texts: lm35 Temperature Readings are not right after sealing with Hot-melt adhesive (How mush has it Soldering max Temp toleration ?)

texts:
I need to seal the LM35 temp sensor so, I used this device for sealing it:

The code I have used are:

/*
 * PreciseLM35: A simple LM35 wrapper with optional voltage calibration facility
 * Version 1.0.2 (2017-04-30)
 * Written by belidzs
 *
 * Features selectable reference voltage.
 * Actual AREF value is polled from MCU, eliminating inaccuracies due to changing
 * AREF value (depleting batteries, etc)
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 3 of the License, or (at your option) any later version.
 *
 * See file LICENSE for further informations on licensing terms.
 *
 * CalibratedDefaultRead.ino
 *
 * Use this if you need to measure temperatures higher than 110C or
 * other analog sensor needs to read values higher than 1.1V.
 * Otherwise CalibratedInternalRead gives you more accurate results
 *
 * Uses MCU's reported Vcc voltage instead of a nominal value of 3.3V or 5V
 * which can change over time due to depleting battery, unstable power
 * supply, etc.
 *
 * Calibration:
 * - First run with measuredVsReadAreFratio = 1.0
 * - Use a multimeter and measure voltage on AREF pin. It should be around 3.3V or 5V
 *   depending on your Arduino
 * - Divide this value by the displayed AREF value and use it as measuredVsReadAreFratio
 * - Run the sketch again and check if serial terminal shows correct value for AREF
 *
 */

#include <PreciseLM35.h>

const int pinLM35 = A0;
const float measuredVsReadArefRatio = 1.0; // enter here your ratio between measured and expected AREF
PreciseLM35 lm35(pinLM35, DEFAULT, measuredVsReadArefRatio);

void setup() {
  Serial.begin(9600);
}

void loop() {
  Serial.println("Temp (C): " + String(lm35.readCelsius()));
  Serial.println("Temp (F): " + String(lm35.readFahrenheit()));
  Serial.println("AREF: " + String(lm35.readPreciseAref()));
  delay(2000);
}

So the result have been this kind:

the output is:

Te235.04
AREF: 4829
Temp (C): 113.70
Temp (F): 236.66
AREF: 4829
Temp (C): 97.60
Temp (F): 207.68
AREF: 4850
Temp (C): 87.20
Temp (F): 188.96
AREF: 4850
Temp (C): 82.40
Temp (F): 180.32
AREF: 4829
Temp (C): 77.70
Temp (F): 172.04
AREF: 4829
Temp (C): 73.90
Temp (F): 165.02
AREF: 4850
Temp (C): 65.40
Temp (F): 149.72
AREF: 4850
Temp (C): 62.50
Temp (F): 143.78
AREF: 4829
Temp (C): 59.70
Temp (F): 139.46
AREF: 4829
Temp (C): 55.70
Temp (F): 132.62
AREF: 4829
Temp (C): 57.50
Temp (F): 135.14
AREF: 4850
Temp (C): 53.50
Temp (F): 128.30
AREF: 4850
Temp (C): 59.20
Temp (F): 138.92
AREF: 4829
Temp (C): 56.10
Temp (F): 132.98
AREF: 4829
Temp (C): 61.30
Temp (F): 142.34
AREF: 4850

I have removed the adhesives from the lm35 sensor and could be seen here:

so the output backed to home temp 25 Centigrade degree like this:

Temp (C): 26.50
Temp (F): 79.70
AREF: 4850
Temp (C): 26.50
Temp (F): 79.52
AREF: 4829
Temp (C): 26.40
Temp (F): 79.52
AREF: 4850
Temp (C): 26.50
Temp (F): 78.08
AREF: 4850
Temp (C): 26.40
Temp (F): 79.52
AREF: 4829
Temp (C): 26.50
Temp (F): 80.60
AREF: 4850
Temp (C): 25.60
Temp (F): 81.32
AREF: 4829
Temp (C): 26.90
Temp (F): 79.52
AREF: 4829
Temp (C): 26.50
Temp (F): 78.08
AREF: 4850
Temp (C): 26.50
Temp (F): 80.42
AREF: 4829
Temp (C): 26.40
Temp (F): 79.70
AREF: 4850
Temp (C): 26.50
Temp (F): 79.70
AREF: 4829
Temp (C): 26.40
Temp (F): 79.52
AREF: 4829
Temp (C): 27.00
Temp (F): 80.60
AREF: 4850
Temp (C): 26.50
Temp (F): 79.70
AREF: 4829
Temp (C): 26.50
Temp (F): 80.42
AREF: 4850
Temp (C): 25.60
Temp (F): 79.70
AREF: 4850
Temp (C): 26.50
Temp (F): 79.52
AREF: 4829
Temp (C): 26.50
Temp (F): 79.70
AREF: 4850
Temp (C): 27.00
Temp (F): 79.70
AREF: 4829
Temp (C): 26.40
Temp (F): 79.52
AREF: 4850
Temp (C): 26.50
Temp (F): 79.70
AREF: 4850

I like to know why this happened ?and also I don't find the tolerance resistance for some actions like using hot-melt adhesives, in its data sheet?

Thanks.


texts: Static and Dynamic Ground Difference in Daisy-Chain powering scheme

texts:
I am using a +24 V distribution bus to transmit power to 10 loads spread over a meter (e.g. each one at 0.1 m distance). The power distributed daisy-chain style using 2x10 flat cables (computer cable) for ease of assembly and because these cables are very low cost. The wires ares connected in parallel for sufficiently low resistance.

NOTE: Daisy-chain is a requirement for assembly purposes.

I also need to transmit a common control signal (on/off) to all the 10 loads. Due to the high current, there will be a ~1.5 V static ground shift between the most distal and proximal loads. So that means if I use a common driver to send a +5 V logic signal to them all the most distant one may suffer logic problems (or reduced margin). Add on top the inductance and it may problematic when the loads turn on off.

Here is my brainstorming for solutions:

Repeat the signal, in a daisy chain approach as the ground between adjacent loads is not that different
Use differential signaling (e.g. RS-485 style)
Use optocoupler on each load
Use a +24 V logic/control signal, so the ground bounce eats less margin

I concluded an optocoupler approach is the simplest, lowest cost solution. I welcome your input.


texts: I need help with a simple IR circuit to control electromagnets

texts:
I have a project , I know what I want it to do but don’t know how or the components needed.

I want this IR beam-break trigger to control two of these 12v magnets (.33A each). When the beam is broken, I want the magnets to release. As soon as the beam is restored I want the magnets to re-energize.

The 12V power supply is a battery commonly used on lawnmowers. The IR emitter and receiver are 5.5V and 20mA. The distance between
IR Emitter and Receiver is 6”.

I know this is a simple circuit for most of you but I need help. I don’t know how to make the 5V IR break beam control the 12V relay. Your help would be appreciated. This old man needs help.


texts: What are these components in this schematic?

texts:
I have a schematic of my mobile phone. when i saw in the schematic, i saw two odd component. look:

For number one: What are these both components? What's the usage of
these?
For number two: Is it a transistor? What's the difference between this
component and a transistor?


texts: How to clear a 4 bit shift register with no clear input?

texts: I have 4 bit pipo shift register 74ls95 . It does not have an clear input. Is there any way to clear the register without giving all the parallel inputs as zero. I am using it as an component of shift add multiplier so it needs to be reset whenever the process is started.


texts:
Im using a op amp as a voltage follower on the front end for my data acquisition card
Choose the AD817 amp powered with a 12v single power supply
I have a 4v peak to peak signal going into my system
The signal im getting on the output of the AD817 seems to be just the positive 2v peak
Don't seem to be getting the lower 2v part of the signal


texts: Is there any applications for short data transmission?

texts:
In some applications like IoT,
the transmitter turns off for power saving when the transmission is not needed.
I'm not sure but I heard that:
when the transmitter is on, the data length - in time - tends to be us(or ms) length @ 2.4GHz.
Just for my curiosity,
is there any other applications whose data length - in time - tends to be sub-us(ns) length?
(regardless of the frequency of carrier)


texts:
I am building an interactive art project based on a large array of IR emitters and IR photodiodes -- there will be 240 photodiodes altogether. I know how to wire them to get the effect I want, and I've tested a single-diode setup successfully. In my setup, the anode is connected directly to ground, the sensor value is read from the cathode (connected to an Arduino), which has a 10K ohm pull-up resistor to 5V power. The input reads 5V when no IR is shining on it, and the voltage drops as the IR light increases.
Here's the problem: I'm going to need 240 pull-up resistors, which will be wired in parallel. That means the effective total resistance is 10K/240 = 41 ohm. Should I be worried about this? Is there a different way to handle it? Can I just increase the resistance value of the pull-ups? Should I switch the whole thing to use pull-down resistors instead?
Thank you!
EDIT: I fixed the anode/cathode mistake (the photodiodes are wired in reverse bias)
EDIT: Here is a version of this project I made a couple of years ago. It has 61 photodiodes (one in the center of each LED ring). It uses the design I described above, and it works pretty well.
https://www.youtube.com/watch?v=46i9tALT3e8


texts: Magnetic hysteresis BH curve to compare "Fe-Ni" "Fe-Si"

texts:
I am compiling some training material and would like to include a graph to indicate the different characteristics of silicon steel "Fe-Si" and mumetal "Fe-Ni".  The best curve I could find in SI units below seems theoretical.

Does anyone have a better graph that can be used?


texts: Should a UPS transformer heat up on no load?

texts:
I have a ups, APC-1100BX whose transformer heats up so much that the top of the body of the UPS gets heated up too. It gets hot to the touch when there is no load.

The UPS is ventilated and when the ceiling fan is turned on, it gets a little cooler.

There is a fan that cools the transformer but it only kicks in when the mains power goes off.

Is it normal for a transformer to heat up so much even when the UPS is off and there is no load present?
Could it also be the sensor that detects the temperature and should turn the fan on automatically is broken?

The battery seems to remain cool.


texts: Why only common collector method is used in class AB amplifiers?

texts:
I have recently started to study about class AB amplifiers online, as a newbie, i have found every schematic of the class AB amplifier is in common collector circuit just like this
Schematic i find everywhere in internet...

simulate this circuit – Schematic created using CircuitLab
But i eager whether the circuit can be used in common emitter mode, so i have drawn my own circuit below , in which, everything is same but the connection of the transistors. I dont know whether my made circuit will work or not, but i don't want any harms to happen while i am testing the circuit so , i considered that it would be better if i ask this topic on stack exchange before implementing.
My drawn circuit below...

simulate this circuit
So here are my questions ...

Why is class AB amplifier used in common collector method?

Can class AB amplifier be implemented according to my drawn schematic in which transistors are in common emitter ? If my drawn circuit cant be applied, then please explain why .

Why is common collector chosen best for class AB amplifiers?

Thank you so much !


texts: Synchronizing an oscillator signal and a single wire signal

texts:
On some 32bit MCUs(PIC32MX, STM32F4), those SPI pins can read a continuous signal such as I2S/PCM.

So I thought to read a single-wire signal that has MHz fixed frequency as SPI.

First, I made a prototype with D flip flop circuit with a crystal oscillator with the same frequency as single-wire signal.

As shown in this logic analyzer image, a result signal was synchronized. But I can't get an accurate data because a signal deviation affected the interval.

Increasing the oscillator clock reduces the uncertainty but MCUs can't receive so high frequency.

I also tried to divide the clock, but sometimes the edges changed, so I could not get the ideal result.

As this is a hobby at the moment, but I'll use other than if these are cheap as logic ICs. Is that possible?


texts:
I am using a Trinket's (not pro) analog inputs to read differing resistances from button presses. When any of the buttons are pressed, I want the internal LED to light up.

I have the buttons returning stable values, but the analog pin is inconsistently returning random results.

My board is set up as such:

R4 isn't connected to my circuit as I am using pin 3 which has an internal pull_up.

#include <cmdline_defs.h>
#include <TrinketKeyboard.h>
#include <TrinketKeyboardC.h>
#include <usbconfig.h>

const int LED = 1;
const int analogPin = 3;
int value = 0;

void wait(){
  for(int i = 0; i < 20; i++){
      delay(2);
      TrinketKeyboard.poll();
  }
}

void setup() {
  pinMode(LED, OUTPUT);
  pinMode(analogPin,INPUT_PULLUP);
  TrinketKeyboard.begin();
}

void loop() {
  TrinketKeyboard.poll();
  value = analogRead(analogPin);
  digitalWrite(LED, LOW);
  wait();
  if(value > 612 || value < 609){ //these values are the default analog outputs for this pin on my board
    digitalWrite(LED, HIGH);
    wait();
  }
}

The TrinketKeyboard library can be found here: https://github.com/adafruit/Adafruit-Trinket-USB/


texts: 16-bit timer of ATMega: How to calculate timer count?

texts:
I try to use the 16-bit timer of ATMega on each midi clock tick. A beat has 24 midi clock ticks. So e.g. 60 beats per minute = 1 beat per second = 24 ticks per second.

How can I set the timer for x times a second (depending on the bpm value)?

I'm initializing the timer on my arduino with:

void setup()
{
cli();          // disable global interrupts
TCCR1A = 0;     // set entire TCCR1A register to 0
TCCR1B = 0;     // same for TCCR1B

// set compare match register to desired timer count:
OCR1A = 6510;

// turn on CTC mode:
TCCR1B |= (1 << WGM12);

// Set CS10 and CS12 bits for 1024 prescaler:
TCCR1B |= (1 << CS10);
TCCR1B |= (1 << CS12);

// enable timer compare interrupt:
TIMSK1 |= (1 << OCIE1A);

// enable global interrupts:
sei();
}

I don't get the calculation of OCR1A. It should be depending on a bpm value.


texts: Led driver - constant current or constant voltage

texts:
I have an LED driver that ins't working. i have tried to search for the actual part, and been over to RS to find what I need.

There are two possibilities on RS - but I am not sure if I need the constant current or the constant voltage variety. ([two led drivers on RS])2

It is going to light two strips each with 36 leds in a mirror that was bought from bathstore - who don't seem to want to help.

Can anyone please help?

edit-------- answers to questions

What is the voltage of the driver output when connected to a strip? 12V
What are the values of the resistors? they have '241' printed in tiny letters.
How many resistors? 12 per strip
Are there 32 or 36 LEDs per strip? defo 36 strip (my bad!)
Are the strips wired to the driver in series or parallel?  I am not sure - the two strips are connected together via a 3mm jack plug/socket

What I would say is that the pictured LED driver did work for about 3 years. One day the  main fuse box went (due to toaster). The LED mirror has never worked since. I have replaced the IR sensor - which now works.

RS is 'radio spares' a place to buy electrical components. The link shows two drivers that I thought might work????

----------- end edits

Full strip
Close up


texts:
PIC24FJ1024GB610 from Microchip
Debugger Pikit On Board from Explorer 16/32 Development Board from Microchip

I wrote a program, where I tried to create a 250 ms Delay using Timer 1, and whenever the Timer 1 Interrupt Flag IFS0bits.T1IF is set, the pin connected to the LED PORTAbits.RA7 / LATAbits.LATA7 will toggle.

this is the following code:

#include <xc.h>

#pragma config FWDTEN = OFF //watchdog timer off
#pragma config FNOSC = FRC //Osc source from FRC (8MHz)
#pragma config ICS = PGD2

#define LED LATAbits.LATA7
#define TMR1_IF IFS0bits.T1IF
#define GLOBAL_INT INTCON2bits.GIE
#define TRIS_LED TRISAbits.TRISA7

void Set_LED (void)
{
    TRISAbits.TRISA7 = 0;//output
    ANSAbits.ANSA7 = 0;//Digital Not Analogue
    LED = 0;
}

void Set_Timer1 (void)
{
    T1CONbits.TCS = 1;//Clock Source internal from Tcy
    T1CONbits.TCKPS = 2;//1:64
    T1CONbits.TSIDL = 0;//continues through idle mode

    /*
     Fosc = 8MHz, Fosc/2 = Fcy = 4MHz
     Tcy = 1/Fcy = 1/4 us = 0.25 us
     t = 250 ms = 250,000 us
     t = Tcy*(PRESCALAR)*PR1
     PR1 = t/(Tcy*PRESCALAR)
     PR1 = 250,000 / (0.25*64)
     PR1 = 15625
    */

    PR1 = 15625;

   T1CONbits.TON = 1;//run timer
}

int main (void)
{
    Set_LED ();//Set LEDs
    Set_Timer1 ();//Set Timers

    while(1)
    {
        while(!TMR1_IF);//stay till IFS0bits.T1IF = 0

        LED = !LED;//Toggle LED / LATAbits.LATA7

        TMR1_IF = 0; //Clear Interrupt Flag

    }

    return 0;
}

I run the program into the PIC24, and I expect the LED to blink very fast but instead, it takes (approximately) 40 sec to toggle the LED.

This confuses me, because I checked OSC Datasheet page, and the Timer 1 Datasheet page from the PIC24FJ1024GB610 Datasheet, it seems fine, and I should expect a 250 ms toggle.

Looking at the DS, this is what I deducted:

FNOSC = FRC hence source is FRC (Fosc = 8MHz)
Fosc gets divided by 2, insctruction frequence (4MHz)
Register associated with DOZE is CLKDIV
CLKDIVbits.DOZEN = 0, CPU Peripheral Clock ratio is 1:1, hence Fcy = 4MHz
Tcy = 1/Fcy, Tcy = 1/4 us = 0.25 us

T1CONbits.TCS = 1 Clock Source is internal from FRC Oscillator

Clock Source is internal Tcy which in our case is 0.25 us
No Gate operation

T1CONbits.TCKPS = 0b10 Prescalar is 1:64, (each 64 Clock Source tick will increment TMR1 register by 1
if TMR1 == PR1,T1IFwill be set. TMR1 counts till it is equal to the value in PR1

giving the information I have to make a 250 ms (250,000 us) time delay, I used to following equation:

t = Tcy*(PRE)*(PR1)
250,000 = 0.25*64*(PR1)
PR1 = 250,000/(0.25*64)
PR1 = 15625

I thought that it is straight forward, can someone help me with my question.

Thank you in advance.


texts: I need to replace these (what I think are) capacitors, but the rating seems very high. They are smaller than the tip of my finger, yet the label pretty clearly says 0.33F, 5.5V. This seems wrong, as in my experience, even caps in the range of 100's of μF are physically much larger. A precursory search on DigiKey doesn't show  anything similar. Is this some type of special capacitor, or not even a capacitor at all?


texts: Solid State relay trips when load on Input change

texts:
I am trying to control a 12V door lock using this solid state relay.
In my switchboard, I picked the power from the common power line to power up my SSR at 5V using an adapter, The power line is also connected to an electric fan through a dimmer. The problem here is that whenever I turn my fan switch On/Off really fast or rotate the dimmer in either direction my SSR trips and the door lock unlocks for a moment (100ms maybe) even if I have left corresponding input channel in my SSR disconnected. I am not sure the reason behind it and how to prevent it.

Also, I put my 12V adapter input through SSR to turn on adapter instead of putting it's output through SSR to save power, Would it save any power?

Any help would be appreciated. Thanks in advance.


texts: Is there a formula to figure out the appropriate flyback diode rating vs the current flowing through a relay?  Maybe I'm asking the wrong question and it's only a voltage consideration.


texts: What is tDPL in SDRAM timing and how is it violated?

texts:
The datasheet describes the tDPL as "Input Data To Precharge" time. However, it does not show it on any timing diagram. With an SDRAM controller I am getting this error: "tDPL violation during Precharge" during simulation. The SDRAM verilog model is connected to the SDRAM controller.

What is tDPL? And what does it mean in page and non-page mode. By page mode I am talking about burst mode where we can read/write whole row and not fixed number of columns.

This question is about single data rate SDRAMs.


texts: What's difference between 2 ways of RLC band pass filter?[Circuits added]

texts:
When making AM radio, I know that Band pass filter is necessary.
As you know, there's 2 ways to make R L C Band pass filter, one is parallel R with parallel LC and the other is series R L C.
But almost every AM radio circuit I saw uses R with parallel LC.
Is there any special reasons?

*****These are 2 circuits that used different R L C Band pass filter****


texts: di/dt for R of general RLC, KCL dt algebra

texts:
Basic question. This is an exercise which requires all initial values for i and v0 (both 0), final values (yielding 2,4 A and 9,6 V)

It also asks for di/dt and my question lies on the answer given (last equation, giving di/dt = 4A/s)

I tried writing a KCL equation to observe the currents better, but how do I keep the current source value after deriving the equation

How does it imply that ic = 4


texts:
I would like to hand wind a smps transformer for prototyping work. The specs of the transformer are as follows :

Transformer Parameters

Core Material: EE16, NC-2H or equivalent, gapped for ALG of
88.55 nH/t²
Bobbin EE16, Horizontal, 10 pins, (5/5)

Winding Details

Shield: 15T x 3, 35 AWG

Primary: 105T, 35 AWG

1st Half Bias: 6T x 4, 30 AWG

2nd Half /Feedback: 6T x 4, 30 AWG

Secondary: 7T, 22 TIW

Winding Order

Shield (2–NC), Primary (4–1), Bias (5–3),
Feedback (3–2), 5 V (10–8)

Primary Inductance 1.074 mH, ±10%

Primary Resonant
Frequency 1000 kHz (minimum)

Leakage
Inductance 95 μH (maximum)

I have procured EE16 core, bobin and the copper wires. Can anyone explain me how to actually go about winding this one? specifically:

Which direction to start each winding CW / CCW ?
What to do in cases where turns are very less to fill one layer?
I have seen another transformer design where there were parallel coils connected to same terminals, In this case do we turn both coils side by side or on different layers?


texts:
i came across a problem in circuit analysis ,i have given a circuit and it's thevenin equivalent circuit
Given Parameters are R3(load resistor)=10k, Rth=40.2k,Vth=5v and in the circuit diagram on left source Voltage V1=12v,the voltage across R3 is also given i.e Vl=1v
to find value of resistor R1 and R2 , i know the Rth=R1 || R2 and Vth=V1(R2/R1+R2) but how can i relate this two equations to find value of R1 and R2


texts: Why do smoke detectors go off when lightning strikes?

texts: Just experienced this, I saw lightning outside my window (not hitting our building or anywhere close to it), and immediately after the smoke detector went off for a short while. Can anyone explain what caused this?


texts: Is it 'safe' to use 200ohm resistor to reduce 9v to 5v

texts:
I just bought some lasers and resistors from Amazon and I am a bit confused.
First of all the seller says the resistors are 200 ohm. I am a bit confused because I have only seen resistors with number (23) with (23k) by it.
My question:
Can a 200 ohm resistors reduce a 9 v to 5 v so I can power the laser? Is this safe to do without having anything blowing up?
Picture analysis of laser


texts:
I'm trying really hard to understand inductors and their related kick back voltage when the current is suddenly interrupted.

Example ascii art:

       1   2
       |   |
+ ----- ~~~ --_-- -

Where ~~~ is an inductor, and the beginning + and - is some DC voltage source (yes crappy schematic) and _ is some switch

For examples sake, say the voltage source is +9V

If you connect the switch then I assume points 1 and 2 would be +9V

Now when you disconnect the switch, what would points 1 and 2 be? Would 1 be 0V and 2 be some high positive voltage?

Is it right to say that when an inductor becomes disconnected it basically becomes a "backwards" capacitor with a high voltage source?

Could I somehow use such a circuit to charge a capacitor to a voltage higher than 9V?


texts: Opto-coupler base connection speed influence

texts:
I am using a 4N25 opto-coupler for 5kHz to 10kHz application. In some datasheets the turn on and turn off times are mentioned to be 3us. I am wondering if this opto-coupler is suitable for my circuit's frequency. Doesn't it much distort the output which is supposed to turn on gate of a power Mosfet?

In a SE question, in the accepted answer, it is mentioned that connecting base to emitter via a resistor such as 220k or 470k can increase speed of switching. Does it mean that t_on and t_off decrease by connection via R_BE ? and how much can I expect to improve speed by that?


texts: Will running a DC motor below stall current damage it?

texts:
We have DC motors that power wheels on a car. Because of internal friction, the motors will not actually rotate until they are given 50%+ power.

However, they do make some neat noises within this 0-50% range that we would like to take advantage of for effect.

Would running these motors below the stall current (thus producing sounds) damage the motors?


texts: I can't understand how decimal designation differ by power of 2??


texts: How to add temperature sensor to Mustool soldering iron?

texts:
I have Mustool Soldering iron. It works fantastically however I just want to know the current temperature of it digitally.

Can someone please guide me to it.

Thanks.


texts: Disadvantages of DLL clock generators compared to PLL

texts:
I've been learning from many publications that DLLs offer various advantages over PLLs, such as low-jitter performance and fast locking. So, recently, DLLs have been used for local clock generation in various applications too (edge combining DLL or multiplying DLL).
I was wondering what the disadvantages of DLLs for clock generation are with respect to PLLs, since the latter are still widely used for this purpose.


texts: Whats a good naming convention for part series and shunt components?

texts:
I have an RF receiver circuit which includes a ceramic chip antenna. Our chip antenna manufacturer "fine tunes" this antenna to the board and housing by determining the values of the Shunt and Series components. Throughout all of the designs we've had so far, Shunt01 is left NP. The Series and Shunt02 components will sometimes change from an inductor to a capacitor or vice versa.

However, our Reference designators are listed as C1 for the Series component and L1 and L2 for Shunt01 and Shunt02 respectively.

But since these components sometimes change depending on design, is it good practice to change the ref des to something like Z1, Z2, Z3??


texts: Help identifying connector with screw housing (RG...?)

texts: I presume this should be a simple ID for someone who knows. I am interested in the general family of connector (e.g. RGxx). It's not something I ever use but as I have a box of them I could do with knowing what they are.


texts:
I apologize in advance if I didn't give enough information. I don't really have the mathematical background to this type of problem.

Given the following equation:

$$G(s) = \frac{2s+3}{s^4 + 3s^2 + 3s^2 +s}$$

I need to put this into Jordan matrix form.

$$\dot{{x}}=Ax+Bu$$
$$y=Cx$$

First I did the partial fraction expression:

$$G(s) = 2s+3 = s^3(D+C) + s^2(B+2C+3D) + s(A+B+C+3D) + D$$

$$G(s) = \frac{-1}{(s+1)^3}+\frac{-3}{(s+1)^2}+\frac{-3}{(s+1)}+\frac{3}{s}$$

From this point, I'm not too sure if I'm correct about the $B$ matrix. Since there are 3 repeated roots, would the $B$ matrix contain three 1's?

$$\dot{{x}} = \begin{bmatrix}-1&1&0&0\\0&-1&1&0\\0&0&-1&0\\0&0&&0\end{bmatrix}\begin{bmatrix}x_1\\x_2\\x_3\\x_4\\\end{bmatrix} + \begin{bmatrix}0\\1\\1\\1\\\end{bmatrix}u $$

$$y = \begin{bmatrix}-1&-3&-3&3\end{bmatrix}\begin{bmatrix}x_1\\x_2\\x_3\\x_4\\\end{bmatrix}$$


texts:
From my EM theory book:

I have the solution for this problem, but I don't even understand the first step. How does \$V = r + jx \implies v(t) = rcos(wt) - xsin(wt) \$??


texts: plugged 240v into 110v amplifer - is this repairable?

texts:
I imported a 200w mono subwoofer amplifer from the US and stupidly misread the 250v fuse rating as the input voltage. Plugged it in into my UK 240v supply and the slow-blow fuse blew. I have since replaced this, but the unit does not power on.

If I replace the power supply board with a 240v one (or repair the 110v board and use an inverter), is it still likely that the amplifier circuit has been destroyed in the process?


texts: How to store persistent values in STM32F407VGT6 embedded microcontroller?

texts:
I want to store 3 integer values in the flash memory of the microcontroller so that these values are not lost if the device has a power outage.
I am trying to understand which type of memory to use for this purpose and how exactly how can I write to and read from this memory block.
I am doing a hobby project to use a HMI to input data to a PLC which will then drive several motors to control the movement of toy quadcopter.
I am using the Keil uvision IDE.
Some additional notes:

The values will be changed once every 2-3 months.
There can be power outage during the value update process.
Its not critical if process is interrupted and we lose the latest value entered.


texts:
i'm learning now the about Bluetooth (and BLE) and feel I need some explanation what the advantages of using frequency-hopping method. Can anyone please explain me in simple words (with examples, please) what we earn from the frequency-hopping? i know it should minimize interference, but don't understand how and why.

Thanks!


texts: Calculate the impedance and phase angle of a capacitor

texts:
I’m trying to calculate the impedance and phase angle of a capacitor in software for a microcontroller project I’m working on, and I’ve included a pic of what I mean (not to any scale). I’ve prototyped a simple Series RC circuit and I’m feeding a 1Khz sine wave onto it. Measuring across ‘R’ I’ve collected the data for current through the circuit, and measuring across ‘C’ I’ve collected the data for voltage across the capacitor.

I’m not sure of how to calculate Vp, Vq, Ip, and Iq, and after looking into various methods one idea was to start with the following:

Vp = sum(i = 0 to N-1) ADC(i) * cos(2 * PI * i / N)

Vq = sum(i = 0 to N-1) ADC(i) * sin(2 * PI * i / N)

and similarly:

Ip = sum(i = 0 to N-1) ADC(i) * cos(2 * PI * i / N)

Iq = sum(i = 0 to N-1) ADC(i) * sin(2 * PI * i / N)

Needless to say I'm not happy with the results, can anyone point me in the right direction on how to properly make these calculations.

thanks
kvresto


texts:
I'm trying to use the LPD3806-400 incremental encoder with an Arduino DUE.

I have the problem that the datasheet says 5 V to 24 V and also the output is open collector. Therefore, I have to pull up the output.

I guess this can be done with the standard pull-up resistor method.
However, my Arduino DUE just receives up to 3.3 V, so how should I fix it if I can't add the voltage divider anymore because of the connection to ground conflicting with my pull-up resistor?

As you can see in the attached image, the fact that the 5v of pull up now are grounded too, makes the voltage drop dramatically.
The transistor collector is my encoder output, and the voltmeter is the Arduino input


texts: Will two capacitors with different voltage ratings and identical capacitance work the same?

texts:
Suppose I have a 200 V 200 µF capacitor and a 16 V 200 µF capacitor, and suppose I have a circuit that requires a 16 V 200 µF capacitor.

Can the 200 V capacitor be used instead of the 16 V one and will they work the same? Apart from the obvious overkill are there any disadvantages (speed, power dissipation... certain limitations)?


texts:
This is from a JVC TD R272 tape deck.

A ribbon cable from the head to the board goes into it. I snapped it due to impatience.
Can someone tell me the name of the white plastic block?
It has six pins on the base and the six part ribbon cable slides into it.

The block leaning against the PCB with the six holes it sat into, some of the pins are still in place..

View of PCB from below:

The remnants of the pins on top.

The ribbon cable that slots into block:


texts: Kirchhoff’s Law and Superposition Theorem

texts:
For the given circuit I found the current and the voltage at R1, R2, R3, using the superposition theorem.
1.I replaced the VS2 with a short then calculated:
I1= 0.57mA, I2=0.33mA, I3=0.2mA, V1= 2.68V, V2=2.02V, V3=2.97V.
2. Then I replaced the VS1 with a short and then calculated:
I1=-0.99mA, I2=-0.58mA, I3=0.4mA, V1=3.19V, V2=6.7V, V3=3.2V

So, the total current and voltage  for each resistor is :
I1=0.26mA, I2=-0.65mA, I3=0.91mA
V1= 5.86V, V2=9.16V, V3=5.5V

I have to prove the Kirchhoff’s voltage and current Law are valid in the circuit given.
Can someone help me with this?


texts: Connecting a polyfuse (PTC / resettable fuse) without soldering

texts:
I want to connect up a polyfuse to protect a potentially flammable USB cable and a Raspberry Pi Zero in the circuit below. However it seems that most Polyfuses are supposed to be soldered and I'd much rather avoid doing that.

Is there any way to hook up a Polyfuse without soldering it, specifically with regard to the circuit above.


texts:
Propagation constant is in the form
 P= a+jb (a= attenuation constant b = phase constant)
a +jb = ln (x+ jy).
How do I separate the real and imaginary part in the RHS so that I can equate the attenuation constant and phase constant to it?


texts:
I have had EMI problems in the past and I have decided to implement clock distribution with termination.

I have a 25 MHz crystal that travels through a 50 \$\Omega\$ strip in the PCB and splits into two. After the split the strips have an impedance of 100 \$\Omega\$. Each strip goes to an IC and then is terminated with a 100 \$\Omega\$ resistor to ground. I copied the idea from a book. (High speed digital design. A handbook of black magic)

When I turn on the board, I noticed the ICs don't operate well as they miss clocks. When I remove the terminating resistors all is ok. I am trying to do a good job to prevent problems with EMI.

What am I missing?


texts: please. I want to burn a code on esp32 so no one can access it afterwards.I want to go to final product development. i am using micropython and upycraft.


texts: Can a voltaic pile be used as a capacitor?

texts: The electrolyte of a voltaic pile can be thought of as the dielectric of a capacitor. The cathode and anode of the pile are the plates of a parallel-plate capacitor. So can a voltaic pile be used as if it were capacitors connected in series?


texts:
I have the following circuit right now

Is it possible to connect PHY_TRXP0 on TD1- and PHY_TRXN0 on TD1+ and taking ETH_MX1_P from MX1- and ETH_MX1_N on MX1+ respectively? Signals on RJ45 will go as per the pin mapping?

Any suggestions are appreciated.
Thanks in advance.


texts: Do you need to UL Certified the enclosure with the board inside?

texts:
I want to use the RaspberryPI in an industrial environment that requires all devices have UL certification. The RaspberryPI board has UL certification but there is currently no enclosures that are certified. I have been told the UL certification process is expensive and probably beyond the scope of this project.

My questions are:

Do I need to UL certify the enclosure for a board that is already certified.
Can you certify a enclosure without the board inside of it? (So i can pick up a board off the shelf and put the RaspberryPI in it)
How expensive is the UL certification process for an enclosure where the board has already been certified?


texts:
So I'm tearing down this hair dryer for a school project where I need to make it have variable heat and variable motor speed which can be controlled through an Arduino. I'm currently looking at where I would need to replace the switch and resistor with a rheostat, but just after the switch and resistor, there's an SF169E thermal fuse that is only rated for 10 amps. However, the hairdryer is supposed to be rated for 1875 watts. 10 amps and 125 volts translates to 1250 watts, so where would the other supposedly 625 watts be going?

The hairdryer is a Conair 1875 156QI. I couldn't find a wiring diagram so I made one myself. I know it's not great, and the resistances are made up, but here it is:

Thanks for your help!


texts: OWI Robot Arm Circuit Diagram LED question

texts:
I was looking at the circuit diagram for the OWI Robot Arm Edge in the manual, and happened to notice the LED. To me, it looks like it has been drawn the wrong way around. But maybe I am wrong. Can someone please confirm that this is actually a mistake. And if it is not a mistake, can you explain the path required to turn the LED on ?
I just need a second opinon.

The manual can be found here:
https://www.robotshop.com/media/files/pdf/owi-535_manual.pdf

See page 33.

Also I have attached that particular page for reference:

Thank you very much
Regards
ScottC


texts:
I am trying to make some amplifier circuit like Class - D type. Below is the circuit;

Input is sinusoidal @2500Hz.
I couldn't make gate driver circuit. Thats why i use voltage dependent voltage source which is working fine.

@The H - Bridge, there is some point that i couldn't solve. It has to be sinusoidal output current on the inductor but somehow, it is like below;

Switching frequency: 500kHz.
H-Bridge, All Mosfets are N-Type

Thank you all


texts: Limiting high input voltage on a CMOS input

texts:
I have a CMOS IC that has a low level RESET input. I would like to connect it to MCLR pin of my Microchip CPU but this is problematic because programmer/debugger (Microchip ICD) can put there a level, that is bigger than VCC.

What would be right solution here? Would a simple diode work?


texts: 'Sprint Layout': How do I flip the track layout to place component symbols?

texts:
I have a photo of my through-hole boards copper side, tracks and solder.
I used the: Extras-Scanned Copy, option and imported the image. I choose: 'C1' (Copper-one) right at the bottom of the GUI-window and picked 'Board Side1 - Top' because this board has just the silk-screen side and copper (it's not multi-layered).
I then drew over my image and marked out the tracks and pads.

I need to flip the track-layout so that I can insert components from the library. I tried selecting 'S1' for Silkscreen side but my tracks didn't flip over. I guess I could continue and populate it just the same but I wanted to confirm if this was the right thing to do. How do I then generate a schematic from the layout?

More on what I'm trying to do here: Reverse engineer a simple populated PCB


texts: Are there any methods to attach cables to micro jst pins without soldering nor crimping tools? I can't solder the cables in place due to how small the holes for the female jst pins that any amount of solder would prevent the female pins to connect to the male ones. I only got a set of pliers and im not able to buy other tools to assist, so are there any alternative ways to hold the cables in place and then crimping them?


texts: Why do audio op amps require such high rail voltages?

texts:
This might be a silly question, but I haven't been able to find it addressed directly anywhere on the internet yet.  I also have a handful of related questions in-line, which I hope don't stray too far off-topic.

In pro gear, Line-level audio signals are roughly ~3.5V peak-to-peak, so why do audio circuits routinely require or recommend rail voltages of +/- 12v or higher?

Is this purely a headroom thing?  Or do non-linearities in op amps depend on the supply voltages?

Or to support cheaper components?  Looking at the datasheet of the TL072, the maximum output voltage can be as low as 2/3 of the rail if the load resistance gets low (2k Ohm), but is typically at 90% of the rail for a 10k Ohm load.  But, you could also use a higher-end op-amp that's rail-to rail?

The main thing that prompts this question is looking at the datasheet for the Cirrus CS4272 and the schematics / data on the evaluation board.  In that case, even though the ADC operates from 0v to 5v, they still opt to use a bipolar +/-18V supply for the input buffer.  In that particular example, they're using the NE5532D8, which has a worst-case output swing of 80% of the rail, and supports rails as low as +/- 3v.

So, why would they use +/- 18V supplies if the ADC only supports 0-5v audio (presumably biased around 2.5v), and using a +/- 3v supply would still easily accommodate the 3.5V peak-to-peak range?

According to the datasheet, there is also no scaling (gain or attenuation) happening in this circuit:

  XLR connectors supply the CS4272 analog inputs through unity gain, AC-coupled differential circuits. A 2 Vrms differential signal will drive the CS4272 inputs to full scale.

So any signal that's over line level would wind up getting clipped by the ADC anyways.  Is it better to have the clipping in the ADC vs. the op amp?  Or is the higher rail required for the output stage, even though it would still only provide a ~3.5v peak-to-peak line-level output signal?

In the context of driving a 5v single-supply ADC, what are the reasons that using an input stage with higher, bipolar supplies is better than using something like an LT1215 on a single-supply at 5v? (I can't post a link because I don't have 10 reputation on this particular Stack Exchange yet... It's easy enough to google)

Thanks!


texts: ATtiny13A's timer appears to be very inaccurate, is it normal?

texts:
I wrote this blink program for my ATtiny13A and tried to measure the accuracy with an Arduino Uno but the timer seems to be quite inaccurate.
On the ATtiny I am running on the internal 128KHz clock and using timers to make pin0 high and low at a frequency of 1Hz.

Here is the ATtiny code:

int main(void){

  DDRB = 0;
  TCCR0A = 0;
  PORTB = 0;

  DDRB |= (1 << DDB0);      // pin0 output

  TCCR0A |= (1 << WGM01);   //CTC mode
  TCCR0A |= (1 << COM0A0);  //toggle OC0A on compare match

  TCCR0B |= (1 << CS02) | (1 << CS00); //1024 prescalar
  OCR0A = 124;              //1Hz @ 128KHz internal clock

  while(1){
  }

  return 0;
}

On the Arduino, I am using interrupts to measure the time between each high/low signal. It's a standard Uno with an external 16Mhz crystal. Here is the Arduino code:

unsigned long lastHigh = 0;

void setup() {
  Serial.begin(9600);
  const byte interruptPin = 2;
  attachInterrupt(digitalPinToInterrupt(interruptPin), myISR, CHANGE);
}

void loop() {
}

void myISR(){
  unsigned long temp = micros();    //store it ASAP to minimize delay
  Serial.println(temp - lastHigh);
  lastHigh = temp;
}

I have pulled the pin 2 on the Arduino to ground with a 1K resistor, and connected it to pin 0 of the ATtiny13A.

I was expecting to read a perfect 1s between each blink but here are my readings (in microseconds):

  1063616 1062696 1063608 1062696 1063636 1062692 1063608 1062680
  1063576 1062580 1063512 1062676 1063576 1062660 1063584 1062680
  1063580 1062672 1063596 1062700 1063596 1062688 1063604 1062680
  1063596 1062612 1063528 1062668 1063580 1062680 1063588 1062684

As you can see, the timer is not only ~60 milliseconds off, but it also jitters a lot.

I read on the internet that the internal clock is inaccurate but I'm not sure if ~60ms is too inaccurate or not.

Other than being off, the timings are also very jittery. They go from as low as 1062580 to as high as 1063680 microseconds.

I'm quite inexperienced and am really curious if this level of inaccuracy is considered normal or not. I found it odd because 1000us jitters make the micros() or _delay_us() functions quite useless.


texts: Negative frequency deviation in crystal oscillator

texts: What is the significance of a negative frequency deviation in the freq deviation vs temperature profile of a typical OXCO (e.g. the diagram seen on this page)? My understanding is that a positive deviation on these sorts of diagrams is ± some window around the specified frequency (and so would include situations where the deviation is negative relative to spec), but I haven't been able to find much about what a negative deviation means in this context.


texts: How to power bulbs expecting 24V AC from a car's "cigarrete" socket?

texts:
I'm turning the trunk of my car into a UV-sanitizer chamber -- so that, by the time I return from the supermarket, the bags and the packages handled by strangers there are sterile.

To this end I lined the trunk with reflective film and purchased 8 little UVC bulbs, which I now need to power.

The bulbs need 18-24V alternating current and are said to use about 3Watts each. The socket is (said to be) E17, and I plan to use a wire from a decoration garland.

All of the DC-to-AC inverters I can find produce 110V AC, not 24VAC... There are also 110V-to-24V AC transformers, but I'd hate to resort to the cludge of using two different conversions.

Do the 12VDC-to-24VAC inverters exist, and how do I find one? Do I need ballast for these bulbs -- and how do I add it for all of them at once?

Any other suggestions?


texts: How to adjust picture geometry of a CRT TV?

texts:
I have a HD CRT TV (Silva Schneider 26 inch) which failed recently. So I took apart a working CRT TV (Philips L01-2E AA, 20 inch) and took its mainboard and connected it properly to the HD CRT tube.
The tube lights up, it works, but the picture is small.

How can I enlarge the picture? There are no pots for horizontal and vertical adjustments on the mainboard, also the service menu is currently not available, because of missing remote control.


texts:
I am doing some coursework and research on AC theory and currently exploring the below expression:

$$V= 100sin(100\pi t) + 60sin(300 \pi t - \pi/2) + 30sin(600 \pi t + \pi/2)$$

I need to find the:

Amplitude of Fundamental
Frequency of Fundamental
Amplitude of Harmonic components
The Phase Angle
The Instantaneous Value of v 5.12 ms from the start of cycle.

Now, I have looked on line and everything seems over ambiguous from my Text book on Engineering science and to be honest has made me even more confused.

Now my understanding of this expression is that it represents 3 waves? Thus, I am assume then I can/will have to be broken up in sections to achieve each answer.


texts: How can I find out what is the maximum power through a transistor? Can I look at just the data sheet (if I do look at one, what am I looking for) or do I have to use a meter to figure out the max power through an LED/transistor or a switch. All the components are a part of a circuit, with a purpose of lighting up LED's.


texts: Beginner: 12v solar cell to charge 24v battery and run 24v components

texts:
Trying to use the parts I have available...

I have a wel-bilt #28650 12v solar panel (Max: 7 watt / 583mA / 15-17v)
I have 2x 12v 7Ah sealed Lead-Acid batteries in series for 24v (from a APC UPS #APCRBC123).

I also have a number of components from the recent RadioShack closures. Various diodes, transistors, caps and so on, but nothing specific for this.

I want to make a charger from the 12v solar panel to charge the 24v battery that will then run a 24v security camera and PtP wireless station.

At current the camera is run from POE but it is tethered to a ethernet cable that is then in turn tethered to a 120v extension cable. This is no longer acceptable because I want to move the camera. Further, there is no point in having it on a wireless system if still having to use a cabled power source.

The wireless PtP device and camera are both using 24v POE (https://www.ubnt.com/airmax/nanostationm and https://www.ubnt.com/unifi-video/unifi-video-camera-g3) and I can't see any reason not to make it solar powered.

I've looked at a number of IC555 step up tripplers and a few other circuits. But they all seem to provide very low mA (as in less than 100mA).
The PtP wireless device is rated at a max of 8 watts (but i'm only using it at a 1/4 of its max power output) and the camera is rated at max 4 watts.

UPDATE: assuming my meter is correct, the equipment is using 220mA with IR off (day) and 250mA with IR on (night).

This may not work out at all. The solar panel is rated max at 7 watts. So I don't see it being able to charge the battery and provide enough power to run the equipment.

Some advice here would be greatly appreciated. I'm only a beginner here but I want to learn and it's fun to build things!


texts:
Electrician apprentice here.

Earth potential is said to be 0 volts.

Let’s say I have a star-configured transformer which supplies me with voltage. Let’s also say that the transformer is perfectly balanced and that the 0 potential center point is grounded to earth.

Imagine then that we have some sort of electrical appliance downstream. That particular appliance is grounded as well, by use of say a copper rod.

So a TT system.

If a ground fault suddenly occurs at my electrical appliance the current will suddenly run in my local grounded copper rod.

However, I am told that this happens only because the circuit is completed by the grounded transformer on the supply side.

But if the earth potential is already zero, why would the current move between the local ground rod and the supply ground rod? Wouldn’t earth merely be what closes the circuit? I mean, after all a closed circuit isn’t necessary in order for a current to exist. Only a potential difference is, right?


texts:
In this picture is an example of a boolean majority function (may be a bad example) So the rule says that the result or an output of a majority logic function would be a selection of majority inputs, so if there are 3 inputs, then 1 would become result if we input at least two 1's and 0 otherwise.

Does this rule apply to any multiplexer?
And does the output (result) depends on the logical gates being used in a boolean function?


texts: Can connecting just neutral wire of power supply to a PCB (VDD not connected) cause sparks and burn out decoupling capacitor?

texts:
I have an embedded system and one of the PCBs in the module should be connected to a 5V power supply -> positive(+) and neutral(-). The NEUTRAL knob is directly tied to the GROUND knob in the power supply.
I had a power supply with the current knob turned to maximum and a set voltage of 20V.

After turning on the power supply, I connected the ground wire from my PCB to power supply's negative (-). I left the VDD wire from my PCB unconnected to the power supply, it was just hanging around. The PCB required 5V input but the power supply was set to a voltage of 20 V. I thought since the VDD is not connected to the power supply yet, it should not be a problem.

Immediately, the ground connector on my PCB sparked, causing a decoupling capacitor connected to it to badly burn out, followed by a few resistors and  LTC3404 step-down converter chip on the PCB. Then I pulled out the ground wire of the PCB from the power supply.

I do not understand how the connecting of just the ground wire from my PCB to power supply neutral could cause my capacitor to burn out, even though the power supply had higher set current and voltage than required by the PCB.
So, was it the current on the neutral wire that burnt out my capacitor or is there anything to do with the higher voltage?

NOTE: I have been using the same power supply and PCB with 5V and the current knob turned up to maximum, for months and had no issues before.


texts:
In my arduino project, I want to combine 8 half bridge load cells (each has 3 wires, RED, BLACK & WHITE) because i will be weighing irregularly shaped objects and 4 points of contacts may not be enough. I am not planning to make a flat platform on top, just 8 individual load cells raised from floor and object will sit on as many load cells as it would.

I am having a hard time trying to figure out wiring 8 load cells. I understand I may need multiple HX711 load cell amplifiers and combinators. All the help I could find either discusses full bridge 4 wire load cells or combining 4 load cells to make a bathroom scale.


texts: Make: Electronics Experiment 11 - Is this what the loudspeaker should sound like?

texts:
I'm working through Experiment 11 of Make: Electronics (1st edition since I bought a component kit that matches that edition).
I have the circuit configured below, but I'm not sure that the loudspeaker is doing what it's supposed to do. The book describes the sound as an "insect buzz". What I'm hearing is more of a "tick tick tick".
What really makes me think this is wrong is when I read Step 4:

If you wanted to use this audio signal as some kind of an alarm, a steady
droning noise is not very satisfactory. A pulsing output would be a
much better attention-getter.

The sound I'm getting already sounds more like a pulsing output and less like a steady droning noise!
Here's a video of it where you can hear the sound.
https://youtu.be/Mv8m_5eydJs
Can someone tell me if that's right? Or is my speaker connected wrong or malfunctioning?
(I did have a hard time connecting the wire to the speaker's terminals. I had to use alligator clips and I'm worried something might be touching the housing of the speaker)
Update: I forgot to post the diagram


texts: Who can identify this book about electronics

texts:
The link to one of chapters is here:

https://ru.scribd.com/doc/38868597/Chapter-08-Bjt-Small-Signal-Analysis

Who is the author and what is the title?


texts:
I'm building a project that uses a high power LED (3 Watt) in connection with an ESP8266 module using the module as an access point and connecting to it with my smarthpone. I've successfully managed to switch the led on and off with my smartphone and connecting the I/O pin to a logic gate MOSFET using a simple LED circuit with just a resistor and the MOSFET.

Now though I want to have a better and more efficient circuit for driving my LED and came up with this the 1A constant current supply is supposed to be a 3.7v lithion ion battery but i didn't know how to use that with the program I used to make the circuit so by no means is the current supply constant(see image) This isn't my own design, I found it online, the reason why it's better is this:

" Q2 (a power NFET) is used as a variable resistor. Q2 starts out turned on by R1.

Q1 (a small NPN) is used as an over-current sensing switch, and R3 is the "sense resistor" or "set resistor" that triggers Q1 when too much current is flowing.
The main current flow is through the LED's, through Q2, and through R3. When too much current flows through R3, Q1 will start to turn on, which starts turning off Q2. Turning off Q2 reduces the current through the LED's and R3. So we've created a "feedback loop", which continuously monitors the LED current and keeps it exactly at the set point at all times. transistors are clever, huh!
R1 has high resistance, so that when Q1 starts turning on, it easily overpowers R1.
The result is that Q2 acts like a resistor, and its resistance is always perfectly set to keep the LED current correct. Any excess power is burned in Q2. Thus for maximum efficiency, we want to configure our LED string so that it is close to the power supply voltage. It will work fine if we don't do this, we'll just waste power. this is really the only downside of this circuit compared to a step-down switching regulator!

setting the current!

the value of R3 determines the set current."

The problem now is I don't know how to use my ESP8266 again as a switch because I don't know where to connect the I/O pin where as previously I connected it to the MOSFET and basically used it as a switch but in my current circuit I don't know where to connect the I/O pin

This is my full setup for the project with the old LED circuit

I have an additional question about this setup : is it the best way to power both the LED and the ESP8266 using a step down converter in the way I used it?


texts: How to prevent external magnet rotate a motor

texts:
A small dc motor working and moving a disc. When device/motor is power off, a hacker with a strong magnet came and rotate the motor; without touching the motor, just moving the magnet near the motor is sufficient to cause the motor-nucleus to rotate, and hence the shaft rotate and the disc likewise.
A friend told me this happens also with dc stepper motors, but not sure (Currently, no stepper motors available to test.)
Can you suggest a measure/solution to prevent magnet to rotate a motor?
Thanks


texts: Terminating an audio line-in signal when source is disconnected

texts:
I've been trying to DIY a home audio setup. We have a pair of speakers in the ceiling of an upper floor (previously installed), and a new TV on the same floor. We wanted the sound of the TV to come out of the speakers.
The speakers are connected to an amp in the basement, and there are existing CAT5 cables running behind the new TV down to the basement. Rewiring is challenging, so we took advantage of the existing setup and got a cheap pair of audio-to-CAT5 baluns (https://www.amazon.ca/LINESO-3-5mm-Stereo-White-Extender/dp/B01HHO8382), hooked one side to the TV (3.5mm jack) and the other side to the amp in the basement. The TV sends audio to the audio-out port, through the balun, through the CAT5 cable, back through another balun, to the amp, which amplifies the sound and sends it to the speakers.
Now, for the fun part: when the TV is on, everything works great. But, if the TV is turned off and the amp is set to a loud enough volume, there's an audible mains hum (~60Hz) over the speakers. My best guess is that the CAT5 cables are picking up small currents from the mains over their length (not surprising as they run through multiple floors). When the TV is on, the TV's line out presumably sinks these stray currents (if not playing anything) or otherwise produces enough current to drown out the induced currents. When the TV is off, it disconnects its audio output; the amp's 47kΩ input is high enough and has high enough sensitivity to amplify the induced currents into a buzzing noise.
What can I do to reduce or eliminate the unwanted sound, ideally with a passive solution? I have thought about adding a resistor somewhere but I am not sure whether it would be in parallel or in series with the connection, nor what value it should have.


texts:
I guess these are capacitors... but I'm not sure. What are they exactly and how do I read their stripes?

The above picture gives the impression that the background is white paper, but it looks far from white, which obscures the colors of the parts.  If the background is indeed white, then here is a fixed version.  One of these two should be edited out once we know which one is the correct representation.


texts: How do I wire up an aftermarket USB Type-C connector so that it works?

texts:
I recently broke the male port of my USB-C laptop charger. I already got a new one, but I would like to fix and repurpose the old one to be the power for my Raspberry Pi 4 instead of throwing it out.
I ordered a 6 pack of USB-C male ports from Amazon thinking that it would be easy to solder it up especially that I am an electrical engineering student. I am now on the 6th try after knocking out some resistors, soldering the wrong pins, accidentally soldering pins together so I need to get this last one right.
My problem is that I don't understand what pins do what in this charger. The charger cable has red, black, blue, and white wires. The while and black wires are much thicker than the red and blues ones so I first assumed the following:

Red: Vcc
Black: GND
White: Data +
Blue: Data -

...but I am completely unsure if this is correct.
The fact that I get 0V across the red and black wires makes me even more uncertain than I already am. I'm guessing that there must be some enable wires (maybe CC) to tell a switch in the rectifier in the charger to start. But where do I connect it? How do I test it?
I used the image from Microchip in this link https://www.allaboutcircuits.com/technical-articles/introduction-to-usb-type-c-which-pins-power-delivery-data-transfer/ to try to figure out what might be what.
Please see the attached pictures for reference.


texts: Circuit Design for Temperature Sensing PID Controller using Op-Amps

texts:
Basically, the idea is that I'll have a temperature sensor (LM35) that will sense the temperature of a certain metal can. This metal can is subjected to heat by a gas burner, and the gas burner's output would be reduced or turned off if the metal object is at a temperature of 110 deg C, and would be increased or turned on if it falls below 100 deg C. I'm thinking of using a servomotor connected to an Arduino, connected to the PID controller, to mechanically turn off or on the valve when the can is hot or cool enough.

I'm thinking of following this circuit for the PID Controller

For Verr, I will be using a comparator circuit that is connected to a constant V source of 3V, and for the temperature sensor, I will be connecting it to a non-inverting amplifier. What gains, resistor values and additional components should I use to make it work properly?

I am also welcome for suggestions of different circuit designs,as long as it uses op-amp based PID controllers.


texts: Can calibration improve the accuracy of a circuit?

texts:
If I have some resistors and a fixed-gain current shunt amp, that all claim "1%" accuracy can I make a system that's better than 1% accurate, if I put a calibration tuning pot into it, and adjust it manually while measuring it? Will it be better than 1% and repeatable if I do that?

What I'm after is something that's both accurate and repeatable - that once calibrated, it remains in that higher-accuracy state for a long time. What parameters am I looking for in datasheets that will explain how long-term repeatable such a setup would be?


texts: Why do traces on PCB's go back and forth? My first thought was it acts as a delay however the length of it should make the delay unnoticeable, if nearly non-existent. Image of example:


texts: ESP8266 PWM, vary the 220V light bulb intensity

texts:
How can I, instead of switching the light on/off, to dim the light using the PWM of the ESP8266 module?

I read this related question 5 years old
PWM to vary the light intensity of a 220V bulb

And I was wondering if there is a new way of doing it (a new module that I don't know about).

I did some research, I found that I could use BT136 TRIAC, but are there other ways of doing this?

May I get some support links or other ideas?


texts: Is there anyother way to construct an FM transmitter

texts:
I recently built an FM transmitter that uses a combination of coil and capacitor as an oscillator to generate the carrier frequency.

I built this transmitter:

Now my problem is that I find it difficult to wind coils properly. The chance of winding properly is very low. I tried to reconstruct nearly 10 to 15 times and it worked hardly twice or thrice. Also the received signal was very faint and consisted of lot of distortion.

Therefore, Now I would like to know if there is a way to build a transmitter that does not involve any coil. I googled it and found that I could use a crystal oscillator or an IC like 555 or LM385, etc.. How can I do it?


texts: Crystal oscillator - calculation of fparallel

texts:
This is the equivalent circuit for a crystal oscillator.  The two frequencies are fseries and fparallel, the latter being slightly higher.  It is calculated as,

where Ceq is specified as,

The formula given for calculating Ceq is that for series capacitors even though the first image shows Cs and Cp to be closer to being in parallel.
My understanding is that series components all have the same current flowing through them while parallel components all have the same voltage across them.  The equivalent circuit fits neither of these definitions perfectly, but seems to come closer to showing parallel capacitances based on the topology.
What am I missing?


texts: Flyback smps or floating buck converter?

texts:
I want to drive a 180V/1A string leds from 220VAC.

Which topology should I use:

flyback smps (with transformer) or,
floating buck step down converter?

I know that buck converter will be not isolated from the 220V but it's not an issue for the project.
If you also know some circuit, please share.


texts:
I have a question that I hope you can help me with. In schematics below an oscillator is presented that is fed with both AC and DC voltage, to be polarized and to induce movement of it. At the output I have a current that is equal to sum of the currents from two branches and when I try to display them on lock-in amplifier and oscilloscope it saturates and is not displaying anything.

Because of that I want to display just current Im without the Ic current, so I came up with idea of current canceling circuit. My mentor told me that I should use a variable capacitor plus some other components, but online I did not find helpful materials that will help me resolve this issue.

What are your ideas for canceling this Ic currents so I can just have Im?

simulate this circuit – Schematic created using CircuitLab


texts: Storing An Led's Previous state when power is removed with eeprom now

texts: A while ago I asked a question about having 2 push buttons, and an LED and you set the led to an on or off state with the two buttons, and then remove the power, and when turned back on, the led should stay in the state that was set when the power is on. I realized that I couldn't do it with any of the components that I had, and the best solution was a mechanical 2 button switch. Now I have the 24c00 EEPROM chip, 40 and gates, 40 or gates, 60 inverters (not gates), a few 555 timers, 4 NAND gates, an 4 NOR gates (I am not counting the amount of chips, just the total amount of gates). So now with EEPROM, I know that with its floating gate MOSFETS, it can store electrons by tunneling, so I am wondering if there is a way to store an led's previous state with these components.


texts: Unique solution for the damping factor in second order system

texts:
Given an underdamped (\$ 0 < \zeta < 1 \$) second order harmonic oscillator system with canonical form $$ G(s) = \frac{\omega_n^2}{s^2 + 2 \zeta \omega_n + \omega_n^2} $$.
we know that the maximum of the bode plot is given by $$ |G(j\omega_d)| = \alpha = \frac{1}{2 \zeta \sqrt{1 - \zeta^2}} $$.
Rearranging we get $$ \zeta^4 - \zeta^2 + \frac{1}{4 \alpha^2} = 0 $$. Substituting \$ x = \zeta^2 \$ we can apply the quadratic formula $$ x_{1/2} = \frac{1}{2} \pm \sqrt{ \frac{1}{4} - \frac{1}{4 \alpha^2} } $$ and consequently $$ \zeta = \sqrt{ x_{1/2} } $$.
But of course, \$ \zeta \$ is unique, so how do we know whether to take \$ + \$ or \$ - \$ ?
I know that this is usually visible from the plot (if \$ \zeta < \frac{1}{\sqrt{2}} \$ then we have a peak), but is there a more mathematical reasoning?


texts: What is the size of a normal potentiometer screw hole?

texts:
I have a potentiometer that looks like this:

http://www.parts-express.com/images/item_standard/023-606_s.jpg Fig.1

I don't want to solder wire onto the leads.  Instead, I want to do something like this:

 Fig.2

What is the standard size of the hole that I need to put the screw in?


texts:
The other day, a network card was acting up (even thought the software didn't report any functional problems, the network didn't connect in duplex). On checking the board visually, I found these resistors at the network interface:

Even though X probably means x0.1, I've never seen the symbol at the other side of the 5. I suspect the value to be 50 Ohms (to present the correct impedance to the line).

Any helpful reference?


texts: CMOS AND Circuit calculate power consumption

texts:
I need to calculate the power consumption of the CMOS AND circuit and I tried to figure it out myself but I really don't have a clue. I don't need the full answer but a first step into the right direction would be really helpful!
We are using the OrCAD software.
Thx a lot <3


texts:
I'm powering a motor, and instead of rotating at a constant rate, it rotates roughly a third revolution every half second or so; the rotation keeps starting and stopping. There's no load on the motor, but I plan to add a gear pump fixture (en.wikipedia.org/wiki/Hydraulic_pump) onto it. Also, the LED on the wall charger that lights up when the charger is plugged in dims out when I connect the motor.

I have a USB wall charger plugged into an outlet with a USB cable plugged into it. The other end of the USB cable is cut, and the red and black wires are going to the leads of the motor. This diagram demonstrates the setup.

The wall charger is DC 5V 1A supply. The motor is a RS-360SH.

How can I get the motor to rotate at a constant rate?

I measured the amperage that the motor is using, and it was always below 0.5 A. I understand that the motor is drawing amperage from the power supply.

I know that current limiting resistors, other circuits, and PWM are an option, but I'm trying to keep this low cost. Using the formula I = V/R, I get 1A = 5V/R, R = 5 ohms. So my total resistance needs to be 5 ohms or greater to limit at or below the supply amperage of 1A. The resistor would need to dissipate 5W (P=A^2*R, P=1^2*5= 5 watts). I do not have any resistors capable of dissipating 5 watts.

What is the best solution to limit current so that my power supply is protected from burning out?


texts: Nodal Analysis #2 - Where is my mistake?

texts: I am given a problem with its shallow solution (i.e. not all steps/formulas shown). When I tackled the problem (below), my answer didn't match the apparently correct solution. Where is my mistake? The bold writing is the apparent "correct" answer.


texts: How do I step down a 12V pulse width modulation signal to 5V?

texts:
I want to control my new laser module from my repurposed 3D printer. The laser module has a 12V pin for power, a ground pin and a 5V PWM pin. My board's fan-control port can generate a 12V PWM signal, so I think I should convert it to 5V to control the laser's power.
Are there any special considerations when stepping down PWM signals? I'm worried that a linear converter's capacitors might smooth out my signal or that a buck converter could do something similar. Should I just use a resistor?


texts: High side regulation of current for proportional valve

texts:
I'm working with a circuit which is regulating the current over a generic, proportional solenoid valve (L1 in the schematic below). The characteristics of the valve coil is unknown/will vary and the task of the application is to compensate for resistance/inductance variations in the coil caused by temperature changes etc, by means of a PID regulator. Currents are roughly between 200mA to 1A.
We are using high side current sense and a high side driver to achieve this. The current is obtained from a 5V 500Hz PWM signal, which controls a "smart" n-channel high side driver MOSFET. On-resistance shouldn't matter much since the task for the circuit is to compensate for resistance.
The driver uses a raw, non-regulated 24VDC from a vehicle to control the valve. The free wheel diode used is this one.
The high side current is measured over R1 with a high side current sense amp which gives its output as a current between 0 and 1mA. This current is in turn measured over the resistor R4 by the microcontroller, so that 1mA equals the maximum ADC value. (For various reasons ADC ref has to be lower than 5V - in this case it is obtained from an accurate voltage reference.)

simulate this circuit – Schematic created using CircuitLab
The PID regulator is implemented in software and works as it should, compensating for changes in resistance. It does however assume that the inputs and outputs are linear, so the current is only measured once per period, at a fixed point. We've tested that this works by connecting resistors in series with the valve. Everything works fine as long as the valve supply is kept constant.
However, when we change the supply voltage, the regulator will attempt to compensate, but we still notice a non-linear pattern in the output current, much higher than the <1% than can be expected from the LT6106. It can vary as much as 10-20% between 20V and 30V supply.
After much investigation, we came to the conclusion that this is because of some non-linear phenomenon in the coil. At the high-side, the PWM always looks pretty much like a digital square wave, so there's not much to tell from that.
But on the low-side, the curve looks very different depending on supply voltage. We managed to measure this by adding a shunt resistor on the low side, it looks something like this:
22VDC supply

30VDC supply

The above pictures are for the same output, but with the regulator trying to compensate for the change of current caused by the change of supply voltage, hence the different duty cycles.
I'm a software guy, so by no means an expert at electronics, let alone at magnetic fields in coils, please bear with me.

Q1: Is this a known phenomenon and is there a formula I can use in software to compensate for the non-linearity? It is possible for the MCU to measure the supply voltage if necessary.
Since the current is measured on the high-side, everything looks fine there. I can calculate peak or average current, but that's of little use, since apparently the square wave looks nothing like the actual current flowing through the coil.

Q2: How much, if any, impact does the free wheel diode have on the output? Can I change the curve by picking another diode with a different forward voltage, adding series resistors etc?

General feedback on the design is also welcome - I know that the driver IC is obsolete.


texts:
I am looking for a TPIC6C595 EQUIVALENT that works a a logic supply voltage of 3.3V.

I used to use a lot but now have had to use transistors driven from HC595 — very unsatisfactory.


texts: Lipo battery protection circuit. Is this a good approach?

texts: I want to build a circuit for a quadcopter where MOSFETs are connected to the primary and secondary battery. When the voltage falls below certain value in the primary battery the voltage monitor triggers the P channel MOSFET and cut the supply from primary and simultaneously the N channel MOSFET connected to the secondary battery turns ON and supplies the power. Batteries are rated 22 V Max current is 250 A.


texts:
I'm currently designing a self-powered PCB with a STM32L432KCU6 MCU on it. I want to use USB, but D- is already used for a different purpose.

According to the datasheet, D- and D+ have to be connected to PA11 and PA12. For PA12, this is no problem as this pin is still free. However, I'm using PA11 to drive a small 8 mA LED that is controlled via PWM. There is no free pin to which I could assign this function instead.

My question:
Is it possible to repurpose PA11 from a PWM output to D- once VBUS is detected?

Here the datasheet of the MCU:

https://eu.mouser.com/datasheet/2/389/stm32l432kb-956275.pdf

simulate this circuit – Schematic created using CircuitLab


texts:
I am installing 5V 1903 chip 3-wire LED-strings in model buildings and have constant issues with Brown-outs and getting white to be #)*% white.
Have also used WS2011 which are pretty similar and cross compatible (+ - Data)

Brownouts- I inject power at twice the recommended interval and still get purplish whites and off colours. My power supply is well in excess of the 3A per 50 expected draw.

Previously I got around this by overvolting the 5v strings to about 5.8V at the power supply. This seems well within parameters for other scenarios, but it seems to be biting me some weeks later with....

BrownING - yes! the casing (and it may be the filler waterproofing plastic they use) is actually going brownish... this seems bad and the lights are going greenish all down the line! Could this be a burnout chip early on degrading the signal further down the line??

I believe the driver is a lil arm chip if this helps.

PS: one thing people have talked about is using thin wires and inadvertently upping the resistance... mine are thin, but still multi-core and less than 4 meters.

PPS: I do use a lot of screw-down terminals is it possible that they have current limiting connections?

EDIT I have tried a short string and it lights up nicely..


texts:
I'm confused about the sizing of the battery cables for a UPS system,
When the battery is discharging the voltage decrease and current increase to a maximum value (which depend on the end of discharge value of the battery)
Should I size the cables according to this maximum current value (end of discharge) , or according to the maximum current calculated using the nominal voltage (in my case 415V)

Regards


texts: How to check 4 inputs and set flag in Microcontroller

texts:
I have a PIC MCU and have 4 input pins. I need to check the status of inputs and set the value of flag. Like if input 1 is active, then value of flag should be 1, if input 1 and input 2 are activated then flag is 2. FOr input 1,2,3 flag=3. For this kind of logic, I though of using multiple if else condition:

if(input1==high)
{
  flag = 1;
  if(input2==high)
  {
    flag=2;
    if(input3==high)
    {
    flag=3;
    if(input4==high)
    {
      flag=4;
     }
  }
 }
}

Is there any way I can skip this if else and can use some other c logic. Please help.


texts:
simulate this circuit – Schematic created using CircuitLab
Problem:

I need to design a differential pair with a gain of 30dB

To make this design I have to used 4 mosfets transistor 2n7000 with these characteristics

M1:

\$V_t = 1.36\$ V
\$V_a = 4.729\$ V

M2:

\$V_t = 1.6\$ V
\$V_a = 5.6\$ V

M3:

\$V_t = 1.5\$ V
\$V_a = 4.2\$ V

M1:

\$V_t = 1.35\$ V
\$V_a = 3.3\$ V

Characteristics:

To make the design I have to use two mosfets for a differential pair with passive load and two mosfets for a current mirror.

I can't find the \$V_s\$ of the differential pair that come from the current mirror \$V_d\$


texts: Add downloaded components to existing library in Altium?

texts:
I have just started using Altium as a student after using Eagle for a lot of years.
I download part libraries from sites like Ultra Librarian and can use the supplied script to generate a library with symbol, footprint and 3D body, I can then compile so I can use it in a design.
But this is going to end up with me having hundreds and libraries with just one part in each. How can I create one library and import the downloaded files from Ultra Libary (and others) into that library? Bearing in mind that I have no scripting experience.
Basically, I want to end up with one library for say one brand of MCUs, comm transceivers, connectors etc much like in eagle.


texts: Expected output of DFF_2 if DFF_1 has hold violation

texts:
I am trying to figure out the output of flop DFF_2 when

If DFF_1 has hold violation.
My answer - DFF_2(Q) = X
If DFF_2 has hold violation.
My answer - DFF_2(Q) = X

I understand the FF's go to meta-stable when there is a hold violation causing the simulator to assume a value of 'x' on the output 'Q'. Which brings me to my answers of DFF_2(Q) being x for both cases. Assuming i am clocking out data as in the normal operations.
Is there any different behavior that i should know in this setup ? or Are my assumptions wrong ?

simulate this circuit – Schematic created using CircuitLab


texts: What types of wire should I use to pull out from a Test Point while using Cheap Logic Analyser or Oscilloscope?

texts:
The only purpose to ask this question is I use single/multi-core thin wires that snap of in few days. I don't want that. Is there something that doesn't break?

Or some other tricks/connectors or anything else because I really don't know what should I use. It would be more helpful if it is economic solution.


texts: Winding an electromagnet ring coil to get radial magnetic field

texts:
How can I wrap an electromagnet ring coil radially where the north pole is in the center and the south pole is at the outer ring?  Is this possible to wrap?
Example:

I know I can wrap a simple coil to get north at one end and south at another but can one be wound radially to produce a magnetic field like in the picture above?


texts:
one of my electronic appliances has stopped working after several years of use, it is definitely beyond the warranty period however I've been unable to find any more recent appliances that beat it.

With this said, I have looked into repairing the device after repairing a previous one (thanks for those that helped with my previous question). The issue has been reported from various users of the appliance and a few seem to point to the safety capacitor being responsible.

Last time, I was advised to pick one like for like however there doesn't seem to be that much information on the capacitor itself and I am struggling to find the datasheet for the capacitor.

From my understanding the 0.68K means that it is 0.68uF +/- 10%. The voltage is 275V. I measured the outside of it (as it's still attached to the circuit board), it's 26mm(length)*9mm(width)*18mm(depth), height/width can be changed a little as there is space.

The only suitable replacement I have found isn't the right size (the others I have seen are +/-20%).   ECQU2A684KLA

Would it be possible to add wires to the end of a capacitor to extend the pins so that it would match the holes for the pins on the circuit board? If so, what effect would this have? Would it reduce/increase the resistance?

Thanks.


texts: How can i make a ceramic piezo operate at a specific frequency?

texts:
I recently just ordered several ceramic piezos used to aerosalize water and essential oils.http://www.aliexpress.com/item/Free-shipping-20mm-atomization-chip-board-dedicated-ultrasonic-atomization-transducer-piezoelectric-ceramics-Humidifier-Accessor/32352358688.html

I'm fairly new to working with piezos and oscillators and have no idea how to get it to funtion at exactly 1.7MHz (or close to it). i have scoured the web for exaample schematics and as of yet have found nothing. Could anyone point me in the direction as to what i need to do to get the piezo to operate at 1.7MHz?


texts: Doubt on the Voltage Regulator Application with LiPo Battery

texts:
If I have a LiPo battery with the maximum voltage of 12V and I want to use it to power a 5v(L7805) voltage regulator. Assuming the maximum current passing through the regulator is 500mA. From datasheet, the thermal resistance is 50°C/W.

Does that mean that it would generate a power loss of 3.5W and it would raise the voltage regulator's temperature by 175°C? The maximum operating temperature of the voltage regulator is 150°C. Would that means I need to drop the input voltage of the regulator?

Additional info from OP comments:

I am not able to get a switching regulator and the great power loss is not a concern. Would the thing work if I stack multiple voltage regulator together?


texts:
I have a multimeter type VC9205S.  I plugged it in to power 9 volts because the battery is empty.
Hours later, negative readout values began to appear.
1- Can the device be calibrated or not repairable?

2- I measured the cut-off transformer input voltage for a power circuit and had a cut-off frequency of 160 kHz and voltage 300 volts so is that the cause


texts: Can I use a Bakelite MES Globe Holder to convert a lantern into a table lamp?

texts:
I want to turn a Moroccan cast iron lantern into a table lamp. Could I use a Bakelite MES globe holder to wire in a light globe?

Bakelight MES Globe Holder:


texts:
I am working with Benthowave BII-7186 Miniature Probe Hydrophone. In its datasheet I have come across the following information about wiring:

I am not sure what is Digital Common, and how different it is from Common?

The datasheet in question: https://www.benthowave.com/products/Specs/BII-7186Datasheet.pdf

Kind regards,

Dejana


texts:
I want to build a simple USB lamp (maybe colored LED lamp) which will be controlled by PC. So, actually, i want to get practice in linux kernel modules development, but i need to get appropriate schematic. It is clear for me that basically i want to switch on and switch off this lamp from userspace utility, which will manipulate with device through the driver. Further, maybe, i will add lamp color changing using principles from this article
http://www.diylife.com/2008/01/25/make-a-usb-color-changing-light/

But now i want to understand one thing, as i said before, i want to build a scheme with lamp and without microcontroller, which will connects to PC through the USB interface. And i want to manipulate (switch on switch off and further maybe color changing) this lamp directly using usb data channel. Is it possible? Can anybody helps me to find appropriate schematic?
Thanks.


texts: Easiest way to find matching li-ion cells (3.7V, 18650)

texts:
I recently acquired 50 used li-ion cells (18650).  I'd like to efficiently determine which cells are good matches (i.e. which cells have similar: capacity, charge times, & discharge times) so that I can put them into battery packs that will perform optimally (e.g. they don't punk-out early because one or more cells discharge too fast or over-charge or over-heat as slower charging cells lag near the end of charging).

What would you suggest would be the best way to test multiple cells to get such information?


texts: How exactly does the low-pass filtering in a lock-in amplifier correspond to a time-averaging?

texts:
In this white paper of Zurich instruments two ways of explaining a lock-in amplifier are shown: low-pass filtering and time-averaging. Whereas the explanation with time-averaging can easily be done with complex numbers, the low-pass filtering seems to be more complicated (since it involves Fourier analysis to get from the time to the frequency domain?): https://www.zhinst.com/others/en/lock-amplifiers
A larger bandwidth in the frequency domain seems to correspond to a smaller time interval for time-averaging in the time domain. Therefore, there is a trade-off between good time resolution and high SNR. The signal buried in noise can vary over time, therefore it is important to set the right bandwidth. Most modern lock-in amplifiers work digitally by applying a low-pass filter, right? But couldn't they also perform the mathematical operation in the time domain (multiplying the sin and cos / complex numbers) ?
My question is if somebody can explain this relationship between the time and frequency domain more exactly. I couldn't really find any information about that. In the white paper it is also not explictly explained. And what exactly does the lock-in amplifier do when it applies a digital low-pass filter?


texts: 0.5V virtual ground with single rail op amp

texts:
[EDIT]

I am working on a 0.5~3.3V voltage source with 0.5V virtual ground. Any problem with the design so far? (The high side probably needs to be switched to a class AB amplifier as well)

I am designing a 0.5~3.3V voltage source with 0.5V virtual ground. My question is, if there is no R28 (right most resistor), and VREG/VGND aren't connected to anything, would there be a stability problem on U3.2 ? Any suggestion on improvement?

(original schematic)


texts: NMOS inverter with enchancement load behaving weirdly in LTspice

texts:
The green line is the output voltage and the red line is the ferivative of the output voltage.

I was simulating this circuit and the derivative shows horrible fluctuations. I don't know why this is happening.


texts: Where to connect DB9 Ground Pin on a Serial RS232 connection?

texts: I want to connect my DIY basic stamp via RS232 MAX232 to the serial port on my laptop. Now since I'm a complete newbie in electronics, what do I do with Ground Pin 5 on the DB9? I assume ground means I have to connect it to some insulator with 0V? Maybe you can also explain why there has to be a GND pin anyway, what is the purpose?


texts:
In my design I want to convert a 48V input voltage to a 12V output voltage. In order to achieve this I want to use the AVD120-48S12-6L. The following external circuit is stated as recommended:
However, I am not sure why the transformer is needed, since in most circuits a simple inductor is used. Can someone maybe explain this to me?


texts: DC and low signal Analysis of Common Source Amplifier: wrong drain current and amplification?

texts:
For a Coursera test I need to analyze a common source amplifier:

I need to calculate the

DC gate voltage - easy: -2.3077
drain current Id - should be easy but the results are wrong. I use this formula from the course or from here:
$$
I_d=(\frac{\sqrt{1+4*K*V_1*R_{SS}}-1}{2*\sqrt{K}*R_{SS}})^2 \\
V_1=V_G-V_{TO}-V_{SS}
$$
the drain voltage Vd=Vdd-Id*Rd which gives me -3.7719 V with the "wrong" current ??
the amplification which gives me -24.8174  (which is wrong!)
$$
\frac {V_{out}}{V_{in}}=-\frac {R_D ||R_L}{r_s+R_S||R_3}\\
r_s=\frac{1}{g_m}\\
g_m=2*\sqrt{K*I_D}
$$

OK.

Here are my calculations from Matlab:

Vdd=15; Vss=-15;K=1.1*1e-3;Vto=2;R1=150000;R2=110000;Rd=10000;Rs=5000;
R3=200; Rl=10000;

Vg=(Vdd*R2+Vss*R1)/(R1+R2)
Vg = -2.3077

V1=Vg-Vss-Vto
Id=((sqrt(1+4*K*V1*Rs)-1)/(2*Rs*sqrt(K)))^2
Id=0.0019

Vd=Vdd-Id*Rd
Vd = -3.7719

gm=2*sqrt(K+Id)
rs=1/gm
gac=-R_parallel(Rd, Rl)/(rs+R_parallel(Rs, R3))
gac = -24.8174

No I wonder am I too dumb to be true or is there a flaw in the automatic grader?

In case I am too dumb, please, tell, where my error is. Thanks.


texts:
I need to make a small heater. I was looking at this project:

http://www.makeuseof.com/tag/make-your-own-temperature-controller-with-an-arduino/

but I need to design the heating element. I was considering taking 120VAC from the wall, running the hot side through a 1 amp fuse, running that into a relay, then running the relay output into a 300 ohm power resistor for a total of 50 watts. Looking at this part currently:

http://www.mouser.com/ProductDetail/Vishay-Dale/HL05006Z300R0JJ/?qs=sGAEpiMZZMtbXrIkmrvidHh8qJ0vS%2f1J%252bhAYDyLahp8%3d

Questions:

Do I need an AC isolation transformer? If so, why? Isn't the 1 amp fuse enough for safety?
I am not planning on using a fan or heat sink, only ambient air. What is duty cycle of such a power resistor? Generally I would expect that it can dissipate 50 watts 100% of the time (taking into account the ambient temp derating of course), and I've also seen the 1000h component life spec. Any thoughts?
Max voltage = (P*R)^1/2, which in this case comes out to 122V. Obviously this is close to wall voltage, and peak to peak is much higher than 122V. This thing looks like it's built like a high voltage component though, will this really be an issue? (If it is I can adjust the dissipated wattage downwards a bit, while still using a 50 watt rated resistor)

Thanks!


texts: Why does my circuit work with ceramic capacitors but not electrolytic?

texts:
I had used some capacitors as decoupling capacitors for my USB powered device. Due to some chip issues, this resulted in using three 47 uF capacitors.

I used electrolytic capacitors. Three in parallel, between Vcc and Gnd. However, there were still problems.

This other group I am working with used ceramic capacitors. They gave me their modified part and everything worked.

I thought that the main difference between the different materials in capacitors was when they are used at high frequencies. Why is it that ceramic capacitors worked in this case and not the electrolytic type?

Some links I used as reference:

http://dev.emcelettronica.com/guide-to-capacitors-electrolytic-capacitor-ceramic-capacitor-and-others
Can I replace all electrolytic capacitors with ceramic ones?


texts: Send more than one value via SPI/arduino, MAX5483, 10-bit digi-poti

texts:
With help from efox29 I worked out to control the MAX5483, 10-bit digital potentiometer (data sheet here) with an arduino using SPI. Now how can I trigger more than one value?

I tried to do that with a simple for-loop, but it doesn't work. To be precise it produces a strange resistance value (68 Ohm). And even just putting a delay seems to cause the same issues..

For example

digitalPotWrite(197); //
delay(10000);
digitalPotWrite(60); //
delay(10000);

Should change the resistance between 2.1k Ohm and 688 Ohm. I assume that, since by putting just

digitalPotWrite(197);

or

digitalPotWrite(60);

alone without delay(10000); I can measure this values with my multimeter between the pin 10 and 11 of MAX5483. But by putting it all together like I tried above, I strangely measure only 65-68 Ohm. This doesn't change by only putting the following lines:

digitalPotWrite(197); //
delay(10000);

Here the measured value (between pin 10 and 11) is still 68 Ohm..
Here is the complete code:

#include <SPI.h>
const int csPin = 3;
const int selPin = 2;

void setup() {

 SPI.begin();
 SPI.setBitOrder(MSBFIRST); //We know this from the Data Sheet
 SPI.setDataMode(SPI_MODE2);

 pinMode(csPin,OUTPUT);
 digitalWrite(csPin, LOW);

 pinMode(selPin,OUTPUT);
 digitalWrite(selPin, HIGH);

}

void loop()
{
    //"sweep" small range (from 1.7 to 2.1 KOhm)
    // 158 to 197
//
//    for (int i=158; i < 211; i++){
//    delay(1000);
//    digitalPotWrite(i); //
//   }

digitalPotWrite(197); //
delay(100); // seems to cause issues.. without this line it works

}

void digitalPotWrite(int value) {
digitalWrite(csPin, LOW);
delay(1);
byte command=0x0;
byte byte0 = (value & 0x03) << 6;
byte byte1 = (value & 0x3FC) >> 2;
SPI.transfer(command);
SPI.transfer(byte1);
SPI.transfer(byte0);
delay(1);
digitalWrite(csPin, HIGH);
}


texts: Read serial data from unknown source using Raspberry pi

texts:
I have a fuel dispenser, which has one keypad and two displays, each display has three of 7 segment LCDs.
I want to control the fuel dispenser with a PC or a phone. The way to do this in my knowledge is by attaching Raspberry to the fuel dispenser; program the raspberry pi so that it can imitate the same work as the keypad; and read what is written on the display so that I can insert it in a database as a record. Then I can communicate with the pi in different ways.
Now the imitation of the keypad was very easy and I have no problems with it. The problem I am facing is that I am still not able to read what is written on the display.

Let me first show you what does the display looks like:

Now the kaypad has 12 buttons ( from 0 to 9, an A button, and F button).
. If I click on A (which means I want to insert maximum amount): the size LCD shows nothing and the amount LCD shows one "0".
. If I click on F (which means I want to insert maximum capacity): the size LCD shows one "0" and the amount LCD shows nothing.
. If I just start pumping fuel with typing nothing, the display starts showing the calculations on the size LCD and its equivalent amount on the amount LCD.

Now data comes from the motherboard, which is sealed to the display through the 10 Pin IDC cable. After measuring each pin of the cable I found:
. 2 Pins of ground
. 2 Pins of 12V
. 1 Pin of 5V
. 2 Pins of 3V
. 3 Pins of -0.3V

So I started to look for which pin sends data. I used Raspberry pi 3B+, and I attached the ground of the raspberry pi to the ground of the cable, and the serial RX of the raspberry pi to each of the other pins (I used 1k Ohms resistor in between).
I found that:
. 2 Pins of 12V and 1 Pin of 5V has nothing
. 1 Pin of 3V sends data each 1 seconds (It also sends data when I click on the keypad)
. 1 Pin of 3V send data each 2 seconds or maybe 3 seconds (when I click on the keypad, it sometimes sends data and sometimes it doesn't)
. The other 3 Pins of -0.3V send only zeros (Even if I click on the keypad)

Now the problem is that I don't understand the data that I receive from the raspberry pi. I just see it as random numbers.

Here is what I see from one Pin of 3V:

This is from the other 3V Pin:

It even changes it value other than 165 sometimes.

This is the python code I am using on Raspberry pi:

import serial

ser = serial.Serial("/dev/ttyS0", baudrate=9600, bytesize=8, timeout=1)

try:
      while 1:
            response = ser.read()

            if response:
                  print response
                  print ord(response)
                  print bin(ord(response))[2:]
                  print "---------------------"
            #line = ser.readline()
            #if line:
            #     print line
except KeyboardInterrupt:
      ser.close()

I tried changing baudrate and bytesize, and received the same random numbers.

Here you can find the datasheet of the "PCF8576CT" LCD driver:
https://www.nxp.com/docs/en/data-sheet/PCF8576C.pdf

I apologize for making this long, and I hope you can find solution to this.

Thank you


texts: Converting a summation to an integration

texts:
I've seen it done a few times, it's always roughly apparent that "oh yeah, okay, they've dropped this, pulled this there, yeah, okay, kind of convincing" - but I've never why or how to do it for myself.

I probably don't understand it enough to be searching in the right way, but I'm unable to find anything useful by Googling.

There's a really nice mathmo derivation that I barely understand a word of here.

And a thoroughly unhelpful Physicist "thus it is this" non-explanation here.

But how about a nice not-mathematically-proper-but-it-works method for Engineers?

To be clear, I want to know how to go from:

$$
\lim_{\Delta\omega\rightarrow0} \sum_{n=-\infty}^{\infty} \dfrac{G(n\cdot\Delta\omega)\cdot\Delta\omega}{2\pi} \cdot e^{jn\cdot\Delta\omega\cdot t}
$$

to:

$$
\dfrac{1}{2\pi} \int_{-\infty}^{\infty}G(\omega) e^{j\omega t} \cdot d\omega
$$

and vice versa, and know how to do this for other problems, since as I said, I can sort of see that we've kept the limits, integrated wrt the limit, and removed the summation variable \$n\$. But if I did that on another problem, I wouldn't know I was 'doing it right' - and going in the other direction, how do we know where to put the \$n\$ back in?


texts: How do you tell if a Li-ion battery has a protection circuit?

texts: I bought a li-ion battery off of ebay. The listing claims that the battery has a protection circuit, but a week later, the battery didn't cut out or anything. With a multimeter, it is reading 10V when the battery is listed at 10.8-12.6V. Does this mean the battery doesn't have protection or should the cutoff be lower?


texts: Why the redundant Fuse and redundant rectifier diode(Series)

texts:
I would appreciate if someone would share his thoughts on why would someone put a fusible resistor in series before an NTC ? . Also in the rectifier diode stage there are two extra series diodes in each branch (L1,L2,L3 & N), i tried to simulate the series diode in LTspice and i could not find any noticeable difference ....

For more information on the circuit for context , this a 3 phase AC/DC power supply used in a reference ATSAM4L electricty meter.

Thanks in advance