texts: Switching mode power supply for Power Line Communication

texts:
For a Powerline Communication device that uses the frequency band 42 to 89 kHz. I need to choose a power supply that will not add noise in the powerline and kill my communication band. There are two devices with certain current requirements; the first needs 1 A and the second needs 4 A.

I have looked at the available power supplies and tried adding a mains filter to suppress the EMC noise out of it (see figure below).

This will attenuate the communication signal as well, due to the Cx cap on the line (see figure below). So my best option at this point is to choose a better PSU to solve the problem.

I am looking for two designs or models of a switching mode power supply that will output 1 A or 3 A that has a high enough frequency that it harmonics will not interfere with the communication band between 42 to 89 kHz.


texts:
Hey, I'm trying to implement a 4bit ALU based on this 8bit alu design. The ALU has 8 different operations, given by an input of X Y Z

The 8 operations are

(edit: the last one is just A not, made a typo)

I'm pretty lost as to how to start on the abext. I've determined I need two muxes, one for A and one for B, encoded as either " 0 = Pass A/B, or 1 = Preform a logical operation". However, I'm totally lost as to how to implement each logical operation according to the input of XYZ. I tried to make a 2 input decoder that takes Y, Z and enables "and" gates that are paired with the output of the decoder and the output of each mux, all connected to an or, however that only gives me one output, and I need two.

I'm really just not sure how to create an ALU that demands these requirements, I've never made a normal 4 operation ALU, let alone one with 8 operations. What I'd really like is a a nudge in the right direction in the form of some components I might need to achieve the ia and ib output. Or an example of a similar ALU, as I haven't been able to find one on the internet, and my textbook does not explain the implementation of the abext.

I think for the A mux the selector is X, and for the B mux the selector is X or'd with inv Y. That's all I've tried. Really stuck, would appreciate some help.

(Progress Edit 1)
So with the help given below, I arrived at this solution to the abext schematic. Its a little messy, as I'm not the best at organizing these things, but it gets the job done!

http://i.imgur.com/vCTq724.png

What I've done is for input a, created a 4 to 1 mux paired with a 2 to 1 mux, the 4 to 1 mux has its selectors as Y and Z, and the 2 to 1 has it's selector as X. If x is low, we just take the raw input of a, otherwise we take a logical operation.

For b, we I used two 2 to 1 mux, the first mux takes the input b and b not, this is for addition and subtraction. It's selector is Z. The other mux takes the input of the first mux, and 0. If X' and Y' are both low, it takes the input of the first mux, otherwise it's 0.

Off to hopefully finish the rest of this thing!

(Progress edit 2)

And I'm finished! The rest of the design follows pretty much exactly to the diagram, but here's my implementation of the logic for CIN incase anyone is interested in that. http://i.imgur.com/bMLlhbn.png


texts: Is that a capacitor and how does it work?

texts:
I'm trying to understand how my (rfid?) travel card works. It looks like this:

I'd like to know if the two portions of wire shown at the end of the arrows are capacitors and, if it is the case, how does it/they work(s). Could it be for example charges that accumulate on the surface of the wire creating a capacitive effet?


texts:
I was reading in a book how to derive the equivalent circuits for TE, TM, TEM modes of a generic ideal (without losses) waveguide. After some computations, it found this equivalent circuit for TE modes:

It is written that for f > fc (cut - off frequency of the mode), this structure allows propagation because L1 dominates on L1, while for f < fc there is not propagation because C1 dominates on L1. It is shown in the following schemes:

First question: why should the circuit at left allow propagation, and that at right not?

Now let's consider the equivalent circuit for TEM mode:

It is written that it allows propagation at any frequency.

Second question: Why? From a circuital point of view, if f goes to infinity, L becomes open and C becomes short, so we should have 0 output voltage.


texts: Can single clamp measure total current from 3 wires?

texts: Single AC clamp can measure current flowing through a single wire in a non-invasive way. There are AVR/Arduino projects use such a clamp to measure house power usage. However, they use 3 clamps for 3 main wires that come into house breaker box. Unfortunately, I don't have access to separate wires in my breaker box. I can only access main power cable that comes to my house through the roof, and that cable has all the wires inside itself (is this a good assumption?) without possibility to separate them. If that is so, then the question is can I use a single clamp on that main cable for my own little power usage measurement AVR project, and if I can then is there some reason for it to be less reliable then 3 clamps solution?


texts: How to switch power of microcontroller by button?

texts:
I have a microcontroller device with battery power. Currently I toggle power by simple on/off switch. I want to toggle power by one pushbutton with minimal modification of the schematic (and microcontroller program probably) and with no consumption when device is off. How can I do it?

ADDED. I know following trick:

Here at start microcontroller sets PB3 to high and thus hold power for device. But this is not a solution for my problem, because I need also to off the device by pressing S1.

ADDED. Can I exclude VT2 from circuit (i.e. microcontroller drive base of VT1 directly)?


texts: Ideas for triangulation of a small object within 6 feet

texts: I'm looking to build a system that can detect the location of a tag within a 6 foot range to an accuracy of one or two inches. I have briefly looked into RFID sensors but I haven't found any that satisfy my needs. Does anybody have a suggestion?


texts: How to power Arduino Pro Mini via VCC pin (12v input)

texts: According to the Arduino Pro Mini spec it has Input Voltage of 5 - 12 V (5V model). Is it possible to input 12v by using any method other than usb? If so are there any downsides/limitations?


texts: Calculating transfer function of second order high pass filter

texts:
I'm struggling with calculating the transfer function H(s) of a highpass filter, calculating a transfer function of a first order filter is no problem but I haven't mastered second order filters yet.

I assume I should use KCL to do it as efficient as possible?

Best regards


texts: How to accurately measure electric motor torque?

texts:
I'm currently doing an experiment on an AC motor to measure the torque output from a servo drive using fishing line wrapped around the servo shaft / gear while the other end is connected to a luggage scale.

The shaft is connected to a gear of 1/2'' radius. The fishing line is wrapped around the gear and the other end of the line is attached to a luggage scale.  The motor is rated for 11 lb-in of continuous torque, corresponding to 22 lb-force for half-inch radius gear. However, I am not able measuring nearly that amount even at the maximum torque input current. My scale barely budges past 2lbs even at maximum torque (by applying the largest control input value). Any clues as to what I'm doing wrong? Thanks!

FYI I'm using an Applied Motion products Servo Drive model J0400-305.


texts: Half-Adder Digital Logic: Not as Expected

texts:
In a lab for an "Introduction to Electric Circuits" course, I built a simple Half-Adder circuit using an 74LS08 IC & 74LS86 IC. However, I'm experiencing issues with the output.

My input voltage supplied to Pin 14 on the 74LS86 IC was +5V and I verified that the output voltage (Pin 3 on the 74LS86) was +3.4V. The results from this IC were what I had expected; however, the output of the AND gate (Pin 3 on the 74LS08) was LOW when the two inputs were HIGH and was HIGH when the inputs were LOW. Below is the Truth Table for the 74LSO8 IC.

A   B   Y
0   0   1
0   1   0
1   0   0
1   1   0

And here is the Circuit Diagram

What would cause this behavior? As I understand, when the inputs are LOW the output should be LOW and when the inputs are HIGH the output should be HIGH.


texts: How to get a LDO voltage under 1.1V with lm1117 adj LDO?

texts:
I'd like to get voltage under 1.1v with lm1117-adj in 5v input.
The problem is that I don't know,  is this possible to get what I want the voltage under 1.1v?
update
This is what I've got exactly the same schematic.


texts: 2/4 Wire Conversion Circuit For UK Telephone

texts:
I am currently trying to build an op-amp circuit which allows seperation of send and recieve signals from the UK telephone line (or a simulation of the telephone line).

I am having difficulty understanding how certain values are calculated within the circuit.

The basic circuit is:

-Unity Gain stage from output from send

-Telephone impedance matching network

-Differential amplifier taking in signal before mixed onto the line and after mixing onto the line.

I need the diff amp output to be on a offset (as I am running it on single rail supplies).
The idea is that the output from the diff amp should be just the received signal (i.e. none of the transmit signal).

The major confusion comes from the level of the signals at each stage and how to adjust the component values to match this. I suppose really I don't understand how the line termination works and so therefore how to effectively remove the send signal from the transmit path.

Here is a circuit diagram of what I have currently built (if you right-click and open it in a new tab, it's possible to zoom in to view my component values):

Any help would be most appreciated!

Thanks

-- EDIT
Following the suggestions I have updated my circuit diagram. However the issue I now get is that the output ADC_IN does not contain any of my received signal (if I place a waveform generator on the other side of the line). I am assuming I have missed something....


texts: How to use the LEDs on Sainsmart protoshield

texts: I have an Arduino Uno with a top-plugged SainSmart proto shield. There are 2 LEDs on the proto shield, but I don't know how to make use of these LEDs in a sketch. Are they directly controllable out-of-the-box, or do I first need to solder the LED leads to analog/digital (not sure which) outputs on the proto shield to make them accessible? And how to use the "S1" button?


texts: Why does the relay in this touch circuit not work?

texts: Apologies for my lack of knowledge, I am trying to teach myself how to work with electronics and have put together this circuit. Can somebody tell me why the relay is not working?


texts: Okay, so I have this piezoelectric barbecue igniter so that I can make a remote igniter. The problem is that if I add a length of wire the spark becomes very small. Is there any way to make the spark travel further? If not could I use a spark plug or something and make a simple circuit with common electric components? (I have scrap circuit boards that contain big capacitors if that's any help) Thanks for the help.


texts:
Of the circuit I need to know the name of and what it is; my guess is, is it an AC to DC current converter? Is anyone able to confirm or deny?

What does it act as when its all formed together? (Once again my assumption is up there.)


texts: Control stepper motor with low current and high current

texts:
I am learning about stepper motors and i have the following question. Let's say i have a bipolar, 2 phases, NEMA34 with a 5A rated current. I am using a driver capable of delivering 5Amps or 2Amps at a voltage between 24-80V. How will affect these different current values the behaviour of my stepper motor?
First i set the current limit to 5A and then to 2A. In conclusion, how does adjusting the current limit of my driver affect the stepper motor?


texts: I have a schematic and there's this symbol I don't understand. I tried reading list of circuit symbols but couldn't find a match.


texts:
I am working on a IOT application and I want to control a switch as per two way wiring using SSR.

I have made it with Relay which is having two NO NC contact but I wonder how will it possible with SSR.

Two way wiring diagram is as follows.

With SSR I can't have this

Any help would  be appreciated

Thanks in advance


texts: Questions about a wiring diagram of a transducer

texts:
I have an old current output wind-meter with the following diagram:

Unfortunately there is no online documentation about the device so I had to take the above photo.

I'm curious what could be the the parallel vertical symbols around at some junctions as shown in the upper red question mark?
The gn(green) and br(brown) wires seem to already be connected to each other inside the transducer. What could be the reason they are showing a connection needed outside of the transducer as in the bottom red question mark?


texts: How is this 50Hz noise coupled to the sensor and why does it disappear when wired in a particular way?

texts:
I'm using this amplifier with this load cell.

There is a section in the amplifier's manual which states:

First of all above terminal 5 in the amplifier's screw terminal which is called Screen/Ground is not internally connected to supply GND or output signal GND ect.

The load cell on the other hand has many wires to be connected to this amplifier One of the wire is connected to the load celløs metalic surface. Lets cal this wire load cell screen LC_S.

When I connect the load cell to this amplifier properly I have the follwing observation:

If I connect the load cell's screen wire LC_S to terminal 5 of the amplifier, the noise is typical.

But if I do not connect the load cell's screen wire LC_S to terminal 5 of the amplifier, there is 50Hz noise added(observed at the amplifier's output) which is bigger than the typical noise.

Why does this 50Hz noise disappears when I connect the metallic surface of the load cell to the amplifier's screen terminal? I don't get this because this connection do not have any eventual connection to the earth. The load cell is floating and the terminal 5 is not wired to anything(I checked with continuity test). Im really curios what makes this noise to disappear.


texts: Circuit simulator with microphone support

texts:
I am working with a circuit that consists of a condenser microphone. The circuit will filter through all sound signals except very sharp high pitch sound. But I cannot find any circuit simulator that has microphone component. I have tried CircuitLogix, QUCS, LTspice etc.

I understand that sound signals may be simulated but it would be great if this simulated component could get signals from microphone in my computer. Is there any simulator like this?


texts:
I am connecting digital output from a camera to a light source using a relay (see below).

The relay uses SONGLE SRD-5VDC-SL-C Optocoupler:

RELAY DATASHEET

The camera manual says "Uses an open-drain NFET transistor with the source connected to GND in camera. If used
with an external relay, a diode must be connected in parallel with the load for protection
against voltage transients. Max loading is 100 mA."

It seems to me there would be little possibility of transient voltage.  I am seeking advise if the TVS or Flywheel diode is really necessary?


texts:
I have been having some good success with my first PID controller. It seems it needs just a little bit more work. Below is a picture of a sample run with my controller implemented. Currently I only have the proportional term correcting the signal and I am just graphing the integral term to see where is lies. My first question is, does the integral line seem to be "right"? It doesn't seem to be related to the other values in the way I would think. Mind you this is my first experience with closed loop controls, so I guess I probably shouldn't know what it should look like.

Legend:

Red - Commanded value (psi; this is the command prior to the correction)
Purple - Actual Value (psi; this is the actual output with only the proportional correction)
Yellow - Proportional correction (This value is added to the commanded value to produce the actual value)
Orange - Integral correction (This is simply being graphed to see where it would lie)

It just seems that the drop-off in the middle of the graph of the integral term is just random. I think it might have to do with a overflow condition with an Integer I am using, but then again I'm pretty sure the value should shoot to +-INF if thats the case.

Also, where the integral term is about constant (on the left side), should it not be around zero instead of 25? Because at those points in the graph (again on the left) the commanded and actual values are almost the same, why would the integral term command more to the signal if the signal is already where is should be?

The one other thing to mind is also, I only have the proportional term correcting. I have not added the integral term into the correction. This might effect how this graph would look, though I do not want to put the correction in and have the system react badly, thus why I am graphing it first and asking questions!


texts: PIC32MX470F512L not appearing on harmony setup?

texts:
I installed Harmony plugin in MPLAB X IDE because i can't put this pic working with MCC.

I was going to do a new project for this pic and when i was going to select it, it doesn't appear on the list! anyone with this problem?

Using:
-MPLAB Harmony Configurator 3 (v3.3.0.1)

-MPLAB X IDE v5.05


texts: Python serial between Arduino and Raspberry Pi: Data is modified upon reception

texts:
I'm using an Arduino for sensor readings and sending them to a Raspberry Pi via USB, using PySerial for data reception.

It works great, except for the fact received data is awkwardly modified (And set as constant). For example, I'm reading voltages and calculating currents. The results on the Arduino serial are as follows:

Volt   Current
4.93   0.38
4.92   0.37
4.92   0.37
4.92   0.36
...    ...

However, on the Raspberry Pi, it's constantly read as follows (Notice how the digits are changed to zero):

  Volt   Current
    4.99   0.30
    4.99   0.30
    4.99   0.30
    4.99   0.30
    ...    ...

I've tried several turnarounds, but with no luck. I'm not sure where the problem lies, as I am very confident my code is flawless. I even converted the readings to string before sending and yet the constant readings and zero'd digits keep appearing. I appended a counter integer which was sent correctly with no problems.

Has anyone ever tried this before? Any thoughts on how to solve this?

Raspberry Pi Code:

from time import gmtime, strftime
import time
import serial
import struct
ser = serial.Serial('/dev/ttyACM1', 19200)
f = open('results.txt','w')

while 1:
        temp=strftime("%Y-%m-%d %H:%M:%S", gmtime())+'\t'+ser.readline()
        print(temp)
        f.write(temp)
        f.close()
        f = open('results.txt','a')
        time.sleep(5)

Arduino Code:

...

  double volt = 5.0*(analogRead(A0))/1023.0;

  double current = 5.18 - temp;   //Resistance ~= 1 Ohm if you are wondering

  buffer += d2s(volt,2)+'\t'+d2s(current,2)+'\t'+ d2s(count,0) +'\t' + d2s(minCount,0);

  Serial.println(buffer);

...

//I got this from the web

String d2s(double input,int decimalPlaces){

  String string;

  if(decimalPlaces!=0){
    string = String((int)(input*pow(10,decimalPlaces)));

       if(abs(input)<1){
          if(input>0)
              string = "0"+string;
          else if(input<0)
              string = string.substring(0,1)+"0"+string.substring(1);
  }

  return string.substring(0,string.length()-
decimalPlaces)+"."+string.substring(string.length()-decimalPlaces);
}

   else {
     return String((int)input);

}
}


texts: What is the difference between a transformer and a coupled inductor?

texts:
Transformers and coupled inductors seem very similar. Is there a difference in construction? Or only in use?

This question asks something similar, but the answers don't address my question:
Coupled inductor vs an actual transformer?


texts:
I'm trying to interface the TLV5606 with an mbed via SPI.

The connections I've made are as follows:

Note: mbed is powered from same 5V supply.

I modified the mbed SPI helloworld prorgam:

    #include "mbed.h"

SPI spi(p5, p6, p7); // mosi, miso, sclk
DigitalOut fs(p8);

int main() {
    fs = 0;

    uint16_t fixed = 0x4000;
    uint16_t value = 1024;

    value = value - 1 << 2;
    uint16_t final = fixed | value;

    spi.format(16,1);
    spi.frequency(1000000);

    fs = 1;

    fs = 0;

    spi.write(final);

    fs = 1;

}

The first 4 bits (from the left) should be 0100, and the last 2 bit, 00. The 10-bit value goes in between. This is explained in the datasheet (http://www.tij.co.jp/jp/lit/ds/symlink/tlv5606.pdf).

I've used the bit pattern 0x4000, and XOR'd it with the 10-bit value, which is shifted by two. This should result in a bit pattern accepted by the DAC.

At first, OUT, as measured by the voltmeter is around 9mv (usually -9mv). After between 5 and 20 seconds (approx), the voltage spikes to around 1.6v, and once 3.3v. With a value of 1024, you would expect a value close to 3.3v (the reference). On occasion, the 1.6v spikes up to around 3.3v after a few minutes. Also, after having risen to 1.6v or 3.3v, the voltage will often drop back down to 9mv after some time.

I should mention that I haven't used a capacitor in this circuit, although I don't think it's necessary to test the basic functionality.

Any thoughts on what's going wrong?


texts: DQ Currents in the Induction Motor Model

texts: While studying the Induction Motor modelling and also its Vector control using DQ currents decoupling method.. I am finding it hard to see which current is which on the model diagrams. Can anyone point out which currents in the model circuits are Iq and Id?]2


texts: Is it possible to solve for the resistance of R3 in this question, without knowing the total current of the circuit beforehand?

texts: P.S. I'm not asking for the actual answer, I just need to know how to, so clues or reminders regarding the fundamentals would be fine by me


texts:
I have an older working aircon with a broken control-board.  Replacing the control-board is not worth the cost for this older unit.  I am attempting to wire it as a simple "on/off" fashion.

Where I am stuck, is with the fan-wiring.  The fan model name is "YDK 16-4".  I have googled and found many different fans, and even my question on this specific fan-model, but no clear answer has to how to hook it directly to 220V power, either with/without additional components, so it will run continuously.

The wiring-diagram on the side of the fan-motor is:

The wires coming from the fan-motor are 2 groups of 3 here:

The wiring-diagram for the control-unit is this:

My assumption is that - on the brown/black/yellow wire-set, I should connect Brown and Black to each leg of 220V and YW to Ground - direct with no additional components.  Please correct me if this is incorrect.

But on the other set of 3 white/black/red wires, it appears I need to put a 1.2uF external capacitor inline (referencing the fan and controller-unit diagrams), but I am lost as to which wire(s) should be connected to what in those 3.

High-speed is necessary, but the ability to switch to other speeds would be a plus.

Thank you for any guidance - I really don't want to burn this motor out playing trial-and-error.

Later Edit:

@Drew - Note on the Control Unit diagram there are 2 outputs to the fan.  The larger one is Bk, Wh, Rd - which would be the one labeled "CNU" on that diagram - assuming the sizes of the plugs corresponds to that diagram's appearence.

That diagram shows the capacitor (found on both diagrams) as well as "STR" on that "CNU" output - and I think "STR" is the same "thing" as the symbol next to the white wire connection ("WH") on the fan-diagram.  I don't know what "STR" is, or recognize that symbol, though the diagonal line would indicate "variable" or "disconnect" - guessing.

The Control Unit diagram does not show the colors of the wires, so I am not sure of this.  The actual order has the white-wire in the middle - not corresponding to the mystery-symbol on the Control Unit diagram, which is connected to a wire on an end of the connector.


texts: Sawtooth Wave Fourier Series - General derivation and Matlab issue

texts:
I am working on one of my first Matlab projects. I am trying to graph a sawtooth wave with 10-V Pk-Pk, 0-V average value. 50% duty cycle, 2.5 khz.

I first attempted to find a general equation for such a sawtooth wave.

$$\frac{-V_{pp}}{2} + \frac{jV_{pp}}{2\pi} \sum_{n=-\infty}^{\infty} \frac{1}{n}e^{jnw_0t}$$

From this, for the particular function I am trying to plot I have the equation

-5 + j*5/pi Sum (from n=-inf to inf) (1/n)e(j*5000*pint)
$$\ -5 + \frac{j5}{\pi} \sum_{n=-\infty}^{\infty} \frac{1}{n}e^{j5000\pi nt}$$

And my code:

%% SAWTOOTH WAVE

t = linspace(-2,10,1e4); % time vector [s]

%% constructing approximation x_N(t), N = 100

n = -100:100;                            % indices included in the summation, n is a 101 element vector
X = (5*1i)./(pi*n);                          % this constructs the coefficients of e^(*) terms
X(n==0) = 5;                             % C_0

% X is a horizontal vector with the coefficients of the exponential term
% corresponding each n-value from -100 to 100.

XM = repmat(X.',[1, length(t)]);         % This is a matrix that replicates the transpose of the
                                         % vector X as many times as t is long
                                         % now, XM is a matrix with identical values in each row.
% Each column has a coefficient of an exponential term corresponding to an
% n-value, repeated throughout
basis = exp(1i*pi*5000*n.'*t);              % basis is a matrix containing the exponential part,
                                         % each column corresponding with each n-value
                                         % and each row corresponding time

x100 = -5 + sum(XM.*basis);                   % x100 is matrix resulting from summing down the rows of element-wise
                                         % multiplacation of XM and basis

if max(imag(x100))<1e-15  % this checks to see if the imaginary part of x
x100 = real(x100);      % is below Matlab's noise floor (approx 10^-15).
end                     % If so, we get rid of the imaginary part.

%% plots

% we will use these variables to keep the limits on our plots uniform
tmin = min(t); tmax = max(t); xmin = -6; xmax = 6;

figure(1);
%subplot(3,1,1);     % this command allows you to plot several graphs
%                    % on one page
plot(t,x100);
axis([tmin tmax xmin xmax]);    % sets the plot's axis limits
title('N=100 approximation of Triangle Wave');
xlabel('time [s]'); ylabel('amplitude [a.u.]');

However the period here is 2 seconds, which seems totally wrong to me. I'm having trouble figuring out where I went wrong.

Also - I apologize, I am also having trouble getting MathJax to preview my math on my browser, I don't know what's wrong there. I am sorry for the messy looking representation of my math.


texts:
I would like to power a device via the 5V USB port on a computer, because I will also be communicating with the computer via the USB data cables.

I know that USB ports provide 5V, but from what I've read here.

USB 1.0, 2.0, and 3.0 all give variable amperage outputs. The device is supposed to negotiate with to computer to ask for more amperage, and the default is set at 100 mA.

I would like my circuit to run on 10 mA. I understand the relationship between amperage and voltage. (I.E. Ohm's Law)

Using:
$$ R = \frac{5V}{0.01A} = 500\Omega. $$

Perhaps I'm having difficulty understanding the concept, but does this mean I will receive 10 mA regardless of how much is flowing out of the USB port?


texts: What is the importance of using asynchronous reset instead of synchronous reset?

texts:
I have a simple Verilog module with only one synchronously reset DFF:

module scratch (input clk, reset_n, serial,
                output reg serial_ff);

   always @ (posedge clk) begin
      if (!reset_n) begin
         serial_ff <= 1'b0;
      end
      else begin
         serial_ff <= serial;
      end
   end

endmodule // scratch

When running a lint check (hal 06.20-s004) on my design for ASIC, I get the following warning in the DFT category:

*W,FFWASR (./scratch.v,9|0): Flip-flop 'serial_ff' does not have any asynchronous
set or reset.
------
Flip-flops must have asynchronous set or reset. If a flip-flop
does not have any asynchronous set or reset then it is not
controllable from primary inputs.

The following example illustrates this problem:

if(rst)
port_a <= '0';
elsif rising_edge(clk) then
port_a <= var_a;
port_b <= var_b;
end if;

In the above HDL code, the value of 'port_a' can be
brought to '0' using asynchronous reset 'rst', while
this is not the case with 'port_b'. This may cause
issues during simulation.

I am already using a synchronous reset for the FF, so it is getting initialized. But the warning tells me to use an asynchronous reset instead. But why is this important for testing? What sort of failures can this DFT methodology (asynchronous R instead of synchronous R) identify?

In short, when should I care, and when is it okay to ignore the warning?

Update: I found a parameter mentioned in passing in the documentation: "setreset_type". I grepped the entire doc set and it appears its undocumented. So I guess Cadence REALLY wants everyone to use async resets religiously. But the truth is that resets shouldn't be implemented religiously, but that the designer should consider the trade-offs and design requirements for any type of reset. This is the resounding conclusion of the answers so far, so you all get points for being helpful! I will update if I can find how to use that undocumented parameter. That was the only possible setting I could find after digging through all related documents. For now, I ignore the warning since we already have considered the design of the reset from the system architecture level.


texts: Clean DC power supply from a dirty souce

texts:
I'm building a guitar pedal which uses a series of relays to switch various signals. The relays are currently being powered by a cheap 5V switchmode supply and the audio path is inducting high frequency noise (109Khz) which I assume is from the power supply.

I cant do anything about the power supply - it will always be a switchmode wart though what should I do about replacing this noise? Will an electrolytic + voltage reg filter the noise?


texts:
Many times when we design a PCB we might get stuck with PCB board real estate shortages. Of course we can overcome it many times by increasing the number of layers, subsequently making it more complex and expensive.

But, a few times the size of the components and the board size availability is just not balanced. For example, I have a board of 10x10 (centimeters).

I calculated the area occupied by all the components (including passives) and I come up with a number. The available area is 100 cm2. What should be an ideal total component size (total area of all components)? Is there a rule of thumb as such to get away with?

Like if the total component size area is 'x' then a minimal of 15-20% extra board space is required more or so. This argument would be helpful in tackling customers who keep asking for smaller PCBs to fit their enclosures.

I understand that this could be very vague, but I would appreciate any points you can kindly share please.


texts: Why is my H-Bridge driver coupling low input into the high side?

texts:
I have struggling for about a week with this problem and I am not sure how to fix it , so stack exchange community please help :).

Ok so basically I am making a h-bridge using 4-N channel mosfets, and in order to drive the high side I am using IRS2001 High and Low side drivers.

Here is my schematic :

Larger pic : http://i.stack.imgur.com/ayE0L.png

Here is an updated schematic of how my signals are inputted :

Larger pic : http://i.stack.imgur.com/EkNCB.png

I am using a 5kHz PWM signal to switch on for about 0.5secs and then turn off the mosfets to drive the motor in one direction and vice versa for the other direction.

The motor seems fine but when I probe the input and out of the gate driver I see problems.

The low output seems to couple with the high side output even though the high input signal is clean as shown in the oscilloscope output below.

Another question i have is what are the best capacitors to be using for this mosfet driver, at the moment i am using an electrolytic type capacitor around 10uF, is this applicable?

The green signal is the HO  ( high output signal)
The yellow signal is the HIN ( high input signal)

The blue signal is the LIN( low in signal)

Here is where I am probing

So my question really is , why is this happening and how can I solve this ? Thanks


texts:
I'm hoping to try to control the rpm of a DC motor. AFAIK, I'd need to generate PWM for that. How does one find out which frequency is needed for a certain rpm? Is the frequency of the PWM signal supposed to be related to the speed of the motor?

Thanks


texts: 'Corroded' / White Spots / Dots Appearing on Rubber Side of Components & Cable?

texts:
I'm trying to refurbish a second hand +3 year old monitor speakers and noticed that there are lots of white spots / dots growing out from the rubber wrap on the speaker's inside cable & component. It feels rough to touch, and this white spots appear to only appear on specific components' shielding & cable wrap that seems to be made by the same rubber material.

The speaker works fine, but should I be concerned that this will affect other components in the future? Should I try to clean in by sanding it lightly?

Could this simply be a manufacturing defect on the rubber wrap or are there something else going on inside with my speaker unit?


texts: Why base emitter voltage (Vbe) of BJT is not showing as 0.7v in proteus simulation?

texts:
I was just trying to simulate a simple transistor circuit as common emitter in Proteus 8. However the I observe that the base-emitter voltage (Vbe) of the transistor 2N2222 is showing as 1.36v instead of 0.7v. This is a huge difference. Is there anything wrong with the attached circuit? Also Vce is 2.82v and I am not sure whether it is in saturation or not.

Below the the text script of the transistor model.

{*DEVICE}
NAME=2N2222
PREFIX=Q
{*PROPDEFS}
MODEL=LISA Model,STRING
PACKAGE=PCB Package,PACKAGE,0
PRIMITIVE=Primitive Type,HIDDEN STRING
{*INDEX}
{CAT=Transistors}
{SUBCAT=Bipolar}
{DESC=Silicon NPN Low Power High Frequency Bipolar Transistor (500mW, 200ºC)}
{*COMPONENT}
{PRIMITIVE=ANALOGUE,NPN}
{MODEL=LX_NPN_SSHF,BIPOLAR}
{PACKAGE=TO18}

UPDATE:

I tried using different transistors and found that this behavior occurs for transistors of LISA model. It is found working fine for transistors of SPICE model e.g. 2N222A, PN2222, BC548C etc. But still why LISA model does not give 0.7v for Vbe?


texts:
I need some input on implementation of a high-speed (>100Mbps) wireless digital communication design.
The part which concerns me is from the data input to the RF PA, we got a guy working one the project, who is an analog RF expert, so he can build the PA.

I was thinking about something like this (shown for the TX):

data -> FPGA -> DAC -> I/Q Modulator -> PA -> ANT

But are there some standard available chipset for doing this?

Or some document describing an example design?

And is I/Q modulation a good way to go?


texts: ARM Processor or FPGA to video signal processing?

texts:
I want to design a PCB where a video camera will take images and they will be shown in a display HD. So I have several questions in order to achieve it: I would like to know what is the best option for video signal processing, use a FPGA or a ARM processor? In the case that I use a ARM processor, I will have to install in the processor an OS like Linux? and how I load the firmware in this processor?
Thanks in advance Regards
 Javi


texts: Is the following Wikipedia statement true?

texts:
Only nine types of element (memristor not included), five passive and four active, are required to model any electrical component or circuit

From the Wikipedia "Electrical Element" article.

Is this statement correct?


texts:
I tried to make a basic R2R digital to analog converter in a simulator.
Even with all bits set, I get an output of 4.98V rather than the 5V I would expect. I expected 5V since so many online resources say things like the output "ranging from 0 to 5V", so I may be (mistakenly) assuming that all bits set = 5V. However it makes sense to me that you'd want the output from a DAC to range from 0 to 5V exactly so you won't have to care about how many bits the thing supports, only knowing that 0 = min and 5V = max supported.

Where have I erred?
Edit: Furthermore, I assume I've erred because when I try to copy the same number as shown in the video (172, or 10101100), I don't get 3.4V but rather 4.884V:
Video's image:

My result:


texts: Little doubt about amplifier current requirement and THD + N

texts:
So for this amplifier IC - PAM8403 - which is a 3W + 3W class d, what is the current requirement or in other terms, what will be the load current. I know since this is an audio amplifier, load current is not always fixed. But as a generalization, what will be the value.
I was planning to use a 3.7V 2600mAh cell to power it, through a 5V regulator. I doubt that it is 0.6A per channel. For other ratio of voltage and power, the result is not the same.

Just want to know how long that cell can power this amp.

In datasheets, different values for power based on different values of voltages are listed. That is understandable but for the same voltage and load, they also put forth that if THD + N is 1%, power will be different and if THD + N is 10%, power output is little more than the former, even though the voltage supplied and the connected load is same.

Is there a particular way to select/switch an appropriate Total harmonic Distortion + Noise figure, while designing?

Thanks.

EDIT - The speaker driver is rated at 4 ohm.


texts: Understanding power rating of switches at 5V

texts:
I have a hard time selecting a switch for my 5V project (somewhat of a newbie to the field). I would like to power a LED strip that consumes up to 1.2A at 5V. A typical load is usually lower at about 600mA at 5V.

I have come across some nice switches such as this one. Which states that it supports 0.4VA maximum @ 28V AC/DC maximum.

What does that mean for my use-case? How can I convert such ratings to 5V?


texts: Is it safe to hook up a device with a higher voltage battery through a regulator like this?

texts:
So using a 6v 26 Ah battery and a 5v regulator, am I safe to hook it up to a 5v by 2.5 A max power draw device? I think so, I'm still get familiar with EE concepts though. What complications could arise? What is efficiency like on regulators, I know they heat up, so the must lose power.

[from the O.P.'s comment] The regulator in questions is MC7805.


texts: How to pass a signal from one module to another using dot operator in verilog

texts:
I have got a memory module which consists of a memory

module memory(clk,rst,addr,data,wrt,rd);
reg [7:0] mem [254:0];

I am using this memory module in the execute module and I want to use the memory without replicating it again in the execute module.

module execute(decoded_instr,clk,rst,instr_in);
if(instr_in[3:2] == 2'b00)
      PR = mem[AR];
    else if(instr_in[3:2] == 2'b01)
      DR = mem[AR];
    else if(instr_in[3:2] == 2'b10)
      GR = mem[AR];

One method is to copy the content pointed by the register AR into a temp register in the memory module and use this temp register in the execute module like

temp_AR <= mem[AR];

and tie temp_AR in the execute module and use temp_AR like

      PR = temp_AR;

My question is, is there a way to perform the same operation using dot operator and access the memory?

Thanks in advance


texts: can i be host usb without OTG and USB-A on stm32

texts:
Okay, hello everyone !

I'm a little bit confused with USB possibility and stm32 MCU !

I have a stm32l433rb and it has just an usb full speed (device) capabilities. In the other hand, on my hardware, I wanted to add a USB typeA connector.

So I'm not OTG, so can my STM32 can be host anyway to read some data from an usb key plug on the USB-A ? Or I can just be device ? In the guideline for hardware implementation : http://comm.eefocus.com/media/download/index/id-1010928, they show me how to implement a downstream line without OTG, so in this mode, i'm host, and I read data from a device but ... i don't understand how to do this without OTG ?

And If I use the stm32l475RC, with an OTG port, I think I can force the MCU to be host with a USB type A connector (put ID pin to ground no ?) so I can read a usb key but if I want to transfer data from my MCU to a PC, can I be seen like a device or my pin ID put to ground will block this ? (maybe a host can talk to a host ... ?).

Thanks for reading !


texts: If i lower voltage drawn from a battery will it last longer?

texts: I have a water pump that operates between 5-12v at 3amps. At 5v the water flows slower and at 12v it flows fast. If I have it connected to a 12v battery and use a step down converter to convert the voltage to 6-8v, will it draw less amps from the battery and be able to run longer?


texts: Spartan-6 input data: Use data pins or GCLK?

texts:
I am designing a PCB which connects to a Spartan-6 via a connector (Opal Kelly XEM board). The PCB hosts some analog components which will communicate with the FPGA (ADCs, DACs). The FPGA board itself is completely autonomous (has own clock, PLL, ...).

My input signals to the FPGA are:

SPI signals (MISO/MOSI/SCK) from different ICs
LVDS data from the ADCs (serial data) + skew matched clock to latch these data at the FPGA
CMOS clock signal which may be used to clock the FPGA itself or synchronize certain signals on the FPGA (maybe not used but just in case).

Currently I connected all these inputs to the FPGA data pins (e.g. L32P_0, L2N_0 and L3N_0/L3P_0, L66P_0, L66N_0 etc.)

Now I am wondering if I should connect some or all of these signals to the global clock network (GCLK), e.g. L34P_GCLK19_0, L34N_GCLK18_0, etc).

Is it a good idea to connect any input that is/can be a clock (will be used in always @(posedge) to GCLK?
How would I decide which signals I connect to the data pins vs. GCLK?
What is the purpose of the global clock network (GCLK pins) and what are the advantages/disadvantages?
Can the GCLK pins also be safely used as LVDS input (e.g. L36P_GCLK15_0 and L36N_GCLK14_0)?


texts: Calculating power absorbed by each element

texts:
I have this question:

I'm sure that I am doing something stupid here as it is not difficult. I get some weird answers. I start by calculating the voltage drop across the resistor which should be:

V = IR = 2A * 5ohms = 10V

Total power = VI = 6*2 = 12W

Power absorbed in R1 would then be I^2 * R = 50W

Now why does the voltage drop not equal the source voltage according to KVL? The only reason that I try to calculate it in the first place is because I assume that, due to the question, that there will be a voltage drop across the current source.

Also, why is my power calculation way off? Obviously the power dissipated in one element won't be greater than the power supplied. Help with the power delivered/absorbed in the other two elements would also be great.

Any help would be really appreciated. This is a practice exam paper not homework.


texts: Converting int to float and vice-versa in HDL

texts:
I am trying to write an HDL code for converting floating point numbers in IEEE-754 format to integers and vice-versa. For eg.

    for floatToInt operation:
    input = 8.9 (in IEEE-754 format)
    output = 9  (an integer number)

    for intToFloat operation:
    input = 10 (an integer number)
    output = 10.00 (in IEEE-754 format)

In my code, I also need to take care of all the exceptions that might be generated while doing this. Please explain or point me to a good article which exhaustively explains the general procedure/algorithm to do so. I would be very obliged. Thanks in advance.


texts:
I need to clear out my doubts regarding my Home Automation project.
I am working on project based on IoT Home Automation project. There are three entities in this project:

Web Server
Embedded Client
Android App

Android App will send data to Web server to ON/OFF switch on Embedded Client. Server Receive data and decide to send to which client. Server send data to appropriate client and get feedback and send back to the Android APP.

Multiple Embedded Client can be controlled by Single Application.

Now I have decided to use the Websocket Protocol, As using WS I can make server-Client communication realtime and Avoid polling/Long polling.

But as I have studied about WS more, I found it is not secure and easy to hack.
Please guide me which technology should I use for this project, and what should be server and client requirements to fulfill the objective of the project.


texts: High Voltage Non-Standard Common Mode POE

texts:
What is a quick and dirty circuit for implementing midspan power over ethernet?

I would like to operate over two unshielded twisted pairs, at 100 Mbps using common mode injection. Essentially, I want to implement 802.3 mode A PoE that is non-standard in a few ways:

To transmit more power I want to increase the common mode voltage as high as I can without frying the (non PoE) ports on the devices I'm connecting
I can do without the handshaking and polarity detection that are part of standard, and would omit them for simplicity
To reduce the diameter of the cable, the unused two pairs of conductors will be removed

Most of the circuits that I have seen are doing the power injection at the endpoints of the link, pulling from the center tap of the ethernet isolating transformers.

Can I just wire up two more ethernet connectors in parallel at both ends of the link and pull from the center taps of the transformers in those, or will that screw up the signaling? Do I need extra filtering between the transformers and the DC/DC converters?


texts: Safety when working with CD burner laser

texts: What kind of safety precautions should I take when working with a laser I've taken out of an old CD-RW burn drive? I'm making a small laser writer/printer to write on wood. Should I wear glasses? Encapsulate the laser somehow? I don't know the strength yet of the laser, but it's from a standard CD-RW drive.


texts: Difference between 'high in vhdl and $high in verilog

texts: Is there any difference between 'high in vhdl  and $high in verilog??


texts:
I want to control voltage on the motor (R1) by microcontroller output (Vin).  The problem is that maximum output of the microcontroller is only 2V, while I want voltages on motor up to 12 V.  So I decided to make a voltage divider (1:10) to scale down the voltage on the motor before putting it on the opamp.

However, the results are quite unsatisfactory.  I have measured voltage Vin and voltage on R4 and they are quite off.  Here is the list (V4a for no motor and V4b for motor)
Vin   V4a   V4b
0.00  0.01  0.04
0.10  0.13  0.07
0.20  0.24  0.11
0.30  0.40  0.15
0.40  0.51  0.18
0.50  0.61  0.58
0.61  0.70  0.66
0.71  0.78  0.77
0.81  0.86  0.86
0.91  0.92  0.95
1.01  0.99  1.04
1.11  1.05  1.13
1.21  1.11  1.22

Is opamp faulty or is there something wrong with the circuit?  (I've tested two opamps with the similarly bad result.)
VDD = 16V.
EDIT: following the suggestions from others I have checked the voltage on the load.  Below is the oscilloscope picture for a load of 1 kOhm.  There is huge variation of voltages between 9V and 15V with frequency of 100kHz.  Interestingly, using smaller resistor (40 Ohm bulb) the variation gets smaller, between 11V and 13V.


texts: Analog to Digital convertor using capacitor

texts:
I found out that I can use a capacitor in order to get the data from an analog sensor in a digital manner(Connecting the analog sensor to the GPIO of a Raspberry Pi).

I have a 1μF polarised capacitor. Is it suitable? How should I connect it in order to work?

The sensor I'm talking about is the below push sensor.

Is it ok to connect GND to GND, VCC to 3.3V Power and the capacitor with the positive branch to OUT and with negative to the GPIO pin?

Here is the datasheet of the sensor: http://www.robofun.ro/docs/2010-10-26-DataSheet-FSR400-Layout2.pdf

Thank you!


texts:
I'm building my first CNC machine, it's a 40W Laser Cutter.
I'm planning on adding a security feature that cuts the laser power supply if the enclosure door is open during while operating.

I want to use this Solid State Relay
I want to use a simple mechanical switch like this and just wanted to see if you think it would be a terrible idea for any reason. I would send 5v to the switch and then to the relay. When the door is closed, the relay would get the 5v and allow electricity to go to the laser. If the door is open, it would kill it.

Thanks in advance.


texts: Net type, variable type, data type and data objects

texts:
I am really confused by the conception of net type, variable type, data type and data objects in SystemVerilog. I am using the simulator inside Xilinx Vivado 2018.02 for all the following codes.

logic in SystemVerilog can partially substitute the role of wire in Verilog. Say I have the following code within a module

logic q_bar;
logic q;
assign q_bar = ~q;
always_ff @(posedge clk or negedge rst) begin
    if(!rst)
        q <= 1'b0;
    else
        q <= q_bar;
end

Does the compiler infer a net type for q_bar since we assigned it? q is of variable type since its assignment is in a procedural block.
Another example:

typedef logic [7:0] mem_t[3:0][3:0];
typedef wire [7:0] byte_wire_t;

The first line is legal, but the simulator complains about the second one: "SystemVerilog keyword wire used in incorrect text". But the grammar of typedef is

typedef data_type type_identifier { variable_dimension } ;
| typedef [ enum | struct | union | class | interface class ] type_identifier ;
...

Isn't wire a data type? Is net type a data type?


texts: Tachometer air core meter - how does it operate?

texts:
This is a question from a total noob, out of pure curiosity.
I've been tinkering with my bike's instrument panel and took it apart -
I found out that this sin-cos marking is the base of the air core gauge.
I've seen the wiki explanation on how it works, sin current and cos current give a certain trigonometric value and swoop the needle to that position.
What I don't get it how the signal is measured.
I looked at the diagram, found the wire that goes from cluster connector to the ECU, and measured with voltmeter with bike running. It gave about 8.5V but it would jump to 9V with a bit of throttle applied.
Is this the correct way to interpret how it works, it gets voltage from ECU to the coil? How does it separate cos and sin signal to get the needle angle?
Some tutorials online suggest that the only right way to test the meter is with multimeter + peak voltage adapter.


texts: when applying net voltage to my device and converting the AC to DC, what type of protection should my circuit have? I've already thought of overcurrent and reverse polarity, because I'm going to be hooking up the device to a battery. Any tips?


texts: Check my automotive solid-state power switch schematic for mistakes

texts:
I've spent a lot of time designing a simple circuit for my car. Here's what it does: it has 2 inputs, and whenever one of them is triggered, the output switch is shorted, connecting power supply to some load. So it's a switch with 2 inputs that implement logical OR. Now, here's the trick:

input 1 is connected to the ignition key (ACC pin), so it must accepts 11-15 volts and must tolerate whatever interference there is when the engine's running (hint: there may be a lotta interference). Labeled ACC_IN on the schematic;
input 2 is triggered by 3.3V from an MCU's output port. Labeled MCU_PWR_CONTROL_OUT.

So I've searched for some automotive-grade parts, and came up with this circuit:

VNP14NV04 is an automotive-grade smart protected power switch with logic-level input that should be triggered by the 3.3V signal from the MCU. TLE4264G is 5V output automotive-grade voltage regulator that I'm using to convert the noisy 12V input to something more predictable.

Thoughts? Will it work? Did I miss something? I did miss the R2 resistor initially, so figured I'd better ask before stuffing my car with this stuff, especially since debugging it on site, in the car, will be less than pleasant. I need it to work reliably.


texts: Trasferring Arduino chip from prototype platform to a PCB (Serial Communication)

texts:
I have been working on a little project where my Arduino Uno sends the IMU sensor's data to the PC via serial (Printing the data on serial monitor. I ma planning the transfer the programmed Arduino chip (Atmega) from the prototype platform to a PCB. I have read that I just need a crystal and a couple of capacitor to run the already programmed Arduino chip on a PCB. And I could use the prototype platform to program the chip and transfer back o the PCB.

My question here, can the Arduino on the PCB still perform the serial communication with the PC? Does the PCB need extra components such as a USB-to-Serial converter in order to perform the serial communication? Please explain.


texts: Looking for resources for determining cable requirements for high wattage (MW) applications

texts:
I'm doing some personal research on the specifications for cables that can handle megawatt power draws. As an example, the wires needed to supply 450VAC @ 2000A (0.9MW). I'm looking for wire diameters and insulation requirements.

Rough ballpark values are suitable for my needs. I'm not worried about voltage drops, temperature considerations, or the like.

I'd rather not pester people with this every time I want to try different voltages and/or amperages, so an online resource would be appreciated (suitable for a lay reader would be ideal but I'll try to work around something geared for actual engineers).


texts: Connecting hc-05(bluetooth) with clicker2 with STM32(ARM)

texts:
For a school project I a got HC-05 bluetooth module and MikroE Clicker2 with STM32 (ARM).

When I connect and use module with Arduino, 9600 BAUD rate and all other settings used with SoftwareSerial work and module properly communicates with my Android device.

Once I connect HC-05 with clicker, on some of UART ports(there are 4 on my board), communication works but data is corrupted. Actually data is always composed of same values (exact value is 192).

Both sending and receiving work, module is properly connected rx/tx tx/rx, but data is always equal to same value.

Any idea what can cause said data corruption? Since it works on Arduino I am sure its not between module and android device.


texts:
With microcontrollers it is pretty easy to switch a LED on/off, by writing on a register.

This question is instead an attempt to write to a PCI device register in a desktop computer.

In a similar way, I would like to read/write the registers in the motherboard to control fans (on, off or even speed) or the power or hard disk LEDs, or temperature sensors.

Given - for example - an Asus motherboard and a Linux OS, is it possible? And what kind of datasheet should be readed, if it exists, to obtain the register names in the motherboard? I never found for a consumer motherboard something like the datasheet of a microcontroller.


texts: transistor as an amplifier in detail from ncert book of class xiith

texts:
While going through transistor as an amplifier in detail from ncert book of class 12th(*),
m finding after equation 14.16,when it says when input voltage vi is not zero,we get,$$ V_{BE}+v_i = V_{BE} + I_BR_B + \Delta I_B (R_B + r_i)$$
m finding there is a printing error in this, it should be VBB not VBE in VBE+vi as it is a continuation of equation 14.16,it should be
$$V_{BB} +v_i = V_{BE} + I_BR_B + \Delta I_B (R_B + r_i),$$
where from eqation 14.16 VBB equals VBE+IBRB and vi equals delta IB (RB+ri),

*: See page-498 of this freely available pdf


texts: Use SR 830 lock-in amplifier to detect the second harmonic component with respect to an external reference

texts: I have a sine wave external reference at frequency f0, which is connected to BNC REF IN. The response signal is fed into input BNC A/I, I want to detect the second harmonic component in the input signal at 2*f0. Is there any simple way for this? I guess I may need a frequency synthesizer. Thank you.


texts:
A transistor has an npn junction. It has collector, base and emitter region. For it to be in cutoff, we can make the base lead in open mode. Now, what will be the correct schematic diagram, (showing each pn junction's voltages) of a cut off? thanks

PS: im pertaining to the proper placement of + and - signs in collector-base and base-emitter junctions. if possible, include real valued dc bias


texts: 8051 baud rate calculator using 16-bit timer for software UART timing

texts:
I'm making a project in which pulsed laser beam data is sensed through many optical sensors (one sensor per port pin), so essentially, I'm going to be making 4 UARTs to sense this.

Currently I am using an AT89S52 microcontroller with a 22.1184Mhz crystal attached to it, and I used Keil's baud rate calculator and noticed that it couldn't give me a value for low baud rates (like 100bps).

The reason why I'm asking for such low rates is because the data being sent isn't much (maybe 2 bytes every 1/5th of a second), and also, the microcontroller is doing other tasks as well.

I really only need maybe 100bps speed, but I might have to up it to 110bps because that's the next computer standard serial speed?

The question

If I configure the 8051 timer 1 to 16-bit mode, what values do I plug into TH1 and TL1 for 110bps? Remember, I'm doing 4 software UART's here and the one hardware UART is used by other processes, and the timer 1 interrupt needs to be fired at the right time so bits won't be lost.

Details

What I'm trying to do without the need of additional microcontrollers is to implement laser tag. Each player's vest will have different sets of sensors and I'm treating each set of sensors as separate receive-only UARTs and the laser as a transmit-only UART and the wireless remote control is connected to the hardware UART. Since humans don't pull a trigger 1,000x a second, I can get away with making almost every UART at low speed.


texts:
Has anyone had problems getting a solid state relay to work?

EDIT: see Spehro Pefhany's answer. Lessons learned:

don't accidentally take out current limiting resistor
solid state relay rated for AC load will probably just turn on small DC load.
It makes a LOT of sense that since there's an LED inside you need a resistor, that's a Basic concept.

I'm using a SSR to control a AC load. To test it I'm using an LED load. The problem is, I can't get the relay to turn on.  I'm using the S202S02 from Sharp (digi-key part 425-2403-5-ND.

First a was using a uP (Atmel XMEGA128A1) but that wasn't working so I switched to just straight up using Vcc. (Note: I didn't bother with a transistor, just connected it right to uP)

The SSR has 4 pins: the output pins (indicated by the AC tilde) and two input pins: + and -. The problem is that I apply vcc (3.3/5V) to plus, ground - and then connect one output pin to vcc and the other pin to an led which is connected to a resistor and then ground.

link if image doesn't embed

I know the led works because if I connect vcc to it it turns on.

What am I doing wrong? I'm pretty sure SSRs can switch DC loads.

I've used two different relays in my circuit so I don't think I have a bum relay


texts: How do I tell which wire is which if I have a copper wire, red and green coded wire? Is the unshielded copper wire ground?


texts: Amazon PWM Utilizing Transistors to Boost Voltage And / Or High Drain?

texts:
I picked up a couple of these: https://smile.amazon.com/gp/product/B0814MKZVW/ref=ppx_yo_dt_b_asin_title_o05_s00?ie=UTF8&psc=1 and am trying to do a basic circuit.
First, maybe if you could give me the proper name for the circuit I am trying to build, that would help so I know what I am looking for. Since this isn't with a 555 timer, I tend to get lost in some of the other responses to similar questions.
Ok, so using a 5V in, I was able to check with an LED and the PWM is working properly, so I hooked it up to a breadboard with an LED light strip to visualize the output power.
I have a wide assortment of transistors from tearing apart TVs, power supplies, amplifiers, even one an electric city train, so not just the small ones. Most I have so far seen are NPN or NFET. I tried  laying it out with the following transistors:
https://datasheetspdf.com/pdf-file/678667/Savantic/D998/1
https://datasheetspdf.com/pdf-file/660793/InfineonTechnologies/11N60C3/1
https://www.mouser.com/datasheet/2/149/KSA916-66917.pdf

I am sorry for the artwork, I am not great at reading schematics and wanted to make sure I conveyed what I was doing properly. I am getting the 110V DC from a bridge rectifier and the 5V from a wall plug transformer. To test I have the PWM at 2Hz and 10% duty cycle. Sometimes I can see where it looks like it is almost working, I can see a pulsing in the LED strip, but I am not sure if it doesn't have enough to drain the internal capacitor on the transistor, because it stays on all the time, just flickering.
I am not sure what I am missing here, but I hope to be able to drive a variety of gadgets using the same type of circuit once I understand what I am doing wrong. Currently I would like to drive an ultrasonic inductor and 1-5HP motors (not at the same time, those are just the two projects).
I assume to drive something the size of the IGBT (CM400DU-12F https://www.mitsubishielectric.com/semiconductors/content/product/powermodule/igbt/nfh_series/cm400du-12nfh_e.pdf) I will need to step up my input voltage to maybe 24V, but the rest of the schematic would be exactly the same, right?


texts:
I was just experimenting with some different combinations of transistor stages and got this:

simulate this circuit – Schematic created using CircuitLab

Q1 and Q2 represent cascode, where voltage amplification is achieved, then the buffer stage with intent not to decrease the voltage gain just by connecting load straight to the output of cascode stage.

DC currents were biased so that collector current through cascode is approx. 2mA and the collector current through voltage the buffer approx. 1mA. C_comp is meant to be used as compensator of Miller capacitance.

Open loop gain voltage gain of shown amplifier was measured to be a bit more than 10 dB (a bit to low I guess).

With the loads of 1k ohm and 470 ohm, the output signal is pretty stable and its amplitude is decreased from open loop signal for a few tens of mili volts. At the load of 100 ohm and lower, more significant effects start to occur within the circuit.
 Around 30% of negative half of sine gets clipped (without that compensation capacitor much more than 30% + significant output amplitude decrease); so input signal must be lowered to lower voltage levels. Voltage decrease is also significant here, which is rather normal then unexpected. And the last thing is output distortion - it occurs when no person is around the circuit (min. radius half meter from the circuit), but as I approach my hand to the circuit or right above it, at that time the distortion disappears...

*It is not the first time I noticed such version of distortion.

Output amplitude, when the my hand was right above the circuit:

Output amplitude, when I removed my hand away from the circuit:


texts: I am looking for an inexpensive device with a potentiometer to slow down a fan and reduce the temperature of the heating element in a 120v hot air popcorn popper. This is an experimental project. Any feedback or suggestions are welcome. Thanks for your help.


texts: What is the purpose of this polygon arrays on PCB?

texts:
I'm interested what is the purpose these polygon array on below picture.
Thermal management?
Thanks for the help!


texts:
I would like an or circuit with two inputs and one output. It will be operating at 12v dc with less 1 amp current. Either input would be capable of providing this power. However the inputs cannot (obviously) be in any way connected.

I was wondering of the simplest way of implementing this? Would a diode or circuit work? Excuse my ignorance, any help much appreciated.


texts: Logistical issue with power transistor and arduino

texts:
I have a transistor which will be triggered by an arduino digital pin. When the transistor switch is closed, ~5 A is going to flow from the collector to the emitter. However, I was under the impression that both the base and the emitter need to be grounded at the same place. I'm worried about that kind of current going into the Arduino's ground, because I've heard it can't handle that much current. Is there a better way of doing this? Any advice is much appreciated.

Edit: I'm using a TIP3055 transistor and switching 12 VDC.


texts:
I am attempting to build a motorcycle display for my older bike and need a way to get the RPM into my 3.3V microcontroller. My thought was to just wrap some magnet wire around the sparkplug wire a few times and connect it to a optoisolator and run that to a interrupt on the board, but I cannot seem to get any signal with my DMM or REALLY cheap O-scope.

Do I have to test this with the board or is there some way of seeing the signal before hand? And am I even doing the right thing with this design? I've heard of a few people sensing spark by using a high voltage neon light...


texts:
I am using an Atmel's XPlained mini board with Atmega328PB. I am trying to use ADC interrupt, however I can't get it to fire. Here's the code that I have a problem with:

#define F_CPU 16000000UL
#include <avr/io.h>
#include <avr/interrupt.h>

ISR(ADC_vect){
    PORTC ^= (1<<PINC2);
}

int main(void)
{
DDRC |= (1<<PINC2); //pin 2 as output
DDRC &= ~(1<<PINC3); //adc pin as input
sei();
ADMUX |= (1<<REFS0); //reference voltage VCC
ADMUX |= (1<<MUX0);
ADMUX |= (1<<MUX1);// channel 3
ADCSRA |= (1<<ADPS2);//
ADCSRA |= (1<<ADPS1);//
ADCSRA |= (1<<ADPS0);//prescaler to 128
ADCSRA |= (1<<ADATE);//auto trigger enable
ADCSRA |= (1<<ADIE); //adc interrupt enable
ADCSRA |= (1<ADEN); //adc enable
ADCSRA |= (1<< ADSC); //start conversion

while (1)
    {
    }
}

As far as I understand the code should enable a constant conversion in a free running mode with the frequency of 16MHz/128, and each time the conversion is completed the ADC_vect should fire toggling PIN2 of Port C. The problem is it doesn't. I am guessing I am not initializing the ADC correctly, however I can not pin point were the problem is.

EDIT:
After pointing out that the adc was not being run in a free running mode I cleared the ADTS bits. However I still couldn't toggle the pin. I think something else is at fault here.


texts: Incandescent bulb for 220V vs 110V and difference of their resistance?

texts:
I know that 40Watt,110V incandescent bulb has about 302 ohm resistance of tungsten filament (which is metal and of course have low resistivity) comparing it to 40Watt, 220V bulb which has about 1200 ohm.
My question is ---  how that much big resistance is produced in tungsten filament?  I know about R=resistivity X length/Area but is that enough to get such higher resistance


texts: Over designed heat sink or a well designed one?

texts:
I designed a heat sink for the first time. I am not sure if it is over designed or a well designed one?

I use IRFP460 in a two-switch forward converter. The maximum power of the converter is 1000 watts and the efficiency is 90 %. Each MOSFET dissipates 50 Watt. The maximum dissipation rating of the MOSFET is 280 Watts and the maximum Tj is 145 degree centigrade in its operating point. For the ambient temperature of 45 degree and the thermal resistance of the Tjc+Tcs=0.7 the maximum thermal resistance of the Tsa=1.3.

By the below link I need a heat sink with the below characteristics:
Aluminum material

height 4 cm
width 6 cm
length 6 cm
10 fins; 2 mm thickness
1 lit/sec fan

Is there any body to verify my design?


texts: Measuring an Arduino's power source voltage using Analog In

texts:
I am powering an Arduino using a 5v battery (3.7v to a step-up module), and I need to measure the voltage. Let's say the battery delivers high current, is it safe to measure the voltage via Analog In? As in this:

The reason I'm asking is that I don't know much about the Arduino's ADC architecture and limitations. So normally, I'd do so for safety:

Are the connections in the first diagram safe for the ADC? Thanks in advance!

Note: A similar question was asked here: (Monitor DC Power Usage), but it doesn't answer the question of high current loads on the battery.


texts: Why don't we use cascoding in RF amplifiers?

texts: I need to design an RF amplifier with high gain. It seems every RF book teaches cascading, but not cascoding. Is there a disadvantage to cascoding? It seems like we don't need to match impedances with cascoding, making our lives easier.


texts: how to choose a dual power supply for rail to rail amplifier?

texts:
I need +15VDC and -15VDC dual supply for rail to rail supply of op-amp.
I have found buck-boost inverters used for this task.
I have a doubt whether the inductor in the buck-boost inverter circuit can affect or add noise to the amplifier circuit?
I have found several circuits as follows

1. charge pump inverter

2. voltage inverter

3. buck-boost inverter

4. positive and negative switching power supply

which one is most suitable for noise sensitive application?

examples
module 1
module 2
module 3


texts: Simulation mismatch when shifting a +5v pulse to -12v

texts:
I am attempting to switch a N-channel mosfet (IRF740) running on a -12v rail using an arduino which outputs a 0v/+5v pulse. The end goal is to supply a -12v/-7v pulse to the MOSFET gate.

After four days of simulating many unsuitable and complicated circuits involving comparators or countless transistors, I have finally come up with this circuit which appears to achieve my goal of a -12v/-7v pulse at RLOAD1:

This is the output of the simulation using Kicad simulator; The white line is the Arduino output, and the blue is the voltage at RLOAD1:

With the blue line indicating the voltage at RLOAD1, it appears to achieve my goal.

Following a victory cheer, I replicated this circuit on a breadboard. When testing with an oscilloscope, I am seeing a -8/-3v pulse rather than the -12/-7v pulse I expected - this will result in the mosfet being constantly saturated.

Is there a reason for the mismatch in voltages, and how can I correct
this?
Is there a better overall way to achieve my end goal?
Have I simply made an error in my configuration of VPULSE's voltages?

Thanks in advance for your help.


texts: How to Boost an AC Voltage signal from 18 Vpp to 30Vpp range

texts: I am interested in creating a portable diagnostic tool, and as such would like to passively (no wall plug) amplify the 18Vpp sine wave signal that I have (4-7 kHz range) to about 30 Vpp to adequately power a disc style PZT on my device. I have searched extensively and have not been able to come up with a good solution thus far. Alternative ideas require using some sort of MOSFET circuit still requiring a larger external voltage. This is not ideal, since I was hoping to use the setup and signal I have right now to power my device. Thanks.


texts:
This problem requires solving for V2/V1.
My approach: R2 and R4 parallel reason: R2 has virtual ground and  R4 is connected to the ground.
 Applied Nodal Analysis and got the following answer(incorrect).

The correct answer should be:

How should I tackle this problem?


texts: Doesn't voltage on ground make it not ground anymore?

texts:
simulate this circuit – Schematic created using CircuitLab

Beginner here, trying to learn enough to start using a microcontroller.

If the I/O pins are internally high, wouldn't pressing one of the buttons put voltage on the ground wire, making it no longer ground?  Including Vss?
I added R1 = 100Ω based on the STM8S003F3 datasheet max "Total current out of VSS ground lines (sink)" = 80 mA, and R2 = 270 Ω based on max "Output current source by any I/Os and control pin" = -20 mA.  Am I doin' it rite?  Is an additional resistor needed to limit current through (decoupling capacitor) C1?


texts: I have a mission-critical device, which involves a micro and mosfet controlling a pump. I want to implement a failsafe, so that if basically anything happens to the micro, or the mosfet blows, the system will engage and turn on a backup pump. The easiest way to do this, it would seem to me, would be to have an always-engaged (NC) relay that is disengaged by a failure, energizing the backup pump. So, my question is, is it a good idea to have a relay on continuously for what may amount to years? The extra 20ma for the coil is negligible in this application, but are there any other consequences to doing this?


texts:
We are trying to hook up phototransistors in parallel so we can sum the output currents and put it over a resistor to get an output voltage.
When we do this, the first phototransistor (closest to the voltage source) seems to be greatly affecting the output voltage, and the others are negligible
We are sending 3.1v to the phototransistors in parallel.
What can we change so that each phototransistor will equally affect the output voltage?


texts: How do lasers measure short distances (<1cm) when electronics are too slow for time-of-flight to work?

texts:
I was wondering how LIDAR sensors are able to measure distances less than 2mm. I don't see how they can possibly do that.

The speed of light  is 300,000,000 m/s, so the round-trip time should be within  14ps which is far beyond the capabilities of modern electronics (>71 GHz).

So how do they do it?


texts: Problem with designing finite state machine

texts:
I'm learning now finite state machines and I'm stuck with this exercise from a book "Digital Design and Computer Architecture" by David and Sarah Harris:

First I tried to solve it without looking at the answer. My idea was to store An-1 (previous value of A) in FSM's current state. So there is 2 possible states of FSM: S0 (if An-1 == 0) and S1 (An-1 == 1).
Here's my state transition diagram (note all arrows with A lead to S1 state and arrows with A bar lead to S0):

And here is state transition table with equations for S' (next state of FSM) and Z (output) below it:

Then I wired this FSM in Logic Circuit program. What it looks like:

And my solution seems to work. I thought it is the best solution. But then I checked the answer and there is another solution (screens below). They use 4 states, but I can't understand what are these states for? How does it work? I've built this circuit too and it seems to work in similar way as mine. But then I noticed, that my circuit doesn't have feedback part. So it is not finite state machine and my solution wrong?
In short, I have 2 questions:

Is my solution trash or not?
What are these 4 states of FSM in solution and what is the main idea of it?


texts:
While I was designing a board I thought, if we want to make a better path for the current what is the best choise?
Small vias and big in numbers or fewer but with bigger hole?


texts: How to use a MOSFET driver directly to drive DC motors with PWM?

texts:
I need to control a DC motor runs at 9v with PWM signal 3.3V  vpeak.

I found MOSFET driver noninverting MCP1401.
Can this MOSFET be used directly with a Back EMF diode (diode as usual across the motor terminals)?

The motor current rating is 200mA and voltage is 9V. the MCP1401 is 500mA
Is the above diagram correct?


texts: RC filter lower PWM voltage from arduino

texts:
I have a RC filter with a 1k Ohm resistor and 47uF capacitor between the PWM output of an arduino and the input of a motor controller. The problem is that when I connect the output of the RC filter to the controller, the voltage goes down significantly with respect to what is expected (3V instead of 3.8V). However when I disconnect it from the controller the output of the PWM gives the correct open voltage. I am suspecting this is due to the resistor in the RC which is too high but don't exactly understand why so?
Thank you very much for your help!


texts: Should I Use a Diode to Protect LiPo Battery?

texts:
I am building a Bluetooth speaker and will have two power options running into a DPDT Switch. One side of the switch will go to an 11.1 volt 2200 milliamp battery which will be regulated to 12v. The other side of the switch will go to an AC adapter receptacle. This will give me the option to run off the battery or a 12v AC adapter but neither at the same time. The battery will be charged separately off a different circuit receptacle.

My question is would it be a good idea to put a diode on the positive battery line running to the DPDT in case the switch ever failed while running off of AC? This would be a safety measure since I know LiPos can be dangerous and I wouldn't want power going back into the battery from the AC adapter source. If this is a good idea what type of diode should I get and would it only go on the positive side and before or after my regulator before going into the switch?


texts: How is a higher torque achieved in a single phase cap-start cap-run motor?

texts:
The starting winding come capacitor circuit is there for starting the motor. When the motor reaches 80% rated speed, the centrifugal switch cuts the starting circuit out and leaves the run winding only.

Now, in a cap-start cap-run motor, the centrifugal switch cuts out only the start capacitor and leaves the run capacitor in series with the starting winding. For what purpose is this?

Also, If torque depends on the current and the starting winding has a higher resistance, wouldn't it make more sense to cut out the starting winding completely to achieve a higher torque?

I am a bit confused as to how this cap-start cap-run  arrangement produces a higher torque as opposed to a normal cap start motor. Please assist.


texts: Where to put the Flyback Diode in a Relay Module?

texts:
I'm working with a relay module to switch a solenoid with an Arduino, Im having problems because the arduino get some noise in an LCD but I'm not sure where to put the diode, there is 3 pins, In, Vcc and GND. I think there should be a diode between In and VCC/GND but looking at the internet there is a diode between VCC and GND, shouldnt it be in the In because there is a direct connection with the Arduino?

Edit1 (sorry for my bad drawing)

I add my diagram, this the connection with the problem, and it only get noise when the valve is connected with the 12v source


texts: Connection between two pre-amplifier stages

texts:
In the circuit shown above, I am unclear how Q1 connects to Q2+Q3.  I understand Q1 is part of a common base amplifier and Q2 and Q3 form a direct coupled amplifier.

The circuit is described at

http://www.zen22142.zen.co.uk/Circuits/Audio/dyn_mic/dyn_mic.htm

My problem is in reading the Schematics/picture.  Specifically, how are the 2.2uf, 4.7 uf , and 47k ohm componnets connected in the center of the picture?  Thanks


texts: what is the difference between these two buzzers?

texts:
I am looking for a 5v buzzer and I saw a chinese pack of 24 for 9 dollars on Amazon
https://www.amazon.com/tatoko-Electronic-Magnetic-Continuous-Arduino/dp/B07QBHPG2X/ref=sr_1_17?keywords=5v+buzzer&qid=1573580272&sr=8-17

And there is a pui audio buzzer, the one costs over 1 dollar.
https://www2.mouser.com/ProductDetail/665-AI1223TWT5V5R

which is better? is there any difference I would find in terms of sound loudness? Thanks in advance


texts: How do KCL and KVL equations look like in a circuit with a switch and two voltages sources?

texts:
Let I1 be the current through R6, V3, and R7
Let I2 be the current through R5, and V2
Let I3 be the current through R4

Suppose I did not know V2 = 36.4V, but I know the voltage across R7 is 15V.

How do I figure out V2 ?

Here is my KCL =

I2 = I1 + I3

KVL

30I1+25 + 50I1-V2 + 20I2 = 0

-20I2 + V2 -75I3 = 0

When I solve the above 3 equations I get V2 = 25, not 36.4. What am I doing wrong?

simulate this circuit – Schematic created using CircuitLab


texts: How fast is the response time of a battery for a particular current demand?

texts:
If you demand a particular amperage, can the battery provide that amperage instantaneously or will it need some time to build up to that level?

I guess it will need time, but would like some references/thoughs.


texts: Clock Domain Crossing for Pulse and Level Signal

texts:
For pulse we use Pulse-Synchronizer and for Level Signal we use 2-flop synchronizer but what if the signal can be of Pulse or Level behaviour. Is there any way to synchronize that?

EDIT:

After @Paebbels's answer, there is modification in Circuit, it should be like that, signal transformation is in tx-clock domain instead of rx-clock domain.

and its simulation is like below,

But now issue is to transform number of cycle on tx-clock side to rx-clock side. Atleast level CDC will converge to level at rx-clock domain, we can remove the constraint of number of cycle transformation.


texts:
Old batteries (I mean AA, AAA -sized 1.5v ones) usually have some residual energy, which can be used, for example, to charge mobile phones/pads. I have seen some schematics on the Net, but all of them try to connect old batteries in series without checking for really bad ones.

I was thinking about building smarter power source using old batteries, but my knowledge is not enough to choose the component for switching batteries on and off.

The idea is simple: Switch the battery out of the chain when it consumes more energy than produces. If switches were mechanical, I could have used something like the following:

When non-rechargable battery B1 is low on power, S1 and S2 simulatneously switch to path 1-3 (in mechanical terms it is DPDT-switch). Threshold could be residual voltage. I do not know what is optimal value, but I guess when it drops below 0.6v (without voltage), we can declare the battery dead (it can switch back at some higher voltage, say, 0.7v. These values are arbitrary, optimal old-battery energy-harvester may need them lower.).

The question is, what can be a switching component for this, which will not require a lot of energy for maintaining the state? I can use some large capacitor and voltage regulator to get the stable voltage, so switching time can be larger. However, switching S1 and S2 should be synchronous.

I have an extension of this idea to have several series of batteries, connected in parallel, but it will complicate the switching logic and may be require MCU to control it.

UPDATE: closest (but too costly) component, which in my opinion can serve the purpose is dual coil latching relay, one per battery. E.g. G6SK-2F-H. What can be more economically feasible solid-state counterpart?


texts:
I want to build a prototype device that manages to do the following:

Take a HDMI signal with at least 4k resolution at 60fps (for simplicity without DHCP for now,) change a few pixels (say a red circle in the center of the screen) and output the altered signal at 4k60fps and add less than 10ms of latency.

Price of the hardware matters, since I need to build a small batch of these devices (less than 200.)

The two viable options I see currently (please tell me if you see better options.)

A small desktop computer with a HDMI capture card plus a workstation graphics card that either supports GPUDirect (Nvidia) or DirectGMA (AMD.) However, these graphics cards are expensive (800$+) and I suspect even with GPUDirect/DirectGMA it will be difficult to add less than one frame (16.6ms) of latency going that route.
Some FPGA (which though?)

While I have done  some small FPGA projects in the past, my know how is very shallow at that point, so what I'm looking for is the cheapest FPGA that can manage to decode a 4k60 HDMI stream and encode another.

From the information I gathered so far, I understand that:

The 'smallest' 4k60 HDMI signal is 4:2:0 chroma subsampling with 8bit depth per channel (http://community.cedia.net/blogs/david-meyer/2018/05/16/hdmi-data-rates-for-4k-hdr) which requires a 9.0 Gbps link speed
HDMI sends data over 4 TMDS channels (https://en.wikipedia.org/wiki/HDMI,) 3 for data, one for clock (I'm not sure whether that means I need at least 9.0/3 = 3.0Gbps speed per channel or whether I need at least 9.0/4 = 2.25Gbps per channel.)

What I wonder now is what the minimal hardware requirements in an FPGA are that I need to look for to get this done.

Looking at the Intel Cyclone V FPGAs, the more expensive GX and SX chips are advertised to have "3.1 and 6.1 Gps Transceivers" (anywhere between two and 12 of them), whereas the lower cost FPGAs do not have these transceivers - however, all of them (including the cheaper ones) also are indicated to have multiple "LVDS channels", which according to wikipedia is a differential signal (like TMDS) carrying 655Mbps (but apparently up to 3Gbps should be possible.)

Looking at Xilinx's Spartan 6 FPGA's they are advertised as having 3.2 Gbps "transceivers" in the more expensive LXT boards, and no transceivers at all in the cheaper LX boards.

My questions are now:

Do I need these 3.x or 6.x Gbps transceivers to get this task done? If so, which ones and how many?
Do FPGAs that are not advertised to have these 3.x/6.x Gbps transceivers have no transceivers at all, or are the ones they have simply slower?
What are the minimum FPGA feature requirements for decoding and encoding 4k60 HDMI signal?
Any idea on what sort of added latency I could expect if doing this through an FPGA?
Are there more viable alternatives to FPGAs do to this?


texts: How can I create female-to-female jumper wires from female-to-male jumper wires?

texts: In a similar spirit to this question, I want to create female to female jumper wires.  However, I only have individual female to male jumper wires and I don't really want to go out and buy new wires.  I hypothesize that there might be a way to remove the female end from one wire and connect it to the other to create a female-to-female jumper wire.  How can I best accomplish this?


texts: Atmega16U4 (Hardware USB) does not show up as DFU device on device manager

texts:
I am trying to get the Atmega16U4 to show up in windows device manager. Right now, when I connect the atmega16U4 through USB to the computer it does not do anything (does not even play the USB connection sound). I have wired it up following this guide for a similar chip.
I have connected a 16Mhz crystal oscillator with 2 - 20pF capacitors provided with the crystal. The USB D+ and D- lines use 22 Ohm resistors as recommended by the datasheet. VBUS on the USB is connected to VBUS on the Atmega16U4. Power to the USB module is connected (UVCC and UGND are connected to 5V and GND).
Is there anything I'm missing here? Or could it be that my chip is not entering DFU bootloader? (the datasheet says that the Atmega16U4 comes with the DFU bootloader factory programmed)
Things I did before this was to change the fuses - CLKDIV8 fuse disabled (enabled by default). To change this fuse I had to first do a Erase Chip operation. I read that the Erase chip option does not erase the bootloader, was I wrong with this assumption? If yes, then what can I do to get the bootloader back on?
Here's the datasheet for the Atmega16U4
Any help would be extremely useful to me right now.
EDIT: Attached schematic. This version of the schematic does not include the !HWB connected to ground but I have connected it on hardware. (pin 33 to ground)

Thanks in advance,
Harid.


texts:
My question is about CPLDs in general, but take for example this cheap Xilinx one.

I understand that unlike a microcontroller, a CPLD does not have a clock; external edges activate the logic immediately, without waiting around for an interrupt dispatcher to create a context switch and call a function.

On the unit linked above, the "max" Tpd is shown as being 10ns. Does that mean it's literally anywhere from 0ns to 10ns on a given edge, or is it more consistent within a certain set of environmental conditions? Which conditions would affect that delay most heavily?


texts:
so i'm going to use IRF530 as a LED driver for my project, but as soon as i open datasheet, i can't find K for calculating current Id. so how to calculate Id to make sure i'm supplying enough current for 10-15 LED @ 1 watt (350mA) and not overrated it? i've heard from other source that you just don't use K. i mean if that was true...how to precisely control current that passed MOSFET?

thanks in advance


texts: Summing two voltages without the use of an operational amplifier?

texts:
Is there a way of summing two voltages without the use of an operational amplifier?
http://www.electronicspoint.com/threads/add-two-voltages-without-the-use-of-a-opamp.242875/
This article said to use an operational amplifier but I want to see if its possible without one. Is there a way to make a circuit that accomplishes what the article says without an op-amp? Theoretically, is there a circuit that can sum the voltages of two voltage sources without the use of an op-amp and without hooking up the two voltage sources in series?


texts:
Powering an arduino board using batteries via the the barrel connector, is it ok to use the negative terminal as ground wherever its needed?

For example, I have a shield that takes +5 and Ground from arduino pins - is it ok to use the negative from the battery as the Ground?

UPDATE: I attach a rough sketch. I've ignored control lines etc. The M is for a motor that is being controlled by the H-Bridge which requires +5/GND from arduino and external power.


texts: Multi voltage power source and negative dc line

texts:
I'm working on an audio project with a Teensy board.  The teensy itself is powered by 3.3v, but I want to use balanced audio in/out module that both need a negative voltage rail and a higher voltage altogether.  I relatively new to that universe, so I've powered everything I worked on so far from the MCU board.
So I'm looking for two things:

A 3.3v rail
+/- 15v rails

Also, on the long run, I'll want the option to have that unit battery powered.

Any read/tutorial/article/precious knowledge you guys can share?


texts: Grounding of heatsink for SiC MOSFETS half-bridge

texts:
I was working on SiC Mosfet half bridge for dual active bridge, Each half bridge has two SiC MOSFETS Rds0n=0.035 mohm , the bus voltage peak is 600VDC on the primary side. and I was wondering should I ground the heatsinks' two pins to mitigate the noise from the switching node?
The heat sink for two TO-247 packages for two SiC Mosfets: here.
And two thermal pads on each Mosfets here.
Thanks in advance.


texts: I watched a DIY video recently on building a brushless DC motor.  Can someone demonstrate for me how to calculate the max torque & max rpm of that motor based on the components that are used in the video--not by using a dynamometer or any other device to measure the mechanical power/torque or rpm of such a device?  There must be some EE method/s to reverse engineer & use such data to redesign a similar motor to your own specifications.


texts: Making a bi-directional tri-state buffer using two normal tri-state buffers, is it possible?

texts:
I need to use a tri-state buffer on a I2C bus and I have lots of 74125 (uni-directional tri-state buffers), so I'm wondering if is possible to connect two buffers back-to-back to make a bi-directional buffer.
Something like this:

(source: tiago.eti.br)
Does it work?


texts: Unbalanced to balanced audio signal conversion

texts:
When I was looking for some information how to convert unbalanced audio signal to balanced, it was hard to find info other than "use transformer" or "buy X device to do this".

Then I found this circuit:

source: http://www.fivefish.net/diy/balanced/default.htm

but I'm not sure if this is correct solution. I mean that on this schematic you can see low pass filter which cut-off freq is about 140 kHz, which I think is way to high (changing 220p to 1n would help?), also where op amp in inverting configuration seems rather ok, but non-inverting shouldn't be done differently (according to https://www.electronics-tutorials.ws/filter/filter_5.html)?

Same thing with capacitor connected to pins 2 and 6 - I think it should rather be connected between output and those pins, not ground, and short between unbalanced signal + and gnd (or it's just compression of image that creates this illusion)

Anyway, I'm better in digital electronics than analog, so maybe someone with greater knowledge help me here with this.

EDIT 1:

Based on SSM2142, I created the following circuit that, I think (or rather I hope) should work correctly, making unbalanced audio signal balanced. Am I right or wrong?

simulate this circuit – Schematic created using CircuitLab

Instead of TL081 I was thinking about using LM358.


texts: void loop executes even when the while loop inside is true in arduino

texts:
I made a simple mobile application to send LED_ON or LED_OFF when a button is clicked. In the below code the while loop is not fully completed while execution but the controller is going to the void loop() and continuing from there.

char command;
String my_final="LED_OFF";
#define led 9

void setup(){
  Serial.begin(9600);
  pinMode(led, OUTPUT);
  Serial.println("ready");
}

void loop(){
  if(Serial.available() > 0){
    my_final = "";
    while(Serial.available() > 0){
      command = (byte)Serial.read();
      my_final += command;
      Serial.println("test");
    }
    Serial.println(my_final);
    }

  if(my_final == "LED_ON"){
    Serial.println(my_final);
    analogWrite(led, 255);
    my_final == "LED_ON";
  }

  if(my_final == "LED_OFF"){
    Serial.println(my_final);
    analogWrite(led, 0);
    my_final == "LED_OFF";
  }
}

The main problem happens in my_final="" as i have to do this to accept new input from the bluetooth. i just cant seem to find a way around this problem.

EDIT

This is what im getting in the serial monitor. test L test E test D test _ test O test N.


texts: Circuit analysis with two loops, resistors, and independent/dependent sources

texts:
I am working on this sample circuit problem, which knowledge of KCL, KVL, and how resistors in series or parallel add up in terms of resistance. However, in this circuit there is a voltage controlled current source that supplies 29 times greater current than the current I somewhere else in the circuit. I am supposed to find the voltage drop across this VCCS, labeled Vy. I think it's this element that is throwing me off. I am not sure how to go about analyzing this. Here is my work so far, hopefully the picture is clear enough.

I have these equations written down from KVL. I know that there should only be two loops, I am just not sure whether which loop to analyze would be better. Although either one should give me the same result, I believe, if I do it right. But I am stuck on finding Vy, as well as the voltage drops across the other resistors, because of that VCCS in the circuit.

How should I go about analyzing this circuit?


texts: Solar cell efficiency on self tabbed cells

texts:
I am tabbing solar cells myself and of course it is not done perfectly on all tabbing wires.

My question is, does solar cell efficiency drop if tabbing wire is not fully tabbed on all places, or do electrons flow to the closest soldered part if there are empty spaces?


texts: Driving a LED matrix wall clock display (e.g. 64x16) from a Raspberry Pi?

texts:
My goal is to create a single-colour LED matrix display to show world times for several cities - e.g.:

Sydney        22:55        London        11:55        Tokyo        08:55

I saw that I can pickup the actual display fairly cheaply on eBay - for example 64x16 red LED matrix display for $40:

http://www.ebay.com/itm/DIY-Merry-Christmas-Lighted-Sign-64-16-Dot-matrix-LED-for-Arduino-UNO-Pro-mini-/331138827859

So size-wise, something like the above is probably suitable. However, I still need to obviously drive it.

I can code in Python, but not really in C++ - hence I figured a Raspberry Pi might be easier than an Arduino to get this project running.

Also, ideally, I'd like to have a NTP client running to sync time, and I figured that'd be easier on the Pi as well.

My understanding is that I can either use the GPIO ports on the Pi to drive it, or connect it through to an Arduino which then drives it.

I know there's a Pi-Lite module that's meant to make this sort of thing trivially easy on a Raspberry Pi:

http://shop.ciseco.co.uk/pi-lite-lots-of-leds-for-the-raspberry-pi-0805-red/

However, this is only available in a fairly small-sized version, which wouldn't be suitable for a wall clock.

I wish there was a physically larger version, but I can't find anything.

Are there any other similarly easy ways to drive a large-ish display (e.g. 64x16) LED display from a Raspberry Pi?

Or any good walkthrough guides targeted at a beginner?


texts: Could you please explain to me how to complete this truth table?

texts: How do I know when a short-circuit occurred based on the state of the transistors and the MOSFETs? If all the MOSFETs and transistors are OFF, does it mean that we have a high impedance in the switches?