, or using external chip (simpler for me). My design time-frame available for both hardware and firmware is 2 months, so I rather spend extra $4 per product then time writing software.

Thank you for your advice, especially if you are already experienced designing air-core gauge drivers.


texts: Trying to come up with a overvoltage overcurrent reverse polarity protection circuit, is option 3 done right?

texts:
I´m reading for the past week about P-Channel mosfet reverse polarity protection circuits.

Then I´ve found this post

http://kaktuscircuits.blogspot.com/2014/07/reverse-polarity-and-overvoltage.html

So I grab the main concept and first I´m trying to build it with the less amount of components needed.

Then I wanted to add the overcurrent protection circuit (like a E-Fuse)

So if you have this on your input side of your DUT it will be protected against reverse polarity, overcurrent and overvoltage protection.

My main goal in doing this is to use it in combination with a Boost converter to charge a laptop on the go.

I´ll appreciate the input and hope that this idea is good for more people.

Last but not least I´m just a electronic amateur, I only have tangible knowledge of what I alredy done, burned or fixed, but no high degree education in the matter.

Thanks


texts: Dealing with Real time variables and compensating the errors from adc

texts:
I tried to implement real time systems using micro controllers and often used sensors/adc as input to monitor my surroundings so that i could adjust well with it.but how should one deal with the real time variables?. I have seen codes which implement median filtering and low pass filters(in firmware code) to the raw data obtained from sensor/adc.I have seen adc readings varying abruptly when taken continuously.

What is the best practice to avoid anomalies in sensor/adc readings such that  s/m will continue to work as expected.And how to fix the threshold and ranges of the variable?
I feel that real time variables must be carefully handled.
So How much effective is this median filtering and low pass filters than the direct raw data  processing?
Is there any better methods that effectively trade off b/w raw data acquisition time and processing time.

ok.
I am using pic18f  controller and using the adc channels of it as well and i am taking adc values continuously to monitor my system(Temperature controller). It shows slight variations in the adc conversions when i tried observing those values.
Then i heard about this median filtering and low pass filter techniques implemented in Embedded system for monitoring continuous*variables(Temperature)* in it.

The purpose of those techniques were to filter out the junk values as a result of EMI or any other external sources as far as my understanding.

So my point is :
Is it the only technique that embedded systems are using to get rid of absurd data they obtain..or there exists better techniques(lesser cycles).

Regards


texts: PIC16F1776 interrupt triggered with no evident source

texts:
I have a Microchip PIC161776 running at 32 MHz.  Interrupt Code has been generated with MCC, with the preemptive option set.
typically, about once every hour the interrupt routine gets called with no apparent set flag.

The MCC generates code like:

ISR(){

if (IF1)
{
}
else if (IF2)
{
}
else if ...
{
}
else
{
THIS  PART OF CODE GETS CALLED!
}
}

Anybody know of issues with this particular microcontroller ? As far as I know (and checked with debugger), no unkown interrupt sources are enabled.


texts: Which buck converter can be used for 120 V AC to 5 V AC rated at 5 amps?

texts:
I have used buck converters that can move from 30 V DC to 5 V DC, their maximum current is set at 400 mA, I need 3.5 amps. I am looking to move from 120 V AC to 5 V AC. I'm then going to change it to DC current using the rest of the circuit. In my searching on Google I have found many many voltage regulators that can move small amounts of current and i'd like to move high current.

EDIT:

I am looking for a solution I can build  instead of using a prefab solution. This is the way learning my power supply. Also looking for specifically a buck converter, as there are other options.. but I'd like to know that it can be done similarly with buck converters and which buck converter could do it.

EDIT:
i have decided to use a isolated transformer circuit to step down from 120V AC to less voltage and then use a buck converter. This was for safety reasons. This post has a valid question that i no longer am pursuing an answer for. If there isn't a need for electrical isolation a buck converter circuit is practical. If someone answered the question with reference to a buck converter i accept the answer.


texts: pulse width modulation versus amplification

texts:
If I want to make a sine-wave inverter where the output AC voltage is lower than the input DC input voltage, how can I see that using pulse-width modulation will be more efficient that just using a transistor as an amplifier if I have a sinusoidal gate driving signal at the desired frequency?

I've heard that transistors generally operate efficiently when "on" or "off", but not in an intermediate regime.  My impression is that this is true for both BJTs and FETs, but I'm not sure.  This rule of thumb is consistent with other things I've learned, like the fact that CMOS integrated circuits tended to be lower power than equivalent TTL chips, and also the fact that switched mode power supplies are efficient and popular.  I've never really challenged this idea before (that switching a MOSFET with a given duty cycle is more efficient than using it as an amplifier). I spent about an hour trying to fact check it earlier and didn't manage to get through it.

What I've done so far: Firstly, I decided to focus on MOSFETs. Secondly, as an example I decided to look at a specific n-channel MOSFET, a Toshiba K3767, because I have a LD7550-based switched mode power supply that uses a K3767 as its power transistor. Thirdly, a bit of internet reading tells me the two main losses will be switching losses and conduction losses.  So I guess I could do two calculations, one where I switch with a square wave at a high frequency, like 65 kHz as described in the LD7550 datasheet, and another scenario where I drive the K3767 with a sine wave at a low frequency like 60 Hz.

Am I on the right track here? Is there some really obvious answer, like I2R losses will be huge if I use the MOSFET as an amplifier with a sine wave on the gate?

How can I show that rapidly switching a transistor between on and off at a given duty cycle is more efficient than operating it as an amplifier to achieve the same average output?


texts:
I have below circuit which produce 4-20mA and by adding resistor (before the TVS) I can get

50ohm => 0-1V
250ohm => 0-5V
but unable to get 0-10V since when I add 500ohm resistor, the voltage max out at 5.62

Why this is happening how can be fixed,

I have Dac out put is 0-3v and my Vref is 3V to.

This design is base on XTR111EVM
XTR111 datasheet

"Q18 is an external transistor (QEXT) that
forms a cascode for the current output"

I even removed the D18 ans still same problem


texts: Unusually high ESR of cheap ceramic capacitors

texts:
I recently bought the De5000 LCR meter and have been measuring some components I have on hand to get a feel for the meter.

Measuring electrolytic and Mylar capacitors have given reasonable ESR values based on their data sheets yet when I measure the ceramic capacitors I have on hand they read ~10-100 ohms of ESR. I am measuring them using 10/100Khz as specified as the most accurate in the data sheet for the capacitor values I am using -- 22pf to 22nf.

Is this typical of cheap ceramic capacitors? I don't have the data sheet as I bought them from some Chinese ebay store. Could I just be measuring them wrong?

Thank you for your help.


texts: Arduino: RS232 Level Shifter or RS2323 Breakout needed?

texts:
I am trying to establish communications between an Arduino Mega2560 (Master) and a customised controller (Slave) via a Master-Slave RS232 link using Modbus RTU. The communication should be bi-directional.

Currently I am simulating the customised controller using ModbusSimulator and connecting to the Arduino using a Sparkfun RS232 level shifter (https://www.sparkfun.com/products/449). It is working.

I am asking if a RS2323 breakout board (https://www.sparkfun.com/products/11189) is necessary for communications to the real controller? Or how would I know this? Is the Arduino capable of producing the RS232 signals itself with the level shifter?

Thanks


texts: What circuit can use a falling edge to trigger this damped oscillating impulse waveform?

texts:
What circuit can generate the waveform shown below upon receiving a falling edge trigger?

The closest I've gotten is that it looks like an RLC that got charged then the loop got closed.  I'm guessing maybe I can use a transistor to close such a circuit, but honestly analog is really not my strong suit.  I'd like to be able to alter the amplitude, decay time, and oscillation frequency, so please provide formulae.

For what it's worth though, the divisions on the oscilloscope are 5V and 0.1ms.  An interesting twist on this is that it is powered by a 9V battery, but somehow the peak voltage is ~20V (it's not necessarily "double", it could be an arbitrary voltage).  So, somehow the impulse must be able to have a higher amplitude than the power that drives it.

I should also add that the triggers come more than once, sometimes milliseconds apart.  A delay to causing the pulse is fine as long as each trigger causes a pulse.

If you can recommend specific components (or types of components, e.g. ceramic vs electrolytic capacitors) I'd appreciate it.

Thanks!


texts: A question about sampling with an ADC device

texts:
There is a data-acquisition device with BNC inputs similar as follows:

It is single ended and when run by the software it is multiplexing all 16 adjacent channels.

I connect only first lets say the first three channels to signal sources by BNC cables; and the rest adjacent thirteen BNC inputs are not connected to anything  i.e they are floating.

But the data I obtain at the end for the unconnected floating BNC channels have the same signal with the third channel. They copy the last connected channels's voltage signal.

How can this be explained?


texts: Maximum rotation speed for a potentiometer?

texts:
After a slight purchasing mishap, I am to end up with an encoder whose max RPM is too low for the application for which it is to be used. To achieve roughly the same purpose (that is, sensing of an angle) with a lower budget, we are now looking to use a potentiometer. Just to make sure that we don't make the same mistake again, is there a maximum speed which potentiometers can generally be turned? Say, something faster than the 60 RPM max we found out about on the purchased parts? I've looked through the data sheets for a couple different potentiometers, but I can't seem to find anything (though I suppose that makes sense since these potentiometers are fixed rotation).

Any advice is appreciated.


texts: How to check a discrete time system if the following is linear and time invariant?

texts:
I have the following system:

$$y(n) = x(n^2+n)$$
where x(n) = 1 if 0<=n<=3; 0 otherwise.

I tried doing the usual check if yd(n) = y(n+d), but that's not giving me the right answer.

Anyone know how to attempt this?


texts:
While buying hardware, the Netduino Plus was not available so I bought Netduino and Ethernet shield. These days I have been trying to create and example of web server using Netduino and Ethernet shield and so far haven't got it working. I've tried to read and write to SD card mounted on shield but none of the examples I have found on the internet have worked.

Has anyone combined Netduino and Ethernet shield and successfully created any project which included SD card reading/writing and/or network communication?

If anyone knows what are the required libraries, how to set up a development environment (configuration in VS) and is perhaps willing to share a piece of code that works I would be really thankful!


texts:
So for those who don't know, the race hazard theorem (RHT) states that:

A x B + A' x C =  A x B + A' x C + B x C

I understand the other part of the RHT, about time delays and such, but I don't understand why the logic statement above should be true, can someone help me understand this?


texts: In North America, why is the wide prong neutral instead of the narrow prong?

texts:
The wide prong is neutral on 15 amp US power outlets.

Is there a reason it was designed this way, or could the narrow slot just as easily have been neutral instead?  Was this design decision arbitrary?


texts:
So i am designing a device that is supposed to connect to the PC via USB and draw power from the VBUS (+5v) of the USB.

I am wondering if I need to put a voltage regulator in between the +5v from the USB and the microcontroller on my device. I've tested this device on my own laptop and it works fine. But I'm not sure if I can make any assumption regarding the stability of the VBUS on other computers. I looked at some Arduino designs and they don't seem to place any voltage regulator when it is powered through the USB.

So is it safe to assume that the +5v coming from a PC USB connection is fairly stable?


texts: 8051 microcontroller assembly language elevator coding

texts:
ORG    00H

MAIN:
    MOV P1, #00H        ; motor
    MOV P2, #00H        ; buttons P2.0-2.2, sensors P2.3-2.5

FLOOR1:
    JNB P2.0, FLOOR2        ; check button
    SETB    P1.1            ; start motor to go down
    JNB P2.3, $         ; check sensor, cont until it reaches 1st floor
    CLR P1.1            ; stops motor
    SJMP    MAIN

FLOOR2:
    JNB P2.1, FLOOR3
    JNB P2.3, FLOOR2DOWN    ; check if lift is on floor 1
    SETB    P1.0            ; starts motor upwards
    JNB P2.4, $
    CLR P1.0
    SJMP    MAIN

FLOOR2DOWN:
    JNB P2.1, FLOOR3
    JNB P2.5, FLOOR2        ; check if lift is on floor 3
    SETB    P1.1
    JNB P2.4, $
    CLR     P1.1
    SJMP    MAIN

FLOOR3:
    JNB P2.2, MAIN      ; check button floor 3
    SETB    P1.0
    JNB P2.5, $         ; cont until it reaches floor 3
    CLR P1.0

    SJMP    MAIN

END

I am working on a very simple model elevator using 8051 microcontroller (above is my assembly coding for it). It will have:

Ground Floor
First Floor and,
Second floor.

I have trouble in configuring the coding with sensors (I will use IR sensors later). Now I am using pushbutton to replace the sensor.

The thing is, when I press button on my keypad which is a "pushbutton" the motor ONLY keeps running as long as i keep holding and pressing the switch.
And I need the motor to be running until it reaches a certain floor and sensor detect it reached that floor and stops.

The elevator motor should work like, it will check all the sensors and if there is elevator car in that respective floor it will move the elevator car/cage to that position and motor will stop.


texts: Capacitor with specific self-resonant frequency?

texts:
I have a datasheet that calls for "a 15 pF capacitor with Self-Resonant Frequency in the 1800/1900 MHz range".  It then recommends a capacitor (Murata GRM1555C1H150J) that (so far as I can tell) from the datasheet doesn't specify it's SRF.

I'd like to use a different, slightly larger SMT capacitor, but I understand this may lower (or just change) the SRF.

Mouser's part search engine doesn't include an SRF parameter.  Is there some way to obtain capacitors with a specific SRF?  Can the SRF be reliably derived in some way?  Or does this property have to be measured?


texts: How to crop/resize images in video stream on frame grabber with FPGA?

texts:
I am attempting to simply crop or resize the images as they are streamed to the frame grabber using the FPGA onboard this Euresys Coaxlink Quad CXP-12 frame grabber. The frame grabber has an XCKU035 FPGA and comes with this Custom Logic design kit that allows me to upload my own FPGA bitstream to the frame grabber to perform any image processing needed.
I'm new to HLS and FPGAs and am not exactly sure where to start on this. I read into the Xilinx xfOpenCV library that has a resize function but I have no idea if it would work in my case or how to implement it yet. Does anyone know where I should start on this?


texts: Can I use electric tape instead of soldering for Speakers?

texts: I want to get a 3W 4Ohms Speaker for a bluetooth speaker project that I'm doing, but the speakers require me to solder wires onto them, while I don't have any experience in soldering. Am I able to use Electric Tape as a substitute, or are there any better substitutes, if any, that I can use?


texts: Why does the buzzer in this circuit have a voltage drop of 0.7V?

texts:
I set up a buzzer circuit in my Radioshack learning lab with a 100 kohm resistor to do some test measurements with voltage dividers (I didn't expect it to sound, I was just trying measurements.). I measured the resistance across the buzzer to be pretty high, 1700 kohms. With two components being resistors, I saw this circuit as a voltage divider with a 3V input voltage , and expected the voltage drop across the buzzer in to be 3 * (1,800,000)/(1,800,000 + 100,000) = 2.84 V.

However, when, I measured across the buzzer, I got a reading of 0.7V, 2V below what I expected. Why did the buzzer give a reading of 0.7V when I expected 2.84V? I also measured the current to be 22.8 microamps. I tried ohm's law: a voltage across a 1700 kohm buzzer with a current of 22.8 microamps would be 0.0000228*1,683,000 = 38.4V. That's way off my previous guess and measurement. Why did my ohm's law guess give a buzzer voltage that big instead of 0.7V?

simulate this circuit – Schematic created using CircuitLab


texts: What type of ultrasonic transducers are used in medical ultrasound devices?

texts:
When I search on DigiKey for ultrasonic transducers, all I get back is the circular transducers that are sold for the various DIY projects. i.e. the picture below:

However, the "medical" ultrasound devices have a wand, that houses an array of what seems like a linear ultrasound transducers. i.e. the picture below:

Question is, what is the correct term to name (search for) the rectangular shape vs the circular shape transducers?


texts: Who sets "standard component" standards?

texts:
For example: the LM317. Wikipedia says it was invented by National Semiconductor employees in 1970 — but now if I search for "LM317 datasheet" the results include PDFs from Fairchild Semiconductor, Texas Instruments, ON Semiconductor, Thomson Microelectronics, STMicroelectronics. Perhaps there is some variability, advantages one might have over another, but my understanding is that any LM317 is theoretically fungible for another.

I'm wondering how this comes to be, and if there's any term for this — something like "reference component" or "standardized IC"?. Now in the case when an intellectual property is violated, you might have "knockoffs" of a "proprietary" chip design. And certainly you could have legitimate licensees, like ARM does with their design cores.

But many components, say a 2N3904 transistor or IRF530 MOSFET or the aforementioned LM317, seem to be something of public domain designs yet meeting some sort of industry standard specifications.

Who sets the standards for these sort of standard components? Is there any central authority for their identification? Or is it as simple as that an original inventor both created and named a particular chip of their own as usual, but if it became popular enough, other manufacturers just began to manufacture (legal) "knockoffs" under the same name/parameters as soon as any monopoly rights expired?


texts:
Thanks for the reply JYelton,
Below is the requested diagram of my circuit.

simulate this circuit – Schematic created using CircuitLab

How to short a DC motor?

I was trying to short motor with the help of the circuit given in the above link.

My circuit specification are

Motor=9V dc motor,115mA(max)
Diode and capacitor across motor
Q1=2N4401,hfe(typical=200)
Q2=2N4401,hfe(typical=200)
Q3=2N4403,hfe(typical=200)
Supply for Q1 and Q2 is from Arduino=5V,
R1=1.68k
R2=10k
R3=100ohm
R4=100ohm
(Base resistor for Q2)

ISSUE: Motor takes off rather than stopping after the required time.
The brake time given is 50msec soon after the transistor Q1 is turned off.
Is it the base resistor R1 and R4 that causing the problem or the transistors?

Kindly please advice what's wrong in the circuit design?


texts: What is the role of including bulk input capacitor and startup resistors in the flyback dc to dc buck converter?

texts:
In the above figure \$Cin\$ is the bulk capacitor and \$Rstarup1\$ and \$Rstartup2\$ are the startup resistors (Startup circuit).For the given circuit I am using UCC28C40.In it's datasheet it is said that \$Cin\$ is used  to maintain an acceptable minimum bulk voltage level (Vbulk(min)).

But what is purpose of setting bulk voltage to minimum value? What will happen if these components (Cin and startup resistors) are not included?


texts: Silk-screened 'buttons' on a touch-tone phone?

texts:
I've been taking apart a recent, standard touch tone phone with the aim for automated dialing via a separate MCU with transistors activating the contacts (Smirk. An assistive technologies project designed for my grandmother, not 'robo-calling').

Removing the solder mask it is quite clear how to accomplish this in this case--

However, I had another question: Namely, does anyone know what process/method is being used here to trigger the switches ?

Rather than any physical device, the button contacts seem to be overlaid on the board themselves with a type of 'black substrate'. No visible connections are already apparent between the buttons.

At first I thought perhaps captive touch, but then they are activated by basically a rubber pad on the matching side, plus a plastic 'number button' on top.

My second thought here was that somehow the button press might be creating 'arcing'-- but could the voltage really be so high in this case?

I wondered if anyone had any thoughts as to what is going on, or what process is being used?


texts: What happen if the car charger don`t supply 1A, only 400 mA, if the device needs 1A?

texts: I am trying to splice a cable (barrel port to a cigarette port). This is for a radio with 5V, 1A. In the package, there was a normal AC plug to barrel port. My plan is to just cut the cord and connect it to an old cellphone charger adapter. It is a really old charger, without any information on how many many amps it supplies. Since it is such an old charger it might only deliver a 400 mA. Can I safely test this out and if the radio work, can I assume that it worked flawlessly? Or do I have to check to overheating and stuff? (I do not have a multimeter)


texts:
What methods exist to introduce dead-time in a MOSFET H-bridge?

(to prevent shoot-through)

(other than software methods, or using MOSFET driver ICs with internal dead-time generators)


texts: Arduino charger, can I use a step up regulator in the circuit?

texts:
The question is: how would I modify the below circuit to make it work with an 18650 3.7V 2500mah battery which I want to charge at 1C during constant current phase? Note, 1C should be fine as datasheet says battery can be charged in rapid-charge mode with 4A, 4.2V.

I want to build a battery charging circuit with an Arduino Uno, IRF510 mosfet, temperature sensor, and some resistors, based on this article. The original setup is to charge a AA battery. Here is the design, the battery goes between 5V and analog pin 1 reader:

The cool thing is you can use the Arduino to measure current by measuring the voltage on both sides of a resistor (R2 in the schematic). Depending on the battery voltage, you then adjust the current up to some maximum.However, I want to charge an 18650 battery, which should be charged to 4.2V, not 1.6V. The problem is the resistor would drop the voltage from 5v to below 4.2V, so it won't be able to charge the battery. Does it make sense to add a step up voltage regulator somewhere in the circuit to circumvent the issue?

What should I add to the circuit to make this work? Sorry, I'm an electrical noob.  Note, in terms of safety, I will follow the multi-phase charging profile as specified by the battery manufacturer (i.e. trickle, pre-charge, constant current, constant voltage, cutoff at max time or min current or max temperature).


texts: How to hold SMD parts in place while soldering?

texts:
I go through this every time I have PCBs I need to populate with SMD parts, and this has become more an issue as pin spacings have gotten tighter, and my hands have become less steady with age.

So far I've modified some curved tweezers with a rubber band for grip tension, to help hold a component in place until 1 or 2 pins can be soldered. It works but it can be cumbersome. The clamping force needs to be very light, and it seems one slight tap with a sharp iron tip will still move it. I've also tried various glues, placing a pin drop of glue in the center of where a component would go.

That sometimes works, but all the glues I've tried either waste my time waiting for it to dry, or dry (skin over) too quickly when grabbing some more. Worse, too often even a pin drop of glue will spread onto the pads, and then I have to waste more time cleaning things up.

If I had my druthers, all SMD pars would come with peel off self stick backing. But anyway, suggestions would be welcome. It will be a long time and many test markets before anything I'm doing will be populated for me with pro pick and place machines.


texts: General approach of signal detection after demodulation of BPSK

texts: I'm very new to electrical engineering. I'm trying to understand the basic approaches/options to detect symbols after demodulation of BPSK. I found some articles mentioning Maximum Likelihood detection (http://ecelabs.njit.edu/sdr/lab3/overview.pdf). Are there other options? With Maximum Likelihood detection, are there other required parameters needed besides the signal data?


texts: Non-rectified Voltage output across the capacitor

texts:
So I am testing my PZT Piezoelectric material's Voltage output across a Capacitor of 1000uF after converting AC to DC using an Oscilloscope. Oscilloscope model: Gwinstek GDS-2102.

The diagram is my model for testing the Voltage across the capacitor.
I am trying to see the output across the capacitor when I tap the PZT. this follwing waveform is from my AC to DC converter.

So as you can see, my AC to DC works perfectly. But now the Voltage across the capacitor is shown in the next waveform.

So as you can see it is not a DC rectified waveform.
Could anyone please let me know what is going on here?


texts: How do I use this impedance converter? (AD5933)

texts:
I want to measure a complex impedance with this impedance converter. I have been trying to find out how to use it, and I am confused. I figured I should put my impedance between VIN (5) and VOUt (6), and get 2 serial outputs. One for the real part, one for the imaginary part. The IC has a serial data pin which is SDA (15). I thought that must be the serial output and along with the SCL, it can be communicated to a microcontroller through I2C. However, on page 8 in pin function description SDA is describe as I2C data "input".

I am confused because it is called an input. Can you please clarify this?

Also, how are the real and imaginary values distinguished?

Thanks in advance.


texts: Why am I getting verification errors with avrude?

texts:
I am constantly getting verification errors with avrdude and atmega168. I googled a lot, but everyone is getting them at first byte, whereas I am getting them at random bytes:

avrdude: verifying ...
avrdude: verification error, first mismatch at byte 0x0692
         0x91 != 0x8c
avrdude: verification error; content mismatch

Sometimes it works, sometimes it doesn't. I noticed that if one hex file doesn't work once, it won't work at all, unless I will change something in code, thus changing the hex file. It happened with multiple processors and two programmers.


texts: Could I use a heatsink to interconnect transistors mounting base?

texts:
I'm designing a CMOS H-bridge single sided board. To keep it small as possible, I would like to not connect the transistor's drain by trace. In spite off, as they are connected to the mounting base and I will be using heatsink, I would like to know if this connection is enough. This doesn't sound a good design to me, but since it's a low current application (2A, with 4A peak), I think there will be no much problem (actually, the heatsinks are not even mandatory, since them are almost at room temperature).

The question is, how bad is this practice? Should I really avoid it at any costs or are there specific cases that I'm allowed to do this?


texts: Capacitor Size for a DC motor. Do I even need one?

texts: A couple months ago the AC motor on my wood lathe went out so, following a number of YouTube tutorials, I swapped it with a DC treadmill motor.  On the surface everything seems fine and it works.  The project got me interested in electronics again, so I've started taking online classes and trying to learn more.  I've recently started learning about capacitors and inductors and it got me thinking about my lathe circuit.  The circuit is very simple, it's basically a cheap SCR voltage controller ran into a bridge rectifier.  The more I learn though, I'm thinking I might need to add a capacitor after the bridge rectifier to smooth the voltage to the motor.  So my question is 2-fold.  Do I need a capacitor and how would I calculate what size I need?  The specs I have available for the motor are 2.25hp, 130V, 12.9A.  The max I ever need to use it is maybe 80%, after that it's almost too fast to be useable.  I've attached a rudimentary schematic of what I did below.


texts: Repurposing auto cigerette lighter heating element

texts:
Been trying to solve this and was looking at making custom heating elements with wire but is was getting way too complicated for me. My thought, which would completely solve this assuming I can control how hot it gets somehow. Wanting to use the heating element of a lighter. All I know is cigarette lighters run on 12v DC with a 10 amp fuse. A spring and switch on the arm would start and stop power.
At 12v 10 amp its starts stuff on fire and glows. Thats too hot...
My question is: Can the temp be controlled simply but altering the voltage going to it? Im looking for something around 150 degrees, it would be held in place for X seconds based on the material.
I have no idea where to start doing the calculations etc, and Ive spent hours trying to figure it out...
Any help or direction greatly appreciated.
[


texts: STM32L-Discovery programming on Linux with Eclipse

texts:
my problem is following.

How to configure Eclipse + ARM in order to code for this microcontroller?
I installed Eclipse and ARM plugin for it but I can't understand what to do after that :(


texts: What power cord for 5V / 5A power supply

texts:
I am rather new to electrical engineering topics.

I am currently building an audio player with multiple components (Raspberry Pi, Amplifier, LEDs, etc.) that all need 5V and all together will never exceed 5 A (actually 4). That’s why I though about getting a RS-25-5 power supply and build it right into the case.

My question is: What type of power cord do I need to feed the power supply OR/AND how much current will the power supply draw – will it be up to 5?

I’d love to be able to use a smaller power cord C7/C8 (rated for 2.5 Amps) instead of the huge C13/C14 (rated for 10 Amps) cable socket combo.

I am living in the EU. My wall socket provides 230V and maxes at 16A.


texts: AC capacitor computational problem using calculus

texts:
A current is flowing through an ideal capacitor, C = 25μF, the current waveform is a sawtooth. I need to find the formulas that plot the voltage waveform ,which is also shown in the figure,right below the current waveform. I need help to spot my mistakes in my computations when i apply the formulas.

$$\text{when}\,\, 0<t<1: i(t) = 5×10^6t\,\,\text{because slope}=\frac{5-0}{1×10^{-6}-0}=5×10^6$$

$$
\begin{align}
u(t) &= \frac{1}{C}\int_0^t i(t)dt\\ \\
&=\frac{1}{25×10^{-6}} \int_0^t\,5×10^6t \,dt\\ \\
&= \frac{5×10^6}{25×10^{-6}}\left.\frac{t^2}{2}\right\vert_0^t\\ \\
&= 0.1×10^{12}t^2\\
\end{align}
$$ Thus, between 0 < t < 1 i get a parabola pattern y = ax^2. I think that part is correct(judging from the volts waveform). Below comes the problematic part which i suspect i get it wrong and i need help please to find the correct solution.

$$\text{when}\,\, 1 < t < 2: i(t) = 5×10^6t\,\,\text{because slope}=\frac{0-(-5)}{(2-1)×10^{-6}}=5×10^6$$

$$
\begin{align}
u(t) &= \frac{1}{C}\int_0^t i(t)dt\\ \\
&=\frac{1}{25×10^{-6}} \int_{10^{-6}}^t\,5×10^6t \,dt \\ \\
&=\frac{5×10^6}{25×10^{-6}}\left.\frac{t^2}{2}\right\vert_{10^{-6}}^t\\ \\
&=\frac{5×10^6}{2×25×10^{-6}}\Bigr(t^2 -(10^{-6})^2\,\Bigl) 0.1×10^{12}\Bigr(t^2 -(10^{-6})^2\,\Bigl)\\ \\
&= 0.1×10^{12}t^2 -0.1
\end{align}
$$

BUT $$0.1×10^{12}t^2 -0.1 \,\,\, \text{is of the form } y=ax^2+b\, \, \text{I was expecting the pattern } \frac1x \text{ as the volts graph suggests when }1<t<2$$
I would like to ask for some help to find the correct solution.(this is an unsolved excercise from schaum's outline series electric circuits 2nd edition ex 1.42)

EDIT: test the formula u(t) for t = 1.5 x 10^(-6) seconds, when 1 < t < 2.  It outputs 0.125, invalid, because 0.125> 0.1. That's why i suspect there is probably a mistake.


texts:
simulate this circuit – Schematic created using CircuitLab

I'm trying to use an attenuator with a PIC32 microcontroller. Basic idea is that;

1) I enter attenuation value through computer

2) Computer sends information to PIC

3) PIC gives 8-bit output from its pins

4) Those pins connected to attenuator

5) Attenuator take input and operate x dB attenuation

I have a problem between the steps 3&4. PIC succesfully gives output. However, for only a specific pin(P3), there is a voltage loss when PIC and attenuator pins are connected. Except for P3 pin, attenuator works fine.

P3 succesfully gives 3.3V. But when connected to attenuator, I measure 1V. And attenutor does not take that 1V as "high" obviously.

Should I put some buffer between PIC and attenutor?
I have no idea what is the problem.

Thanks in advance

edit:
PIC32 datasheet  &  Attenuator datasheet


texts:
Suppose, AVR microcontroller is handling an interrupt. Interrupts disabled. At this time the same interrupt occurs. Will microcontroller handle the interrupt again after return from the first handler?

If "yes", then how can I avoid this? (I want to use INT0 interrupt (on low-level) with a button. But because of bouncing the interrupt can occurs again when microcontroller handle it.)


texts: Discharge constant 2A-3A current from a battery

texts:
I am supposed to drain a constant current of 2A or 3A from a battery (most probably a NiMH battery). What could be a possible way to do that ?
Purpose of doing it is to calculate the battery's Energy (using a micro controller) for the discharging cycle, while keeping its current constant.

Thankyou,

EDITED

What if i am using a buck-boost converter with a micro-controller to charge my battery and then discharge it? (Buck topology will work during the charging cycle and boost topology during the discharging cycle.) Would the following idea be practical ?

I mean if i choose a resistor (lets say for discharging 15V battery @ 20A) and connect it to my circuit given above during the discharging (also disconnecting my circuit from the main power supply), would i be able to drain a constant current for my test purpose ? I dont know exactly how the boost topology will exactly  work during the discharging cycle. But looking at the circuit, will i be able to draw a constant current out of my battery using PWM from my micro-controller ? And, would placing a constant value resistor for the discharging be a correct method to do (in this case) ?
Please help me if i am thinking totally wrong. Please tell me would my idea be practical or i am just being silly here.
(sensors and resistors which will be used to measure the voltage & current supplied to and drained from the battery are yet not drawn here by me)
Thankyou.


texts: What impact does winding tightly versus loosely have on transformer performance?

texts:
To make it simple (and actually, directly relevant to what I am working on): what impact does winding tightness have on transformer performance? Lets assume typical laminated EI / EE 60hz transformer, operating at 60hz, within the maximum flux density of the core material.

I suppose this is also a good way to illuminate the oft-mentioned qualitative idea of the "flux capturing" effect of a high permeability core versus air. If most of the flux is in that core, then who cares if there is a little more air, right? But...imagining that holding as "loosely wound" approached infinite diameter seems..shaky.

For instance, so I have a transformer where the primary is wound tight on the core, and another, where the primary is the diameter of the solar system, and because they both encircle the same flux in that core, there is no change in performance? That can't be, right?

So I am imagining leakage inductance probably increases. But, physically, why that is (mental model), doesn't seem to be sinking in. Is it simply because the more air there is inside the turns, the more paths there are for the magnetic circuit? And its as simple as that? I'm imagining actually calculating the flux in the air part of the circuit is probably not trivial, but is that the mental model?

What would be really handy is an engineering type mental model explanation, and then maybe a little mention of why Maxwells equation makes it so.

EDIT: I just realized that the "air part of the circuit" is a little ambiguous. What I mean is, as the additional area inside the turn which is not the core containing the transformer/mutual inductance flux goes up, the ability of that turn to store energy goes up (air core inductor)..i.e. leakage inductance.

Separately is the question of increased mutual inductance, i.e. transformer action through the air, but lets pretend that the secondary winding is always wound tight..for the moment. (or compare/contrast wound tight or also increasing)


texts: AC Adaptor converted in USB charger, is it safe?

texts:
Is it safe, or maybe I should I say "logical", to take an AC adaptor and splice the wires, reconnect them and solder together with a USB cable to power a device?

I had an old gameboy advance sp laying around and had an idea (sometimes my ideas are good, but most of the time they are not so good), well I cut the ac adaptor wire about half way and then took a usb cable, cut it and then soldered the wires together. Not knowing which wires should be connected to the corresponding wire, I took a guess and matched most of the color coded wires together. There were some that didn't match up so I just guessed and prayed.

The original plan was to be able to use it as a transfer cable, but like I said sometimes my ideas aren't so good. It turned out, it actually charged the gameboy. To my surprise, nothing bad happened, it charged the gameboy just fine, no smoke came out from anything, no sparks either. But that brings me back to my original question; is it safe? Would the watts or amperage be an issue with the original charger being 100V-120V?


texts: Looking to bring 24V inputs to PC to store in database

texts:
I've been given a project that sort of bridges the electrical/PLC and PC/software world.

I have to take a 24VDC photoeye and 24VDC encoder (1/4" to 1/2" pulse @ 540FPM ~ 1 pulse every 2.3ms-4.6ms) input and store their derived measurements in a database.

Essentially I am measuring how many pulses the photoeye is blocked to get box length, and how long it is unblocked to get gaps between. Storing both the gap in front, the length of the box and the current time in a table/database and repeating.

Program wise I know a PLC is the best solution, but storage wise, I need this to be stored preferably in a database (CSV, MySQL) so that it can easily be exported to excel and analyzed for throughput and the like.

Thus I was looking at using a compact X86 based PC communicating with some type of 24VDC IO Arduino microprocessor to receive and process the IO, and then send to the PC and the PC will take care of storing the data, calculating gaps and length and handling HMI. The Arduino would likely also take input from the PC to control outputs.

Is this the best solution? Are there lower cost PLC's that can do this type of data storage while keeping the data easy to extract? Will an Arduino be capable of accurately picking up 2-4ms signals?

Thanks for the help guys!


texts: I'm thinking of Using 3W RGB high power LEDs for a project. I will only have one color on at a time so I'm pretty sure that it would be 1W of ussage at a time. (please correct me if I'm wrong) My question is how hot do they get? I'm planing to use heat sink but trying to gauge if this is realistic for my project or will these be too hot for what I want to use them for. Nothing I read talks about temperatures it just says "they get hot!"


texts:
If the diode's dynamic resistance was zero , will not we be able to increase the voltage across the diode above 0.7 v ?
(I am assuming forward bias )

I am asking this question because my book ( electronic devices by floyd ) says that the increase in forward voltage across the diode above the barrier potential is due to the voltage drop across the internal dynamic resistance of the semiconductive material .


texts: how to properly use external memory flash with MCU (dsPIC33)

texts:
In my project, I need to store (and read) large amount of data ( >128 Mbits). Of course, I need external flash memory (I think SD card won't work because speed is an issue in my project).

So I plan to use parallel flash memory with a dsPIC33 MCU (I'll use the DSP capabilities to compute data that will be store in the flash memory). My data will be 16 bits word but the sdPIC only ave an 8bits parallel memory bus)

I'm looking for information/documentation about the proper way to use flash memory like :

How to correctly store 16bits data word with an 8bits bus
what is the fastest way to do it ? word by word? multiple word at the same time ?

It's my first project where time is an issue, I only used SPI memory in the past.

Thanks a lot if you have answers or tips for me.

Max.


texts: Can I Move a wheelchair with two outrunner motors?

texts:
I am trying to turn a wheelchair electric and want to use a VESC to do so. However, I was wondering if an outrunner brushless motor with a belt to a larger gear would be effective and could move the wheelchair with a person if I had two of them. I am looking at a motor like this: https://www.amazon.com/vanpro-Brushless-Outrunner-Motor-Electric/dp/B07FNHQ3JK/ref=sr_1_2_sspa?keywords=brushless+scooter+motor&qid=1561407288&s=gateway&sr=8-2-spons&psc=1

and a VESC like this:
https://www.amazon.com/HGLRC-FLIPSKY-SK8-ESC-Electric-Skateboard-EScooter/dp/B07GFB55NV/ref=sr_1_1?keywords=vesc&qid=1561408198&s=gateway&sr=8-1

Please feel free to suggest other solutions if this does not seem reasonable as I am still new to electrical and mechanical engineering.

Thanks,
Maanit


texts: AC circuit to act as a relay for another DC circuit

texts: In this circuit, I have caused an AC current to power the gate pin of the Thyristor, which in turn should allow the 10v DC current to pass even after the AC current inverses - it is not a Transistor. However, when I check to see the voltage after the Thyristor (at the Voltmeter), the value is always fluctuating from positive to negative - as you can see, the Anode pin of the Thyristor is receiving the full 10v, so why is the voltage fluctuating so much after the Cathode pin?


texts:
I have a Nokia 6310 display which I would like to reuse as a display controlled by an ATMega. I can find plenty of information about N3310 display but almost nothing about 6310.

Does anyone know the type of the display and where to find its specification (pinout, protocol)?

On the metallic cover, there is "01222P02148DS" imprinted and "DMD06868" engraved. On the display itself, there is nothing. The display has 8 pins connected to the rest of telephone.

Any hints are welcome.

UPDATE:
Thanks, in the meantime, I've found http://www.module.ro/nokia_3510.html with more details.

  Nokia 6310 & 6310i lcd pinouts

    Lcd chip: Philips pcf8511 / pcf8813 (I think - not tested but it looks to be the same lcd driver used in N3510)
    Resolution: 96x65
    Protocol: SPI 3Wire
    Die size: cca. 2,85x10,85 mm
    Spare part code: 4850163

Pin8 _Reset
Pin7 _Cs
Pin6 Gnd
Pin5 Sdata
Pin4 Sclk
Pin3 Vio  1.8V
Pin2 Vbooster in  2.7V
Pin1 Vlcd  (from internal dc/dc converter)

I'm still unsure about Vlcd (3.3V?), so I will look for the datasheet and if it works, I'll post the details.


texts: Question about Vbe and operation regions of BJT

texts:
Updated/Corrected question:

Realizing what confuses me the most, I will make this more straight-forward. Say that a transistor works in the forward active region and it receives an ac input signal at its base.

Is there a chance that the change in the base voltage will decrease Vbe and force the transistor into the cut-off region? Is there any chance this might happen before first entering the saturation region?

Original post:

I'm soon taking an exam on transistors and I've just started my revision. After having a look at the conditions for each region of operation and some example problems, there is something I don't understand or that maybe I don't remember very well.

The condition for an npn bjt to be on is that the base emitter voltage is above 0.7  volts. From what I remember this is not an accurate value but let's say it is around there.

When we analyse the small signal model of a circuit , the values we calculate are superimposed on the dc values, right? So, when we apply an ac signal to the base of the bjt, the base emitter voltage changes.

So, my questions are :
Is there a chance that the ac input signal will take the bjt in the cut off region?

If yes, how do we check it?

If yes, when deciding on the swing of the output voltage are we more worried about entering saturation or cut-off region? I mean, which comes first as the swing increases? Does it depend on the operation point?


texts:
A recent question over on Android Enthusiasts got me to wondering how volume control headphones work.

I don't mean volume control which works by attenuating the incoming signal, but the kind of volume control that signals to the device to increase or decrease the signal output.

For instance, according to the Crossfade LP product page, the volume controls are only for apple devices:

  Universal Compatibility and Microphone Communication
  LP comes with 2 cables for universal compatibility with all modern mobile and audio devices. The 3-Button remote microphone cable is designed for the latest Apple devices, including iPhone®,iPad®, iPod®, and Macbook series. The long audio-only cable and 1/4" adapter is universally compatible with all audio devices and professional equipment.

However this sort of device apparently works with some android phones and the question implies that it works with some computer sound cards on Windows machines too, but not being an Apple buyer (and only recently getting my first smartphone) I haven't seen this sort of thing before. I've done a quick google search, but can't find anything on standards for this technology.

How does this work?

Is it something as simple as shorting left/right/mic channels?
If so, could using headphones of this type with equipment that doesn't support this technology, damage that equipment?
Is it a serial signal, for instance sent over the mic channel?
Does it just require a headphone TRS connector or a headphone  +microphone TRRS connector?

Does this technique have a name?
Incidentally, is someone could answer this, I can probably look up the rest of the information myself. *8')
Is it as standard as it appears, or is everyone just following Apple?
Is this something that is patented?

If so, who holds the patent and do they charge a license fee for people to use this technology?
If not, is there an open standard for it?

There is some excellent information in an answer to the question What protocol does a headphone jack use? but it doesn't answer the specifics of how this type of volume (etc.) control works, since it now seems to be rather more common and standard.


texts: Difference between 3x1w and 1x3w power supply?

texts:
Buying small power supply for 3w led chips. Most are listed as 3x1w, but some are listed as 1x3w.

What's the difference?


texts: What Type Of Switch Is only on for a second

texts:
I am looking for what type of switch is only only for a split second (1 second max) even when held.

Basically:
Press and hold button-->LED only on for a split second and back off even though I am still holding it. If It is not a 'Switch' then what would I need to do to accomplish this.

EDIT: The Reason I Posted this one is because I'm a beginner, I have No Idea what a Logic Gate is. Is the a component I can just buy?


texts: Recommended Minimum Connections for dsPIC30F4011?

texts:
In the dsPIC33FJ06GS101 (pdf) manual a recommended minimum connection circuit it specified for that chip, pdf page 22. This includes decoupling capacitors, pull-up on MCLR and a few other things. For the dsPIC30F4011 (pdf) nothing is specified, not even in the Family Manual (pdf).

Where can I find such recommendations? Decoupling capacitors are surely recommendable.


texts: Find the voltage Vab and current of the circuit I

texts:
I was asked to find the voltage  Vab and the current of the circuit I.
I tried finding the voltage in ab using voltage divider, but I have two voltage sources and I don't know how to make the respective formula
A voltage divider is  E*(R1/R1+R2) for the respective place you want to measure, but what about when there are two voltage sources?
I'd like to ask for some guidance as to where I am supposed to look or how to start. As for the current of the circuit, maybe finding an Rtotal and then using two Ohm's law?


texts: LM324 op-amp wheatstone bridge amplifier formula

texts:
I'm planning to use an LM324 opamp as a signal amplifier for a cell load (strain gauge in a Wheatstone bridge). This particular application is shown in the datasheet (see image). It shows the Wheatstone brige (bottom-left resistor is the strain gauge) and the opamp in a differential amplifier circuit.

My problem is I can't quite figure out how the formula is calculated.

I get I have to use Thevenin on both sides of the bridge. This gives me:

$$R_{t-}=\frac{R}{2}$$

$$
V_{t-} =\frac{ V_{REF}}{2}
$$ for the right side of the bridge and
$$R_{t+}\approx{\frac{R}{2}}$$

$$
V_{t+} \approx{\frac{ V_{REF}+\delta V_{REF}}{2}}
$$
for the left side. Now the circuit becomes:

and the differential amplifier circuit formula gives me:

$$
v_o = \frac{R_f}{R/2}(v_{t+}-v_{t-})=\frac{R_f}{R/2} \frac{\delta V_{REF}}{2}
$$

which differs from the datasheet formula for a 1/2 factor.

So, what's wrong with my calculation?


texts:
The Fluke 732A has among 10V and 1V references also a 1.018V reference (whereas the 10V is the "main" references and the others are formed by resistive voltage dividers).

While having multiple reference voltages is surely convenient, why exactly 1.018V? Some references have a \$2^N*10^M V\$ value, which makes somewhat sense for ADCs to better have steps of \$10^K V\$, but why exactly 1.018V here, what is the significance of this value?


texts: Analyse images before storing them in memory

texts:
Physicist here, so please be gentle ;-) I am designing a device to acquire in a few seconds a large amounts of images (a few terabytes), that then need to be analysed, possibly on the fly. Is there a way to screen the images and filter them before saving them, so to store in memory only those with the desired features? Thanks!

The setup I'm describing already exists (http://www.pnas.org/content/109/29/11630.full) and I am looking for ideas to improve it (the quantity of generated data is enormous, and improving the pre-screening would help to make the cells detection faster).

Regarding the accepted answer, the process could be

Data → SDRAM storage → GPU/FPGA prescreening → storage of the selected images → CPU processing

right? Please correct me if I got it wrong.


texts: Practical efficiencies of available solar cells

texts:
I had a completed answer to this but when I went to post it it was closed, so :

I understand that "multijunction" cells, particular those made from Copper Indium Gallium diSelenide, are the most efficient kind today.

What are the most efficient solar cells available today for me to purchase in quantities of 1-10? Types? Manufacturers? Brand names? Vendors?


texts:
I use a simple circuit to notify user the reverse biased voltage to prevent some issues.
Vcc can be -18~+18V, and two LEDs have exactly same reverse voltage (5V), but they have different forward voltage (because their LED wavelengths are different, blue one has 3V, red one has 1.8V). Will this setting cause a problem? In my test this circuit not failed but I'm not convinced. I think if the LED voltage is within the range of the reverse voltage, it's just okay. Is my thought right?


texts: VNA Tuning in Enclosure -- LiPo Battery Detuning Antenna

texts:
I've got a finished design, that I tuned the matching network using bare boards.

Say for example, my tuned TX board has an over-the-air 3 meter reading on my spectrum analyzer at -50dbm. (This is at VSWR 1.2:1).

When I put the TX board, into the transmitter enclosure I see significant signal attenuation.  My tuned TX board now has an over-the-air 3 meter reading on my spectrum analyzer at -75dbm. (At unknown VSWR).

Unfortunately, in the 4 months since I tuned these boards, my USB VNA is not working, so I had to re-order another one, so I can't measure the impedance in the enclosure quite yet.

I have chalked it up more to the plastic attenuating the signal, as opposed to a massive impedance change.

Is it possible there is that much change to the impedance when a perfectly tuned TX board is put into an enclosure?

UPDATE: It's definently not the plastic per se, weakening the signal. The TX signal gets weak when the LiPo battery is positioned in a certain way in the enclosure.  Not sure if that is a change in the impedance or some other electro-phenomenon, until I get a working VNA to make the measurements.

RESULTS:

TX bare boards in your hand, battery hanging in free space: -50dbm.

TX in the enclosure, with battery inside (10mm away from the board – huge space): -75dbm.

TX in the enclosure, with battery hanging outside the enclosure: -48dbm

--

(I tried shielding the battery with copper tape, it doesn't seem like it is some LiPo magic anti-RF waves are being emitted and messing with the transmitter IC or something else).


texts:
I am looking for any recommendations or suggestion for Ground Planes for two different grounds

I am designing a battery powered device with two voltage sources, 1 coming from the AC wall and other from a Li-ion battery when there is not energy available from the AC wall.

in the PCB design state I am facing a concern about the ground planes because it is very important for the design (reduce heat, impedance control, EMI) so I added a gas gauge to monitoring my battery state, but it requires a Rsense from the battery to my load. my question is now I have "two" different Ground separates for a miliOhm resistor, on stage for my DC-DC input converter and the other for the Battery to the load. is it right? how can I can handle the ground planes if one is "isolate" for a mOhm resistor.

should I keep my two different ground loops as small as possible?

Details:
input 9V
Load 5v/5A
battery 3.7v (high current 15A max)

I added my Block diagram for the design

any recommendation for monitoring the current in a different way? or any battery charger IC with gas gauge feature?
Thanks


texts: How to connect a TVS to protect the data lines in a USB device port?

texts:
TVS is a good practice to protect USB ports.  A USB (at least 2.0) connection has the power path supplied with a 5 V source (Vbus=5V0) at the host side and the data path supplied with a 3.3 V sources (3V3) at both ends of the connection.

A TVS protecting the data lines (D+, D-), is connected like the following:

Should it be connected to 5V0 (Vbus) or 3V3?  Why so?  Arguments?  References?

(This is especially interesting in the case of FTDI and similar ICs whose transceiver logic is supplied from the internal 3.3 V LDO.)


texts: Impedance of USB-A cable when disabling data pins with tape

texts:
I have an interesting situation.
I have a USB-A 2.0 (4 pins) to USB-C cable. I need to fully disable the data connection, so I used a painter's tape to cover the two middle pins (D+ and D-).
When I connect my phone to the computer, it works as intended. The phone simply charges, does not show as a connected device. Before, without the tape, it would charge and also connect as a storage.
I have another device (a modem), however, that is behaving strange:

Without the tape, connected to a charger: it charges only (as expected)

Without the tape, connected to a computer: it charges and the device shows it is connected to another device (as expected)

With the tape, connected to a charger: it charges and the modem flags it is connected to another device (NOT expected)

With the tape, connected to a computer: same as above (but the computer does not show a device is connected to it).

How would you explain that?
Am I right to assume that this modem uses very short impedance, and maybe the tape is causing some impedance, so it senses a data connection is available?
I also tried to mask with a paper, with same results as above.
Any idea why the modem might be sensing there is data when I cover the data pins?
Thank you!


texts: Triggering a relay using CL100 transistor

texts: I am trying to trigger a 5V relay using a CL100 transistor using TTL logic without success. I guess using a driver transistor like BC547 in the input side of CL100 may do the trick, but I want to avoid a driver transistor and keep the circuit simple. Am I doing anything wrong here?


texts: Building a water jet cutter using Arduino, CNC shield and GRBL firmware

texts:
I am building a water jet cutter using Arduino Uno and CNC shield for control.
    The CNC shield uses A4988 drivers to control the stepper motors. I uploaded the GRBL (for this shield) firmware to the Arduino and got ready to use Universal G-code Sender to send g-code instructions that the machine will work on.
    Now my question is this: if I want to choose to work on full step, half step or 1/16th step mode, does the Arduino, shield or the GRBL firmware know what my option is? I am asking this in order to know if I can use another motor driver (if I choose full step and the GRBL handle it well then I can use L297 driver for example, which only work on full and half step mode).
I hope I made it clear...


texts: I am at-home electronics hobbyist and tend to salvage majority of the components I use from old/broken items. Recently I took apart a microwave and desoldered most of the the components from it. I have never seen one of these (picture) before. What is this and what does it do?


texts: Clock Dividers with Clock Domain Crossing

texts:
I am doing a design in FPGA that looks like this:

100 MHz is the clock available in my FPGA board. It feeds Module 2. Module 1 is  needs a slow clock of 10 MHz clock. So I used a clock divider with flip flops. I thought of not using PLL to make my code purely RTL. Module 1 is transferring some data along with control signals to Module 2.

My current assumption is that:

The main clock and the divided clock are synchronous, and their phase relations are known to the synthesiser. And hence there is no Clock Domain Crossing here. So that I can simply constraint both the clocks and put multi-path SDC constraints between Module 1 and Module 2.

But I am not sure whether I am right. Is this a case of asynchronous CDC ? Will I need any synchroniser between Module 1 and Module 2 ?

Any feedback is welcome.


texts:
I'm trying to save board space used up by regular cartridge fuses. An horizontal fuse holder for those occupies about 27×10mm in my board (vertical mount is not an option). An obvious solution seems to be replacing those by automotive blade fuses:

The mini fuse above is 10.9 × 3.6mm, so mounting a horizontal holder like this would save me a lot of space. So this solution seems good. In fact, too good: now I'm wondering why I don't see automotive blade fuses in PCBs everywhere. Are there disadvantages to this kind of fuse, when compared to regular cartridge fuses? Is there some reason (mechanical, perhaps) for not mounting blade fuse holders directly on PCBs?


texts: Fourier Series Expansion of the phase current of a three phase full wave bridge rectifier

texts:
I am really struggling with this homework problem where I am asked to calculate the harmonic components as a ratio of the first fundamental harmonic of the phase current of a three phase rectifier with an RC parallel load.

Obviously with the capacitor in parallel with the load I figured there will be some phase shift on the phase voltages when their respective diodes are forward biased but I thought I could still potentially find the Fourier coefficients with the knowledge that the line to line voltages on a 3 phase delta wye connected rectifier like the one shown are as follows:

$$va(t)= \sin\omega t$$
 $$vb(t) = \sin\omega t - \frac{2\pi}{3}$$
 $$vc(t) = \sin\omega t - \frac{4\pi}{3}$$

My next line of reasoning was to follow this section of the course textbook explaining that the phase current through the primary phase a is active when the line to line voltage of phase A and B is highest for a given period followed by another period wherein the phase to phase voltage between phases A and C is highest. This is shown in the bottom plot below:

So I've tried to come up with the fourier expansion but it is proving difficult. I calculated that the magnitude of the signal should be 28.64 (voltage divided by impedance) using values in the first image.

Sorry guys I know I could have written this all in mathjax but I was low on time and inexperienced with this site and need to get my point across. So assuming that I am correct with the expression in the photo about the fourier series expansion, how do you evaluate this since it is 2 sine functions multiplied? Also I think the 28.64 is wrong because on the simulation the phase current has a magnitude of a little over 10A. I have no idea how because I got this by dividing the phase voltage by the impedance.

If anyone has ever worked a problem like this and can provide a hint, a link to a useful resource or anything I'd really appreciate it.

Thanks for your time,

Simon.


texts: Half Wave Voltage Doubler Simulation stuck

texts:
I'm trying to simulate the following circuit on LTSpice

simulate this circuit – Schematic created using CircuitLab

The capacitors have 10Meg Parallel Resistance

.model D_ideal D(Ron=0.1n Roff=10Meg Vfwd=0.7)

And I'm using a voltage switch and a diode for my SCR model:

.SUBCKT SCR 1 2 4
S1 3 1 2 0 VSW
D1 3 4 D_ideal
.MODEL VSW SW(RON=0.1n  ROFF = 10Meg VT = 1 VH = 0)
.model D_ideal D(Ron=0.1n Roff=10Meg Vfwd=0.7)
.ENDS

When CHRG turns off the SCR my simulation gets stuck.

Any insights?


texts:
Im creating a guitar effects pedal as a final year university project and I'm running it all from a single supply

I understand the concept of a virtual ground such that the input signal is biased in-between the power rails however Im having a hard time understanding the correct way to connect the input signal to the op amp

Im using OPA2350 op amps with TLE2426CLP rail splitter.

The jack lead connection from the guitar provides a mono signal with the ring being 'ground' and tip being the audio signal

Should I connect the ground of the jack lead to 'real' ground (supply rail) of the op amp then connect the audio signal to both virtual ground and the input of the op amp through a capacitor (biasing at \$\frac{V_{in}}2\$)
Or should I connect the ground from the jack lead to the virtual ground from the rail splitter then connect the audio signal straight to the op amp such that the 'ground' from the guitar would be raised to \$\frac{V_{in}}2\$?

Which way would be correct?


texts:
I'm planning on testing three different circuits for their response to a power surge (in the event that a surge protector fails). They'll each be drawing 5V power from an AC to DC power supply and they're each different constant current laser diode drivers.

First, I'm going to try a few power supplies to see if there is any difference there and then move onto measuring how the circuits perform with surge-like transients on their 5V input.

In summary, I'm looking for suggestions on how to safely create a surge on a 220V 50 Hz line.


texts: Why are "flicker flame bulbs" always bulbs or how do flicker flame bulbs work?

texts:
In other words, I've never seen the type of filament (if filament is the correct term—if not, what is the correct term?) outside of a bulb—as seen in the video linked to below.  Is there something about the way it works that makes them unsuitable for use when not encased in a bulb?

Random YouTube video of the type of bulb I'm talking about.


texts: Reverse engineer VFD control signal from schematic

texts:
There's a TLDR at the bottom!
I got a brushless DC motor and VFD from an old treadmill, both are Baldor brand. Unfortunately it looks like they were made by Baldor specifically for this treadmill, and no separate documentation is available for them. It's a Burdick T600 treadmill, and I also got the main "brain" board from the treadmill, although I have reason to believe something may be wrong with it.
My goal here is to use the motor and VFD for another project (not to fix the treadmill). So I want to speak directly to the VFD and eliminate the treadmill mainboard.
I followed the instructions in the service manual for the treadmill to put the treadmill main board into "test mode," where I can run the motor easily. Initially, when I commanded it to start the motor, it ran back and forth about 1 time a second. I started playing with things, and I found out that if I don't allow the speed control signal to get from the treadmill main board to the VFD, but I allow the start/stop/power lines to work as normal, the VFD spins the motor up to max speed (4000rpm) no problem. So if the VFD sees an open circuit across the two speed control lines, it seems to interpret that as max speed.
Reading between the lines in the service manual, it sounds like maybe the VFD is expecting to see a variable resistance between the two speed control lines. If I leave the lines open and measure the voltage across them coming from the VFD, I get about 15VDC.
I have the schematic from the treadmill main board, and this is the section that is responsible for the speed control lines.

The service manual seems to imply that there is a PWM signal driving the optocoupler, but no idea on the specifics of that signal. I don't have a scope handy right now, it'll be 4-5 days before I can get access to one, or I'd just check.
TLDR: Is this optocoupler-in-parallel-with-a-resistor arrangement a pretty typical way to make a digitally controlled variable resistance? And if so, what value of potentiometer should I use to mimic this? (I want manual control over VFD speed.)


texts: I need to control my el wire from Arduino Lilypad. I am going to use MOSFET switch circuit. El wire is ran from 9V battery and inverter circuit. Inverter is using about 90mA current. Lilypad has 3.3V output, so I am connecting it to IRLZ44 MOSFET and as inverter has a transformer in it inside, I need a flyback diode, right?


texts: Is it possible to remove the write back stage in 5-stage pipeline?

texts: In this graph, can we simply remove the write back stage since the mux is pushed back into the memory access stage and there is no logic in the write back stage. Is it because of the register file that cannot be read and written simultaneously, we have to wait an extra clock to let the write finish? What if the register file has internal forwarding, can I remove the write back stage?


texts: FOC for a BLDC motor with Hall sensors but no encoder

texts:
I am trying to implement a FOC algorithm in an MCU to use with a BLDC motor.

My problem is that I only have the Hall sensor feedback, no precise encoder can be used. With this 4 pole pairs motor, Hall sensors give 15 degree resolution.

I think this is the reason my algorithm is failing and I cant get a DC constant d and q values.

Is there any better way to drive a BLDC motor than FOC? What I need actually is a way to feed torque/ current to the regulator and be able to precisely read the feedback.

My analog circuitry for measuring \$I_a\$ and \$I_b\$ currents works fine, I just don't know how to calculate the needed feedback value.

In other words, can FOC even work for BLDC without an encoder but just with Hall sensors? If not, what is the better way?

My analog circuit:


texts: How to show that this filter is a bandpass filter

texts:
i got a system with transfer function given by:

$$H(\omega)=1-e^{-j\omega}$$
I already plot it, and that seems to be a periodic function with $$H(0)=0$$ $$H(\pi)=2$$ $$H(\infty)=1$$ is that enough to show that this is a FIR bandpass filter. thank you very much


texts: How does a wire dipole antenna work when not straight?

texts:
I recently bought an FM antenna for a receiver like this.

I've flattened it out a good bit on my windowsill but it's far from straight and is fairly wavy/curled from being bundled like this for who knows how long after manufacturing.

How does this still work as an antenna? I was under the impression antennas were (when practical) designed to be straight and some nice fraction of a wavelength.


texts:
I'm attempting to blink an LED with the Timer1 overflow interrupt on a PIC12F629, but all I get is a constant LOW value on the GPIO pin.  I'm using a 32.768kHz crystal oscillator with 82pF load caps and a 0.1uF filter cap across Vdd and Vss.  The GPIO pin for the LED is set to sink (anode tied high, cathode to GPIO through resistor).

I had it all working when using the internal oscillator (4MHz) but haven't had any luck while using the LP crystal.  I'm pretty sure it's not a hardware issue since I was able to get it to work (with the LP crystal setup) using MPLAB's built-in __delay_ms() function.  I also checked the LED GPIO pin with a logic analyzer to make sure the LED wasn't just blinking faster than I could perceive.  Here are my code snippets from several .h and .c files:

#include <xc.h>

// CONFIG register
#pragma config WDTE = OFF     // turn off WDT
#pragma config FOSC = 0b000   // LP crystal

// Set up LP crystal GPIO
TRISIObits.TRISIO4 = 1;
TRISIObits.TRISIO5 = 1;
WPUbits.WPU4 = 0;
WPUbits.WPU5 = 0;

// Set up interrupts
TMR1H = 0;
TMR1L = 0;
PIR1bits.TMR1IF = 0;
PIE1bits.TMR1IE = 1;
INTCONbits.PEIE = 1;
INTCONbits.GIE = 1;

// Set up Timer1
T1CONbits.TMR1GE = 0;
T1CONbits.T1CKPS = 0b00;   // prescaler = 1
T1CONbits.T1OSCEN = 0;
T1CONbits.nT1SYNC = 0;
T1CONbits.TMR1CS = 1;
T1CONbits.TMR1ON = 1;

// Set up GP2 (LED)
TRISIObits.TRISIO2 = 0;
WPUbits.WPU2 = 0;
GPIObits.GP2 = 0;

// Interrupt service routine
void interrupt isr(void)
{
    if(PIR1bits.TMR1IF)
    {
        PIR1bits.TMR1IF = 0;
        GPIObits.GP2 ^= 1;
    }
}

From the datasheet, here's Timer1's signal flow:

From my calculations, with prescaler set to 1, using a 16-bit timer and a 32.768kHz crystal the timer should overflow every 2 seconds.  Any ideas where I'm going wrong?

EDIT:  Uh oh, there's an errata for Timer1 :(

EDIT2:  Fixed the math in the above paragraph (forgot to invert the 0.5Hz to get 2 seconds).


texts: Is there a way to bypass a component in series in a circuit if that component fails?

texts:
Imagine a couple of speakers connected in series. Could there be a way to build such circuit with the ability to close the circuit if one component isn't working anymore? Like a different path that ignores the malfunctioning component, maybe using a voltmeter to trigger a switch in the circuit when it reads zero.

(just a question I'd given my electronics teacher in class. He failed to give me an answer)


texts:
I am trying to detect the presence of +12v on V2 to trigger a digital pin on a micro controller.

I am using an opto isolator as I am under the impression that it is the best way to isolate my circuit from the potentially noisy automotive circuit.

When V2 is activated by the vehicle, it outputs betweeen 9 and 12v, activating the opto and pulls the digital pin low.

However, when V2 is inactive, it is outputting around 2v, which causes the digital pin to read high, with an occasional low. Ideally, I would like to avoid disturbing the vehicle's circuit as much as possible.

How can I ignore V2 unless it is greater than, say, 5v? Is a Zener diode between V2 and R1 the proper way to solve this?

simulate this circuit – Schematic created using CircuitLab


texts: What to do with unused opamp inputs in STM32L4?

texts:
Im wiring up a STM32L4R5QII6 and am not sure what to do with the  OPAMP1_VINM pin. Pin PA7 can be configured as either the OPAMP2_VINM function or the SPI1_MOSI function. The latter is needed so that takes care of that one easy.

PIN PA1 has the function to be OPAMP1_VINM or ADC1_IN6. According to the reference guide, the opamp can be disabled. If we were to disable the opamp what would the proper thing to do with the input be? I've read that for unused opamps you should terminate them properly like configuring them as a follower. Is this the same for a disabled opamp? Im not entirely sure what that means, do they become unpowered? I haven't been able to find anything in the datasheet or the reference guide that helps me.

If we were to configure this pin as ADC1_IN6, should this pin be grounded. Looking at this post I believe I should but it also says there are some pins that may not need to be. Again, cant find much information on these pins. We also are not planning to use the ADC so I think we can leave these floating.

Datasheet: https://www.st.com/content/ccc/resource/technical/document/datasheet/group3/98/80/dc/e5/f8/4b/4b/a3/DM00366448/files/DM00366448.pdf/jcr:content/translations/en.DM00366448.pdf

Reference guide:
https://www.st.com/resource/en/reference_manual/dm00310109-stm32l4-series-advanced-armbased-32bit-mcus-stmicroelectronics.pdf


texts: Measure High Dc Voltages 0-150V using a STM32F446RE MCU

texts:
Does anyone have any suggestion on how to build a circuit that can convert high Dc voltages from 0-150 V to lower voltages so that I can use my MCU to read them and display them on my 16x2 LCD?.
I also use Mbed online compiler to write my mcu code.


texts:
Ok, my first question here. In my spare time, I run a small PA company. On Saturday, I had a concert at a sports center where I´d never been before. Power for the event came from a standard 5-pin, 16A outlet. After connecting to my distribution unit, I got the multimeter out and checked the voltages. I found:

Line -> Neutral = 230v (on all 3 phases).

Neutral -> Earth = 0v;

Line -> Earth = 0v.

The last reading obviously threw me. Over the years, I´ve seen all sorts of 'floating' earth to phase voltages, but never 0v.

So I checked the voltage at the outlet on the wall in case my cable or distro was the problem, but found the same thing. I then checked with the guy in charge of the place, but he wasn´t much help. There was no other outlet in the hall, nor would he let me into their mains 'cubby hole' - at least not without their electrician present, etc, etc. All he said was that they have regular events there and have never had any problem with the power.

So I set up, made sure that the mics, etc. were safe and did the gig.

So my question is simply, what circumstances would produce a 0v Line to Earth reading?


texts: For superconducting inductors, does the "magnetic current" flowing in the ferrite of an inductor suffer from "magnetic resistance"?

texts:
In this answer to "Inductor made out of super conductors", the experiences recounted included "ramping up the inductor" or "charging it up".   Absolutely fascinating is the thought of two currents continuously flowing -- the electrical current inside the superconductor, and the magnetic current inside the ferrite.
I know that every normal conductor has an electrical resistance, and that the electrical resistance is mostly removed in the superconducting conductor.
It is my understanding that there is also a "magnetic current" flowing in the ferrite of the superconducting inductor.  (I don't remember where I heard this.)  I know that there are losses involved with changing the amount of that flowing current.  But if the superconducting current is a full short-circuit, and is therefore "holding", that is, maintaining the flow of current without loss, then...
Is there another efficiency loss, similar to electrical resistance, that affects the continually flowing magnetic current, assuming that the magnetic current is not changing at all in magnitude?  Is there magnetic resistance?

This is my guess:  even though I have been told that a magnetized inductor has a magnetic current flowing, the stored magnetic field to me seems more like a coiled spring, not in motion, but yet still "containing" potential energy.  Hence, my guess is that there is no resistance because there is no motion.  The action of compressing or uncompressing the spring is more of a kind of motion that shows a kind of "resistance" in the hysteresis losses, actual crystal deformation if I am right.  What confuses me is the flux, which seems like a flowing fluid.  Please either confirm or correct my concepts of these things. Thank you.


texts: Why do we need to calculate the resonant frequency for antennas?

texts: Is there any reason to cancel the inductive and capacitive reactance out for an antenna operating on 13.56 Mhz ? Why do we need to cancel the reactances out I followed a tutorial when designing a T-match antenna but I did not really understand the relationship between the antenna and the resoncance frequency. How will that affect the antenna?


texts: How do I amplify an input signal to match the peak of another signal

texts:
I would like to build building a Voltage Controlled Oscillator (VCO) for audio applications beginning with a relaxation oscillator build from op amps.  Adding a potentiometer to the feedback loop allows for frequency control, but as I increase the frequency, the amplitude of the signal reduces.  I'l like to build a circuit that takes that signal and adds a dynamic gain to make it so that the final output signal of the oscillator rises to the same peak voltages regardless of frequency.  I am having problems constructing such a circuit using op amps and would appreciate any ideas you have to get me on the right track.  Beore writing this post, I searched for: Voltage Normalizer Circuit and Voltage Stabilizer Circuirt.  Neither searches yielded anything useful.

I have an idea of how I need to accomplish this using plain math, but can't figure out how to translate that into op amps:

Step 1: Create a peak detector on the input signal using a Voltage follower, diode and capacitor to hold the voltage in place.  (+-7V swinging about ground for this example).  I think I can handle this part.

Step 2: Provide a reference signal to a desired peak input voltage (+-11V for this example)

Step 3: Establish a gain ratio from the desired peak and the input peak (for this example if I were to focus on just the positive side, it would be 11V/7V = ~1.57).

Step 4: Create a non-inverting amplifier off the input signal using the gain ratio determined in Step 3 as the resistance in the negative feedback loop.  (For this example, it would essentially take the input signal with a peak amplitude of 7V and amplify it by 1.57 to output a signal with gain that peaks at close to +-11V).

I'm stuck on Step 3 and 4.  I don't know how to create a "voltage controlled resistor" that I can use as part of the negative feedback gain loop of an op amp circuit.  This looks like it would have a pretty simple solution, but I'm at a loss as to discovering/understanding it.  I'd appreciate any help you all can provide on this design issue.

Thanks!


texts: Arduino for detecting low voltage on UPS

texts:
Scraping together some parts, I managed to build a 22AH 12V battery pack, but I don't want to damage the batteries.

I am using 4x 12V 5.5AH UPS batteries wired in parallel.

I have an Arduino Uno, and don't want to spend money on additional equipment. Is there a way that I can use the Arduino to detect low voltage and kill the power?

I've done very little light current electronics, but have a basic understanding. First time working with Arduinos. I bought the Arduino for a different project, but if I can use it for this it would be great.


texts: Identifikation of components GTE PSA 18B

texts: Trying to idenify a device inside a kid's toy car. It is a two pin part with ca. 19 * 10 * 30 mm dimensions. It is located within one wire of three leading to the two motors of the car. UnfortuSeems to be a power device as it has two thick (3mm) copper rods as connectors. Wires are welded to them.


texts:
I am working on a project where i have to log data of many Analog and Digital sensors, GPS with lots of processing Algorithms. I am in a hunt to select a Microcontroller for my application.
My question : How do i know, how much processing speed do i require for my application.? as well as How much RAM do i need for it as well.?

anybody help.

thank you


texts: Kicad: Connect power to bidirectional pin

texts:
My design uses an IC with bi-directional I/O pins. For various reasons I need to connect GND to one of these pins, but Kicad warns about this:

  ErrType(4): Conflict problems between pins. Severity: warning
  * Pin 1 (Power output) of component #FLG032 is connected to
  * Pin 4 (Bidirectional) of component U1

I can override this warning globally in the ERC settings, but is there a better way to disable the warning for just this one pin?


texts: Is direct current really better for pumped-storage hydroelectricity facilities?

texts:
Currently the article equivalent to War of the Currents in Russian Wikipedia section says that direct current is beneficial to pumped-storage hydroelectricity plants and provides no reference to that claim. The English section makes no such claims.

I don't get it. A pumped-storage hydroelectricity plant is connected to the power grid and alternates two processes:

feeding water from the higher reservoir and using freed energy for generating electricity and feeding that energy into the grid (during peak consumption) and
consuming energy from the grid and using that energy to pump water to the higher reservoir (during off-peak consumption)

Both processes require passing lots of energy between the grid and the plant. The grids aroung the world use high-voltage AC most of the time.

Why would using direct current at a plant be beneficial?


texts: Microcontroller board with ethernet for computer sensors

texts:
I'm considering the possibility of using an ethernet-connected (SNMP would be a bonus) microcontroller board of some sort to monitor a RAID card inside a server that doesn't have OS support; the card has LED headers and an I2C header. So:

Which board? Arduino or something more specialised? I'd be OK with a through-hole kit but would prefer pre-assembled to save time; SMT or etching a board are right out.
Where should I mount the board? should I run wires through ventilation holes and have the board outside, or make up some sort of expansion slot mounting bracket and have the board physically inside? Being inside the server does give me access to +5V/+12V for power.


texts: Multiple poles triple throw switch or electronic equivalent

texts:
I have made several "programmer" boards for different MCUs (ATTiny85, ESP8266-1, etc.). They are pretty simple - there is a socket for the MCU, socket for the programmer interface (Arduino as ISP, FTDI, etc., depending on the case), headers for the MCU pins broken out and the proper connections between the MCU and the programmer. All this slapped on a protoboard.
It basically is this:

Converted into this:

They work fine and are pretty useful and handy, but there is a little problem. If I have something more "sensitive" that is to be connected to the GPIO pins (like a servo for example) I cannot simply use the GPIO breakout headers. Because it would be always connected, even during programming. Which would mean it would "see" all the signals sent from the programmer to the MCU during programming, since it is connected to the same pin. In some cases it could lead to unwanted and even destructible effects.
For now in such situations, I just have the circuit being prototyped somewhere else (usually on a breadboard), I take the MCU, put it into the programmer (with nothing else connected to it), program the MCU, take it out, put it on the circuit, power on, test, power off, repeat. It works, but it is tedious. Plus, all these chip removals and insertions may eventually damage the chip legs if not done carefully.
I hope my explanation is clear enough.
So, I am looking for a way to "redirect" the MCU pins to either the programmer, the circuit being prototyped or floating (as if the chip was removed).
For that I would need a device which acts like (or is) a multiple pole triple throw switch. So when I want to program the chip I flick the switch to "programming" position, program it, then switch to "neutral" to effectively power down the MCU and disconnect it from everywhere, then flick to "operational" mode where its pins are connected to the target circuit.
I tried to find such mechanical switches, but with no success. The ones that were remotely close to what I want were enormous in size and quite expensive.
Then I thought of doing it with multiple relays, controlled by a single SP3T switch. It could work, but would require quite a lot of relays and again - the size and cost of the "device" would be too big.
I looked into analogue (or bilateral) switch ICs and they look like almost what I want. The problems I have with them are two - they are double throw, not triple throw and they are not "ideal" switches - they have limitations for the voltage and current passing through them, and they add resistance and eventually crosstalk. I guess I could use 2 8PDT analog switches as one 8P3T switch and pretend they act like normal switches - after all, they will be switching low voltage and current GPIO pins, plus MCU's VCC and GND but it probably won't be a problem.
My question is - is there a better way? Like a device that is small, cheap and does exactly what I want - acts as or is a multi-pole-triple-throw switch? Either mechanical or electronic.


texts: Is it OK to drive a LED matrix with constant current?

texts:
I bought one of these LED matrix modules as described in this Adafruit PDF:
https://cdn-learn.adafruit.com/downloads/pdf/32x16-32x32-rgb-led-matrix.pdf

The PDF says "they do not have built in PWM control of any kind. Instead, you're supposed to redraw the screen over and over to 'manually' PWM the whole thing."

The information on Aliexpress, where I bought the module, says that the refresh rate is 400Hz and the power consumption is 1400W per square meter, which is 36W for my 160*160 cm module. At a scan rate of 1:32 this yields 0.28W per pixel and that's 56mA at 5V. Now I don't know if these RGB LEDs are driven at a constant 56mA (19mA per color) or if I'm supposed to manually create a duty cycle of 50% because the LEDs might be driven at 112mA, or if the duty cycle is created by the refresh rate.

The question is, if I turn one line on full white and do not manually PWM it, will it burn the LEDs? Or does the module itself maintain a 50% duty cycle at 112mA or 100% at 56mA which should be OK for RGB LEDs?


texts:
I'm trying to run a backup pump that will be actuated by a no flow condition from the primary pump. Everything is 12V DC. The flow switch can only handle 0.4A at 12V DC. The issue I'm running into is finding a solenoid that can be actuated with less than 0.4A that is affordable and reliable. I've only found a traditional mechanical solenoid which is actuated by 0.7A.

I've been told that the flow switch can activate a relay which in turn activates a solenoid.  How would I design a circuit like this?


texts:
Can I charge my bluetooth speaker with 12v adapter, if it says on him 12.5v?
Will it damage it or will it just charge slower?


texts: What's causing this ramp on a video signal?

texts:
See this image, it's a composite video signal on my scope.

As can be seen the dc offset of the signal is varying with time; it also varies with brightness in the scene.

I am plugging the signal from a composite video signal directly into my scope, however the cable is also spliced and goes to my computer's TV card. Without the TV card attached I do not see this. Now I would like to be able to debug my signal using the TV card, but it seems to be interfering (maybe it's loading the signal too much) - what could be causing this? I have another card I'm going to try but I'm not hopeful. Apart from buffering the signal using expensive video buffer amps, what can I try?


texts: Is there a proper way in VHDL/Verilog to access block RAM given a multi-hot vector?

texts:
I am currently trying to learn how to program in VHDL with the goal of implementing an LDPC decoder in hardware. My understanding is that log-likelihood ratios (LLRs) serve as inputs to the decoder.
Is there an efficient way of reading from RAM if, for example, I have 1) 8-bit LLRs stored in a block of RAM that is 16 addresses deep, and 2) a 16-bit vector where a 1 in position X denotes that I want to read from address X.
As an example, given the 16-bit vector "1010100000000000", I would like to read from addresses 0, 2, and 4 (assuming that the LSB is on the left). My first thought is to use a loop through the entire vector, which seems inefficient in terms of clock cycles. Is there a way to quickly read from those three addresses, either in quick succession or in parallel?