texts: Resistive touchscreen with 5-wire connection & Freescale IMX28

texts:
I have a IMX28EVK board and I would like to to connect this board to a 5-wire resistive touchscreen. In the Reference Manual of the I.MX28, Freescale said:

  LRADC2 - 6 can be  used for 4/5-wire touch-screen control. LRADC6 can be used for the wiper of 5-wire touch-screen controller and external temperature  sensing, but they cannot be enabled at the same time in hardware configuration. LRADC5 can be used for Y- of 4-wire and LR of 5-wire; LRADC4 can be used for X- of 4-wire and UR of 5-wire; LRADC3 can be used for Y+ of 4-wire and LL of 5-wire; LRADC2 can  be used for X+ and UR of 5-wire; For pull-up or pull-down switch control on LRADC2~5 pins, please refer to HW_LRADC_CTRL0 register.

I think that there's an error. The word UR is repeated 2 times and UL never appears

I have this touchscreen:

Model: EL-TS-104F-5H
Type: Analog resistive 5 wire B-type.

This touchscreen has 5 pin:

1 - RT; 2 - RL; 3 - SG; 4 - LT; 5 - LL

|----------|
|LT      RT|
|          |
|LL      RL|
|----------|

I've made this connection:

RT <-> UR
RL <-> LR
SG <-> wiper
LT <-> UL (?)
LL <-> LL

But the touchscreen doesn't work properly. Is the connection that I've made is correct? If not, what's the right connection? Any suggestions?


texts:
I'm developing an USB application for a STM32 MCU.

For now I have 2 interfaces for CCID classes and I want to add another for a Virtual COM Port. On a STM32F4, The limit of IN endpoint in FullSpeed is 5 plus one reserved for control (80). I already used 4 IN endpoint for the CCIDs.

Does Interupt IN for CDC class is optional?

I think i have to declare 3 endpoints like this:

Bulk IN
Bulk OUT
Interupt IN

Note : I know that in HighSpeed there is 7 endpoint available but i don't have time to develop a custom board (need an external phy chip and other things).


texts: Nixie tube and high frequency AC (drawbacks)

texts: Recently I salvaged a piezo humidifier driver board which produces high frequncy AC volage. Naturally I decided to touch it's output. It hurt so I deduced there might be enough voltage to power a nixie tube with it. To my surprise it lit up, but with purple flares around cathodes. So the questions are: what are the drawbacks of powering a nixie tube with high frequency AC, why does it even work and what are these flares?


texts:
I've been searching for a small (20 to 30mm Dia) disc shaped EM lock for a project I'm working on but can't find any. This type of lock's function, where when the EM is energized the magnet activates, attracting a pin or plate, is what I need it to do but I can't find them small and flat enough. I then found some 24V EM brakes for a "Duplicator" (copy machine?) where the size may be ok but if they were flatter it would be better. From what I understand these work the opposite way. The brake pad is normally engaged ("locked") to the hub by a spring, then when energized, the brake pad separates from the hub allowing it to rotate. Is this correct?

Would it be possible to convert the EM brake into an EM lock merely by reversing the wiring or would I need to reverse the direction of the winding? Would that work to then attract a plate when it is energized?

Also, how much could I reduce the voltage and have it still attract a metal plate with a decent pull strength - say from 1/4" away?

Thanks for you help!


texts: How do i analyze the following waveform to find out the voltage at t=6us?

texts: How do I analyze the following waveform to find out the voltage at \$t=6\mu s\$?


texts:
For a solar powered project I'm using a 5V solar panel to keep a 3.7V Li Ion battery topped up.
The Li Ion charge regulator IC is an MCP73831T and can handle a Vin from 3.75V to 6V. This is fine for the most part but the solar panel can actually output up to 10V when in direct sunlight. And so I wanted some sort of over voltage protection for the charge regulator IC which doesn't compromise too much current.
I looked into standard voltage regulators but these require a much higher input voltage. LDO regulators could work but I don't think they would be able to handle the power dissipation.
I also looked at Zener diodes but these work by conducting current once their reverse breakdown voltage is reached. I'm worried that this will reduce the current used for the charging the battery and so isn't an efficient solution. (Correct me if I'm wrong)
I was wondering if there was some sort of voltage clamp IC or circuit which operates normally until the voltage gets too high and then it can regulate it. Looking for an efficient solution since the solar panel can only produce 500mA max and I want as much of this to be used for charging the battery when it's available.


texts: Need help determining if a component is acceptable for use in a production design

texts:
For the sake of not going too broad, I am only referring to this single OLED LCD board component from Newegg being used directly within a prototype device that I have designed. My end goal is to take this final prototype device to market in the U.S. with all necessary certifications.
As the title mentions, I mean acceptable in terms of being integrated out-of-the-box with my production version PCB (the rest of my electronics) and also not preventing the final product from being certifiable (UL, FCC, CE, etc.).
In practice, do designers and industry integrate components like this into their production designs? Why or why not would designers use this OLED display or similar, aside from cost?


texts: Is it good practice to use an ESP32 DevKit in a product?

texts:
I am developing a small electronic product which, if all works fine, I think about producing and selling in small numbers.

Currently I use an ESP32 DevKit for the development. That is the ESP32 development board with "everything" included like power regulator, USB connection, etc.
https://www.aliexpress.com/item/4000093185394.html

The schematic for that DevKit is published here https://www.espressif.com/en/support/download/documents

In theory, when I want to build my own product I could:

A) Use all or most of the PCB design of that DevKit board and add the few extra components which I need all in one PCB.

B) Or I could design my own PCB and solder the DevKit board on my PCB which would include only a few extra components.

B is much easier for me because the DevKit boards are ready and cheap available.

Is it good practice to do that? Or are there good reasons to put everything on one PCB including the parts which are now on the ESP32 DevKit board?


texts: Sound spectrum analysis, adverse harmonic tones, micropython, adafruit, fft

texts:
Explanation
In this Micropython project I wanted to build a cheap/small sound spectrum analyser to identify specific tones during testing.
Initially I tried to connect the Adafruit sound sensor with an ADC and RPI but then faced a lot of timing problems and therefore went to the ARM-M4 micro-controller which is a pretty good straight forward solution.
On git-hub I found an FFT code written in ARM assembler by Peter Hinch, which allowed me to obtain on-board frequency spectrum calculation of an array, based on the Cooley-Tukey algorithm.

The picture below illustrates the spectrum(top) in a silent room, the middle plot shows the calculated gradients of the domain and the last the reactivity of the specific tones. The system is continuously captures 2**10 samples in 0.1s >10Hz-5kHz, calculates the FFT and forwards output array to PC in 15ms.

The problem is found in the harmonic tones that appear at exactly 1,2,3,4,5,.. kHz (graph was taken in silent room). Second problem shows up when there is a little more noise; spikes(bottom graph) appear around the harmonic tones+/-240Hz, aliased?. The bottom plot shows the reactivity of the tones.
Tried:

No power; all frequency zero except a few low freq show minor amplitude.
Settings of the FFT for 0.5s/0.1s/0.05s/0.01s and 512/1024/2048 samples; but show the same peaks at same freq.
Three different ADC channels on the Pyboard.
Both 3V3 and GND connections.
External regulated 2-5V with shared ground (laptop no charge). (makes it worse; more noise)

What is most likely the cause of this behaviour? Board circuit / Electret-Amplifier / FFT-code / USB-power?

Alternatives?
Does someone have experience with, or has a better alternative for a cheap on-board spectrum analysis:

Me Sound sensor (LM386) amplifier.
Grove sound sensor (LM386) amplifier.
Adafruit sound sensor (MAX4466) amplifier.


texts:
I am working on a project for college and I have to implement a sort of alarm using only MUX's and JK flip flops and a bread board. The problem I encountered is that whenever I power the whole circuit my flip flops have random outputs. I have 2 SN74HC73's meaning I have 4 flip flops. I connected all ports(correctly, checked three times) and have CLR set to HIGH (basically connect it to the power source) for all 4.

Is there a way to ensure that all flip flops default to 0 once I power the circuit on?

Please help me :)


texts: Looking for a timer 20 mins on 5 mins off

texts: I built a solar power heater for my pool. Using 500 ft of black hose and pump. The problem I have is the water that runs through the hose is cooling it down after about 20 mins. I was curious if there is a device or something that I can plug into the outlet that I can set to run 20 mins on and off for 5 mins. Giving the hoses time to heat back up from the sun. I dont even know where to begin to look. Id rather not build one, I would rather just purchase something already that would work. So if you have any ideas I am all ears. Thanks so much


texts: burn a led with the switchs on pic 18F4550

texts:
I'm using the pic 18F4550 with microchip v8.63 and with the C compiler C18.

I want to trigger port RB3, RB4 and RB5. when, I press on respectively S1 (switch 1), S2 switch (S2) and S3 (switch 3). on these ports (RB3, RB4 and RB5) there are leds connected to, the should burn when I press S1 or S2 or S2.

My first question is, How do I stream from my S1 and S2 and S3 to the gates (RB3, RB4, RB5).

And second how can I enable port RB6, there is a light dependent resistor connected to.

I wrote this program: but, nothing is happening. only led 1 goes on.

#include "p18cxxx.h"
void main(void)
{
    // turn off all LED latches
    LATDbits.LATD0 = 0;
    LATDbits.LATD1 = 0;
    LATDbits.LATD2 = 0;
    LATDbits.LATD3 = 0;
    // make port d bits which drive LEDs outputs
    TRISDbits.TRISD0 = 0;
    TRISDbits.TRISD1 = 0;
    TRISDbits.TRISD2 = 0;
    TRISDbits.TRISD3 = 0;

    if(PORTBbits.RB3 == 0) {
        LATDbits.LATD0 = 1;
    }
    if(PORTBbits.RB4 == 0) {
        LATDbits.LATD1 = 1;
    }
    if(PORTBbits.RB5 == 0) {
        LATDbits.LATD2 = 1;
    }
}


texts: Measure currents (~50 mA) at every 10 microseconds interval and store the data

texts: I'd like to measure the current across a tiny load (current range is maximum 50 mA) at every 10 microseconds, and store these values for later reference to plot a Current vs Time graph. Is it possible to measure at such quick intervals using an Arduino Uno? If not, how do I go about it? Thanks.


texts: Controlling a 4-wired fan PWM Signal using Arduino allows only two settings

texts:
I have connected my pwm pin to my arduino like in this tutorial

http://fritzing.org/projects/reading-pc-fan-rpm-with-an-arduino/

It's working properly. I can read and set the speed using a sketch from this website:

http://www.beefrankly.org/blog/2011/12/21/read-out-4-pin-cpu-fan-speed/

int fanPulse = 0;
unsigned long pulseDuration;

void setup()
{
Serial.begin(9600);
pinMode(fanPulse, INPUT);
digitalWrite(fanPulse,HIGH);
}

void readPulse() {
pulseDuration = pulseIn(fanPulse, LOW);
double frequency = 1000000/pulseDuration;

Serial.print("pulse duration:");
Serial.println(pulseDuration);

Serial.print("time for full rev. (microsec.):");
Serial.println(pulseDuration*2);
Serial.print("freq. (Hz):");
Serial.println(frequency/2);
Serial.print("RPM:");
Serial.println(frequency/2*60);

}

void loop()
{
analogWrite(3,20);
delay(5000);
readPulse();
analogWrite(3,50);
delay(5000);
readPulse();
analogWrite(3,100);
delay(5000);
readPulse();
analogWrite(3,200);
delay(5000);
readPulse();
analogWrite(3,255);
delay(5000);
readPulse();
}

It seems to me, like I can only enter values higher than 127 and values lower than 127.
There are no steps between them. The fan won't turn slower when I go from 126 to 0 or from 128 to 255.

Some results I get:

100:

 pulse duration:19058
time for full rev. (microsec.):38116
freq. (Hz):26.00
RPM:1560.00

0:

pulse duration:19160
time for full rev. (microsec.):38320
freq. (Hz):26.00
RPM:1560.00

127:

pulse duration:9032
time for full rev. (microsec.):18064
freq. (Hz):55.00
RPM:3300.00

255:

pulse duration:9151
time for full rev. (microsec.):18302
freq. (Hz):54.50
RPM:3270.00

Is there some mistake I've made or is it possible my fan won't accept precise values?
Can you recommend any 4 wired fans I could use for this or some other way? I thought about using a SG2524N  to controll a two wired motor, but I'm not experienced with this. Thanks for your advice.


texts:
I tried making a simple control circuit the other day, but was a bit of a dud. Hoping that someone can help point out where I went wrong.

I was hoping that disconnecting the switch would draw the MOSFET to ground, with a VGS of -12V, then connecting it to the 12V would bump the VGS to 0V, shutting off the circuit.

Without the control circuit, the motor runs fine. Turning the switch off does not turn on the MOSFET. Is my resistor incorrectly sized? Am I just totally off base? Should I settle for an NMOSFET and low side switching?

Thanks!

simulate this circuit – Schematic created using CircuitLab


texts: Asking for help about gate drive circuit of a bidirectional dc-dc converter

texts:
I have a 40V to 400V 500W bidirectional DC-DC converter as shown the image below.
I have trouble designing the gate drive circuit of the switches at the top of the circuit ( I mean S1 to S4 ) because all four switches are high side switches and I do not know what is the best way to drive them.
Is it possible to drive the four switches mentioned earlier without using a separate isolated source as well as a pulse transformer?
Also, all the switches in this circuit are IRFP4768PbF (TO-247 package).
I have IR2xxx and TC44xx family ICs available for this. If possible, please provide your suggested ways based on these ICs.


texts: What is the AVR's analog comparator speed?

texts:
I need to detect a short pulse (~ 100nS) with the comparator. So I hope that the short zero-crossing pulse will trigger the comparator interrupt, but I wasn't able to find any information upon reaction time/comparator speed of my controller.

Moreover, I'd like to keep CPU clock speed low (1 MHz). Hope that the clock speed is not related to the comparator.

I concerned more about minimum pulse length than reaction time.


texts: When building world devices what wall voltages should you expect?

texts: I want to build a dishwasher safe toaster (more details in other questions), So Simplicity of design is a must. Fortunately toasters are among the simplest of electrical devices consisting of nothing more than a switch and a couple really big resistors called heating elements (one on each side of the bread). I figure I can ignore 440/277 systems and focus just on systems that have a 110 or 220 volt standard. Unfortunately there seems to be significant variation within each range. For example I have seen 110v, 115v, 117v, and 120v secondaries on transformers targeting 110v devices before we get to line loss. Similarly I have seen 220v, 230v, and 240v transformers. When building a device for the world market what are the highest and lowest voltages you would reasonably expect to see from the wall in each of these ranges?


texts: VHDL: How does one assign custom values to identifiers of an enumerated type?

texts:
For a design with seven segment displays, it will be easier in modelsim simulation if one can see the actual display value going into the seven segment display e.g hexadecimal D which is "1000010" in binary could appear as an enumerated type 'ss_D' in the simulation waveform. How does one create an enum with custom assigned values for this purpose?

I know it does not hurt to just concentrate on the value going into the decoder for the seven segment display instead and see it as hexadecimal in the wave window. But the question here is, generally how to assign custom value to VHDL enum type?


texts: Can I wake ESP8266 with photoresistor like in this schematic?

texts:
I want to wake ESP8266 when the light turns on, send information to the server, go to deep-sleep for a few seconds and then send the information again and keep doing that. If the server stops receiving the information, it would mean that the light is tuned off back again.

This is my schematic:

Will it work?

I'm asking specifically about the part where I connect my photoresistor to the RESET pin.

Additional question (optionally to answer): If I'd like to swap resistor with potentiometer, how should I connect it?


texts:
What is the black thing on the below circuit?

Is it used to hide the IC (or other components) that is used on the circuit?

What material is it?


texts: UCN -1 error in Design Complier synthesis

texts:
I have a block for 2's complement in Arithmetic module of a ALU. In the netlist synthesized by Synopsys Design compiler, I find that the 2's complement block output LSB is assigned to input LSB.
ie,  assign y[0] = inp[0];
UCN -1 error due to multiple nets to inp. How does this happen and what is to be done for rectifying this? I am just getting used to the tool.
module twos_comp(inp,x,y);
  input [7:0] inp;
  input x;
  output reg [7:0] y;
always @(inp or x)
begin
if (x)
y = (~inp) + 1'b1;
else
y = inp;
end
endmodule


texts: Explanation and Draw of Line Impedance Stabilization Network (LISN)

texts: I am trying to learn about LISN circuits. As far as I see, there are standards for LISN. But the point is everybody is applying standards, I would like to know why these values are chosen or why there are these capacitors and indictors. If it is a low pass filter, why there are more components? Is it about fourier transformation? and Which calculations exactly. I would appreciate if someone explain these but I am fine to read all from a source (couldn't find good source yet, that's why I am asking here)+ I dont want to waste you guys time as well. Thanks a lot for your all answers. I will add an example circuit here if someone wants to explain on picture.


texts:
I am trying to design an electrical generator that can supply power to my house but without cutting off the utility power supply. The idea is that I could put the generator in parallel with the utility power supply so that if the utility power goes out I still have the generator and vice versa. However I want to make sure that the output of my generator is in phase with the utility power, otherwise I'll get surges or weird wave interference patterns

I live in the US so utility power is about 117 VAC at 60 Hz.

I was thinking that it needs two specific kinds of circuits: one that changes the phase of the generator and then some kind of controller that detects the phase difference between the two signals.

I thought that perhaps this could be done by combining the two out-of-phase AC signals and rectifying them into a DC signal. At the same time the signals from the generator and utility power supply could be rectified and added to represent what the in-phase sum of the power signals would look like. These who DC signals could then be compared by an op-amp controlling the phase shifting circuit, but I have no idea how the details would work out. I'm afraid I have a lot of theoretical knowledge but little practical experience with electronics.


texts: Hiding component designators in rooms in Altium

texts:
I have a multi-channel design that automatically generates rooms from my sheet symbols.
Designators for components in rooms tend to clutter up the silkscreen. Considering that all my rooms in my multi-channel design look exactly the same, I tend to manually hide the designators from all channels but the first, which is enough for identification.
Is there a way to "automate" this, by eg. setting designator visibility for specific rooms or for specific sheet symbols?


texts: Can I replace a power transformer inside a device with a DC jack and external power supply?

texts:
Let's say I have an electronic device, inside which is a power transformer that outputs a known DC voltage. Can I bypass the transformer and wire in a jack to accept the correct DC voltage from an external source instead?
Here's the context: I have a nearly 50 year old hifi spring reverb unit (Sansui RA-500) that has a 60 Hz hum problem even after I replaced its capacitors. I believe the problem may be that the power transformer is inside the unit right next to the spring reverb tank, which picks up its magnetic fluctuations. In guitar amps, one solution to this problem is to move the tank outside the amp to get it away from the transformer. While I don't want to move the tank in this case, it would be great if I could "move" the power transformer outside the unit to achieve the same thing. If I could use a wall wart or laptop power supply, that would be ideal. I assume there would be additional safety benefits to this approach as well.
In case it's relevant, here's the schematic. Page 10 of the PDF, top left, shows the power transformer outputting 21V, so if I can do this, I would try applying 21V to the circuit at that point. But a more general answer would of course be useful as well.


texts: How to identify the type of a microcontroller?

texts:
Assuming that we have an application which a lot of devices can connect and interact each other (like Internet of Things). Is there a way to identify the micro-controller that each connecting device contain inside? For example to identify if one device has a PIC or an Atmel or else? If not can at least identify if the micro-controller is 8bit vs 16bit or else?

edit: Can the firmware return the version of a microcontroller?


texts:
I recently bought a remote control toy for my son which included 2 2S battery packs, with a single SM-3P plug, and a corresponding USB charger as shown here.

Initially, the car worked fine, though within one or two uses (can't recall now), one of the packs simply stopped powering the car, even though the supplied charger seemed to charge the pack successfully.

Soon after, the other pack has done likewise.

I have confirmed the car works fine when I wire up another 2S LiPo pack to it using jumper leads, so it is clearly the supplied packs that are under question.

I applied a volt meter across the terminals of the batteries. What I found for both packs is making me question my sanity:

positive and negative terminals of the volt meter across
corresponding battery terminals - 0v
positive (volt meter) to
positive (battery), negative (volt meter) to center (blue) battery
terminal - roughly 4.1v
positive (volt meter) to negative (battery),
negative (volt meter) to center (blue) battery terminal - roughly
4.1v

suggesting the following internal wiring...

simulate this circuit – Schematic created using CircuitLab

This just raises so many questions in my head:

How can a circuit like this provide 7.4V output?
How did the car work out of the box and now exhibit this behaviour?
Can Li-ion cells reverse charge somehow? If so though, why would the charger have caused this anyway?
Why is my hair on fire?

I have not cut open the insulation to confirm the above assessment yet (it seems ludicrous!), as I don't have a good way of re-sealing it all up again and am hoping there is some logical explanation out there and a simple solution to the problem. Any suggestions or recommendations greatly appreciated!

Lastly, for the avoidance of doubt, the SM-3P battery connector in the car has only two pins, which connect to the red and black wires on the battery, as you would reasonably expect.

UPDATE: Just noted this post which suggests a possible explanation. It still seems very odd that this should happen to what should be two brand new batteries with only one or two cycles each, and both exhibiting an apparent full charge level in the reverse direction on the second cell.

UPDATE: Have cut away the insulation now. Here's what I found:

Also, I tried reading the voltage off the charger pins without the battery connected, but can't get a consistent result. It appears to oscillate quickly between about +3V and -3V, though difficult to be certain of those figures. My multimeter (Uni-T UT139C) doesn't update quite quickly enough.

UPDATE: Confirmed cells read normally when tested individually, per comment from Bruce. One reading 4.2v at present, the other reading 3.9v. (Oddly, I'm still getting 4.2v and 4.1v when reading across the plug pins... must be some function of the PCM causing this.) Voltage in series is 8.1v

Likely then that the PCM has malfunctioned somehow (in both batteries)? Perhaps the charger has caused some damage?

UPDATE 15-Apr-2020: So I finally received the replacement PCMs I ordered from AliExpress today. I am now ready check myself into an mental asylum. After switching the old module out for the one of the new modules, the behaviour is exactly the same.  I even tried connecting the old and one of the other new modules to a separate pair of 18650 cells I had and got the same behaviour consistently. 0v across the power terminals of the PCM and voltage seemingly reversed when testing across the P- and BM (guessing this stands for Battery Middle?!) terminals of the module. Testing across the B- and BM terminals gives a reading as you would expect from testing the cell in isolation (that is, it isn't inverted!), though the reading is consistently around 0.1V or so off from the negative voltage reading gotten from P- and BM (similar to what I observed previously). Where do I go from here? How did this ever work? What am I doing wrong?


texts: I want to implement this analog PID controller to control the temperature of a boiler for a coffee machine. I have seen many tutorials on how to do this using digital PID temperature controllers plugged in directly to an outlet. Most boilers I have seen use around 1kW of power. However, the transistor configuration is not able to supply anywhere close to that amount. What would be the best way to regulate boiler temperature using the op amp design in the picture?


texts: controlling one 110v device from three inputs

texts:
I have a commercial controller that turns on/off three separate 110v AC outlets based on atmospheric conditions for a small horticultural tent. I want to have this controller enable/disable one 110v AC device no matter which or how many of the 3 outlets from the controller is hot. As long as any of the three outlets is hot the switched outlet should be hot as well and visa versa.

I'm pretty good at putting basic circuits and all together including basic through hole soldering so I could make a basic circuit board up and box it up for actual use.


texts: Why is this MAX86161 internal LDO wired this way?

texts:
I'm looking at the MAXM86161EVSYS and am not sure why the pulse-ox senseor LDO_EN and LDO output is wired this way

I see the purpose of R1A and R1B, to allow the ability to pull the enable high or low.

But what's with R5? When would I ever want to tie an LDO output to it's own enable?

Eval System Datatsheet

MAX86161 Datasheet


texts:
I'm currently trying to build a rising edge detecting circuit which holds its output until it detects another rising edge using d flip-flops for a homework. Basically the output will change if and only if it detects a rising edge. Holding the input won't change the output. Here is the current logic diagram i got

Where the states are represented by the current input and current output. From this diagram, here is a table that i got with the K map (In is next state input and On is next state output)

But when building it in proteus, i got a falling edge detector instead

Adding a NOT gate for the input fixes this problem

But this changes the logic functions and resulted in a new one which is pretty illogical

I think i read my circuit wrong, but i don't know where and how i should've conveyed this circuit into a logic table and state diagram, which is the part i need help with.


texts: HD44780: How long do I have to wait for busy flag to reset?

texts:
I'm driving a HD44780 controlled character LCD (HY-0802B-104-R) with shift registers (74LS164). So, the communication will be one-way only; I won't be able to read any data from the LCD.

Normally, after sending any command to the LCD, we wait for the busy flag to be reset. Now that I won't be able to read the busy flag, can you tell me how long I must wait after sending a command to the LCD? And, will the waiting time be constant, or will it dependent on the command sent?


texts: Motor controller oscilations with flyback diodes

texts:
Have some motor controller oscillations with flyback diodes when they were added to the build. They emerge with higher rates of signal amount making by controller. So there is a need to reduce the maximum force applied a bit.

The application it DIY FFB wheel driver. They were there and emerges also with the shortest wires and with ordinary 1n4007 diodes while testing there connection plan to the build.

Shall it be overviewed or left as is? Not a big deal, but decided to ask)
May be a distance to the mosfets from flybacks, are a bit higher for it?

https://youtu.be/UwYMtKqMirE
https://youtu.be/moSy942r6xg


texts:
I am trying to understand how convert C code to MIPS code and I have having trouble understanding why the stack pointer( $sp ) needs to be manipulated before and after the procedural code.Isn't the program supposed to automatically increment the stack pointer after every instruction?

C CODE :

int myMethod (int g, h, i, j)
{
  int f;
  f = (g + h) - (i + j);
  return f;
}

If we let g, h, i, j = $a0, $a1, $a2, $a3 and f = $s0 and result = $v0   then, MIPS CODE :

addi $sp, $sp, -4
  sw   $s0, 0($sp)
  add  $t0, $a0, $a1
  add  $t1, $a2, $a3
  sub  $s0, $t0, $t1         #SUB STATEMENT
  add  $v0, $s0, $zero
  lw   $s0, 0($sp)
  addi $sp, $sp, 4
jr $ra

I don't really know why the stack pointer is decremented by 1 word size and then it's value loaded into the f variable, if you look at the subtraction statement you will notice that the value of f is then overwritten by the result of the subtraction so what was the use?


texts:
I have some issues when I start my motrocycle with my Arduino.
When I start my motorcycle, the Arduino loses power or something, but the logs show me that it restarts.
I don't really know why and how to stop it. It's a really simple setup and even if I only just use power to the Arduino and skip P1 and P2 and then start the motorcycle manually the Arduino restarts.
How is it possible to prevent this from happening in this circuit?
If I try a external power supply it works fine, of course.


texts: Proper Spectrum Analyzer settings to match sweep speed to pulsed signal interval

texts:
I was trying to measure received signal level of a pulsed signal (at 433MHz) sending packages of 64 bytes with an interval of 1s. As shown in the attachment, the settings of Spectrum Analyzer are RBW=100 kHz, VBW=300kHz, sweep time=2.5 ms and span=2.0 MHz.

The first problem is the conflict between signal integrity and sweep speed:
When the attenuation got more and more significant (the TX is moving inside a lossy medium), the received signal amplitude got reduced a lot which made it more difficult to detect. That's why I had to broaden the received signal by reducing span and RBW. The result is the received signal seemed to be much "slower" than the transmitted one (which transmitted a package per second). The interval of spikes on SA of the received signal is much longer than 1s. I can't tell if those pulses failed to arrive or I missed them due to I swept too slow.

Derived from the first problem, the second problem is with multiple readings/samplings at fixed intervals:
As I was measuring in a complicated environment, I should take multiple samples of SA reading at each location. And I think I should take the readings with a fixed interval (such as I read SA every 2 seconds or so). However, as the received signal was very "slow" in SA display and didn't follow any periodic norma, I would read many noise floor levelled signals if I read at a fixed interval.

Is any rule of thumb to set the sweep time and RBW so that the above problems could be eliminated?


texts:
I am trying to build the Arduino firmware on Win7 using WinAVR and FLIP. I have successfully built the firmware and have a "arduino-usbserial.hex" file to upload, but when I flash the Uno and plug it back in to my computer Windows no longer recognizes the device and won't use the Arduino drivers for it. If I reflash to the "arduino-usbserial-uno.hex" file that comes in the folder everything works fine. Am I missing a part of the build process? My steps are

set arduino to DFU mode (connect jumper and release)
make clean
make all
manually download with Flip via USB (run, start application, then unplug and plug in)

The makefile has the ARDUINO_MODEL_PID set to 0x0001 and MCU = atmega8u2

Thanks!


texts:
I generally use switching 12V power supplies for my circuits since they are so common, but I understand the 7805 can take a lower input voltage.

If I gave the 7805 a lower input voltage (i.e. 9V), I understand there will be less heat dissipated as it would be a smaller voltage drop. 6V would be even less, assuming my regulator can go that low.

But, is there a disadvantage to giving less input voltage? Performance? More or less noise? And on the power supply side, are lower-voltage or higher-voltage supplies typically better made?

(I've got a 100uF aluminum cap on the input, and 10uF aluminum and 0.01uF ceramic caps on the output.)


texts: Why is Manchester encoding preferred to PIE(Pulse Interval Encoding) for applications were data is transferred through inductive coupling? For transmission of data and power through wireless medium (other than inductive coupling) will PIE be better suited?


texts:
I don't even clear about the differences between crosstalk and interference. Could you explain me please?

I just know that cross talk is the leakage power from other sources, whereas interference is the aliasing signal.

Could you tell me any other differences?


texts: Altium designer: Lock all selected PCB object

texts:
How do I lock all selected objects on a PCB in Altium Designer?

I know about find similar objects but if I need to lock the objects that I've selected manually with the mouse.


texts: How to disable EXTI interrupt under stm32 MCUs with SPL library?

texts:
I need to disable EXTI interrupt under stm32 with SPL. Here is my configuration:
NVIC_InitTypeDef NVIC_InitStructure;
GPIO_InitTypeDef GPIOStruc;
EXTI_InitTypeDef EXTI_InitStruct;

RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA,ENABLE);

GPIOStruc.GPIO_Mode=GPIO_Mode_IPU;
GPIOStruc.GPIO_Pin=GPIO_Pin_4;
GPIOStruc.GPIO_Speed=GPIO_Speed_50MHz;
GPIO_Init(GPIOA,&GPIOStruc);

GPIO_EXTILineConfig(GPIO_PortSourceGPIOA,GPIO_PinSource4);

EXTI_InitStruct.EXTI_Line=EXTI_Line4;
EXTI_InitStruct.EXTI_LineCmd = ENABLE;
EXTI_InitStruct.EXTI_Mode = EXTI_Mode_Interrupt;
EXTI_InitStruct.EXTI_Trigger = EXTI_Trigger_Rising_Falling;
EXTI_Init(&EXTI_InitStruct);

NVIC_PriorityGroupConfig(NVIC_PriorityGroup_2);
NVIC_InitStructure.NVIC_IRQChannel =EXTI4_IRQn ;
NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority =2;
NVIC_InitStructure.NVIC_IRQChannelSubPriority = 2;
NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
NVIC_Init(&NVIC_InitStructure);

I need to disable the above EXTI.


texts: Power Supply negative voltage as ground and ground

texts:
I have a PC PSU and can get GND +5V +12V +3.3V and -3.3V -5V -12V out of it. I need to power a device that needs more than 12V. Am I able to take the -5V as GND and connect +12V to VCC and still use the usual GND as ground?

So I found a solution. I had an other Mosfet Driver laying around so I will use that. My PSU actually has the -5V wire but not the -3.3V so my bad sorry. Thanky you for your answers.


texts:
We as a group have been trying to write an academic essay about advantages of lithium batteries. We have made some research about lithium batteries and found that lithium batteries have high cycle life. This part was given to me. As I have understood, cycle life is a full decharge-charge cycle. But I could not find why life cycle is an advantage of lithium batteries. Would you tell me the exact advantages instead of comparing to other type of batteries?
If there is a free academic source, it would be wonderful.

Thanks.


texts: MOSFETs are dimming my LED lights - checked other threads but it doesn't work

texts:
I'm trying to make an LED strip that I bought off Amazon work with my Raspberry Pi. It works just fine when I connect it through the included adapter which I took apart (shown below):

However, it is a bit cumbersome, so I am trying to connect it through my raspberry Pi instead. From what I could gather, the two big chips are the ones that control the input from the user to control patterns, PWM, varying brightnesses, etc. Since my thing just needs to shine one of three colors, I think I don;'t need them. From what I researched, the three little microchips next to the RGB wires are MOSFETs. I googled tham and found some that could fit on my breadboard, and made sure they were the same logic voltage, the same junction type, etc, etc.

However, when I actually try to actuate everything, including the 12V power supply fed directly into the common line combined with the MOSFET regulated pulse, something weird happens. The lights light up, but with nowehere near the intensity as they do with the PCB it came with. I'm wondering, is tehre something I'm missing? Are the MOSFETs the wrong type?

Here are some images that might help:


texts: How electron movement produces current,instead of having a slow drift speed?

texts:
Just need a clarification here, how the current is produced due to the movement of electrons, in an external circuit,having a very slow drift speed.

Normally in a battery there is high potential terminal and low potential. Using these two terminals the external circuit is closed. Now within the battery the direction of the current flow and the electron flow is opposite to that of the external circuit. If I consider that positive current is flowing from the positive terminal to the negative terminal of the battery through the external circuit then we can say that positive terminal is at higher potential then the negative terminal of the battery.

Now when we are closing the switch of an external circuit, in that case the electrons are moving from negative terminal to positive terminal of the battery, through the external circuit. But we also know that the drift speed is very slow, of the electron. But when we
switch on some of the electrical devices, within a fraction of second the device starts working. If drift sped of electron is low, so how the device is working so fast ,(near about the speed of light,I guess), as we know that current flows due to the flow of the electrons.So how it is possible, in spite of electrons are having such a low drift speed ?

Please help me guys !!!!!


texts: How to clean up high audio noise amplified through a 2x2 electronic switch?

texts:
I have two computers connected through this device:

http://www.audioholics.com/news/press-releases/impact-acoustics-audio-crossplay

to two sets of commercial audio speakers, designed for connection to the computers. (3.5 mm plugs typical to consumer computer sound)

Obviously the idea is to be able to switch the speakers to one source or the other for certain applications but be able to switch them both to one source for other applications.

One of the computers connected through the Crossplay is a MacBook Pro. The other is a largeish "SuperMicro" PC. The signal from the server contains a high-pitched noise in the upper audio frequencies. I haven't put the signal to a counter or a scope but it sounds like it's in the upper audio bands, between 18kHz and 20 kHz if my ear is at all good.

The "Crossplay" itself is powered by what I imagine is the cheapest possible USB-level power supply. Connecting the power supply to different sources, predictably, didn't change the noise on the line. Neither did using different unshielded cables, though the same cables which "had noise" didn't have the noise when connected directly to the MacBook Pro.

Therefore, the noise appears after testing to come from the sound card on the computer. However, since the noise isn't apparent when the speakers are connected directly, they must be getting amplified through the Crossplay.

My EE days are long past. The questions are:

What is the electrical source of the noise? My guess is that since the PC's inner spaces are electrically noisy, the source is the ground plane of the PC. Further, that the very inexpensive and ungrounded circuitry in the Crossplay is part of what amplifies the noisy signal. (My other guess is that the Mac's circuitry is simply better designed, hence, no noise from that source; the Crossplay is still amplifying it but 0x0=0...)

And, how would you filter it? Find a way to ground the Crossplay? Something else?

I'd prefer to just find a way to shield a cable or clamp on some kind of high-pass filter, but I'm handy with a soldering iron and Radio-Shack parts if that's what it takes.


texts: Using an OP-AMP to obtain absolute value

texts:
I want to constantly log the voltage of waveform that is coming off a electromagnetic harvester into a SD card. I wish to use the ADC of an Arduino in conjunction with an SD card to do so.

My problem is that as MCU ADCs cannot measure voltages when in negative form, and because the harvester produces voltages from +6V to -6V, I must create a circuit that can reflect negative voltages as positive. I believe I can do this if i can take the absolute value  of a voltage using op-amp. I do not mind externally powering the operational amplifier. I only want to record the values of voltages coming off the harvester into an SD card.

Please note that I do not mind logging the negative voltages as positives. I only want to calculate the energy across the load of the electromagnetic harvester. Additionally, as the Arduino ADC cannot take in voltages beyond 5V, I can use the simple resistor divider to reduce the the max voltage of 6V to 5V.

I would appreciate if I can be shown how to configure an op-amp to operate as modulus operator to take in the harvester voltage waveform and make a (rectified) waveform. I would also appreciate a recommended op-amp device.

I would like to also mention that by absolute value, i mean the absolute size of a number. That is, we disregard any sign it might have. Example The modulus of −8 is simply 8.


texts:
I want to design a simple LED audio spectrum analyzer kinda like this.

Which method would be less expensive to do:

Use many filters for each frequency band, depending on how much bands and LEDS I want to use
Use a microprocessor to do FFTs

Clearly, doing FFTs will have a certain lag, but would that lag be significant enough to overcome the expensive of the many filters of the first bullet?  Which method would be most power efficient?  Or is this extremely dependent on the hardware?  Any input is much appreciated.  This is the first time I am taking on such a project, and I want to get as much feedback as possible.  Thank you!!


texts: How to eliminate computer noises from audio on shared power supply (12v/5v buck converter)?

texts:
I'm a total electronics noob- I've done a project where I put a Raspberry Pi into an old 80's boombox to offer streaming content. I used a cheap LM2596 buck step down converter to deliver the 5v needed for the Pi. I used this model because I plan to run the unit off batteries part of the time and don't want the inefficiency of a linear converter like a LM7805.

I have my wiring set up just like this (borrowed from another thread)

I'm having a big problem with noise in this system. There is a loud constant buzz (measured 240hz) and I'm also hearing a lot of noise from the computer activity (screechings, etc that time with wi-fi & disk read activity). This all goes away as soon as I remove the ground connection from the LM2596. I tested by using separate ac-dc power supplies for the boom box and the computer and all problems are eliminated. Another point of interest is that bypassing the built in linear PS, and using a 12v wall-wart, greatly reduces the volume of the loud buzz, however the computer noise is still present.

I've come across a couple of suggested remedies-

1) In the thread linked to above it is suggested to add a differential amplifier between the unbalanced audio connection from the Pi to the power amp. This seems to have worked for the OP. With my lack of knowledge in EE, I don't really understand what is going on here or what parts I'll need to build this.

2) Someone recommended I adjust my LM2596 to put out 7.5v and then run that to a LM7805 to minimize efficiency loses while reducing switching noise. I'm just not sure I'm experiencing switching noise so I don't know that this will remedy my problem

3) Use separate power supplies for the Pi and the amp. This is easy enough when connected to AC but much more complicated when running from batteries...I'm open to suggestions.

4) Use audio transformers between Pi and amp. Apparently I will be sacrificing a bit of fidelity and it's rather an expensive option so it would be a last resort.

Any and all ideas welcomed. I'd like to get this device up and running! Thanks


texts: What wattage should I use for a switching adapter?

texts: I have a bad switching adapter. It has a DC output of 14.5V 2.48A Max. I can't find a match anywhere. I think a 3.0 Max will work, but I don't know the wattage. The replacements I've found are 29W, 45W and 60W. Does anyone know which one would work without damaging my device? It's for a Brookstone Smart Projector.


texts: Connecting power cable to device without enabled power supply = battery low?

texts:
Example: Camera or Discman (XP-EV500) with DC power cable:

If I connect the power cable to the device, but the charger is switched off or not connected to the wall, then the camera/discman indicates low battery.

As soon as I pull the powerless cable out of the device, it indicates full battery again.

This does not happen to smartphones.

What is the technical cause behind this effect?


texts:
What is the function of the \$V_{ref}\$ pin for the PCA82C250 CAN controller?

A complete datasheet is available.


texts: Altium Designer : How to make a custom Top paste for D2PAK pad

texts:
I know my way around altium designer but i am not finding a good way to make openings in the solder paste layer for the tab pad of D2pak .
This is what i want :

Altium only allows me to make the paste increase or decrease in size , but it stays a square , so i cannot make multiple smaller squares as the recommended Stencil.
best regards


texts: Solid reasons for switching off mobile devices on air planes

texts:
Recently a flight attendant forced me to shut down my tablet PC for the period of landing the air plane, despite wireless and bluetooth being in air plane mode already.

Questions:

Are there reported cases of mobile devices influencing airborne safety (with or without radio on)?
Can an operating devices in "airplane mode" even hypothetically influence an aircraft?


texts: Impedance matching for wired headphones extension?

texts:
I need some way to be able to lie down in bed and watch stuff on my PC without disturbing people in other rooms.  I have looked into wireless headphones, but am concerned about static issues, having to charge them, etc.  I then began looking into 3.5mm audio cable extensions for my wired headphones.  I am looking at a 12 foot extension cable on Amazon.  The headphones I have now do just fine for gaming, TV, etc. and their cable is about 4 feet long.

Are there any electrical issues I should be concerned with?  I vaguely recall something from a transmissions line web course that I took about the importance of impedance matching to minimize reflections (and thus sound distortion?)...


texts: Band pass filter implementation using 741 op amp

texts:
My assignment for a school project on Circuit Theory, is to construct a Band Pass Filter at least 3rd order with a stop band around 20kHz.

First things first, I need to design the circuit. I have to use a 741 op amp but after I searched a ton of stuff on the internet, I didn't find any implementation that qualifies these meets. Could a combination, of a 3rd order Low Pass Filter and a 3rd order High Pass Filter, give me a 6th order Band Pass Filter?

I also checked Analog Filter Wizard, and after I inserted the desirable settings, it gave me the circuit with all the components but 741 op amp isn't available. What direction should I follow?

Thanks in advance.


texts:
I am trying to understand What happens when the Electrolytic caps fail at the input terminal of a charger? What about at the output of the bridge rectifier?
These two caps below are rated 100uF @ 200V.
The input is 115 AC, 60Hz.
These caps are currently bad, you could see that they already have vented. They're measuring low, ~ 32uF instead of ~ 100 uf and the ESR is higher than normal. That means it will heat up more than usual due to the higher ESR and it will allow for more voltage ripple. Is that enough to cause the charger not to work?

Then there is another film cap (Polypropylene) at the output of the bridge rectifier. The Fluke refused to read it, it kept saying OL. It's estimated to be 39nF (I compared it to a similar film cap of it's size) It apparently also failed.
I am trying to understand if this cap failed how would it affect the rest of the circuit?

Those are the only damage to the board, mostly cap failures.
Do you think If I replace them the charger will go back to normal?
I would appreciate good feedback. Thank you


texts: Understanding flow of current from diagram using AND gate

texts:
I have a question about current flow in the diagrams below, which are from my textbook. I'm in a class called "digital logic" and we are using a zyBooks.com textbook, and it's HORRID, and we are getting no help from the professor right now.

My question is why current flows from the top in the first image, and then it flows from ground in the second image? All the book ever says is that it flows from a point of high-voltage to a point of low-voltage.

Thank you so much!


texts: how to calculate hysteresis resistor value TL431

texts:
I'm creating a small ESP32 based robot controller board. Partially as a self learning experience (mech engineer, self taught on eletrical front but this is for hobby use :P) and partially because it needs to a fairly bespoke collection of motor, servo and ESC outputs.
On the power mangement front I will be using a 2S lipo battery. The intent of the circuitry below is to provide a physical method to turn power on/off (SW1), provide a low battery power cutoff circuit (using TL431 and Q1) and to provide 5v supply for the servos and the controller.
My main questions are around the low voltage cutoff circuit but i've included the rest for context and in case you fancy letting me know i've done something wrong there also!
So for the battery cutoff circuit I have done the voltage divider calculations such that at the cutoff voltage (7.4v for a 2s lipo is the lower limit of safe discharge based on my research) the reference voltage entering the TL431 is 2.5v in line with it's internal voltage reference. I've simulated this on circuit lab and it seems to work well. My issue is that in the real world there will be some hystersis issues around the 7.4v value - I have found that you can add a feedback resistor (R4) around the TL431 but I can't for the life of my find a guided explanation of how to calculate that value such that i have a lower cutoff limit of 7.3 and a higher cutoff limit of 7.4 creating an effective band to prevent the circuit from flipflopping due to some noise or minor fluctuation in battery voltage.

edit 1 - first attempt at re-drawing the schematic for the TL431 to make it easier to read. bit confused by V+ and Vout in diagram provided in comments. In my head the Vout side should come from the battery so that the voltage divider always provides a reference to the TL431 but Vout notation to me sounds like that should be the voltage out of the IC? Also i swapped it to a P type transistor as per diagram - think the original schematic used an N type and a pull up resistor to reduce current drain?

Edit 2 - Took advice and instead of copying the circuit i tried to re-draw my original one. added some notes to help show my understanding of what each bit is doing. I'm a bit confused how the feedback resistor R8 works and doesn't just allow reduced flow through the circuit? I guess the super high resistance value (just used what was on an example i found online - here) causes a big voltage drop.

Edit 3 -
Hi all - I think i got my head round it this morning. here are the calcs i did to set the resistor values!


texts: how much energy is required to create a sound with constant frequency and amplitude?

texts:
Ok, this is a theoretical question, (Forgive my poor English, I am not a native speaker).

Lets assume that I have a power-source with p unknown.
this power-source provides energy to a speaker to produce a sound with constant frequency, f, and constant amplitude, a, given in decibels.

We also assume that all of the energy goes to create the sound (there is no heat or other "noise" disturbances).

So the question is - what is p?

(to simplify the question - I know that the sound is 60 dB with constant frequency - lets say 300 hrz and I need to know how much power I need to provide to the system for that to work)

Thanks a lot.


texts: Precision Rectifier Circuit to detect peaks

texts:
I have a question about speed at detecting peaks.

Essentially, my question is that I have a precision rectifier with a capacitor equipped to the end of it to smooth the incoming full bridge
rectified wave, which works 100%.

however I am concerned, as the application is to play audio through this and capture the current peak. I am worried that the peaks won't be captured in time as audio changes very quickly worst case 1/20kHz.

I understand I need a resistor to discharge the cap so it can change on the next cycle, however when I put a low value resistor (For a faster discharge time) it doesn't reach my peak value anymore oppose to using a big resistor or no resistor which is important as the next stage is a comparator with a fixed Vref to compare to.

How do I balance this? I need a resistor value that can discharge the capacitor fast enough for incoming music in order to capture the peaks of that instant moment. Or is that the trade off?

simulate this circuit – Schematic created using CircuitLab


texts: Identifying a 6 pin and a 18 pin WSON IC

texts:
I have a couple of the following ICs, which I suspect to be some DC/DC converter possibly form TI, but I could not find the exact part number. It is a 6 pin, WSON package IC with a thermal pad.
The top says:
48D6K
L197B

The other IC is a 11 pin QFN one where 8 pins are GND and connected to a thermal pad. It is also suspected to be some kind of DC/DC converter from TI.
The top says:
SBL
TI 481
A052

T1 or TI I am not sure.

Both ICs were acquired about 4-5 years ago.


texts: Amplify square wave signal generator output to high voltage?

texts:
Let’s say I use a signal generator to create a square wave and then want to transform it into a high voltage of, say, 5 kV.

How can that be done? Are there transistors that can handle that kind of voltage? I already have a source of high voltage. How in principle would a circuit look like?

The frequency is relatively low, only 10-1000 Hz perhaps. I don't know the current, but it will be used to generate (highly ionized) plasma between two Tungsten electrodes in deuterium gas, at a pressure of 1-1000 mBar.

Can this be done with some ultra-simple setup with only a few HV-transistors? And a source of HV, of course.


texts:
I am trying to control a galvanometer that requires +/-5V input voltage, my source is a 14Bit DAC (LTC2612) that I control via an Arduino. I use a +/-15v powersupply to power the galvanometer.

What would be the best way to convert the output of the DAC to suite the input needs of the galvanometer? I have a LM358 dual op-amp if that is a way to go?


texts: How can I reduce the size of my PCB without losing features

texts:
I've created a small circuit board that consists of a 4093 IC, a 4013 IC and a BD 233.

I have a hall effect sensor ive tagged onto the end of the board which im not too concerned about.

As you can see from the images I have a lot of wires connecting these 2 components together. Some of which are connected to the same pins. My question is how can I reduce the size of the overall footprint?

I obviously cant shrink the components, I figured I could save some space by reducing the wiring but I just cant figure out how I can "remove" the wires without... well removing them altogether.

Its a shame there doesnt seem to be any software out there that automatically works out the wiring for me given my instructions.

I had a go on fritzing but it was actually counter productive.


texts:
Why do we also use magnetometers when building IMUs, that is why don't we simply and only use gyroscopes and accelerometers?

I also would like to know how does a magnetometer work as a 3-axis device?

Furthermore, how are the three sensors working together?


texts: Drive a VU meter negative from "0dB" to show compression with VCA compressor

texts:
I have a simple VCA compressor based around the THAT 2180 VCA. http://www.thatcorp.com/datashts/dn115.pdf
I would like to use a standard "VU meter" to indicate compression, but work in "reverse." Meaning, the VU meter rests at "0" then moves to the left/negative to show dB of compression. (If you are familiar, this is how compressors like the 1176 indicate compression.)
Somehow bias the meter to "0dB" Then subtract the Sidechain signal from the Meter bias?
The answers I have gotten provide good info. Any circuit ideas or schematics?


texts: how to see dc operating region names in cadence DC annotation for MOSFET

texts:
How do I see the operating region names like "active, saturation" in cadence for MOSFET.

I remember getting it by setting up View> DC annotation> Setup > selecting DC operating region > Display > region.

But Now I am getting the region displayed as numbers "0,1,2"

Can someone please tell how to get the operating region names?

Thanks


texts: Controlling a 3 phase BLDC motor with an absolute magnetic encoder

texts:
I am working on a project where the motor controller needs to be rewritten because it's not behaving properly (the motor is vibrating too much and tuning its parameters is close to impossible). The person responsible for the controller is not able to work on it so I am left to fix the problem.

To be noted: In feedforward the motor works perfectly fine.

We are using a modified 3 phase BLDC motor with a custom power drive with 6 MOSFET's driven by a DVR8301. The PWM generation code-side works fine (FF works). The feedback loop is broken, however.

For the encoder we are using a RM08 encoder by Renishaw. It's a 12 bit absolute magnetic encoder.

My question is what the fastest way is to get this motor controlled with a closed loop. I want to use a velocity control.

The motor is controlled using a Zynq SoC with code written in C++ running at 20kHz interrupts. However, I have everything hooked up to a speedgoat over EtherCAT so I can read and write data at 10kHz over simulink real time as well. If I can get a working principle in Simulink I can translate that to code easily.

Below I have attached a schematic of the inputs and outputs.

The PWM is calculated based on the magnitude. The angle is what we are using in the feedforward controller. We increment the angle by 0.9 units and subtract 360 from it if it gets over that value (to prevent overflow).

My idea was to use a simple p-gain controller where the velocity setpoint is by how much the angle is being incremented and the output of the system would be the magnitude. The magnitude will have to increase to accommodate load on the motor, hence the velocity controller.

So in conclusion, I would appreciate some guidance on how to create this motor controller


texts: Polarity of input signal and capacitor in voltage clamper

texts:
I am stuck at understanding how voltages add up in a voltage clamper, reading through Learning About Electronics - Diode Clamper and All About Circuits - Voltage Clamper, and also YouTube a few tutorials. If I have a simple clamper circuit with an AC input signal series with a capacitor and parallel to a forward or reverse diode and a load, after the first positive part of the input cycle charging the capacitor, once the diode is forward biased, the polarity of the capacitor's voltage would always be opposite to the polarity of the AC input signal (hence, DC-AC instead of DC+AC). The clamper circuit should shift the output signal horizontally through time, instead of vertically on the voltage.

Take the image as an example of a positive clamp circuit:

After initial positive input signal, input polarity reverse and capacitor is charged in the negative direction, thus voltage negative to positive from left to right
Input signal goes positive again but capacitor is charged in the opposite polarity and would cancel out instead of adding up the voltage

Clearly I am mistaking somewhere in the voltage clamper and hope someone can clarify.


texts: Correct representation of 1011 mealy state machine?

texts:
I have a little confusion i want to detect 1011 in my mealy state machine.
the correct graph is shown below.

My Confusion is what would happen if i stay at state S3 instead of going to s1 when i get a '1'.

what i think is that the output will be
input=  101111111
output= 000111111

Until S3 i have detected 101 so when another 1 will come i.e 101 is it going to go back on state 101 and outputting "1" every time
Am i thinking right?


texts:
I'm studying Bob Parker's ESR Meter Mk2 and got caught in a part of the circuit that he calls pulse amplifier, which schematic I copy below:

Figure 1: Bob Parker's ESR Pulse Amplifier

As far as I can tell, the meter submits the capacitor under test to short pulses of constant current that will create a voltage across the cap terminals that is proportional to its Equivalent Series Resistance (ESR).

That voltage (of about a few tens of mV) is then input into the so called pulse amplifier of gain 20. See the explanation copied from the text.

  The current pulses developed across the test capacitor are fed via C7 and R12
  to a fast non-inverting pulse amplifier based on transistors Q7 and Q8. These two transistors are wired as common-emitter stages, with feedback applied via R17 to give an overall gain of about 20, depending on the setting of VR2.

Well, I'm not satisfied. The explanation was a bit too economical for me. So, my question is:

How does this pulse amplifier work?

I'm a bit familiar with using OpAmps to amplify signals, but I have no idea how this circuit above does it's tricks.

Simple Google searches using "pulse amplifier" as keywords have not been helpful as I get directed to very different kinds of circuits.

To be able to see the signals on my oscilloscope, and maybe clarify things a bit, I went ahead and built the circuit in a breadboard. I fed it with a 10kHz square wave from a signal generator (yellow trace) and the result was the following scope shots. The green trace is tied to the PULSE SIG MCU input as shown in the schematic.

Well, that was even more puzzling as the input pulse doesn't seem to have been amplified 20 times as I was let to believe it should have. Also, I seem to be getting a short spike when the input signal goes down. Is this output expected from the pulse amplifier or is my circuit messed up beyond salvation?

Update

I did scrap the breadboard circuit and built it again, fed it with an 8us pulse at 2kHz, just like the circuit expects it (like in Spehro's simulation), and got much better results. See scope shots below.

Apart from any circuit errors, I did seem to be overdriving the amplifier both in input voltage and in duty cycle. Now it seems to be amplifying the pulses alright.


texts:
In a plasma application (Helium or Argon Plasma), we would like to measure the current. The voltage is around 10kV AC and modulated with a function generator.

Currently we only have one of those rings that you put around the cable, but I read that those only work for high-ish amperage >1A. While using this device, we get an output of around 12mV peak to peak, put I think that this is very inaccurate.

Is there any cheap way (we are students) of measuring the current more precisely? Preferably without killing equipment and/or operators :)

For a low voltage circuit I would use a high accuracy resistor and measure the voltage drop across, but I think that this is too dangerous in such high-voltage applications.


texts: What is the name of this crimp connector? It looks like a spade connector (female) with a missing tail. In the picture, it used to attach a thermal fuse. Does it require a special tool to install? Can you make your own by repurposing a spade connector...


texts:
I have an ICs which has an operating voltage range from 3.35V up to 4.5V. It typically needs a 20-milliamps current but it can have 1.9-amps current peak. Moreover, my system will work with a battery and I therefore must keep the input voltage as little as possible. I do not know well the field of voltage regulators; I thought of using a classical linear voltage regulator or an LDO, but none of them seems to fit my need. Which kind of voltage regulator would you suggest for the above-mentioned design?

Thanks!


texts: How to start LED wirelessly in a very compact and cheap module?

texts:
I have been thinking and researching about this issue for a while with no success. I am hoping someone can solve this problem in the community.

I want to have many small modules each with a small battery and LED, not connected to anything else.

I need to be able to arbitrary turn an LED on (no need to turn them off). For example I want to send a command to LED no 10 and turn that specific LED on.

Imagine a number of wireless relays, but with the constraints that each system has to be very low power and very compact (and ofcourse very cheap).


texts:
I have a test board with 2 audio chips: WM8533 and AK4954A.
Their outputs are connected to headphone plugs like that:

WM8533 -- R------ headphone1
              |
              C
              |
             ///

AK4954A --------- headphone2
            |
            C
            |
            R
            |
           ///

So, the first one is a classical RC filter.
But what is the second one? I guess it is also a low pass filter,
but why it is different? I googled for RC filters,
but all examples and tutorials only explain the first circuit
and nobody mentioned the second one.
Do you know the different and advantages of one vs another? Thanks


texts: How to calculate the required battery capacity for audio system

texts:
I'm converting audio speaker to run on batteries.
the speaker is Stagg SMS 8p - RMS 90W, peak power consumption 200W which is consistent with 1A fuse for 220V.

Say I go with 12V battery - peak current would be under 17A. If I choose reasonably priced 20C Li(Fe)Po modules -> I can get this current from relatively small 1Ah battery.

My question is -- if I set the volume to maximum non-distorted level -- how much time would I get playing 'typical' music.
Preferably advise a software to which I can feed my playlist and get peak-to-average power ratio.


texts: Store consecutive UART inputs to register

texts:
I have implemented a UART receiver/transmitter (8-bits) in VHDL for use on a Digilent Nexys 3 FPGA. So far I have managed to read inputs in a FIFO, process each byte individually and write the output byte-by-byte to another FIFO for transmission.

What I ideally would like to do is read the consecutive inputs from the UART module in a std_logic_vector register instead of a FIFO. The number of inputs I am working with is always constant e.g. 4 inputs x 8 bits each = 32 bits. It would go something like this:

inputs in hex (not ascii - sent with e.g. RealTerm): 01 02 03 04
my_reg std_logic_vector(31 downto 0): X"01020304"

I have considered reading out the values of the input FIFO to a register once the FIFO is full, but that would waste resources on my board for the FIFO. Is there a way to do this on the fly, as the UART input values come in?


texts: How to de-couple DMX512 with opto-isolators?

texts:
I'd like to build a DMX512 device.

The problem I have is how to decouple the device from the bus. I decided to use opto-isolators, but how should I wire the diode part of the isolator?

Since I need TTL/RS232 levels on the controller side, I'm using either a MAX485 or ADM485 to convert the RS485 levels (DMX512 is just an implementation using RS485) to TTL/UART levels.
But where and how should I use the opto-isolator? Before or after the MAX485?

I was thinking before, right at the bus, but I'm not quite sure how the circuit should look like.

The device is only supposed to receive, not send to the bus.


texts: Need help understanding a rotary encoder datasheet

texts:
I am trying to design a keyboard and have come across the realization that the datasheet for my rotary encoder asks for 5k resistors connected to terminals A and B of the encoder.
However I am having trouble understanding how the encoder should be wired.

Should the terminals be connected to power as well as specific pins like this?

Or would the pins provide the power for the terminals and all I have to do is connect the resistors to the wire connected to the pins?

The datasheet schematic for the component is:

The micro-controller I am using is the AT90USB646-AU in case that is some info that is needed as well.


texts:
A 3 phase wye-connected, 115 V, 400 Hz generator is used to power a test stand in which a motor controls a wiper arm that operates a three phase Variac to control the voltage across each of the phases. A DVM is used to measure the voltage across one of the phases with respect to earth ground.

The problem is that at the end of a test, the computer controller activates the motor to bring the phase voltage down to 0 V, but the meter measures 3 to 7 volts ac. This causes the test to fail.

The neutral doesn't appear to be connected to earth ground. A resistance measurement between the neutral and earth ground gives about 500 kohm.

Any insight as to why there would be such a high resistance between neutral and ground and what I can do to eliminate the residual voltage being measured from the meter?


texts: Approach to prevent Replay and spoofing attack on CAN protocol

texts: I want to make an authentication system between 2 buses. In order to achieve that I use counter to avoid replay and hash to avoid spoof. The message must be sent in two phases. Is there any proper way to receive back to back messages like A-B without someone adds other, or similar message like A-B'-B ?


texts:
I've been using a free software stack for AVR programming - AVR GCC + avrdude on Linux, with parallel DIY programmer cable.

Since the parallel bitbang programmer doesn't work with USB printer cables, I'm stuck with using my desktop PC.

Is there an USB-based programmer that can be supported by a free-software (command-line based) programming tool?


texts: How can I reduce noise from an analog signal from an Arduino?

texts:
I am trying to read an analog signal from an Arduino board through LabVIEW.

The sensor is an infrared phototransistor, which I have connected in reverse bias (20k resistor) to an Arduino pro mini analog input. The power and ground for the sensor are taken from the Arduino.  The Arduino is then connected through an FTDI breakout board to a COM port, which I am reading through LabVIEW.  I am able to view the signal on a waveform chart, but it is incredibly noisy.    Instead of a single line of data proportional to the light received by the sensor, it looks like the chart is "colored in" completely underneath the signal.

Previously, I read the sensor data directly from a DAQ card without any additional circuitry and got a great signal.  Do I need to add something, like a capacitor, externally to remove this noise?  I am a mechanical engineering student, so I'm learning as I go with the electrical side.


texts: Help regarding Ac current limiting using resistor

texts:
I've 12v(Vrms) 1A  AC transformer. I need to regulate it to 1to 4ma maximum output without having much voltage drop.
Output load is an animal skin which has resistance in it.

Can I just use a resistor in series?
When I used 560Ohms, more current is passed through my hands.
Anyway to calculate currect resistor values,?


texts:
Power calculation from E and H field

Following from the previous post above. The user provided me with some assistance however I am still a bit unclear on how to apply the equations provided. Could someone please assist me in determining if the way I calculated the power received from the RFID tag is correct?

Ex = 0, Ey = 0, Ez = 149 (V/m)

Hx = 0.06, Hy = 0.834, Hz = 0 (A/m)

S = E X H = (-124.27 ; 8.94 ; 0)

|S| = 124.59

P = Aperture area x |S| x cos(theta)

P = 0.013539 x 124.59 x cos(38.54) = 1.32W

The aperture area is 0.013539 meters^2.

The angle was calculated using the picture attached. Is this the correct way of calculating the angle?


texts: Finding replacements for these "big grey" resistors in a circuit

texts:
I have a resistor that I need to replace that looks like this (4 color band resistor that is significantly bigger than the others) :

If I can read the colours correctly (brown / black / gold / gold) this should be a 1 ohm resistor, but it is considerably bigger than the normal resistors.

Is this due to it being a higher wattage ?
Can one somehow derive the wattage by looking at the size of this resistor ?
Does the fact that it is grey also mean anything ?


texts:
I am looking for recommendations for a cheap (~$20) force sensor that can handle up to 10kN in one direction.

I've looked at a few, but most components saturate at about 100-1kN.

EDIT:

For the application I am looking at, it would require a polymer film type sensor (e.g ~0.5mm thick)

The application will monitor (and I use the word lightly), "impulse" forces. So large forces for very short contact times (0.1s - 1s). I realize this would probably put this kind of sensor into a precision component category, but hoping for some unique solutions =)


texts: How to find out Packet Loss in a Broadcasting environment

texts:
Indeed packet loss is an important metric to use when comparing different communication protocols.

To me it is understandable how one would computer Packet Loss in a unicast transmission. Simply the ratio between the number of sent packets to the destination node vs. the number of received packets by that destination node.

But, how would one compute Packet Loss in a Broadcasting scenario? There is no specific destination. The packet is received by everyone. How to handle such a case?


texts: Switching Serial Connections among several devices?

texts:
I have 3 devices that communicate via a serial port. Let's call them Device 1, Device 2, and Bluetooth (BT to serial adapter). The BT is used to communicate with a computer, but it can be treated just like a 3rd device for the purposes of the question. There are 3 modes I need this setup to function in. Mode A would have Device 1 be connected to the Bluetooth, Mode B would have Device 2 be connected to the Bluetooth, and Mode C would have Device 1 and Device 2 connected to each other. Please see attached image for a diagram to make things clear.

I can switch between modes with a 3 way switch or a button. What I am looking for is a way to switch between these 3 modes. I have considered just using a mechanical switch, but given the number of connections, and considering that my final project needs to be very small, this is impractical.

My ideal solution would be to use some kind of IC that would allow me to foreword a serial signal from one pin to another, depending on the mode selected, or a set of transistors that would allow me to switch between different modes. But I am completely open to any other, better, solution.

Any help or pointers in the right direction would be very appreciated. Thank you!


texts: Sizing Through-hole Vias for Power Traces

texts:
I am trying to understand what size vias I should use for my 5V power traces.  The trace typical runs at 0.5-3 amps and is 2mm and about 150mm in length.  The width is huge, but I do have the extra space and I'd like to have as little resistance as possible since I am using a battery.  The power traces only navigate the external layer of the PCB, no inner layers with poor heat transfer used.
But my design software's default via is 0.8 diameter and 0.4 via drill.  Should I expect a voltage drop across the via.  How will the resistance of this size via compare to my trace's resistance?
Edit: this is a 4 layer PCB, with 1 oz copper weight.  Here is a link to my PCB board manufacture's capabilities: capabilities


texts: when do you need to use a power distribution block in your schematic?

texts: So i am fairly new to industrial automation however i have noticed a trend in quite a few schematics which have more than one 3 phase motor involved and the power distribution block is always there. So am i safe to say that when you have more then one motor involved you need a power distribution block?


texts:
I want to know for how long would it be possible to run a wireless sensor reading distance data and sending them to another station (up to 100 meters away) every 5-20 seconds (i know the time would calculationbe also essential) on a 1000 mAh battery.

I don't know how big would be consumption of such a circuit nor how to count it. Even if its possible to send data for such a distance if it wouldnt be clean visibility.

Thanks for any approximately estimates


texts: Electrical isolation in PLC output cards

texts: Every output card spec sheet I read says something about electrical isolation. One I read recently said "Isolated 1500VDC channel to channel". What does isolation mean and what advantages do isolated output channels have over non-isolated channels?


texts: Processing SPI transactions using interrupts

texts:
I'm wondering what the best way to handle SPI transactions when using interrupts is.

I'm  about to write my SPI interface code to an external flash part using a PIC.  I'm going to use interrupts and I know that I'll get one after my byte is transferred, and after one is received.  A typical 16 bit write transaction will look like this:

REGISTER_ADDRESS_BYTE | REGISTER_ADDRESS_BYTE | DATA_BYTE | DATA_BYTE | MAYBE_MORE_DATA_BYTES

Typically what I do is have a function like this pseudo code:

SendBytes(num_bytes, *ptr_to_bytes, address, init_true, callback_function_address);

Then in my SendBytes(...) I have a state machine with two static variables, one keeps track of the state, the other keeps track of the number of bytes sent.  As interrupts come in I call SendBytes(...) again with init_false and step through my state machine for each byte of the transaction.  When I'm all done I either stop or call the stored call_back_function.

My question is this a decent way to handle this, is there a better way using interrupts?  I just made this up thinking about the problem but I assume others have had to handle this as well.


texts: Under what conditions can Vbe exceed 0.7

texts:
I am simulating a transistor switch in PSPICE. The goal is to switch a load (like a lamp) connected in the collector on and off. Imagine that in the place of the R2 resistor there is this aforementioned load.

I understand that the smaller the R1 resistor the deeper in saturation I drive the transistor which is preferable. But how small can R1 be? In simulation I am observing that Vbe can get a lot larger that 0.7 volts and Ib is getting large as well. Is this dangerous? Are there any governing equations for Ib and Vbe in the schematic topology I am using?


texts: LPC1343 when connected to PC acts like a mass storage device.How can I upload code to the microcontroller.Is there any IDE which converts the C program to .bin for uploading the code?If so,please tell me the IDE names.


texts: Run a 5VDC 0.2A fan from a 24VDC 3.75A power supply - Help Needed

texts: I am working on a project that is using a 24VDC 3.75A power supply and would like to have a small fan (5V 0.2A) to cool the amplifier and switching circuits within an enclosure. Could someone help with a solution to this, is it as simple as a voltage divider?, if so what size resistors would I need, thanks in advance.


texts: Unity negative feedback controller, why does Gain K go on the numerator of the transfer function

texts:
I have a system G(s). It has no zeroes, but some poles.

When applying unity negative feedback, with a static gain K, why does K remain on the numerator of my transfer function T(s) which describes the whole closed loop system?

If I have no zeroes, Z(s), then surely K multiplied by Z(s) is 0? But it is K.

In addition, in the denominator, there is another term that is again, K multiplied by Z(s). No zeroes, but this term simplifies to K, and not 0.

I understand that Z(s) is a function, and normally takes the form (s+3)(s+1) or something, but if there are no zeroes, can someone explain why K remains on the numerator?

Thanks


texts: For a PCB design, with ESP8266 I wish to use HiLink 3v3DC as a power source. Since I design PCB I wish to know if a good practice is to add capacitors for increasing power stability to ESP port? if the answer is "YES" i'll be happy to know what are the consideration for type&size.


texts:
I am using an Easydriver v4 to drive a bipolar stepper motor. The Easydriver works fine, if I wire it up and manually toggle the step pin to 5V/GND it steps as intended.

Now I connected both the step and the dir pins to my Arduino. The problem is that apparently the Easydriver pulls 70mA through the stepper pin (which exceeds the maximum current of the Arduino) in turn making the voltage drop to about 2V instead of 5V. The consequence is that the motor does not step when controlled by the Arduino.

I wired everything up just like in the image below:

I both tried powering the Arduino through USB and from the 5V current that is conveniently supplied by the Easydriver.

Any ideas what I might be doing wrong?

Edit:
I just discovered that the behaviour is the same whether or not the EasyDriver is powered or not. Do not know if that makes any difference ...


texts: Compute for resistance (Resistance circuit)

texts:
Hi how do you solve this problem? I am confused.

simulate this circuit – Schematic created using CircuitLab

Find \$R_{AB}\$, \$R_{CD}\$, \$R_{EF}\$, \$R_{AE}\$

I came up with this:
\$R_{A-B}\$ = 1 \$\Omega\$ ,
\$R_{C-D}\$  = 4  \$\Omega\$ ,
\$R_{E-F}\$  = 7 \$\Omega\$ ,
\$R_{A-E}\$  = 2 + 5 = 7 \$\Omega\$


texts: How Simulink determines the amplitute of the carrier in PWM generator

texts:
In Matlab/Simulink, we can use the PWM generator block in order to create pulses.
So, according to this method, the carrier is compared to the reference signal in order to create the pulses.

In order to do so, as you can see in the picture below, the PWM block requires the carrier frequency but not the carrier amplitude. I can not understand how the carrier amplitude is calculated.


texts: What is the meaning of "Sine wave energy per pulse" when referring to thyristors?

texts:
I am looking at the datasheet of a Westcode thyristor (specifically, the  R3968), and it has the following graph:

I am wondering if someone can explain to me what the graph is showing me! I don't understand the meaning of "sine wave energy per pulse."

Thanks a lot!


texts: CANbus to USB adapter, is optical isolation worthwhile?

texts:
I have a motor whose driver board communicates via the CAN protocol.  I need to programmatically command the driver board from my laptop computer using CANopen.

I am looking into buying a USB to CAN adapter.  I came across this article: USB-to-CAN Adapters connect CAN bus devices to PC., which suggests two potential adapters:

USB2-F-7001
USB2-F-7101 (adds optical isolation between CANbus transceiver and CANbus controller, costs $100 more).

(Source)

I am totally new to CAN.  I am wondering:

Is this optical isolation necessary?
Am I really putting my computer at risk by not optically isolating it from the CAN bus?

Related Questions

Does CANbus need to be isolated?

Suggests it may not be a big deal, if the motor is well grounded.  However, it's not specifically for the USB-to-CAN adapter, so I am asking it explicitly.


texts: How can I wire this 6 pin pot to control a speaker and LED. I know how to wire up normal circular potentiometers, and I feel like this pot may be broken, but how can I tell?


texts: 9 (7.4v) Li-ion rechargeable battery maximium drain current?

texts:
Battery such like these:
https://www.amazon.com/gp/product/B078JMHHF8/ref=ask_ql_qh_dp_hza

I found no official information about continuous discharge rate.

Li-ion should have a large discharge rate (10C), however, I have heard otherwise for these "9v" Li-ion batteries (0.5C?)

Have anyone tested the maximum discharge rate for these? If it is truly 0.5 C, then why? (being Li-ion, shouldn't it be 10C?)


texts: Why load in NPN transistor switch are located in collector circuit?

texts:
I make a simple transistor switch. I read the theory and in many sources I saw that load (with NPN transistor as a switch) are connected to collector circuit, not an emitter circuit (pic.1, for example).
Why load aren't connected to emitter circuit?

This is my circuit.


texts: Safe connection of a 4pin Fan to an Arduino

texts:
I'm aware that a very similar question has been asked here before:
https://electronics.stackexchange.com/questions/91015/how-connect-a-4-wire-fan-to-arduino-and-control-the-speed

However, upon checking I have been getting mixed feedback and I have the impression most of it comes from the fact that most people do Fan Speed Control via 2 pins only and expect transistors. So I decided to ask here in hope for some further information.

I currently have my Arduino powered via USB and separately my 12dc Fan with it's own power supply. They share common ground and the PWM line from the fan is connected to the Arduino boars. Nothing else in between (no transistors, resistors or diodes).

It is working correctly, but I haven't had it running for long in fear it may be unsafe.

Should I be concerned about the PWM line connected as such? Can the 12v from the Fan's PSU damage the Arduino with this connection?

Upon research, it seems the PWM line has a 5.25V Max voltage. I'm not entirely sure, but am I right to guess that is the max Voltage that will go through that wire?

I do agree that a diode around the fan is a good idea and will definitelly add that.

*Edit: Thought I'd clarify that I'm using this setup to change the speed of my fan.


texts:
We have a feedback system F(s) as in this figure:

and this is the step response of G(s):

and H=10.

F(s):

We got the root locus of the system F(s) as this:

then we determined the gain at marginal stability:

which is equal to 2.5.

Then, we made H = 2.57 (slightly larger than 2.5) and we obtained the step response of the new system Fh(s). Here is it with the step response of the original system F(s):

Then, we made H = 2.43 (slightly lower than 2.5) and we obtained the step response of the new system Fl(s). Here is it with the step response of the original system F(s):

My questions:

What can we know from the step response plot of G(s)?
What can we know from the step response plot of F(s)?
When we changed the gain to 2.57, how did the system F(s) change? What can we conclude by comparing the step responses of F(s) and Fh(s)?
When we changed the gain to 2.43, how did the system F(s) change? What can we conclude by comparing the step responses of F(s) and Fl(s)?


texts:
I am asked to find the current through the second diode, as shown in the image below.

I have gone through my procedure to find this current, and can not figure out why my answer is wrong.

What I did is as follows:

I assumed that both diodes were conducting. I then checked this assumption by seeing if the current through diode 1 and diode 2 is greater than zero.

current through diode 1 = (12 - 0.7 - (-0.7) - 4) / 4000 = 2mA (which is greater than 0)

current through the second resistor = (4 - 0.7)/ (1.3 x 10^3) = 2.538 x 10^-3 A

And by KCL, current through diode 2 = 5.38 x 10^-4, which is greater than zero.

I appreciate your help and time,

thank you very much.


texts: Help identifying CSUN solar cell and how to use it (preparation, setup etc.)

texts:
My brother has come into a pallet of solar cells that I can't identify exactly.  They seem to have both sides covered so I'm unclear how they are supposed to be used. Getting a lot of false positives in my searching as I'm unsure exactly what to look for.

Here is the packaging it came in.

Here are images of the cell itself.

I guess what's confusing me is why it's coated in white on both sides. I would guess the side with all the small white lines is what you are supposed to connect to?

Does it look this way because it's not laminated to anything yet? What would the process be to get them usable? Does the coating need to be removed somehow before they can be used?


texts: how to gather data of voltage and current produced by a solar panel when inside freezer

texts:
I need help with figuring something out for my Science Fair. I need to test Solar Panels in different temperatures, and I need to test a solar panel's current and voltage inside a freezer. Is there any way I can take my experiment out of the freezer and see the voltage and currents produced by the solar panel when it was in the freezer? I can only use a multimeter (any type), my solar panel, and my freezer.

Proposal for experiment:

  Warming Up To Solar Panels

  I will investigate the effect of different temperatures on the
  efficiency of a solar panel. My project helps the environment because
  this may make solar panels a more efficient energy source, so it can
  replace non eco-friendly energy sources that are going to run out.

  The experiment is testing a solar panel at different temperatures,
  using a metal plate, ventilation, a freezer, and a fan to adjust
  temperature. I will carry out the experiment by building a structure
  for the solar panel to rest on, which incorporates the factors
  mentioned above (fan, etc.). A lamp will be the source of light. I
  will be using a new 40 watt incandescent light bulb for each test.
  From research I know that this light bulb will produce 450 lumens. The
  metal plate will start at 30 - 40 ° Celsius, with ventilation around
  25 - 30° Celsius, with the fan it will go down around 15 - 20° Celsius
  and I will set my freezer to -18 - -25 ° Celsius. I will be recording
  temperatures with a thermometer. The control variables are the solar
  panel and the lumens on the solar panel, the dependent variables are
  the voltage and amperes from the solar panel, and the independent
  variable is the temperature. I will repeat the temperatures 3 times,
  and take these 3 measurements for each temperature and average them
  out to reveal a trend.

  The materials I will need are a solar panel, a voltage meter, a
  infrared thermometer, a heating bath, an ammeter, a fan, a metal
  plate, LEGO bricks, a lamp a freezer, a thermometer. I will need 3
  weeks for completing the experiment, 3 weeks for research, as well as
  2 weeks to complete the write-up.

  (google doc version)


texts:
Let's say I have a regular motor circuit using an arduino. The motor is a standard motor with a motor controller and I connect it to my arduino and get the code working but I realize that the motor is going a little slow.

If I add a transistor to the circuit the right way, does that make my motor run faster or does it not have any effect at all?


texts: To blow or not to blow on the joint, that is the question

texts:
In a certain Electronic Physical Design book, we're advised that, after soldering:

  Do not blow on the joint, as this will cause the solder to cool too rapidly, leading to crystallization and embrittlement.

On the other hand, a (if not the most) famous user of this board, advises us to

  blow on the joint gently until it hardens.

Now this sounds like one of those issues that the EEVblog or even Mythbusters would tackle. So, does anyone know of experiments where the effect of blowing on the joint has been studied?

Updates:

As was pointed out in a comment below, the latter advice may be impractical as it was written because a small joint may harden too fast anyhow for blowing to be helpful in that regard. Still there may be other practical incentives to do it, like cooling the board/parts faster so you can move on to making the next joint without burning yourself (by accidentally touching the traces, parts etc.) So I think it's fair to ask if the advice given in some textbooks (against blowing) is purely ex cathedra or backed up by some empirical evidence. Alas the book I mentioned doesn't cite anything in support of their stance.
After a bit more searching, I found some anecdotal evidence in an EDN blog supporting the claim from the book. Still it seems rather unsatisfactory and possibly not scientific enough since this blog said that all the joints examined at that site were cold joints ("solder was visibly cracked and crystallized in all different directions"), but that could have happened for other reasons, i.e. this anecdotal piece of evidence lacked a control.
As discussed in comments below, blowing on the joint is sometimes the poor man's fume extractor (or deflector anyway). Now, since real fume extractors are standard in most shops/labs and these have non-trivial airflow, I suspect some boffin has studied what level of airflow becomes dangerous for joint reliability.


texts:
I'm working on a project which uses a PIC with a 32kHz watch crystal attached to Timer1. Unfortunately, the chip I'm currently using, PIC16F1827, shares the T1OSI & T1OSO pins with ICSPCLK & ICSPDAT.

I'd like to be able to use the ICSP, ideally without having jumpers or other manual management.

What would be the best way to isolate the crystal from the ICSP?

The data sheet, and other notes I've found around this, are not specific, obviously given the wide range of circuitry that might be connected to the ISCP pins.

  It is recommended that isolation devices be used to separate the programming pins from other circuitry. The type of isolation is highly dependent on the specific application and may include devices such as resistors, diodes, or even jumpers.

Edit to add: I believe the crystal is a DT-26 model, from MEC.


texts:
I am trying to use a quadrature encoder with my NUCLEO-F303K8 board (see code below) and it is working ok but not perfect. I connected the encoder according to fig 4. in the datasheet (I didn't have any 0.01uF capacitors so I used 0.1uF instead). I noticed that occasionally the counter is incremented twice when I rotate the encoder one step. When I modify the prescaler value I noticed that the counter behavior changes a lot. For example a prescaler value of 11 requires that I rotate the encoder 6 steps in order to increment the counter once; the opposite behavior can be seen with a very small prescaler value. Using trial and error I have determined that a prescaler value of 3 works the best.

I am new to encoders and feel like I am doing a lot of guessing here and could use some assistance. Can you see anything in the datasheet that suggest what prescaler value I should use? There is some timing mentioned but I don't know what to do with it. The system core clock is running at 72MHz. Or is there something strange in the code below or something in the way I have connected the encoder I could change?

EDIT:

I connected the encoder to an oscilloscope (measuring at the input pins of the NUCLEO board) and rotated the encoder clockwise; these are the results.

With the capacitors (0.1uF):

Without capacitors:

To me it looks much better without capacitors but in reality when I rotate the encoder it works very poorly without capacitors. Can anyone explain these results it appears strange to an amateur like me.

EDIT2:

I changed the timebase as suggested and now I see the bouncing of the signal. From my observations today it seems worse after the falling edge compared to the rising edge for some reason.

Without capacitors:

Most of the time it looks good with capacitors but sometimes it looks like this or slightly worse:

I bought more capacitors today and tested 0.01uF, 0.022uF and 0.047uF. I would say I got the best results when I used the bigger ones, i.e. 0.047uF and 0.1uF. The rise and fall times are slower but it doesn't seem to have a negative effect and they give a cleaner signal. Is it correct that the rise/fall times can be decreased by choosing smaller resistors? What other effects would it have?

Code I am using:

RCC_APB2PeriphClockCmd(RCC_APB2Periph_TIM1, ENABLE);
RCC_AHBPeriphClockCmd(RCC_AHBPeriph_GPIOA | RCC_AHBPeriph_GPIOB, ENABLE);

GPIO_InitStructure.GPIO_Pin =  GPIO_Pin_8 | GPIO_Pin_9;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;
GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_NOPULL;
GPIO_Init(GPIOA, &GPIO_InitStructure);

GPIO_PinAFConfig(GPIOA, GPIO_PinSource8, GPIO_AF_6);
GPIO_PinAFConfig(GPIOA, GPIO_PinSource9, GPIO_AF_6);

NVIC_InitStructure.NVIC_IRQChannel = TIM1_UP_TIM16_IRQn;
NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0;
NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0;
NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
NVIC_Init(&NVIC_InitStructure);

PrescalerValue = (uint16_t) ((SystemCoreClock ) / 18000000) - 1; // Prescaler is 3

TIM_TimeBaseStructure.TIM_Period = 6;
TIM_TimeBaseStructure.TIM_Prescaler = 0;
TIM_TimeBaseStructure.TIM_ClockDivision = 0;
TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;

TIM_TimeBaseInit(TIM1, &TIM_TimeBaseStructure);

TIM_PrescalerConfig(TIM1, PrescalerValue, TIM_PSCReloadMode_Immediate);

TIM_EncoderInterfaceConfig(TIM1, TIM_EncoderMode_TI12, TIM_ICPolarity_Rising, TIM_ICPolarity_Rising);

TIM_ITConfig(TIM1, TIM_IT_Update, ENABLE);

TIM_Cmd(TIM1, ENABLE);

uint32_t counter = 0;

for(;;)
{
    counter = TIM_GetCounter(TIM1);

    // ...use the value...
}