texts: AVR ATmega32 - C - Gets stuck in function call

texts:
I have had lots of problems trying to get a piece of firmware to work which has worked fine earlier, and is working on a copy of the board I'm having problems with.  I've narrowed in down to the following (at least to start with):

This piece of code works:

#define F_CPU 8000000

#include <avr/io.h>
#include <util/delay.h>

int main(void)
{
   // LEDs - initial setting
   DDRC |= 0x03;                // LEDs on pins PC0 and PC1
   PORTC &= ~(1<<0);             // LED0 OFF
   PORTC |= (1<<1);             // LED1 ON

   DDRD |= 0x30;    // PD4..5 OUT
   TCCR1A = 0xE2;   //0b11100010 (Set OC1A + Clear OC1B on compare match, )
   TCCR1B = 0x19;   //0b00011001 (WGM13:10 = 0b1110 => Fast PWM Mode, TOP = ICR1, CS12:0 = 001 => Use IO clock, no prescaling)
   OCR1A = 18;
   OCR1B = 18;      //  18 / 8000000 =  2.25 us (Output compare match value (OC1A->HIGH, OC1B->LOW)
   ICR1 = 757;      // 757 / 8000000 = 94.625us (TOP value for timer1)

   // Loop blinks LED0..1 alternately
   while(1)
   {
       PORTC = PORTC ^ 0x03;
       _delay_ms(250);
   }
}

It starts the timer and outputs the pulse with the specified timing, and enters the blinking LED loop.

However, this code fails:

#define F_CPU 8000000

#include <avr/io.h>
#include <util/delay.h>

void pulse_init(void)
{
   DDRD |= 0x30;    // PD4..5 OUT
   TCCR1A = 0xE2;   //0b11100010 (Set OC1A + Clear OC1B on compare match, )
   TCCR1B = 0x19;   //0b00011001 (WGM13:10 = 0b1110 => Fast PWM Mode, TOP = ICR1, CS12:0 = 001 => Use IO clock, no prescaling)
   OCR1A = 18;
   OCR1B = 18;      //  18 / 8000000 =  2.25 us (Output compare match value (OC1A->HIGH, OC1B->LOW)
   ICR1 = 757;      // 757 / 8000000 = 94.625us (TOP value for timer1)
}

int main(void)
{
   // LEDs - initial setting
   DDRC |= 0x03;                // LEDs on pins PC0 and PC1
   PORTC &= ~(1<<0);            // LED0 OFF
   PORTC |= (1<<1);         // LED1 ON

   pulse_init();

   // Loop blinks LED0..1 alternately
   while(1)
   {
       PORTC = PORTC ^ 0x03;
       _delay_ms(250);
   }
}

...it's just the same statements as before, moved to the pulse_init() function. When I upload this code the timer is set up correctly and the output pulse is OK, but the program never starts blinking the LEDs on PC0..1.

Any ideas? It's not just this function, this is part of a bigger program with other initalization functions and it seems whenever the program enters a function separate from the main loop it fails to return to main. I am not so familiar with C and how it works on the function block level. I am using Atmel Studio 7 now with the following compiler options:

-x c -funsigned-char -funsigned-bitfields -DDEBUG  -I"C:\Program Files (x86)\Atmel\Studio\7.0\Packs\atmel\ATmega_DFP\1.1.130\include"  -O1 -ffunction-sections -fdata-sections -fpack-struct -fshort-enums -g2 -Wall -Wextra -pedantic -mmcu=atmega32 -B "C:\Program Files (x86)\Atmel\Studio\7.0\Packs\atmel\ATmega_DFP\1.1.130\gcc\dev\atmega32" -c -std=gnu99 -MD -MP -MF "$(@:%.o=%.d)" -MT"$(@:%.o=%.d)" -MT"$(@:%.o=%.o)"

but I had the same problems with avrdude. I also tried reading the full binary from the working board and writing it to the board I'm working on. It should communicate with PC over a USB-to-serial but it doesn't work. When I power up the board it spews a few kilobytes on nonsense to the serial (the same nonsense every time, though) and then freezes, i.e. doesn't send the regular "Waiting for command" message or reply to any commands.

The chip is Atmega32L8AU, 8MHz external crystal, LFUSE=0xFF, HFUSE=0x99.

Any ideas?

Edit: SOLVED - The firmware works after changing the AVR chip. Turns out to be a faulty memory area in the SRAM or possibly something wrong with the SRAM/GPR bus. This was suggested by in comments to Maximus' answer below.

Thank you for all your help!


texts: How can we increase the range of a line sensor to make it work as a proximity sensor?

texts:
Basically, I have this line sensor. It is designed to distinguish black and white lines. It detects white surface and gives me digital 1 as output and 0 in case of black. But the surface need to be too close to it.

However, as it uses infra-red sensors, I wanted to use this sensor as a proximity sensor, to tell me if there is a white surface near it. Is it possible to do this? I think the only problem here is, that we need to increase its range of giving 1. Currently, it gives 1 only when white surface is too close to the sensors. I want 1 even if the white surface is there at a bit more distance.

Also there is an adjustable screw there to adjust something, under which POT is written. I am working on Arduino.


texts: Can someone tell me how the proximity sensor on the Nexus S works or what it is?


texts: Powering a Rasperry Pi Zero, Arduino Uno, 2 steppers and a servo from same supply

texts:
For a project I'd like to use a Raspberry Pi Zero as a web server interface to receive and send data to/from an Arduino Uno which will control 2 stepper motors and a servo. I would like to have only one source of power for all of this and would like your advice on how to do it.
I first thought to connect the power supply to the Arduino and then using a shield ( like this one ) to control the steppers and servo.
But can I also power the Raspberry Pi Zero through the Arduino USB port while also sending and receiving data through USB?
Thank you


texts:
I was trying to design an arbiter puf in SPARTAN 3E while doing that one need to connect d flip flop at last. Problem was that one of the mux output is to be connected to d flip flop which is giving IOB error says clock position is not optimal. But I can't give clock pin number C9 which is inbuilt clock in SPARTAN 3E as it need to come from one of the mux. How to solve this problem considering that I want to use 40 such parallel block. One of block in shown in figure?
I am trying to run a verilog code of following design in figure where there are two pair of muxes and flip flop to make an arbiter puf. I don't understaand how to correct the error.

module arb(a,en,b,qq );input a,en,b;
output  qq;
wire y;
wire p,q,r,s;
mux m0(en,en,a,p);
mux m1(en,en,a,q);
mux m2(p,q,b,r);
mux m3(q,p,b,s);
dff d1(r,s,y);
assign qq=y;  endmodule

module mux(input a,b,s,output q

);
assign q=s?b:a; endmodule

module dff(input d,clk,output reg q

);
always@(posedge clk)
q<=d; endmodule

I am getting error Error message is Place:1018-A clock IOB/ clock component pair have been foundthat are not placed at an optimal clock IOB / clock site pair. The clock component is placed at site .The IO component is placed at site . This will not allow the use of fast path between the IO and the Clock buffer. If this sub optimal condition is acceptable for this design, you may use the CLOCK_DEDICATED _ROUTE constraint in the .ucf file to denote this message to a warning and allow your design to continue.However,the use of this override is highly discouraged as it may lead to a very poor timing results.It is recommended that this error error condition be corrected in the design. A list of all the COMP.PINs used in this clock placement rule is listed below.These examples can be used directly in the .ucf file to override this clock rule.

This error is in place and route option in SPARTAN 3E

So my question in how to write verilog code of given figure and still don't get error


texts: Are there any quick way to tell if a filter is high-pass, low-pass, or band-pass, just by looking at the transfer function in the s domain?

texts: How can I quicly determine if a given filter's transfer function like: \$ H(s)=\frac{k}{s^2+ks} \$, or \$H(s)=\frac{1}{s+k}\$, is either a low-pass, high-pass, or band-pass ?


texts: Why does current in this circuit disappear instantly

texts:
In this circuit initial current of 3ampere is given in both inductors  (just before closing of switch), And after closing   the switch, I calculated current in the circuit by laplace transform and it turns out that current will be zero, so where does all the initial currents disappear?
Or my calculation is wrong and some current will flow after closing the switch?
Here is my solution -


texts: Saving data to an SD card memory module using an Arduino

texts: Is it possible to save data from the Arduino to an SD card memory module?


texts:
I have an ATMega328P microcontroller, and I'm learning how it is programmed. I wrote an example for Timer0 and uploaded it into the microcontroller. It works and a led blinks once a second in while.

When I try to simulate it in Proteus 8.0, the led blinks every 8 seconds. I set the properties of the microcontroller in Proteus but nothing was changed. Why is the Timer0 delayed in Proteus?


texts: Why it has used BPSK modulation after OFDM?

texts:
I am quite new to OFDM modulation. I am reading this from a tutorial. In one of its parts, for showing amplitude variation of the OFDM signals, there is a graph that has used 8 sub-carriers and BPSK modulation as below:

Now I have faced to this question, that we are using OFDM modulation here, so why we have used BPSK modulation? Do we double modulate the signal? I cannot understand the use of BPSK in this example. Any help?


texts: Can a desolder pump aerosolize lead particulates?

texts:
I have been reading up on the dangers of leaded solder. I understand the risk of actually soldering with it are minimal but my question is specifically its removal via "solder suckers."

Does this process of removal cause fine enough particulates to make an airborne risk of exposure a viable one?

If so what steps can be taken to prevent an airborne risk of exposure?


texts: How to erase stored data in MRAM memory devices

texts: When searching in Google about MRAM I was only able to find the reading and writing process for MRAM.  How does erasing happen in MRAM?  Also why there is no need of error correction and checking algorithm in MRAM?


texts: Right now I'm using an N-Channel MOSFET. I am inputting a 2V pk-pk square wave into the gate, the drain is connected to a bare wire (that is connected to nothing) and the source is connected to ground. For some reason there's a voltage reading in the drain of my MOSFET. Is this normal?


texts:
I am doing power dissipation of a power mosfet. My design requirements are :-

20A @ 12-20V (Ambient temp will be around 50 deg Celsius)

The mosfet I am using is :-

http://aosmd.com/res/data_sheets/AOD425.pdf

My doubts are :-

In the datasheet , they have given 2 types of power dissipation as below :-

I understand that they are at different case & ambient temperature but what do they actually mean & how to use this data?

In one more table they have given :-

Rja is given & Rjc is given. Rja = Rjc + Rca. Rca is not mentioned anywhere because that might depend on the PCB layout but still, how do I calculate Rca to do my thermal analysis.

In general, what do I actually use for thermal analysis. If @ an assumed junction temp of 70 deg c, my Rdson is 20 mE & my current is 20A. calculating :-

P= (I2)Rdson = 400*.02 = 8W.

Is 8W okay through this mosfet? If not, how to prove that?If yes, how to validate?


texts: Adapting 120VAC High Pass Filter to UK 240VAC

texts:
I am looking to build a analog high pass filter with a cutoff frequency of 5.3 kHz. I have found a design which suits my need but I would like to adapt it from the 120V AC, 60Hz and a cutoff frequency of 50kHz it was designed for to the UK 240/230V AC, 50 Hz standard, with a cutoff frequency of 5.3kHz. Any ideas on how to do it to maintain a safe circuit and a good signal ?

I also would like to double check it is safe enough. Should I add a 1:1 transformer to isolate the mains ?

The overall procedure I hope to follow is :

"To measure the EMI on the power line, we used the same
hardware used in LightWave [4]. An analog high-pass filter
(HPF) with a 3 dB corner frequency of 5.3 kHz is used to
reject the strong 60 Hz component. The output of the HPF
is sampled at 1 MS/s using a 12-bit analog-to-digital (ADC)
converter in the USRP (Universal Software Radio
Peripheral) followed by transforming the signal into
frequency domain using a 32,768-point fast Fourier
transform (FFT), yielding a frequency resolution (or bin
size) of 30.5 Hz. The signal from the USRP is then fed into
the computer for data analysis. It should be noted that a
USRP was used in this prototype simply for convenience."
from UTouch Paper

I hope that I didn't say anything too stupid. I'm still a novice, but willing to learn ;)


texts:
I am learning to use a comparator (LM393N) and running into trouble. No matter what I do, the output is always LOW. I am running off of a 9V battery, and I've added a voltage divider to send half of that to the V- (inverted) pin of the comparator. Yet, whether the non-inverted pin is connected directly to the positive rail (all the way HIGH) or to ground (all the way LOW), the Output pin always reads LOW (0V). What am I doing wrong? Here's a sketch of what I've set up where:

Pin 4 is inverted pin
Pin 5 is non-inverted pin
Pin 3 is positive power source
Pin 2 is output
Pin 12 is ground

Sorry for the weird pin numberings! I couldn't figure out how to change it in TinyCAD.


texts:
I have a problem setting up Interrupt Service Routine for PIC24F08KA101.
I have successfully initialized IE,IF,IP for interrupts which I need to use.
Part of the code which initializes these:

void
int_init(void)
{
IEC1bits.INT2IE=1; //Enable Interrupt
IFS1bits.INT2IF=0; //Clear Interrupt Flag
INTCON2bits.INT2EP=0;   //activate on positive edge
IPC7bits.INT2IP=3; //Set priority (higher gets executed first)
IEC0bits.T1IE=1;   //Enable Interrupt
IFS0bits.T1IF=0;   //Clear IF
IPC0bits.T1IP=2;   //Set priority
}

I have checked them from the PIC24F08KA101.h. The clock prescaler is not shown in this code.
I have problem initializing ISR for INT2 (External interrupt port 2) and T1 (timer1). I tried to use this ISR, but it does not work. Got it from code examples.

void __attribute__((interrupt,no_auto_psv)) _INT2Interrupt(void); //Declare
void
__attribute__((interrupt,no_auto_psv)) _INT2Interrupt(void)
{
    //Do stuff here
}

I tried the same for timer1, but it does not work too.
I use HI-TECH for dsPIC/PIC24  V9.62 compiler.
INT2 is selectable port for the PIC I use.


texts: Making sparks using a voltage multiplier and a Marx generator

texts:
I have seen people making big sparks using a Marx generator. For the input to the Marx generator they use high voltage sources, sometimes using a flyback transformer.
I don't have stuff to make a high voltage source right now, so I've decided to use a voltage multiplier to drive the Marx generator.

Would it be feasible to do it?
What are the possible problems of using a voltage multiplier to feed a Marx generator?

I'll be using 220VAC as input to the voltage multiplier and produce around 5kV output from the multiplier.


texts:
I captured the usb packets on a usb1.1 mouse using a generic 24mhz logic analyzer.

here is the sigrok capture for the first token.

as per the usb docs.. a CRC5 is calculated for the token by taking into account the address(7bits) and endpoint(4bits) fields.

since both the addr and endp are zero for this transaction, the 11 bits are - 00000000000 so the crc calculated by the crc5 polynomial( 100101) should give zero, but i'm not able to understand that the crc field is 0x2.

now for a different transaction.. after the host has allocated address to the device.

fields are--
addr - 11;
endp - 0;

so, from the datasheet(pg 173), the final 11 bit field is - 11010000000 . when crc5 is calculated on this field.. it gives 4 which matches correctly with the crc field.
I used the long division method to calculate the crc.

am i miscalculating the crc for the first token?


texts:
I want to interface the following CT to Arduino:

So I have the following data:

Primary Current: 600 Arms
Secondary current: 5 Arms
Burden: 2 VA

Burden = 2 VA means that:

Rmax = P/I^2 = 2/25 = 0.08 Ohms max burden resistor (am I right?)

At 5A, there should be a voltage drop of V = P/I = 2/5 = 0.4 Vrms

Let's say that Rburden = 0.05 Ohms:

Pmax = 5^2 * 0.05 = 1.25W.

0.05 Ohms/3W is available on the market, so I'd go for it.

Given Rburden = 0.05 Ohms, at 5A we have Vdrop = 0.05*5 = 0.25 Vrms or 0.35 Vpeak.

So the output voltage at the burden resistor will range from 0 to 0.35V. I want to map this range from 0 to 4V for the Arduino's ADC.

I have decided to bias the signal at 2.5V as follows:

This means I will have a max differential voltage of Vdiff = 4-2.5 = 1.5V. I would want the Arduino to read 4V at 5A.

A non-inverting amplifier will be suitable for this case. Calculating the gain resistors I get R3 = 10K and R4 = 33k. See output waveform below:

To sum up, these are my questions:

Would this approach work properly? Do I need to add some filtering
or adjust something in the current design?
This approach uses the DC bias principle, but another approach is to
use a precision rectifier. Which one would perform better?


texts: Best approach to step down 220VAC to 160VAC?

texts:
Hey Electrical Engineers,

I'm a newbie to electrical engineering (I am a software developer by trade and am starting to work with Raspberry Pis and want to learn about basic circuit design).

My first project involves converting an LED traffic light for indoor use. The lights in the unit I have purchased have 230VAC FuturLED made by Swarco. According to the data sheet -- https://www.swarco.com/futurit-en/Products/Signals/LED-Modules/FUTURLED3-230V-AC the LEDs can operate at full brightness on 196 – 253 VAC, and at a dimmed brightness at 150 V – 170 VAC.

Because I'm a resident of North America, I will be working with standard ~110VAC household power. I could easily step up the voltage from 110 to 220VAC with a cheap off-the-shelf voltage converter, but if I want to operate in "dim mode" I need to either step up from 110 to ~160VAC or step down from 220VAC to ~160VAC (after stepping up from 110VAC).

The wattage of these LEDs is 12W each at full brightness, and 8W at dimmed brightness.

My questions are:

1) I am having trouble finding a step-up/step-down transformer that will output ~160VAC. Do such things exist, or would I need to have one custom built (sounds expensive)?

2) I've read that I can use 2 resistors to "split" the voltage and yield 160 volts, but can this be done with AC? I can't find a conclusive answer in my research, but I'm beginning to think resistors only work with DC current.

3) Is there another approach?


texts: UART Port on the TM4C1294 Board sends garbage

texts:
I am using the TI TM4C1294XL board's virtual COM port that comes on the ICDI interface. This is the code I am using:

#include <stdint.h>
#include <stdbool.h>
#include "inc/tm4c1294ncpdt.h"
#include "driverlib/gpio.h"
#include "driverlib/sysctl.h"

int main(void)
{
    SYSCTL_RCGCUART_R = SYSCTL_RCGCUART_R0;
    while((SYSCTL_PRUART_R & SYSCTL_PRUART_R0) == 0);

    SYSCTL_RCGCGPIO_R = SYSCTL_RCGCGPIO_R0;
    while((SYSCTL_PRGPIO_R & SYSCTL_PRGPIO_R0) == 0);

    GPIO_PORTA_AHB_AFSEL_R = GPIO_PIN_0 | GPIO_PIN_1;
    GPIO_PORTA_AHB_PCTL_R  = 0x11;
    GPIO_PORTA_AHB_DEN_R   = GPIO_PIN_0 | GPIO_PIN_1;

    UART0_CTL_R  &= ~0x1;
    // UART0_LCRH_R &= ~UART_LCRH_FEN;
    UART0_IBRD_R  = 0x30D;
    UART0_FBRD_R  = 0x010;

    UART0_CC_R = 0x0;

    UART0_LCRH_R  = 0x00;
    UART0_LCRH_R |= UART_LCRH_WLEN_8;
    // UART0_LCRH_R |= UART_LCRH_FEN;
    UART0_CTL_R  |= UART_CTL_TXE | UART_CTL_UARTEN;

    while(1)
    {
        while( (UART0_FR_R & 0x0020) != 0);
        UART0_DR_R = 'a';
        SysCtlDelay(1000000);
        // while( (UART0_FR_R & 0x0020) != 0);
        // UART0_DR_R = '\n';
    }
}

Here is what I am getting from putty:

What is the reason for such garbage characters regardless of what is being sent to the UART port? I tried other UART ports available but with no luck.

Update: For some reason lowering the MCU clock to 12MHz did the trick. Can anyone please elaborate on this and put it as answer? Thank you very much.


texts:
I'm going to build a mobile unmanned imitation rock that has a green laser that is going to come on automatically every 15 minutes after dark and it will sweep 90 degrees.

Will I need to have it approved by any entity before selling it to the public/local golf courses?

Does this have to be UL approved?


texts: Connect sensor to 1-wire dual counter - different power sources

texts:
I am much more comfortable in software than hardware, but I'm working on a home automation project to track water usage. I have a Dinel AFP-966-S fiber optic sensor positioned over the water meter - and that works. It changes state when the needle moves. I also have a Hobby Boards dual 1-wire counter. If I manually jump the C-A or C-B input to +5v, I see the counter rise in software. Perfect so far.

But I don't know exactly how to connect them because the Optical sensor requires 10-30VDC and the Dual Counter wants 5VDC. The dual-counter has an internal pull-down resistor, so I presumably have to send it a +5v signal to count. How? Surely I can't just connect the +5V and the +12V to the sensor because the dual counter will get +12v.... I guess here is where I'm stuck. Or do I have to tie in an opto-isolator between the two?

My guess is the internal pull-down resistor is working against me? Otherwise wouldn't I just tie a pull-up resistor to +5V and then tie all GND together? The sensor would pull down the logic pin instead of trying to pull it up? (If this is the easiest solution, I could remove the pull-down resistor, but that's a permanent move.)

Basically, I'm hoping the diagram below just needs one more wire, but where to PUT that wire?!


texts:
I was trying to measure voltage drop caused by length of cables. I generated short high frequency voltage pulse (>200kHz, 70V) and compared the voltage on the generator with the voltage at the end of connected cable.

But my results show that when I used a capacitor with 10nF and the cable with length 30m, than the voltage at the end of the cable increased to 130% (with respect to the voltage on the same capacitor attached directly on the generator output.)

How it is possible that the voltage can increase? I would expect that it can only decrease? Is there anything I don't do correctly?

Example (consider only the red lines):

Description of the example: the red crosses represent voltage pulse on the generator and the red solid line represents the voltage on the end of 30m long cable.

When I used capacitor 100nF, then the voltage decreased to 60%. And it was as I expected.


texts:
Let's say we have three phase diode (ignore SCR in the picture) rectifier:

With no source inductance, diodes are conducting at following angles:

Diode 1: 30º < X < 150º
Diode 4: 210º < X < 330º

Diode 3: 150º < X < 270º
Diode 6: 330º < X < 450º (= -90º)

Diode 5: 270º < X < 390º (= -30º)
Diode 2: 90º < X < 210º

Adding source inductance causes each of the diodes to conduct more than 120º per cycle, causing them to overlap:

QUESTION: Let's assume we add the exact amount of source inductance so that each of the diodes conducts 140º per cycle. Does now diode D1 conduct between 20º and 160º, so the extra +20º degrees split symmetrically, +10º at the beginning and +10º at the end?

Ref: Commutation overlap angle.


texts:
I had programmed a HM-10 module to act as iBeacon with my Arduino Uno's serial monitor using the following steps:

AT+RENEW Restores factory defaults
AT+RESET Reboot HM-10
AT Wait for OK
AT+MARJ0x1234 Set iBeacon Major number to 0x1234 (hexadecimal)
AT+MINO0xFA01 Set iBeacon Minor number to 0xFA01 (hexadecimal)
AT+ADVI5 Set advertising interval to 5 (546.25 milliseconds)
AT+NAMEDOPEY Set HM-10 module name to DOPEY. Make this unique.
AT+ADTY3 Make non-connectable (save power)
AT+IBEA1 Enable iBeacon mode
10.AT+DELO2 iBeacon broadcast-only (save power)
11.AT+PWRM0 Enable auto-sleep. This reduces power from 8 to 0.18 mA
12.AT+RESET Reboot

Now it is working as an iBeacon and one side transmitter. Now i want to reset my HM-10 module to factory settings but AT on serial monitor won't display OK as it used to. Is it now not compatible with Arduino's serial monitor? If not, how to reset my module like it was new?


texts: Assigning a declared wire to connect ports on two different Verilog modules

texts:
I have a top level module that contains instances of other modules.
I simply want to connect the output of one module to the input of the other, like so:
module top_level(
...
);

module_a A(
  .out(my_wire)  // line 32
);

module_b B(
  .in(my_wire)
);

wire [7:0] my_wire; // line 51

endmodule

However, modelsim compiler is throwing an error that

** Error (suppressible): /../top_level.v(51): (vlog-2388) 'my_wire' already declared in this scope (top_level) at /../top_level(32)

I've tried removing the my_wire declaration (wire [7:0] my_wire;) and it compiles OK, but throws an error later because it infers my_wire to be a wire of size 1, when really a wire of size 8 is needed.
What's the recommended way to do this?
I've also tried:
module_a A(
  .out(in)
);
module_b B(
  .in()
);

but unfortunately I have other modules in top_level that have a port named .in which I don't want it connected to

I found this post
https://stackoverflow.com/questions/19327819/output-of-a-module-used-as-input-of-another-in-verilog but the solution didn't work for me.
I also saw this post https://stackoverflow.com/questions/56286714/verilog-proper-way-of-connecting-ports but found the answer a little confusing (sorry Oldfart, I have found your answers helpful in the past though)


texts: Can anyone identify this type of connector

texts: I have a Lawmate 2.4 Ghz Video transmitter which has a small 4 pin input plug. I want to find out what the proper name for this type of connector so I can buy spares for it - maybe someone here can identify it for me.  I've attached a picture below:


texts: Do I copper - pour on mains voltage PCB?

texts: I don't have much experience with designing boards for mains voltage. I've designed a circuit and I have lots of unused space on the board. Do I fill it with copper or leave it blank? I guess the PCB manufacturing house won't be very happy with all the copper to etch. If I copper-pour it, what should I connect it to? Earth?


texts:
We are tring to brinup a new display for a Qualcomm APQ8909W chip that's running Android 8.1.
From looking at the kernel log during boot I can’t seem to see what display driver is being used/initiliased for the display mdss_dsi_osd_disp_fwvga_video.
Shown below is seemingly all of the relevant boot information (can post entire log if required).
[    1.022053] xlog_status: enable:1, panic:1, dump:2
[    1.025760] mdss_smmu_util_parse_dt_clock: clocks are not defined
[    1.025904] mdss_smmu_probe: iommu v2 domain[0] mapping and clk register successful!
[    1.025977] mdss_smmu_util_parse_dt_clock: clocks are not defined
[    1.026096] mdss_smmu_probe: iommu v2 domain[2] mapping and clk register successful!
[    1.027144] mdss_dsi_get_dt_vreg_data: error reading ulp load. rc=-22
[    1.027174] mdss_dsi_get_dt_vreg_data: error reading ulp load. rc=-22
[    1.027200] mdss_dsi_get_dt_vreg_data: error reading ulp load. rc=-22
[    1.028905] mdss_dsi_ctrl_probe: DSI Ctrl name = MDSS DSI CTRL->0
[    1.029389] mdss_dsi_find_panel_of_node: cmdline:0:qcom,mdss_dsi_osd_disp_fwvga_video:1:none:cfg:single_dsi panel_name:qcom,mdss_dsi_osd_disp_fwvga_video
[    1.029423] mdss_dsi_panel_init: Panel Name = OSD Displays fwvga video mode dsi panel
[    1.029661] mdss_dsi_panel_timing_from_dt: found new timing "qcom,mdss_dsi_osd_disp_fwvga_video" (eda037d8)
[    1.029733] mdss_dsi_parse_dcs_cmds: failed, key=qcom,mdss-dsi-post-panel-on-command
[    1.029748] mdss_dsi_parse_dcs_cmds: failed, key=qcom,mdss-dsi-timing-switch-command
[    1.029757] mdss_dsi_panel_get_dsc_cfg_np: cannot find dsc config node:
[    1.029907] mdss_dsi_parse_dcs_cmds: failed, key=qcom,mdss-dsi-idle-on-command
[    1.029922] mdss_dsi_parse_dcs_cmds: failed, key=qcom,mdss-dsi-idle-off-command
[    1.029957] mdss_dsi_parse_panel_features: ulps feature disabled
[    1.029969] mdss_dsi_parse_panel_features: ulps during suspend feature disabled
[    1.029981] mdss_dsi_parse_dms_config: dynamic switch feature enabled: 0
[    1.030012] mdss_dsi_parse_dcs_cmds: failed, key=qcom,mdss-dsi-lp-mode-on
[    1.030025] mdss_dsi_parse_dcs_cmds: failed, key=qcom,mdss-dsi-lp-mode-off
[    1.030148] mdss_dsi_get_dt_vreg_data: error reading ulp load. rc=-22
[    1.030171] mdss_dsi_get_dt_vreg_data: error reading ulp load. rc=-22
[    1.030190] mdss_dsi_get_dt_vreg_data: error reading ulp load. rc=-22
[    1.030233] 1ac8000.qcom,mdss_dsi_ctrl0 supply vdd not found, using dummy regulator
[    1.030754] mdss_dsi_parse_ctrl_params:4072 Unable to read qcom,display-id, data=00000000,len=45
[    1.030905] mdss_dsi_retrieve_ctrl_resources: phy_regulator_base=c7afe780 phy_regulator_size=30
[    1.030918] mdss_dsi_retrieve_ctrl_resources: ctrl_base=c7af6000 ctrl_size=25c phy_base=c7afc500 phy_size=280
[    1.031498] dsi_panel_device_register: Continuous splash enabled
[    1.031814] mdss_register_panel: adding framebuffer device 1ac8000.qcom,mdss_dsi_ctrl0
[    1.039595] mdss_dsi_ctrl_probe: Dsi Ctrl->0 initialized, DSI rev:0x10030001, PHY rev:0x1
[    1.040251] mdss_dsi_status_init: DSI status check interval:5000
[    1.042107] mdss_fb_probe: fb0: split_mode:0 left:0 right:0
[    1.044070] mdss_fb_register: FrameBuffer[0] 480x854 registered successfully!
[    1.044350] mdp3_ctrl_init: mdp3_ctrl_init
[    1.044873] mdp3 1a00000.qcom,mdss_mdp: Unbalanced pm_runtime_enable!
[    1.052396] IPC_RTR: msm_ipc_router_smd_driver_register Already driver registered IPCRTR
[    1.071507] In memshare_probe, Memshare probe success

In the directory drivers/gpu/drm/panel/ there a 7 panel specific drivers:

However, none of  them seem to match the name osd_disp_fwvga_video and I can’t see any of the drivers mentioned in the boot process.
Is there a way to see/know what display driver is being used for the display current plugged in?


texts: vibration sensing circuit doing so great

texts:
I have attempted this diagram from here:

with one modification - instead of the 4093 circuit ( comparator+inverter+hysteresis gates) I have used a HC14 (inverter+hysteresis gates). Can this be why i am not seeing much difference when varying the pot ? Tried with 3 values for C1 - 3.3, 10 and 100 nF. It doesn't seem to make any difference as to how sensitive the circuit is. The output is connected to a MCU pin which interrupts on all changes and blinks a led.

Also, I don't quite understand the bottom two notices from that pdf:

  Attention:

  The point of output must become square wave. (cannot use as shock switch)
  Take low or high of output square wave into your alarm system and adjust sensitivity from the delay time length

I should say that another breakboard of this same sensor works much better by adjusting the trimpot - this one

update

I have read the raw analog output right from the sensor's pin and plotted both the dev board readings and my own PCB readings on the same graph. The dev board readings are much quieter than the readings from my PCB. Maybe the weight of the board and its cables are the main cause in the outputs difference ?


texts:
What's the best way to filter the output of a H-bridge?

I have a PWM output at +/- 20 V and I want to get a 10V RMS sine wave out at 50hz

Also is there a way to do it without inductors?


texts: Were there any non microscopic integrated circuits?

texts:
There is something about history of computer hardware and ICs that confuses me - a jump from wardrobe dimensions of last generation of transistor computers to ICs which were so small as "the size of a little fingernail" (The Story of the Intel® 4004). I cannot understand why it had to be so small at the peak of the "any miniaturisation is success" era.

So this leads me to my question: were there any non microscopic integrated circuits? By that I mean something that would either not be fabricated with photolithography process or dimensions significantly larger than 10 µm (1971)?


texts:
In an example about oscillator

  In the circuit shown in Figure, \$R_1 = 10 k\$, \$R_2 = 1k\$, \$C =
0.002μF\$, and \$L = 1μH\$. If the circuit is oscillating, find the voltage gain \$A\$ of
  the forward amplifier and the frequency of oscillation

and in the solution it is provided the feedback gain
$$\beta=\frac{j\omega L}{R_1-\omega^2R_2CL+j\omega(L+R_1R_2C)} $$
But I can not figure out why \$\beta\$ is this because when I solved for it I found \$\beta =1\$ by considering unity gain as Buffer Amplifier.

I want to know how \$\beta\$ is provided so?


texts:
I'm developing a small micro-ohm meter that I will be powering from USB, due to the ubiquity of USB power bricks and computer power.

I've run into a few questions:

What do I do with the data lines of the USB?  I'm not using them, I'm just interested in USB power, should I tie them to ground, to each other, to +5V?
Do I need to switch from "low power mode" to "high power mode"?  This seems to indicate that you need to ask for high power using something called "enumeration", but the same article also talks about a 2.25W max... which I know is no longer true.
Max capacitance for the USB 2.0 specification according to the above is 10µF.  I've got significantly more than that.  This leads me to believe that I should be using something like the NCP380, MIC2545, or TPS2112.  These are high side switches that can limit inrush current, allowing me to have more capacitance after the switch.  Is this still necessary? Or has the capacitance limit increased since the above linked document was written?


texts: calculate feedback factor in feedback circuit

texts: Below is an exercise with solution about feedback network. I am wondering how the feedback factor is calculated like that. Could anyone shed some light on this?


texts: Fetch RSS value using Nordic NRF24L01 module and RadioHead library

texts:
RadioHead provides a lastRssi() function (http://www.airspayce.com/mikem/arduino/RadioHead/classRHGenericDriver.html#ab04f2ca335d89f5fac1d213c0aea9da2) to fetch the received signal strength.

I tried using this but the value always shows up as zero. I also tried changing the TransmitPower (http://www.airspayce.com/mikem/arduino/RadioHead/classRH__NRF24.html#abf31686ee994851a27d6a9d7dc51771f), however, it still shows up as zero. Any solutions?


texts: Connected 2-Pin Button switching randomly from LOW to HIGH

texts:
I got this ordinary 2-pin push button and now I'm trying to read its state.
Basically I want to turn a LED on and off.

My board is an Arduino Uno and the button is connected to GND and Digital Pin 2.
Also Pin 2 is configured as INPUT_PULLUP.
I followed the instructions in this tutorial.

My issues:

digitalRead(2) returns randomly LOW and HIGH
It seems like there's no pullup resistor configured even though it's definitely in the code
When I take the button in my hands and touch some parts it seems to work?

Questions:

The button is connected to GND. There are also other components connected to the same GND. Could there be too much connected to GND?
Do you have any ideas what I did wrong?
Could my Arduino be broken/fried?

Update:

Here is the datasheet for the button I bought.


texts: How to model an inductor using a behavioural voltage source in LTspice (to get time-dependent inductors)?

texts:
I am trying to make a time-dependent inductor in LTspice, but it is not as easy as for resistors which allow values directly depending on 'time'. I tried using the characteristic equation of an inductor and a behavioural voltage source in the simplest circuit I could think of as follows, but it does not work (the current reaches 10^37A... How could I achieve this?

The current through R6 goes left to right, but I tried adding a negative sign to the V equation anyway, just in case (even if it would not make sense to me).

Solution (thanks to "a concerned citizen")

Which corresponds to the function L(t)=L0*(1+(K*sin(wt))^2), in a series RL test circuit excited by a constant sine wave.


texts:
I have a relay switch. Particularly, leone SC5-S-DC6V.

I am a noob who wants to use this relay switch. And I don't know how to operate it. Can someone please help me?

For now, I just want to use it with a 6V DC power supply to change the state of switch.

I'm sorry if the question is stupid(It might be, I know really little about these). If that is the case, can someone suggest some references I should look at?


texts: Microcontroller resets with motor driver (L293D)

texts:
I am making a simple robot with 2 BO motors driven by L293D on ATmega328P (took out from Arduino Uno). The robot when tested on Uno works fine. But when I put it on the board that I have designed (as I am not allowed to use Uno in college), the motors work for few seconds and then the microcontroller resets.

The problem is definitely not with the code, but some hardware issue that I could not figure it out. I have already tried:

Coupling capacitors -  I changed the capacitors on the input and output pins of 7805. I tried using capacitors from the range of 47uF to 1000uF. But no change.
I am using 33pf ceramic capacitor for 16 Mhz crystal as I couldn't find 22 pf. But I tried 18pf and 15pf, but no luck.
Coupling capacitor on L293D power supply (47uF). No change.
Ceramic capacitors on BO motors, just to ensure the noise isn't affecting the power supply. But still no change.

From the web, I understood the concept of Brown-out reset and I assume that I am facing the same issue. Because the board works fine with other components. But as soon as I connect the motors with the driver, I face the problem of reset. Each motor is drawing out ~100mA, but 7805 should be able to supply it as per the datasheet.

Also one of my friends suggested it has also to do with the track width that I am using. My track width for power lines is 24 mils and 12 mils for data lines (GPIO pins). I am not changing it as I am not sure if this is the real reason

If anyone has experienced this before please help me out with some solution. Thanks


texts:
I'm working with this circuit.

I don't know how I should analyse in a mathematical way.
I don't know how I should take the analysis of the capacitor in this kind of circuits.
 I have to find the voltage of the capacitor(Vc) without initial conditions (V0)


texts: What is this breadboard that can be soldered on a PCB

texts:
Very simple question. What is the part number of this small bread board on this board.

There are two breadboards on it. The smaller one actually is soldered on the PCB and it is connected to IOs of an FPGA. I searched on Mouser for a long time to find this kind of component, but I failed. Could anybody tell me what this would be called such that I could find a supplier?


texts:
I am trying to calculate isolation of an relay in ohm. Can it be approached as calculation of resistance of solid materials?
$$
R_{air} = ρ_{air} * \frac{d_{gap}}{A_{contact}}
$$
Let's say resistivity of air equals 3.3e^15 Ωm and gap is 1mm between contacts with area of 1mm^2. As a result we get 3.3e^12. Can this be an approximate value to real isolation value?
Thank you.
Additional information:
frequency range is from DC to 5GHz. Load voltage Vp is 24 and current is 20mA.


texts:
A high-pass RC filter with a corner frequency of 340 Hz can be built with a 47 Ohm resistor and a 10 uF capacitor.
A low-pass RC filter with a corner frequency of 3400 Hz can be built with a 47 Ohm resistor and a 1 uF capacitor.
But what if I combine the filters, using only a single resistor? Will the corner frequencies of the low- and high-pass elements change?

The input is on the left, the output is on the right, the segment at the bottom is signal ground. The output feeds into a 10K input impedance amplifier input, and the DC blocking of the series capacitor is intentional.


texts: Load Cell Data Problem - INA125P + Arduino Uno

texts:
I am currently reading data from my 30kg load cell with my Arduino UNO board and passing this data to my PC. I am using INA125P to amplify the voltage of my load cell and it is established on a bread board. Here is a picture of my circuit:

Everything works fine, however when move/touch/shake my circuit a little bit the voltage output differs a lot. When this happens, I have to re-calibrate my load cell again. So here comes my question;
Why is my system messed up every time I touch my board ?
Why does my load cell needs to be re-calibrated, aren't they suppose to create a certain amount of millivolts for certain amount of strain ?
Thanks.


texts:
So I'm pretty new to electronics, and I'm getting slightly hung up on the concept of ground. I'm thinking the circuit diagrams below will help me to explain this frustration, because there's not an intuitive explanation as to why these two diagrams are identical.

I'm just going to spew what I believe is correct, and hopefully I get some stuff wrong and learn along the way.

Looking at the rightmost diagram:

My intuition is that (since these are 0V reference points, not actual ground connections) if electrons flow out of the negative terminal of the battery there needs to be a connection to the right 'ground' in order to keep it at 0V relative to the left ground.

Expanding on that, does that mean every 0V reference point can be thought of as being connected by a wire. So if I had 50 more 0V reference points, throughout some complicated circuit, all of them can be thought of as being connected? Thus simplifying any circuit with multiple 0V reference points to only one 0V reference point?

Question: What is the point of doing this? Is it just to reduce the complexity of circuit diagrams later on? Because right now it definitely complicates the one below.

Secondly, say instead of 0V reference points, those ground connections are actually earth ground connections.

The reason why current would instead flow to the negative terminal of the battery is because it's more attracted to that then the neutral ground. Does any minuscule amount of current leak to ground? Also, in the same sense as before, can we think of each individual 'earth' ground in the right diagram as connected?

Thank you!


texts: Does running parallel circuits for LEDs decrease their output?

texts:
Sorry if the questions here are elementary but my electrical knowledge is limited.

I am planning to build an aquarium light fixture and I am having trouble grasping how to best use a driver.

The driver I am looking at is Mean Well ELN 30-48D or the Mean Well ELN 60-48D. The diodes I am looking at are CREE XT-E 5w with 2.85-3.4v and I should be able to run 4-14 on the MW 30-48 and 9-14 on the 60-48.

Now what I don't know is if I run 2 parallel circuits of 14 LEDs in a series, would this effect the intensity of the light being produced? And also of the 2 drivers listed above, the only difference I understand is the minimum number of LEDs which can be in a series. What would be other factors to consider when looking at these 2 drivers?

A little more information. I am trying to build 2 individual identical lights over my reef aquarium and I am trying to figure out if i can have 14 of the same LEDs on light A and 14 on light B working from 1 driver without compromising the color temperature and intensity which I am trying to achieve. If the parallel circuits (28 LEDs) will be as intense as 1 series of 14 then that will save me some money on buying drivers.

If the parallel circuits create the same light how many parallel circuits would the driver be capable of running?

I know it is a lot of gibberish in there and I have probably left out crucial information that is needed to answer my questions, but like I said, limited electrical knowledge.

Thank you in advance.

Michael


texts: I faced problems with the Altium design program. I need to print a PCB schematics to PDF, but when I do it, the dimensions does not match with real device dimensions. The difference on the printed paper between scheme last pad and device last pin is 5 mm. I checked all the settings were good, I used metric dimensions, grid spacing 2.54 mm and the scale was 1.00. In the program, pads dimensions are good and placed perfectly in the right place, but when I printing scheme to PDF file, it occurs dimensional problems. Have someone ever faced this problem?


texts:
I am trying to add a height captor for a line of my production where I work. I found this Banner captor (QS30LLPQ) and it has 2 bipolar discrete outputs (PNP and NPN). Now, I am trying to decide which of those two outputs I should connect to the input card of my PLC. This input card is a sinking type.

Now, I read some information online and from what I got on forums, NPN sensors are current sinking devices and PNP sensors are current sourcing devices. So that tells me that I have to go with a PNP output, since a sourcing sensor output must go with a sinking input.

My question is, if that is true? From what I understand, the sourcing output will drag voltage from the sensor and then the PLC will take it and sink it to the ground, thus bringing the input to a high state from the PLC perspective.

So, will that make my output in the sensor go to a high state when it is activated (it should detect boxes moving in front of it)?

Thanks a lot.

source


texts: What is the mathematical relation between hfe and hie

texts: For a transistor connected in CE configuration, what is the mathematical expression that relates its input resistance hie and current gain hfe? I need this because I am designing a transistor amplifier. In my calculations I need the value of hie. The datasheet provides only the hfe value. So, is there any equation to calculate hie from given hfe?


texts: Altium Issue: PCB Switch Pad Nets for Rubber Button

texts:
I am currently trying to create a component in Altium for a rubber keypad switch. This will be like the ones in TV remotes etc where there are a mesh of fingers connected when the conductive pill makes contacts with both sides.

Having read the following design guide, I have come up with a PCB pattern

The issue I'm having is when I place this component on the PCB. The nets for both sides of the component only show one net:

There is a clearance issue on the left is where the pin has been placed and the nets colliding.

Any suggestions for solutions would be much appreciated.


texts: How to use Gas Discharge Tubes, Transils and other goodies together

texts:
I would like to make a good surge protector for a device that will have a hardwired mains connection. The protected electronics will consist of a ~10W SMPS and a low-power AC load (<100W) controlled with a triac.

I plan to use a mains filter (nothing fancy) behind some combination of GDTs (Gas Discharge Tubes), MOVs (Metal-Oxide Varistors) and/or TVSs (Transient Voltage Suppressors). This is meant to work at 110V (US) but the SMPS is universal so it would be nice if it worked with 230V as well (mostly because this is the standard voltage in the place where I live).

I understand that I want the faster device (MOV, TVS) to have higher voltage rating than the GDT so both have a chance to work when really needed. Unfortunately both GDTs and MOVs have rather lousily specified I-V characteristics and their "breakdown voltage" is more of a "breakdown region".

A GDT with typical 230V breakdown won't work with 230V AC since it may start conducting at as low as 180V. If OTOH I go with a 350V typical (280V minimal) my protection is guaranteed only at 420V since this is the maximum ignition voltage, right? This leaves little room for the choice of the MOV breakdown voltage (which is a voltage range as well) and still places heavy burden on the downstream elements. Is this a lost case and the only solution is to have all the downstream components rated >900 V?

I welcome any articles, suggestions or rules of thumb for designing such (simple) surge protectors.


texts: How can I quickly and safely make defunct electronics safe and free of charged capacitors?

texts:
I am planning a movie set which will contain old circuit boards from TVs, VCR's and other old electronics.  The plan is to go to several Goodwill stores and buy up all of the TV's and such that they have, open them up and integrate them into the set.  There is an electrical danger here due to charges still present on large capacitors.  What is the best way to quickly and effectively remove these charges?  Dunking these devices in a salt water bath seems like a good idea (we do not need for these devices to work.)  If so, are there things we need to be aware of?  If not, is there a better recommendation?

We will be getting around 60 items, so finding and discharging all of the capacitors individually could be a big problem.


texts:
I have built an ATtiny controlled 230 VAC dimmer which has unfortunately burned. I would like to fix the design so it is reliable.
Files – Fritzing Schema · Arduino Code
The dimmer was used to dim halogen bulbs (28 W each, 5 in parallel, i.e. approximately 150 W in total) and produced smoke after 2 months of usage. The bulbs were still on, but could not be dimmed anymore. Physically, the distance between dimmer and bulbs was approximately 10 m, with another approximately 5 m of wire to the last lamp.
The circuit is using a three-quadrant triac BTA316-600D. (As the triac driver MOC3052 is connected over G and MT2, only quadrants I and III should be used.) I have added an RC snubber with R11, C2 and an inductor L1 because the triac fired once when connecting it to AC. This is based on advice from AN437 and AN-08-06.
Optically, it looks like the snubber resistor burned and melted part of the film capacitor.
I wonder if the circuit failed because L1 does not use an air coil (as AN437 states that “Limit high dI T /dt with a non saturable inductor of a few μH in series with the load”), or because the current over R11 can be much higher than I expected … Or something else, because a second dimmer board has been in use for at least twice as long without any issues so far.
What has to be fixed on this schema so the board works reliably?

Circuit

Board

Burned part

Power measurement
This is the voltage measured over a 0.5 Ω resistor in series with a 28 W halogen bulb, cold start. Peak is around 1.75 V (cold filament) which is reduced to 0.29 V (hot filament). (The absolute values seem wrong because it would not fit for a 28 W lamp, but the relative factor should be okay …)

Improved schema
R4 is now a 470 Ω resistor.


texts: What is the reason why my room heater interferes with my computer monitor and how do I fix it?

texts:
I have a computer screen (Acer, not sure the model, it's powered through an external 220 to 19v PSU and connected via HDMI) and a fan heater connected to the same socket with a power string. Unfortunately, when I turn on or off the fan heater, the screen goes blank for a second. Electric and data cables are far away from each other, so it's not direct interference with the HDMI connection.

I tried various minimisation strategies, such as adding a long cable from the power strip to the heater or using a longer power strip, but the problem remained.

What is the nature of the issue, and is there an effective strategy to eliminate this problem?

Edit: please note that while I understand this question may appear off topic for the site, I am interested in going beyond the solution of the problem as a consumer. I do practice circuit design as a hobby, and I want to know the technical details of what is happening and what are mitigation strategies that the monitor may have not implemented in order to deal with such eventuality.


texts:
Looking at the ILI9341 datasheet Electrical Characteristics, I just can't find information about power consumption. The information is also missing from the LCD module datasheet (ER-TFT024-3).
I know that ILI9341 supports sleep modes where power is low, but I can't find data on power consumption under regular conditions.
My intention is to power the LCD (not the backlight!) from MCU pin under the assumption that continuous current will be in the 20mA neighborhood, or even less than that.
(I'll drive the backlight by a MOSFET).

Is it common to drive low-power peripherals from MCU IO pin? Are there any pitfalls except from the current rating (and voltage) of the IO pin?
Does anyone have some experience with ILI9341 or similar module, and can confirm
my assumptions about its low power consumption?

Update
When measuring VDDI + VCI with multimeter I observe a flat 8mA...


texts: It is my first question on this forum. I have a problem with my arduino project. I am working on a mobile robot. I use L298P Motor Shield for controlling the two 5v gearbox motors. The power supply is from 3 x 3.7V 12000 mah batteries.The problem is that after few seconds of use the motor stops because of battery discharge.The robot is around 3 kg weight. Should I buy bigger motors?


texts:
I'm talking in the context of guitar amps, but I assume that this question is relevant for any type of audio amplifier.

Very often in amplifier schematics I see two stages of amplification -- first, the signal is amplified a smaller amount by a preamp circuit and then amplified again by a power amp circuit.

This seems redundant to me. What's the point in amplifying a signal in two small steps rather than just one greater-gain amplification?

My first thought was: does this multi-stage amplification help to reduce unwanted noise from the signal? But the more I think about that, the less it makes sense, since surely the second stage would be amplifying any noise as well.


texts: How do I correctly power the l298n motor driver with 6v?

texts:
Recently, I have purchased the L298N Motor Driver with a couple of 3V-6V motors. I am planning to make a robot buggy to hold other projects I may do with the Raspberry Pi. Currently, I have been unable to figure out how to properly power the motors and the driver at the same time. For now, I have taped four AA batteries together to test the motors on with the driver. On my version of the L298N, the power inputs include 12V and 5V. After scouring the internet for hours, I have not been able to figure out exactly what to do with my dual-motor setup. For now, both of the jumpers on ENA and ENB have been attached. I tried connecting the 12V input on the driver to the temporary AA batteries, but the red power LED on the driver didn't turn on. The red LED would turn on though when I supplied 5V through the 5V punch block. That had not powered the motors sufficiently. What is the proper way to do this?
Here is a schematic of the wiring I have set up.
Keep in mind the pins that the wires are connected to on the Raspberry Pi are random (Couldn't "pin" them down correctly)


texts: difference between max3387ecug+ and max3387ecug+t

texts: can I know what the difference is between MAX3387ECUG+ and MAX3387ECUG+T, the MAXIM datasheet doesn't seem to point the difference.


texts:
I made a simple communication using atmega128. Is syntax for UART0 between atmega128 and atmega8535 different?
Because when i used command "printf" and "putchar" on atmega128, it didn't work, but on atmega8535 worked


texts: How to properly select a transformer in terms of thermal rise

texts:
I'm trying to reach a decision selecting a small transformer for a task, from an overseas company (which only significant because of the language barrier). I thought the selection would be easy knowing my voltage and load requirements, but the transformer's temperature rise specifications are causing me confusion, and I want to make a reasonable choice.

The transformer in question will be "brute force" rectified and filtered (full wave bridge and a filter cap), and from there will be used to operate a 12 volt relay, and some less significant loads (a MCU, an LCD display and some LEds). My worst case draw should be no more than 160mA, and so I've been looking at some 300mA transformers. To further minimize transformer load, I'm selecting transformers whose output voltage change, between "full load" and no load spans from about 7V up to about 10V respectively. Converted to DC, that is a range of about 10VDC up to a theoretical (no load) voltage of 14V. The main draw, the relay, requires 100mA at its rated voltage of 12V, and will therefore be a little lower when the transformer voltage drops, and its coil sees closer to 10VDC.

It is hopefully obvious by the 300mA rating that I'm looking for small transformers. But what threw me a curve on all the models, shapes and sizes offered in this voltage / current range was the "Temperature rise". The transformer is specified to rise a maximum of 60K (which they explained to me simply meant 60C) above ambient.

Well now my head is spinning. I'd planned on using the transformer in an outdoor NEMA enclosure specified to be watertight, and so its obviously air tight too. In the climate I intend to use this, it won't be uncommon for the outside temperature to reach 34C (around 90F for reference). So that means at rated load (300mA), this transformer could get to 94C. As water boils at 100C, that seems way too hot to even consider, especially knowing that the only escape the heat will have will be through my chosen enclosure. Though some kind of plastic, I know it can "take" the temperature, but I don't think it will allow the heat to escape very well. (I will ask the manufacturer for it thermal conduction characteristics, but I'm not sure I'll understand how to interpret them).

As I was looking at transformers with a maximum current of nearly 2X what I anticipate using, worst case, I'm sure the heating will not be as bad as their maximum. But I don't think I can simply conclude that 1/2 rated load will automatically mean 1/2 the temperature rise.

So I'm a bit at a loss for what i thought would have been a simple task. I suppose I could choose a larger transformer, but my space will be limited, and and I have to confess I'm out of my league now understanding how to approximate this. The manufacturer is asking me what an "acceptable" rise in temperature might be, and will offer other alternative transformers. I could handle working that way, but the problem is equating temperature rise in ambient "free air" to realistic temperature rise inside a sealed enclosure. There seem to be so many factors here I'm ready to take my best guess, get some samples, and do some actual testing and just measure what actually happens. But I wish I knew how to approach this more scientifically, and at least make a reasonable guess.


texts: How to select external components for LM2596-3.3V?

texts:
I want to power an ESP8266-12F with a 12V power supply. The 12V power supply is also used to power a led strip. I need to step down the 12V to 3.3V. The maximum load is 1A.

I found the LM2596-3.3V to step down the voltage. However, I am having a hard time finding the right external components.  I have seen many examples on the internet, but they all use different values for the external components. Some even use multiple capacitors on the input or output. In addition, I can’t find examples which use the 3.3V version of the LM2596. Most examples on the internet use the adjustable or the 5V version.

Is the LM2596-3.3V the right choice for this application?
If it is, what external components should I use to get a stable 3.3V output from the LM2596-3.3V?

EDIT:
I took a close look at the datasheet and tried to select the components.
However, I couldn't find all the model numbers specified in the datasheet.
Therefore, I came up with the following components:
Input and output capacitor: 270uF, 50V, Panasonic EEUFR1H271
Diode: SS34
Inductor: 47uH, Cybermax CMLF0705-470KTT

Would this configuration work?

Thanks


texts: question about Vivado synthesis and implementation

texts:
I use Vivado to program my Basys-3 card and I have a quick question about Synthesis and implementation. I noticed that when Vivado knows the inputs of an entity, it calculates the result directly and this calculation is not done on the FPGA core.

For example, I have an encryption algorithm that takes the encryption key and the plain text as input and returns the encrypted text as output, if I declare two signals equal to the key and the plain, the encryption calculation will not be done on the card but at the time of synthesis. Is there any way to disable Vivado's "behavior"?


texts: Is an audio power amplifier (not a preamp), commonly used in the high-end home sound systems of audiophiles, a voltage-controlled voltage-source?


texts: Does location of bulk storage capacitors matter?

texts:
Suppose I want to include a bulk storage capacitor in my circuit to help support a servo motor as it starts up.  Does the physical location of the capacitor on the PCB matter in any practical sense?  That is, is there any disadvantage to placing the capacitor on the trace further away from the power supply than the motor is, or maybe on the other arm of a Y fork, rather than placing it between the power supply and the motor as is conventionally done?

I think it doesn't make any difference, but realized that was just my intuition talking.


texts:
I have an Arduino project that is mostly working on a solderless breadboard and I’m starting to plan on making it semi-permanent by soldering the components in place and mounting it into a project box.

I am thinking about using this Adafruit Perma-Proto Half-sized Breadboard PCB.  Part of the description says (emphasis added):

  The bottom has the 5-hole pad design that matches a classic breadboard, with 4 power bus lines on the sides, and no mask so you can easily cut traces when necessary.

Front:
Back:

What does the part about no mask mean?

I think cutting traces means using a knife to scratch off the connection lines on the back so you can “split” one or more columns and gain more functionality. For example, assume I have a fictional micro-controller whose width would allow it’s pins to fit on this board’s rows E and F (straddling the middle) and its length would use pins 1-10  If I cut the connections horizontally from 1-10 between rows D and C and H and G, that would allow me to use additional components for rows A-C and H-J  and columns 1-10 that I would not have been able to use without the cut.  Is this correct?

ETA: Some of my questions here have been received poorly, so I took the time to make sure I added links and relevant pictures and quotes.  Hope this helps.


texts:
simulate this circuit – Schematic created using CircuitLab

In this drain to gain feedback resistance biasing circuit, it is said that the feedback resistance Rg is large and usually in \$M\Omega\$ range. But no current flow through this resistance.

So why it is needed to be large?

Any value of this resistance should serve the purpose as there is no current or power absorption.


texts: PC power supply for 12v 24A consumer, question on 12v yellow wires

texts:
I want to buy and convert a 350W PC power supply into a 12v power supply for 20m RGBW led strips. I want to do this because I did not find any reasonable priced 12v power supply and simply because I want to build this myself.

I have found several articles and video tutorials on this topic and this seems pretty straightforward. From pure curiosity, however, I would appreciate any explanation why doing this requires cutting all yellow wires and joining them? If the power supply is 350W, means 350W / 12V = 29.2Amps (assuming 100% efficiency), a single yellow wire would not allow to pass this current due to the cross-section of the wire? (Because it will melt or something)

So, is the process of joining all +12V yellow wires mandatory and if yes why?


texts:
Hi I need to use a 25cm (10inch) long slider potentiometer for my project. I can't find them anywhere so I'm thinking of getting a PCB made and putting some resistive material on it. My PCB manufacturer supports carbon ink for contacts, can I use it for resistive element?
Edit: I want to get 12 bits of resolution from the pot. I am using a stm32 chip for ADC with it so I will have a 5V potential difference across it. Aiming for a 10K ohm value. Reliability over sustained use is required since it is a part of MIDI device. I have considered belt gear drive with angle sensor but a slider pot is much simpler and cheaper
Edit 2: contact less options - Would serve my purpose better actually, but I don't know if distance sensors like IR or ultrasonic will work for 25cm length and be accurate enough.


texts:
I am trying to identify the component (I believe is a varistor) in the image below (is from a blender). In another piece of the epoxy I was able to read 14. Should I assume is a 14d241K? Tks!
Lino


texts: COTS solutions for ±18V DC (or even ±20V) and ±30V PCB-mounted power supplies in the 3-5 Watt range

texts:
Most manufacturers make DC-DC converters with only ±15V or ±24V outputs for driving opamps. Opamps generally fall in several max-DC-supply classes. Typical are the ±22V ones (e.g. LM741 and a ton more), some of which do have reliable operation up to ±20V (e.g. the LM741A). Alas DC-DC converters in between ±15V and ±24V (e.g. ±18V) are extremely boutique items than can be very hard to source. So, what are practical solutions for building your own (on par with COTS devices in terms of characteristics) wile using as few components as possible? A ±9V with voltage doublers for example is a practical solution?

The same question applies to ±30V sources that would be useful for getting most output swing out of an OPA551 for example (which has its characteristics given at this supply voltage, by the way.)


texts:
I would like to use a solid state relay (25A) in a 230V max. 1400W environment which will switch in 10 second intervals for a few minutes and then remain idle for hours.

Will this type of switching produce any noticeable thermal output or even require a heat sink? I am intending to place the relay close to the inside wall within a warm box (coffee machine, ~80C) with limited air circulation.

Can SSRs be used for such use cases, or are additional measures required to prevent overheating?


texts:
When a $cast is executed between a base and a derived class objects, does it allocate more memory for the derived class handle?

$cast(derived, base) Upon a successful casting, the handle would be able to access derived class members also. So, how exactly do the internals work?


texts:
First off I'm a beginner at electronics I don't understand much so bear with me.

I've just constructed my first bipolar stepper motor circuit today on a breadboard. I've actually extracted the stepper motor from an old Epson printer. I've used an lm317t adjustable voltage regulator to power the motor driver. Input is a 9v battery and I give 5v as motor power supply to the l293d motor driver. There is a separate microcontroller and its power and ground which is 5v as well.

Now I've used a pot to adjust and multimeter to check the output motor voltage of the lm317 regulator. I have set the pot such that the output is at 5v

Now my question is when the stepper motor runs successfully, the multimeter reading drops from 5v down to 4v. Why does this happen?


texts: 2 LT spice model are the same but one is not generating correct results

texts:
I cannot figure out the difference between these 2 ltspice schematics.  They appear to be identical in settings but one graphs the capacitor charging over time and the other starts the capacitor at full charge.  I see no difference between them, it is bizarre.

Does anyone see a difference?

I do not know how to attach a file, so here are links to both ltspice files.

This one called Capacitor is ok:
https://tresor.it/s#Mr8RP_dn7bhLpmZFFl1-LA

This one called CarBattery is fried
https://tresor.it/s#nJhxnQ5sKx3_m7SkEDVKoA


texts: How to make a DC sweep with negative change in pspice orcad?

texts:
I have the following circuit and I want to varry V1 from 24V to 0v while keeping V2 = 5V, naturally I tried using DC sweep simulation with start value of 24V, end value of 0V and variation of -1, but that gave a variation from 0V to 24V, I've tried changing the variation to 1, that gave the same results.

So my question is : how can I make DC sweep simulation with negative variation?
I am using pspice with orcad 16.4


texts: Arduino Mega Schematic possible "Faults"?

texts:
I'm trying to build an standalone Arduino mega based on This schematic.

At the header of schematic Arduino noted this:

  Reference designs ARE PROVIDED "AS IS" AND "WITH ALL FAULTS".

As a hobbyist i can't really identify IF there's any faults in the schematic provided by Arduino, even though i successfully made an standalone Arduino UNO using Arduino.cc provided schematic but ATMEGA2560-16AU have more pins and is more complicated than ATMEGA328P-PU.

Is This schematic of Arduino mega reliable to build an standalone Arduino Mega based on it or there are "Faults" that needs correction?


texts:
I am on the software side of things and have, only recently, been trying to get into hardware. I have bought an arduino - ATMEGA 328 and got some examples on pin 13 working.

Now I wish to connecting the arduino to the breadboard for more complicated stuff. My arduino is bare-pin and therefore I bought some 2-Way M-M headers (in picture 1) as 1-Way were not available and have plugged them into the breadboard and connected the same to the arduino as in picture - 2 using an F-F jumper wire.

I have to use the above set-up as M-F jumper cables are not available in the locality.

Question: Is the above set up safe (won't blow things of)? Also is a difference in FF jumper cables - I have 5-each of black and red colors in a pack of ten do they have different roles?


texts:
I am designing a circuit for SIM900 and PIC MCU. I am facing few problem on power supply for them. I will be giving 12v to the circuit. Now PIC works on 5volts and SIM900 works on 3.2v - 4.8v. At first I thought of using two different voltage regulators. But Now i am using 7805 to convert 12v to 5v and then using a voltage divider to convert 5v to 4v. Below is the schematic:

Here input voltage is 12v and using 7805 to convert it to 5v which will be given to PIC MCU. This 5v is also used in voltage divider circuit to convert it to 4v for SIM900. I have used R1=100 and R2=400 for voltage divider circuit. Is this circuit safe to use. Does voltage divider circuits are good to use. Please help. Thanks.!


texts:
I was trying to study about bootstrapping in electronic circuits.
When I checked in Internet Wiki says it is a method to improve the input impedance of an amplifier.
In the power electronics context, it has another definition.(https://techweb.rohm.com/knowledge/dcdc/dcdc_sr/dcdc_sr01/829).
Here it has another meaning (https://m.eet.com/media/1152270/24127-45890.pdf).
Could you please clarify bootstrapping?


texts: Accellerometer and arduino lillypad and wearable projects

texts:
I have just bought an Arduino Lillypad and an MMA8452 accellerometer board and i have few questions:
1) Power supply on lillypad
I know that working with accellerometers is a little bit dangerous: if you plug them to 5v instead of 3.3v you can burn them! So, before to plug and burn anything i want to ask if i have to do something to be sure. In normal Arduino board there are a physical pin to move for having 3.3v (or something that doesn't burn the accellerometer).
2) Physical disposition of resistors
I heave read in MMA8452Q_Example.pde (download here):

SDA and SCL should have external pull-up resistors (to 3.3V).    10k
resistors worked for me. They should be on the breakout    board.

and i'm thinking about what is the best way to put the resistors on such a tiny boards: i'm not good in soldering and i don't want to ruin the board, and i can't use a breadboard because it is a wearable project. what is the best? using some male pin strip (*)? Or shall i try to cut a little piece of Perfboard and solder over it? And how put the resitors near the accellerometer? or they could be also near arduino lillypad pins?
What can you advice me? I am quite totally new to electronics so any kind of advice or documentations is a valuable help.
(*) male pin strip http://eval.3dpublisher.net/showmodels/TraceParts/Parts/10-05032010-135382/Pictures/10-05032010-135382M.gif


texts: Built a power supply but output isn't smooth enough?

texts:
I built an ac to dc power supply using the lm2576t. I have a full wave rectifier and a filtering capactor going into the lm2576t. The configuration I used for the lm2576t is the one on the first page. The output measures 4.97V dc but looks  messy on an oscope. I tried plugging my power supply into my digital timer circuit but it ends up timing fast. I figure it's due to the messy output from my power supply. It works perfectly with a battery pack. I also used it to power my microcontroller project but it doesn't work like it does running off a battery pack. Do you have any suggestions? Attached is the datasheet for it below.
http://www.mouser.com/ds/2/405/lm2576-405253.pdf

update:

Rebuilt my power supply on a prototype board and soldered all the components. All good now!


texts: HF signal in a null experiment. What is the exact mechanism?

texts:
Since I've tried to experiment with electronics, I am faced with the problem of HF  noise and signals bypassing almost anything I try to stop them. This begun with my attempts to filter the noise of a simple ATX PSU, and this occurred once more recently with my attempts to rectify a 5MHz modulated signal at 1khz.

Regarding switching PSU, in 9.6.8 D, the "Art of electronics" says "The switching noise can be heavily bypassed at one point, but just put your scope probe a few inches away  and they're back." Later (9.9), he also quotes James Bryant in answer to the question  "How can I prevent switching-mode power supply noise from devastating my circuit performance?", Answer: "With great difficulty - but this can be done".

For them, the problem is that switching PSU are full of noise at a very wide range of frequencies, that occurs in a variety of ways (see end of 9.6.8 D).

In my opinion, and as I will try to show below, the problem is much more fundamental and its interpretation is not so easily found, if ever it has been processed. But let see what you say about that, guys !

This time, I've realised what Douglas C. Smith calls a null experiment, in a way that can be easily reproduced and should help to rule out many incorrect interpretations. Here is the experiment:

Around the coil of a grid dip emitting at 5MHz, are rolled 2-3 turns of electrical wire. (see 2 pictures below). Notice that one extremity of the wire is left opened.

The other extremity of the wire (at about 1.5 m) is brought near the two joined extremities of the scope probe. The probe is set at x10, and the scope at 1mV/div, 1ms/div. As expected, nothing occurs but some weak background noise (picture below).

Now, without moving anything, the two joined extremities of the probe are in contact with the extremity of the wire. In the first picture below, the grid dip is set in continuous wave modulation (CW), and in the second picture, it is set to modulate the carrier wave at 1kHz (MOD). This leaves no doubts that the grid dip is generating a signal in the scope. As can be seen, the scope is now indicating a signal of about 2mV, that is 20mV (since the probe is x10).

The question is: by what exact mechanism is a signal generated by the grid dip in the probe?

Moreover, I add:

like for switching PSU, it is very difficult to "stop" or rectify this signal or more precisely, to know with the scope whether or not it has been stopped: after all, this null experiment says that you have no hope to learn anything with the scope no?
the orientation of the loop formed by the probe does not matter at all in this experiment: this may prove that there is no magnetic influence through air.
Only a contact with the wire produces the effect.

Note: A grid dip is not necessary to perform a similar experiment, but it is a good choice because it emits at a relatively narrow bandwidth. If this condition is relaxed, the same can be done with a noisy ATX PSU switching in the MHz range like this one:


texts: How do you output a frequency/note with a 1V octave keyboard controller?

texts:
To be specific, I made this:

from here

And to test the CV output, I used this schematic:

from here

It works as a oscillator. Every time I hit a key it will oscillate at that note, but it wont stop.

How can I make it so that when I hit a key, it produces that note, and stops when the key is released?  (The circuit does not have to use a 555 timer, that is just what I have available at the moment.)


texts: How do you set up a VFD to run a motor at 2 different speeds?

texts:
I'm already familiar with the concept of altering the frequency to change the speed of the motor. So in this scenario, I'm looking into running a pump at 40Hz (high speed) and 23Hz (low speed). This is so that the oil pumped doesn't overflow or exceed the requirements.

On the drive itself there are analogue input and analogue output terminals. Where would I connect if I want the motor to run at 2 different speeds and why?

Any sort of help would be appreciated

Link to drive manual:
http://www.google.com/url?q=http://www.invt.com/uploadfiles/2017/10/pc_self_service_2017102511020828.pdf&sa=U&ved=0ahUKEwjqnLbrkbPfAhVRzhoKHUwFC7QQFggRMAI&usg=AOvVaw2Q69nCaCrAiIFEycntYFjl


texts:
simulate this circuit – Schematic created using CircuitLab
This is probably a very stupid question. I am new to electrical engineering in general, I was working with NOT transistor gates in order to make a simple SR Latch and came across this case. D2 and D1 in my circuit are both pulled to ground even though when simulated D2 should still be fine the only reason I decided to ask about this is because I couldn't find anything on the internet about it (maybe I was using the wrong terms?). If someone could take a moment of their time to tell me why this doesn't work that would be amazing. The desired result is to have D2 be ON while D1 is pulled to ground and OFF.
It seems I lack understanding in the topic and I'm trying to get a better grasp on it.


texts: Dependence of oxide charge distribution in the flat band voltage of MOS

texts: The linear charge distribution is given in the oxide as in the figure a and b. I have calculated the flat band voltage for both the case which is -0.77 and -1.54 microvolt respectively. My question is if I calculate the total charge of the distribution, which is simply the area of the triangle, it will be equal,then why the flat band voltage is coming different what is the physical reason behind it?


texts: How do I neatly bridge to a ground plane?

texts:
I have boards that through a mistake of my own have a bunch of vias that should connect to the ground plane, but are actually isolated. See all of the holes that are isolated:

So, I need to bridge all of them to the ground plane. Since there is no solder mask I figured I could just use solder to bridge the connections. Here is what my solution looks like:

Not so pretty. I am wondering if there are any suggestion of what I can do to short these in a better manner. I will have it fixed in my next board revision, but it is a few weeks before I will have the boards and need to solder a few of these up now.

ADDITION: The biggest problem I was having was the ground plane heated up very slow and It didn't seem to want to stick to both the pad and the ground plane at the same time.


texts: What is a sensible approach to connecting devices to your computer via wireless technology?

texts:
I remember with fondness the X-10 days, when you could connect your computer to every wall plate in your house, using power-line carrier to transmit signals to addressable receivers (with varying degrees of success).

OK, so maybe I don't need to turn on my microwave from my computer remotely, but I still think it would be cool to have a wireless controller scheme for some home automation, maybe even put a webcam on my Roomba, or some temperature sensors outside.

What is a sensible overall way to approach this?  Wifi endpoints are really attractive, but they seem a little pricey.  Are there alternative approaches using radio?  Or is power-line carrier still the way to go?


texts: Input impedance of a one stage voltage amplifier?

texts:
This is not a school/university assignment; I'm a physicist trying to learn some electronics. I'd like to calculate the input impedance of the following circuit.

simulate this circuit – Schematic created using CircuitLab

We know that C1 has a reactance of \$X_{C1}=\frac{1}{2\pi f C1}\$, which must be taken into account. That's roughly all that I know! For example I don't know if R2, C2 and the impedance of the output device are important in the calculation of input impedance as well. Also, I'd like to know the equations which show that the input impedance increases by replacing Q with a Darlington pair.


texts: what happen if I use EMI filter at more then specified current

texts: I want to use Gaia EMI filter. my load requirement is 1.7 A continuous and 3.5A Max. Voltage is 28 V. Because of the max current I have to use FGDS-10A-50V(load current can go up to 10A) but this size to too much for me. So my question is if I use FGDS-2A-50V(load current 2A) filter and when in some case my current will go 3.5 A what will happen with the filter? will it stop working and when my load will be again less the 2 A it will start filtering..? Or once the current will go high my 2 A filter will not be workable again.


texts: Negative and positive electrodes on a battery - confusing results

texts:
We created a voltaic pile battery and tested voltage with a multimeter. Each cell is comprised of a penny and a nickel with wet paper in between (vinegar + salt solution). Then you simply connect these cells serially.

The penny end is supposed to become positive and the nickel end is supposed to become negative.

However, we see positive voltage readings on the multimeter by connecting the the negative probe to the penny and the positive probe to the nickel. I've verified that the probes are of correct orientation. Am I misunderstanding something about negative electrodes, i.e instead of being the end of a battery where there is a buildup of negative charge, are they instead the end where negative charge "wants" to go to?


texts: Using a 555 timer and 14-stage binary divider for 2 hour timing circuit

texts:
I am researching how to design a timing circuit that will activate a relay with a push button and deactivate the relay after two hours. My understanding is that I can feed the output of a 555 timer to the input of a 14-stage binary divider. Then feed the dividers' output to a relay driver. Then, after two hours of the divider receiving pulses, its output will change thus changing the state of the relay drivers output.

My question is, can a 555 timer reliably produce a ~1Hz pulse? And if so, will this be too low of a frequency for a binary divider to reliably handle?

Thank you!


texts: Count car weels without using visible light (camera/laser etc) and without interaction

texts:
For this project we need to count weels of a car (if possible at all), one side only. The scenario is within the following scope:

The car is always passing in a straight line
It is cars only, so all other traffic can be ignored
Road type is asphalt. Bricks, macadam or concrete detection is optional
Distance to the car will be around 4 meter (13 foot)
The tires will have a deviation to the measurement device of 20cm (8inch)
The scope is set to car tires of maximum 20" in diameter
At maximum speed of 130km/h or 80mph
Minimum speed can be any, but cars will never stand still, they will eventualy move (traffic jam)

The method of measuring should comply with the following rules:

No visible light sender or receiver can be used
Interaction with the tire is not possible (example: a cable to run over)
The measurement device can become dirty
Must be all weather type
Power consumption should be as low as possible
Device can be in sleep mode
Size should not exceed 50x50x50cm (20x20x20inch)

Since we cannot come up with possible measurement methods i'm looking for inspiration on how this might be achieved. Even if it might not work but it is viable we will look into it.


texts: Why wavelength is not measured with a unit of time?

texts:
While learning Fourier transforms, I have this little doubt about wavelength.

Why is that wavelength for a sine wave, or any other wave, is measured with a unit of distance?

If it travels w.r.t. time, why is it not measured as a unit of time?

I think, in the below drawing, the green line is the wavelength. So, why measure it with a unit of distance?


texts: Is it possible to use an opamp to generate 13V VPP for ICSP?

texts: I have used a 34063 DC boost converter to generate a 13V VPP voltage for a PIC ICSP programmer, but would it be possible to use an opamp instead? The circuit pictured below seems to generate 13V (according to the simulation), so if the input to the opamp was driven by an IO pin would that work instead? This is for a PIC (16F684 say) which doesn't use VPP for the actual programming, just as a signal to put it into programming mode (i.e. the load on the line is very low).


texts: Purpose of the diodes in DRV8301 motor driver circuit

texts:
This schematic is used to drive a motor with DRV8301. But the datasheet of DRV8301 doesn't show diodes. What is their purpose?
VDD is 14.8V (16Vmax). MOSFETS are BSC016N04LS

Schematic with diodes:

The datasheet of DRV8301:


texts:
I would like to capture and decode the ADSL traffic going on between my modem to the CO equipment.

I am thinking of a setup similar to the one shown in this paper, but it seems the necessary hardware is totally out of my reach.

Alternatively maybe some high impedance tap to plug on some ADSL chipsets evaluation boards to do the hard job of demodulating etc ?

What would be the most cost effective option to go for ?
Can someone suggest some simple schematics and low cost equipment that would do ?
The capture needs not to be real time, and should be capable to see the exchange in both directions.


texts: Funny this is my third question in a row about RC circuits, but I wanted to figure out some stuff I'd been wondering for a while.  What I was confused about the power while charging.  Like say that you have a battery that is able to produce 1 amp at 1 volt of electricity, and you have it connected to a 1 volt, 2 farad capacitor (for simplicity).  The energy it can store is 1/2CV^2 which is equal to 1 joule.  What confuses me is if the time constant is low, like 0.01 seconds, it would suggest that the capacitor would be able to become 62.3 percent charged in that little time, but if the power source can generally only supply 1 watt of DC power, isn't that a limiting factor which would mean it would charge in 0.623 seconds.  In other words, is the power supply a limitation in this situation or could it still be able to charge in that amount of time?


texts: Help needed on wheatstone bridge problem

texts:
My circuits 1 professor gave us some practice problems for an upcoming exam, and I'm not sure that I know how to do this one.

My approach was to apply the circuit divider formula for the left and right sides, and that gave me the current across both parallel branches of the bridge, but I'm unsure of how to proceed. I was also wondering if I can place ground at some point on this circuit? Or would I need a voltage source to be able to do so? Thanks in advance.


texts:
For a EV battery recycling project I am going to play with EV batteries.
I will read out parameters from them (element configuration, charge, etc).

I will NEVER try to recharge nor dismantle them: other people on another (hopefully safe) site is going to work on recharging them and one battery will be moved to my lab only for reading purposes.

Wandering around the Net I saw that there are two ways to manage battery safety:

lighthearted: plastic goggles, no protection against fire and explosion, battery on the lab floor;
Fort Knox-like: steel walls, fire brigade ready in the parking, fire extinguishers, and so on.

I would assume the truth is half way, perhaps a little bit more on the fire brigade side.

Is there any reference or regulation about how a proper test environment should be done? Any example from a real company?

Thank you in advance.


texts: How to upgrade StdPeriph drivers for STM32F103 project

texts:
I have an old project which is built on using "StdPeriph drivers" for STM32F103 MCU and Keil environment. It uses various drivers for gpio, adc, can, dac, dma, i2c, spi, tim, uart etc.

As these drivers are obsolete now so I want to move to new available ones. But I don't know how much work will be involved in migrating to new drivers let us say CubeMX.

I have heard that CubeMX are not as efficient as was expected of them. Since my application is not very time critical so i think i can live with it so long as my new project-code would be maintainable and scale-able.

I want my project to be easily maintainable and scale-able so that's why I am considering to upgrade to these newly available libraries as well as TrueStudio. But I don't know how much bigger the task will be time-wise and difficulty-level-wise. I have to hire some engineer for this task. How can I quantify this task?


texts: how to use a second power source to automatically switch on another

texts:
I'm working on a little car based project, where I have an inverter protected by a 40a internal fuse. I need this inverter to only recieve power when the ignition switch is on (i.e. when car is running, so I won't kill the battery). Unfortunately, the only existing accessory power sources are protected by a fuse rated for only 7.5a. So tapping into these sources will ultimately result in a blown fuse.

Constant power sources have much less restraint (40-50a), but would normally require either manually unplugging the inverter, or wiring up a switch, that I'd have to manually flip to save my battery.

So, in the name of laziness (and the rule of cool) I'd like to create a switch that works automatically based on whether or not there is power to an accessory source. I've tried Google of course, but the closest I've gotten is either a transfer switch (not applicable - it's only being powered by one source) or an automatic switch based on whether or not the main source has power.


texts:
I have a circuit in which bulb is attached, I want to let arduino know if bulb is functional or fused. Obviously when bulb will be fused it will become open circuit. I am using mains AC to power the bulb and I want to make feedback signal to send to an arduino

My bulb is running on 220 V controlled through relay.

I have connected the bulb in series with an AC - 5V DC converter, however, the bulb flickers when connected this way.

simulate this circuit – Schematic created using CircuitLab

How do I detect whether the bulb is conducting or blown?


texts: Are the two op-amp terminals at equal bias for positive feedback?

texts: For negative feedback op-amp circuits, we know that V+ = V-. However, does that also hold for positive feedback circuits? According to my simplistic SPICE simulations, this seems to be the case, but I want to confirm.


texts:
An unexpected need emerged in my design, which is to control 2 slave SPI devices simultaneously.  At first, of course, I was planning to to use the SPI Bus as usual and control both devices using the /CS pins so everything seemed fine.

By reviewing the datasheet of device A today, I noticed that it expects all of the data in one go, which means I cannot do the procedure I originally had planned:

1) Select device B
2) Read data from B
3) Unselect device B
4) Select device A
5) Write data from B
6) Unselect device A
7) Repeat until all data from B goes to A (around 1.1 Mbit)

The device A assumes that when its /CS goes high it's the end of data stream. Of course I cannot read everything from B in one ran and store them to MCU RAM, since the data are way bigger.

Naturally, the next thing that came to my mind is to use 2 separate master SPIs at the same time: select both chips, read on byte from B and feed it immediately to A.

So my questions are:

a) Is that possible using an ATmega32u4? It has a critical role in the overall design and changing to another MCU Would be a step back.

b) I read that the USART can act as a second SPI master. Is that viable and reliable? How hard is to implement?

c) If, unfortunately, is not possible and I have to change MCU, which one would you recommend? Note that the USB capability of ATmega32U4 is essential.

d) Is the new process (read from B, feed to A) likely to cause any unexpected behavior? Does not seem in my point of view, I am asking just in case since I am a new engineer.

Any other idea or direction is welcome! Thanks in advance.

UPDATE
In case it plays a significant role, Device A is an FPGA while B is an flash memory. The MCU has a dual role: Download the bitstream from the PC via USB and store it on the flash ROM / use the stored bitstream to configure the FPGA upon reset/power on. Both FPGA and flash use SPI. According to the datasheet of the FPGA (ice40 family, Lattice, "iCE40 Programming and Configuration" p.26), the image has to be programmed without interruption.


texts: Arduino: Common Ground Issue? Powering Buzzer, LEDs via transistor as a switch

texts:
I'm working on an ugly Christmas sweater with a Lilypad Arduino.

Previously it was setup to power LEDs on each side of the sweater using just the voltage from the digital output pins (alternating sets of LEDs to the beat of the music), while also operating an inductive buzzer (connected to a PWM output on pins 5 and Arduino gnd) to play Christmas tunes via modulation.  This was obviously pretty under-powered and I'd like to nearly deafen/blind my friends with this project.

So this year is V2 that uses transistors as switches to pump closer to 18V from 2x 9V batteries to the LEDs.

I was having an issue getting this setup to use a separate power supply and still operate properly with the buzzer.  I'm using NPNs (TIP31) that are setup the following way (from memory, so hopefully I recounted it right, but the setup is functional):

Base -> Arduino output pin
Collector -> GND on the Arduino board
Emitter -> LED (-)
V+ -> LED (+)
V- -> GND on the Arduino board

V+ = 18V via 2x9V batteries

Arduino powered by a separate onboard battery.

Simplified schematic attempt below (doesn't show 2nd set of LEDs and 2nd transistor)

simulate this circuit – Schematic created using CircuitLab

My issue was that, when the buzzer is connected (even if its not being operated) the LEDs were staying lit.  I'm pretty sure it has to do with the Arduino board and the separate power supply for the LEDs sharing a common ground.  Disconnecting the ground from the (-) terminal of the buzzer confirms this.

Is there some way I can set this circuit up to have separate grounds, and would that even help?  I figured I could use optoisolators to fully isolate the circuits, but I don't have time to order any in.  Is there a solution simply using the NPN transistors I have available?  Total novice here, so please bear with me!

Thanks in advance!


texts: Can I connect an Android smartphone to an Arduino Uno?

texts:
I'd like to connect my main Android smartphone (it's a ZTE Blade X) to my Arduino Uno. My main reason is I'd like to use the camera on my phone as a sensor for the Arduino, for various projects.

Is this possible to do, by simply connecting the 4 wires of the phone charger into the Arduino? (The 4 wires are positive, ground, data + and data -, as I'm sure you all already know.)


texts: What are the consequences of connecting two motors in parallel?

texts:
I am using two DC motors rated at 36V and maximum current draw of 5A. To reduce the number of motor-controllers, I am planning to connect them in parallel.

The two motors are required to run at the same speed, so wiring them in parallel will ensure same PWM signal to both these motors.
Both the motors are unidirectional.
Both the motors are identical (electrical rating, manufacturer, load).
Also, they need not rotate at exactly the same speed, there can be slight variation (15%).
The motors will be driven in an open-loop, there is no feedback.
The motors will be connected to brushes.

My concern is:

What happens if one of the motor stalls? Theoretically, this should not  affect the other motor as they are in parallel and the UN-stalled motor will receive the required voltage and also assuming that the batteries are able to supply sufficient current.
What happens if one of the motors produces back EMF?
Is it possible for a stalled motor to produce back EMF?
Should I be using a circuit-breaker/PTC fuse/fast-acting fuse in series with the motors?


texts: DC/DC system has voltage between grounds

texts:
My system is powered by 60 V battery. First converter is 60 V / 12 V isolated, second converter is 60 V / 12 V non-isolated. Two converters power own system component. When I measure the voltage between converters' grounds, the voltage is -6.90 V. Why is the  voltage like this? And How can I find the problem?

editing: I measure the voltage between converters seconds(outputs) grounds.


texts: I need to transmit 100khz /90khz FSk at 9600 baud over 4km

texts:
What cable characteristics should I look for when designing a copper (or other) conductor cable for transmitting FSK @ 100kHz/90khz, 3V pp in order to achieve a maximum attenuation of not more than 26dB over 4km?

I expected to need to use shielded twisted pair but advice on alternatives is welcome.


texts: Highlight pads of connected nets when dragging

texts: I recall that Altium has some option that would highlight pads with matching nets on other components when dragging something in the pcb editor. I wasn't able to find the option. Was it removed in AD20 perhaps?


texts: How do I leave electrical connection of heat-sink body?

texts:
I usually see that some heat-sinks have thick pins to solder on the PCB, and I'm going to use one of them. Since they are going to be soldered on the PCB, the question rises in my mind about their electrical connection.

My ideas are:

Connect them to the ground:

Directly
By a large resistor (>1M\$\Omega\$)
By a capacitor
By a large resistor parallel to a capacitor
By a small resistor in series with a capacitor
By a small resistor in series with parallel connection of a large resistor and a capacitor

Connect all heat-sinks in the circuit to a separate ground
Leave them unconnected

What is the best solution?

And, if I should connect the heat-sink pin(s) to somewhere, should I connect only one or all of them?

(Note: The circuit element to be cooled is electrically isolated from the heat-sink body.)