texts: What could possibly destroy a current limited stepper motor driver?

texts:
I was working with STK6714AMK4 connected with arduino to make a stepper move with the change of a potentionmeter resistance (stepper knob).

The motor at first worked well but didn't respond to the potentiometer.
Anyway, One day after that, I powered the circuit again but the driver got so hot and the motor held at its position with some noise. So, I disconnected it and tried again but the driver wasn't working (I tried the stepper alone and it worked).
So, what could be the reason? Can unfiltered power supply destroy such a circuit?
 (I connected the circuit as shown but didn't connect any capaitor in my circuit)

Datasheet


texts: DIY small motor that turns for x seconds every y seconds

texts:
I'm a civil engineer, hiker, and hobby photographer. I am trying to build a little device that gently turns a small motor on every x seconds, keep it on for y seconds, and stop it for z seconds. For example, Set the motor to run every 30 seconds, have it run for 45 seconds, and stop it for 37 seconds. In addition, the movement of the motor must be such to minimize vibration on the camera that it will support.

Above all this device must be portable in a regular backpack.

I have played with the raspberry pi a little bit (I don't own one) and have dabbled in electronics a touch


texts: How to #include files in other folders in Eclipse IDE?

texts:
Here is the directory structure of a project I have downloaded:

The problem is that when I compile I keep getting fatal error message that say that the specific header file does not exist. For example, right now there is #include "fatfs.h" inside the fatfs_disk_io.c.
The error message says "libfatfs/src/fatfs_diskio.c:46:19: fatal error: fatfs.h: No such file or directory"
As you can see, fatfs.h does exist but in another folder. If I use a relative path inside the #include directive inside fatfs_disk_io.c, then the program will compile. The issue is that there are a lot of references in different files to different headers. I can take my time and change them all to relative paths but please tell me, why in the world is Eclipse not able to just find the header files when they are inside the project directory? What do I need to do to make Eclipse realize that all the .h files being referenced are somewhere in the project folder so just find them.


texts: I2C: How to adress the second page of a eeprom

texts:
I have an eeprom and I can't properly adress everything out of the range 0x00-0x1f.
Using the Raspberry I send the following I2C command to the eeprom:

"sudo i2cset -y 1 0x50 0x00 0x10 0x29"

This command writes the byte 0x29 at the adress 0x10 to the eeprom.
I can than look if it worked by using the command "sudo i2cdump -y 1 0x50 i"

But if I use the same command as above but with a higher second adress value (for example sudo i2cset -y 1 0x50 0x00 0x80 0x29) and then try to look if it worked with i2cdump I don't see any changes. If I change the first byte adress value (for example sudo i2cset -y 1 0x50 0x01 0x10 0x29) then the value change is displayed at 90/0 in the i2cdump output.

Here is an example output of i2cdump so you can better understand what I mean (not my i2cdump output):

     0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
10: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
20: 8a 8b de bb c9 d8 d0 1d ff ff aa c1 9e c1 9e e3
30: ba cc a8 d8 b2 ed c2 e4 bb 3c 32 e1 e1 e1 00 00
40: 01 c3 00 00 00 00 40 50 2d 01 01 40 01 95 00 a3
50: 10 01 80 ff ff ff 00 00 11 ff ff ff ff ff ff ff
60: 8a 8b de bb c9 d6 d1 1d ff ff aa c1 9e c1 9e e3
70: ba cc a8 d8 b2 ed c2 e4 bb 3c 32 e1 e1 e1 00 00
80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
90: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
a0: 8b 8b de bb c8 d9 d1 1d ff ff ab c1 9e c1 9e e3
b0: ba cc a8 d8 b2 ed c2 e4 bb 3c 32 e1 e1 e1 00 00
c0: 01 c3 00 00 00 00 40 50 2d 01 01 40 01 95 00 a3
d0: 10 01 80 ff ff ff 00 00 11 ff ff ff ff ff ff ff
e0: 8a 8a de bb c9 d8 d1 1d ff ff aa c1 9e c1 9e e3
f0: ba cc a8 d8 b2 ed c2 e4 bb 3c 32 e1 e1 e1 00 00

Here's a link to the datasheet from my eeprom, it says a page is 32 byte big, I think that explains why I can`t adress anything bigger than 0x1f. But I don't understand how I can adress the next byte address after 0x1f ?!

Am I interpreting the i2cdump wrong or do I have to use other byte addresses ?

https://cdn-reichelt.de/documents/datenblatt/A300/ST24C32_ST24C64%23STM.pdf


texts: How does a fuse prevent battery overcharging/discharging?

texts:
How does a fuse protect a battery? I know that it prevents short circuits, but what about overcharging and over discharging?
I asked a previous question here, and the recommendation I got was to get a fuse.
If a fuse dosent prevent overcharging or over discharging, than what should charging and discharging look like?
I built a 48V 80A NiCd battery pack. I have no idea of where to buy a BMS system or what kind of voltage detection IC I need to prevent overcharging/overdischarging. I need to know what people do to protect a battery pack like this one, or if they protect it at all.


texts: Can a D667A NPN transistor be replaced with a BD139 NPN transistor in this PSU?

texts:
I have a PSU that had a D667A NPN transistor that took some damage. I am not 100% sure what its goal is in the circuit, but I have the impression it is used to drive the power transistor mounted on the heatsink you see in the picture.

The psu had a fuse that got blown violently, and there were some shorted components in the PSU (shorted power transistor, shorted electrolytic cap, shorted schottky diode)
I replaced the shorted components, and replaced the D667A NPN transistor this particular transistor with a BD139 NPN transistor I had lying around.
The original D667A NPN transistor datasheet mentions a transition frequency of 140Mhz.
In the BD139 NPN transistor datasheet I could not find this frequency, although other sites mention it as being 190Mhz. The other parameters were the closest I had compared to the original one, making me think (perhaps wrongly) that this is a suitable replacement.
Is my thinking correct, or should I replace it with a more suitable transistor. And if so, what would that replacement be ?
Although the fuse is kept intact now, I am not seeing any DC output voltage, so I am wondering if this BD139 might be the cause of that. (it not being able to turn on the power transition properly).


texts: How to wire relay documented in Chinese?

texts:
I got a sensor based relay and I am unable to understand the purpose of the white wire (coded XF).

For the others I assumed these:
* Connect relay black wire (N) to neutral from the socket (Blue) which is also connected to the Lamp blue wire
* Connect relay red wire (L) to socket wire L (Brown)
* Connect relay yellow line (L0) to lamp brown wire

I tried to use it without connecting the white wire to anything but it doesn't seem to work.

I am inclined to believe that "fire control line (F)" may be the poor translation of ground-wire but I don't want to risk anything.

http://s3.sbarnea.com/ss/Monosnap_2017-01-07_14-33-11.png


texts: Interfacing Switch Input with Seven Segment Display using ARM 7

texts:
I am trying to detect a switch input so that, if the switch is pressed, a number is incremented on the seven segment display. For example if the seven segment display shows 0, and the switch is pressed, the SSD will now show 1. If pressed again, it will show 2 and so on.

My seven segment display is connected on P0.0 to P0.6
MY switch is on P0.9

How can I detect each time the switch is pressed? I am trying to increment a variable k in my program so that each time the switch is pressed, k is incremented, and thus I will be able to perform different functions each time the switch is pressed. However this part is not working properly.

I am thinking something similar to the following program. However, I must be overlooking something as only the first button click is working. When the switch is pressed, 1 appears on the display. Nothing happens when it is pressed again.

#include <LPC21xx.h>
#define a 0x00000001
#define b 0x00000002
#define c 0x00000004
#define d 0x00000008
#define e 0x00000010
#define f 0x00000020
#define g 0x00000040

void small_delay (void);

void infinite (void);
int main (void)
{
int k = 0;
unsigned int SW1;

PINSEL0 = 0;                                //Set P0.0 - P0.15 as GPIOS
PINSEL1 = 0;                                //Set P0.16 - P0.31 as GPIOS
IO0DIR  = 0xFFFFFDFF;               //Setting  P0.9 as input for SW1

while (1)
{

    SW1 = IO0PIN & 0x00000200; //switch connected on P0.9

    if ( SW1 == 0x00000200 )        //when not pressed
    {

    }

  if ( SW1 != 0x00000200 )  //when pressed
    {
        k++;

        if (k == 1){
        IO0SET = b;
        IO0SET = c;                         //displaying number 1

        }

        else if (k == 2){

        IO0CLR = c;
        IO0SET = a;
        IO0SET = b;
        IO0SET = g;                         //displaying number 2
        IO0SET = d;
        IO0SET = e;
        //small_delay();
            }
        }
    }
}

 void small_delay (void)
 {
 unsigned int i, j;

 for (i=0; i<1000; i++)
 {
    for (j=0; j<1000; j++)
     {
     }
 }
 }

Any suggestions or pointers on what I could improve, would be appreciated.


texts: What is this part (label is 23LCVB I/P JWD 1336, 8-DIP package)?

texts:
I found this part in a box with random parts. Mostly they were voltage regulators, opamps and transistors (both BJT and FET).

The closest match I found was this SPI SRAM, but the part number didn’t match completely.


texts: my spi protocol in verilog is not working

texts:
I have written an spi protocol in verilog and it is showing error.
here is the link from where i took the information for spi.
https://www.nxp.com/files-static/training_pdf/26821_68HC08_SPI_WBT.pdf
And this is the code I have added detailed comments so that anyone who is reading could comprehend easily what is happening. Please review my code and I would be thankful for your suggestions.
module spi_master(clk,sclk,miso,mosi,ss);
input clk,sclk;
output reg miso;
output reg mosi;
output ss;

reg [7:0] receive_register_slave; //slave receive data register
reg [7:0] shift_register_slave; //slave shift register
reg [7:0] data_in_slave; //slave data register that transfers data to system
reg [7:0] transmit_register;  //data transmitting register
reg [7:0] shift_register; //data shift register
reg [7:0] receive_data_register; //receiver register
reg sptie;  //interrupt signals for master
reg cpol ,cpha; //clock polarity and clock phase register
reg [7:0] data_in;  //data comming from system
reg sprf; //interrupt which tells all 8 it data is transferred
reg sprie; //interrupt which indicate receive register is full

parameter op1 = (cpol==0)&&(cpha==0), op2=(cpol==0)&&(cpha==1),op3=(cpol==1)&&(cpha==0),op4=(cpol==1)&&(cpha==1); //defining the parameters for cpol and cpha
parameter idle = 1'd0; Master = 1'd1; slave = 1;d0;  //defining parameter for idle and master and slave

//block to initialize the values

initial
begin
    sptie = 1'd0;  //interrupt to tell if transmit register is full or not
    transmit_register = 8'd0;  //initializing transmit register
    shift_register = 8'd0; //initializing shift register
    receive_data_register = 8'd0;  //initializing receive data register
    cpol = 1'd0;  //initializing clock polarity to zero
    cpha = 1'd0;  //initializing clock phase to zero
    clk = 25000000; //initializing the 25Mhz clock
    sclk = clk/4; //initializing the clock value
    ss = 1'd1; //initializing the slave select to one
    sprf = 1'd0; //initializing the interrupt
    sprie = 1'd0; //initializing the interrupt to zero
end

//condition for assertion of ss
assign ss = (sclk == idle)?1'd1:1'd0;

//condition for assertion of master and slave control
always@(posedge sclk)
begin
    if(shif_register <= mosi) Master <= 1'b1;
    else if (miso <= shit_register_slave) Slave <= 1'b1;
    else Master && Slave = 1'b0;
end

//if interrupt is enabled data from system is written into transmit data register of master
always@(posedge sclk)
begin
    if(sptie) transmit_register <= data_in;
    else transmit_register <=  8'dz;
end

// if interrupt is not enabled data from transfer register is moved to shift regsiter
always@(posedge sclk)
begin
    if(!sptie) shift_register <= transmit_register;
end

//if ss is low data from shift register is moved to output mosi
always@(posedge sclk)
begin
    if(!ss) mosi <= shift_register;
end

//data comming into slave shift register and is from there transferred to system register
always@(posedge sclk)
begin
    if(Slave)
    begin
        shift_register_slave <= mosi;
        receive_register_slave <= shift_register_slave;
        sprf = 1'b1;
        sprie  = 1'b1;
        data_in_slave <= receive_register_slave;
        sprf = 1'b0;   //i made these bits low because currently i dont have a main program
        sprie = 1'b0;
    end
end

//shifting data out from slave shift register through miso line
always@(posedge sclk)
begin
    if(!ss) miso <= shift_register_slave;
end

//receiving data frokm slave and transmitting data to system
always@(posedge sclk)
begin
    if(!ss)
        shift_register <= miso;
    receive_data_register <= shift_register;
    data_in <= receive_data_register;
end

end

endmodule


texts: Separating power from data micro USB to HDMI

texts:
I have a camera which both draws power and sends its data through a battery pack to a custom monitor. The monitor also draws power as well as receives the camera data through the battery pack. (Both the camera and the monitor connect to the Battery pack with Micro USB) I intended to use a monitor which uses its own power supply so I used a Micro USB to HDMI converter meant for phones(MHL). However it didn't work, the adapter smelled burnt and the HDMI port on the monitor no longer worked however the HDMI cable itself still works. I figured it must be because the battery pack outputs both the camera data as well as power, the power must have burnt out everything. Is it possible to separate the power output from the data output and to convert it from Micro USB to HDMI without burning out the ports?
Additionally I opened the monitor that came with the battery and camera and the Micro USB Wire connected to a circuit board with a smaller red, black, and green wire. The battery pack consists of two 18650 rechargeable batteries(3.7 Volts, 2500mah).


texts: Sudden raspbery pi power cut or random long delay when running stepper motor using pigpiod

texts:
So I wrote another program that can run stepper motor nema 34 using leadshine DM860 driver and this is the example of my code:

import time
import pigpio

START_DELAY=580
FINAL_DELAY=480
STEP=1

GPIO=20

pi = pigpio.pi()

pi.set_mode(GPIO, pigpio.OUTPUT)
pi.set_mode(21, pigpio.OUTPUT)
pi.set_mode(26,pigpio.INPUT)
pi.set_mode(16,pigpio.INPUT)
#pi.write(21,1)
pi.wave_clear()

statee = 0
run = True
try:
    while run == True:

        pi.write(21,statee)
        pi.wave_clear()

        wf=[]
        offset = pi.wave_get_micros()
        for delay in range(START_DELAY, FINAL_DELAY, -STEP):
           wf.append(pigpio.pulse(1<<GPIO, 0,       delay))
           wf.append(pigpio.pulse(0,       1<<GPIO, delay))

        for i in range(500):
            wf.append(pigpio.pulse(1<<GPIO, 0,       FINAL_DELAY))
            wf.append(pigpio.pulse(0,       1<<GPIO, FINAL_DELAY))

        for delay in range(FINAL_DELAY, START_DELAY, STEP):
           wf.append(pigpio.pulse(1<<GPIO, 0,       delay))
           wf.append(pigpio.pulse(0,       1<<GPIO, delay))

        pi.wave_add_generic(wf)

        wid2 = pi.wave_create()

        #pi.wave_send_once(wid2)
        pi.wave_send_using_mode(wid2, pigpio.WAVE_MODE_ONE_SHOT_SYNC)

        if pi.read(26) == 0:
            pi.wave_tx_stop()
            run = False
        if pi.read(16) == 0:
            pi.wave_tx_stop()
            run = False

        time.sleep(0.7429)
        if statee == 0:
            statee = 1
        elif statee == 1:
            statee = 0
except KeyboardInterrupt:
    print ("\nCtrl-C pressed.  Stopping PIGPIO and exiting...")
    pi.wave_tx_stop()
    pi.stop()

It runs without code error but sometimes the stepper motor when moving got random long delay even I already decrease the value from START_DELAY,FINAL_DELAY, and time.sleep() (with the range between START_DELAY and FINAL_DELAY value is 100 and time.sleep() value depend how smooth movement).

When I use START_DELAY,FINAL_DELAY, and time.sleep() value like the example code (the lowers speed) sometime the raspberry pi got power cut (stepper motor stop moving and lcd monitor show blank screen with text 'no signal'). So, is the problem realy cause from my code? I already update pigpiod to v68.

This is how it is wired:

I use jumper wires (using male to male and female to female, because I dont have male to female jumper wires) between driver to raspberry pi 3 and connection between DIR- and PUL- using ordinary copper wire.

This is the pulse width modulation result that I check using piscope:

NEMA34 bipolar stepper motor specification:

Holding torque 5.9 Nm
Step angle 1.8°
Resistance / phase 0.33±10% Ω
Inductance / phase 3.00±20% mH
Max load axial 65 N
Max load radial 200 N

https://www.igus.com/info/drive-technology-nema-34-ca

DM860 leadshine with an output current of 1.0 - 7.2A , and an input voltage of 24 - 80 VDC.   I have the driver configured with 24V power supply.

This is the driver current and pulse/rev setting:


texts: External interrupt does not work on Proteus (PIC16F883)

texts:
I'm developing a basic circuit for a shooting game. When some area of the target is reached the microcontroller must add the current value to the reached value.

My problem is that I can not make any interrupts work on Proteus.
(RB0 external interrupt)

I'm using the Hi-tech C compiler (free version)

What am I doing wrong?

/* Main.c file generated by New Project wizard
*
* Created:   qua jul 12 2017
* Processor: PIC16F883
* Compiler:  HI-TECH C for PIC10/12/16
*/

#include <htc.h>

//digits (0-9)
const unsigned char disp[] = {0b00111111,0b00000110,0b01011011,0b01001111,0b01100110,0b01101101,0b01111101,0b00000111,0b01111111,0b01101111 };

//enable specific display using array index
const unsigned char ob[] = {0b00010000,0b00000010,0b00000100,0b00001000};

void set_display(int val, int display);

int value = 0;
int total = 0;

void interrupt rb0(void){

   if(INTF){
      value = RA0 + (RA1 * 2) + (RA2 * 3) + (RA3 * 4) + (RA4 * 5) + (RA6 * 6);

      total += value;

      INTF = 0;
   }
}

void main(void)
{

   // Set RB0 as input
   // Set RB1 - RB7 as output
   TRISB = 0b00000001;
   PORTB = 0xff;

   // Set RC as output (default 0)
   TRISC=0X00;
   PORTC=0X00;

   TRISB0 = 1;
   GIE = 1;
   PEIE = 1;
   INTEDG = 1;
   INTE = 1;

   //Set internal oscilator to 8MHz
   IRCF2 = 1;
   IRCF1 = 1;
   IRCF0 = 1;

   while (1){
      int a = total/100;
      int b = (total/10)%10;
      int c = total%10;

      set_display(value,0);
      __delay_ms(25);

      set_display(a,1);
      __delay_ms(25);

      set_display(b,2);
      __delay_ms(25);

      set_display(c,3);
      __delay_ms(25);

   }

 }

 void set_display(int val, int display){
    PORTC = disp[val];
    PORTB = ob[display];
 }

Download project(Proteus 8.5) and compiler: https://1drv.ms/f/s!AipcmZDTZPIPlOknaPJ06hKTQbzLiA


texts: What's the purpose of this circuit section?

texts:
I'm experimenting on VCA circuits and found the same (or similar) pattern in many linear VCA projects found in internet using LM13700 OTA.
The specific section I'm curious is made by an Op-amp, a transistor, a diode and some passive parts, and is used to feed Control Voltage to OTA's Iabc "amp bias input". In this example image, is composed by parts R2, IC1A, D1 and Q1.

Can somebody explain the purpose of this section?
It seems to me like a voltage-to-current converter (it makes sense, since CV is a voltage and Iabc is a current), but I'm not sure.


texts: Unable to find a source for rotary mirrors, how should I search for them?

texts:
Can someone suggest a source for rotary mirrors? I'm looking for something along the lines of the ones in the image below, but I'd be interested in any alternatives as well. (I'm building a continuous laser harp, so the basic idea is I need to sweep an arc of about 45 to 60 degrees, or so.)

From what I understand these are fairly common in some barcode scanners and laser printers, so I'm open to salvaging them if there isn't a good place to buy them independently, though I'm not entirely sure what I should be looking for (in terms of what kinds of barcode scanners / what parts of the laser printer).


texts: L293D outputs different in different motors. Are there different types of DC motors?

texts:
I recently picked up a used Spider King RC toy from a thrift shop (http://amax-toys.en.alibaba.com/product/337890538-212191267/rsc_9021_RC_Spider_King_car.html).  It had no remote or battery charger so I pulled out the PCB and battery and now have the four pairs of motor leads running out to a breadboard where I've mounted two L293D chips and wired up an Arduino UNO R3.  The arduino is powered from the DC barrel jack, and the motors are being supplied with 5V from a computer PSU, both sharing a common ground.  Two of the motors control the axial rotation of the front or back treads for lift, and the other two control the forward/backward rotation of the left or right pairs of treads for forward and backward motion (if you check the link above this should make more sense).

Now, the two axial rotation motors which control lift work fairly well.  When powered in either direction with 5V and the digitalWrite(pin, HIGH) supplying 5V to the correct directional input (and 0V to the other), I get .5-1.5V on the LOW side Y(output) value, and around 4 on the HIGH, resulting in 3-4V across the motor.  Although not my main question, I am concerned as to why these are not 0V, 5V, and 5V across the motor.  Should this not be the ideal reading?

The more concerning issue however is when I try to power the other two motors.  The results for both these motors under the same input values are 2V on LOW output and 2.5-3V on HIGH, giving .5-1V across the motor... not enough to move the gears even without the load of the toy's weight on them.  I have tried switching out the Arduino (I have two) and switching the 2 L293Ds with no change.  The motors all look the same and each has a 220nF ceramic cap across it.  When hooked up directly to DC all four are eager to spin in either direction.  Even given that this is a used toy and there's no telling what the previous owner put it though, it seems that since I am getting the same results from like motors in a given pair there might be some correlation in the solution.

Is it possible that these are two different types of DC motors and one set is not compatible with the way the H-Bridge chip powers them??  I have never heard of this but then I have not been working with this sort of thing very long.  I can put together a schematic and post it as well if anyone thinks that would help but I'm not thinking it would as everything is hooked up the same in both the working and non-working situations.


texts:
I am planning to use a battery cell similar to the picture below in a product I'm designing. Is it ever appropriate to mount these directly on top of a PCB? (all components will be on one side of the board, so would be mounted on bare side) Is there some sort of insulation material to wedge between the battery and board?

I guess what I'm asking is, what is the standard way of mounting cells like these?


texts: Efficient alternative to a charge pump for stepping up a 3V supply to 3.3V?

texts:
I'm currently using a charge pump ic chip (http://www.digikey.com/product-detail/en/microchip-technology/MCP1252-33X50I-MS/MCP1252-33X50I-MS-ND/529831) for stepping up a 3V coin cell to a 3.3V regulated supply.

I originally chose this chip seeing as how, "it got the job done". However, I've realized that operating in this range (3V -> 3.3V) is only 60% efficient. I've also learned that high current draw from a coincell should be avoided seeing as coin cells have high internal resistance. I'm afraid that implementing this regulator is going to strain my battery even more than it already is.

The coin cell I'm using is a CR2032, but there's a chance I'm going to be switching to a different battery type soon.

So I'm curious, is anyone aware of a more efficient method for doing this?

Ideal solutions feature:

Purchasable IC package (i.e. I don't feel like designing my own regulator circuit).
Something of a small form factor (surface mount chip height).


texts: Can I use USB data pins as a power source?

texts:
I'm trying to build a circuit as seen below, where a sequencer controls the flashing of some LED sections, and an SPDT switch controls power to either the left or the right section of LEDs.

However, I want the PCB with the switch and power source to be located a distance (~1 meter) from the LEDs and sequencer, and I was wondering if I could use USB to connect them.

To be clear, I am NOT connecting this to any sort of computer or microcontroller, I want to know if it is possible to have a USB cable provide VCC and GND from one circuit to another, and then use D+ and D- to provide/disconnect power to the LEDs via the switch. All voltages would be 5 V, and I can adjust the current draw of the LEDs as necessary.

If this is not possible, is there an existing type of cable that can achieve this (three power leads and a ground), or will I have to solder my own?


texts:
I am not clear how to read the datasheet about dropout of this buck regulator:
http://www.diodes.com/_files/datasheets/PAM2320.pdf

pag.9

"As the input voltage approaches the output voltage, the converter turns the P-Channel transistor continuously on. In this mode the output voltage
is equal to the input voltage minus the voltage drop across the P-Channel transistor:
VOUT = VIN − ILOAD (RDSON + RL)
where RDS(ON) = P-Channel switch ON resistance, ILOAD = Output Current, RL = Inductor DC Resistance"

I plan to use this buck for converting from 5V to 4.2 at about 500mA and peaks of 1.6A (so I choose a 3A buck for safety margin).

Will be OK?


texts:
I'm hoping someone on here can give me a simple explanation of what a TRIAC does.

To give this request some context, I'm an embedded systems software engineer, so I interface with hardware, but I have no formal training in it. I was looking over a schematic for work and I saw a bunch of TRIACs being placed, but I am not familiar with this. I read the Wiki, but it's a bit much for me.

Can some one give me a basic example of what a TRIAC does and why you'd need them?

EX. I know a resistor, resists the flow of electricity
    I know that a capacitor stores electric charge
    I know diode's allow the flow of current in only one direction.

So like these basic concepts, can someone explain a TRIAC to me? Thanks.


texts:
Is it possible if we run AC analysis using general current PMW controller & not the actual PWM controller specified by the vendor? Reason is because I asked the chip maker regarding their SPICE modelling however they don't have that modelling for that specific model. My actual part is High-Voltage, Quasi-Resonant, Controller Featuring Valley Lock-Out Switching

I'm wondering on how power supply designer do their compensation during AC simulation without using the actual model. Is there any "general model" that can be use as reference during the initial small signal simulation? Or they using hand calculation?

I'm thinking to do modelling from C.Basso A Quasi−Resonant SPICE Model Eases Feedback Loop Designs using SIMPLIS for my flyback QR converter.

I'm not expect the result will be totally same but I'm hope that it can help me to do estimation of compensation on my power supply

I'm also trying to understand & derive the transfer function of this flyback QR, however it is really difficult for me (maybe lack of understanding in control theory). Does anyone have tips on how to learn & improve this?

I need your advice because I'm worry that I'm take the wrong step to do the analysis.

Thanks.


texts:
I have an Atmega4809 (Arduino Nano Every) connected via UART (Rx,Tx,5V,GND) to a BLDC controller. Then I have connected a little display (Rx,Tx without GND.)

When it is connected everything works fine. When I follow the connection, disconnection steps, nothing gets damaged.

The BLDC controller and display are connected to a DC source of 42V and GND separately

When I disconnect the BLDC controller and reconnect it, it gives a spark because the capacitors are charging. The display remains attached.

When this happens it destroys my Atmega4809. It gets very hot and it is irreparably damaged.

Could it be that some current flows through from the BLDC Controller to the Atmega4809 to the fisplay to GND and not over the connector when it sparks?

Can this fixed by an electrical circuit or component?


texts: Instantiating and using ppc440 core in Virtex 5 FPGA

texts:
I am new to Virtex 5 which has an embedded PPC440 core in it (XC5VFX70T). I am using the Xilinx ML507 board for my design.

I created the embedded core using XPS and instantiated it in my HDL project. As peripherals, I am using a DDR2 controller, BRAM, SRAM, one UART and a few GPIOs. However, I could not see any address/data bus ports from the embedded core which I can use in the FPGA fabric.

I have a few RTL IP cores which require memory mapping. How do I connect these IP cores to PPC440 core? Also there are a few registers implemented in the FPGA fabric which are used for system initialization. I want the PPC440 core to write to these registers during initialization. How can I achieve this if the embedded core doesn't have address/data bus as external ports?


texts:
I was looking for solution how convert float value to binary in STM32 and I found this:

float foo = 1.23;
uint32_t bar;
bar = *((uint32_t *)&foo);

My question is how does it works? I know it's some kind of pointer conversion, but I don't understand how precisely does it works.


texts:
I am using a MFRC522 RFID reader I have read that it's antenna when in close proximity with metals then interference could be generated. What should be the distance between the antenna and the metal to minimize the interference
reference link first paragraph of this link another link I am also sharing the screenshot of the same


texts:
I have a sound system that has a TRS auxiliary input port, and I would like to connect a smartphone or tablet to it. I found out by experimenting that using a TRS-TRS setup will not do - contact was poor and more often than not I'd be losing signal there.

So I bought two cables, with the following characteristics:

One has a TRS male plug on one end, and two female RCA plugs on the other end;
The other cable has a male TRRS plug on one end, and three RCA male connectors on the other end.

My idea was to find out, by trial and error, which RCA connectors in the TRRS cable would take the left and right channels. I would then weld them to the RCA ends of the other cable and cut the remaining RCA connector off, which should carry either the mic or ground channel.

Experimenting with this setup, I found out that I know nothing about how these things work.

By connecting one channel at a time, I got two channels that would give a very faint signal, almost inaudible, and one that would give a weak signal to one of the stereo channels only. This was the red connector in the TRRS cable (it's red-white-yellow, with white in the middle).

By connecting two at a time, I found out that the yellow and white connectors together get very noisy and weak signal. Now this is where I was surprised: using both red and yellow or red and white gives me a clear signal, although not as powerful as I get when connecting a computer's sound output to the same sound system (using s TRS-TRS setup).

Even more surprising to me: by connecting the free male RCA connector to any of the two connected ones, I get a huge boost in power (though not in all frequencies). I realize this is just shorting out two channels, right?

So my questions proper are:

Why do both the yellow and white cables work just the same?
Will I eventually fry my cell phone/tablet if I keep shorting the cables like I mention above? I haven't tried it for more than a few seconds at a time.
Is there a smarter, more elegant way to achieve what I want, with the materials I have available?

I am not a native speaker of English and I know some terms I use here might be wrong. If so, please edit the question to make it more clear :)

P.S.: I don't know if this is relevant... I am using Samsumg devices (a SIII phone and a Galaxy Tab 2). I believe their pinout is different from Nokia and Apple devices, right?


texts:
I was looking at contiki how it defines port direction for telob/sky:
https://github.com/contiki-os/contiki/blob/master/cpu/msp430/dev/hwconf.h
and am buffled.

I mean, in plain msp430 jurgon you could do this

P1DIR = 0x01;

to set up, for example, port 1 or

P1SEL &= (~BIT0);    // Set P1.0 SEL for GPIO

Now, the contiki master programmer has something like:

#define HWCONF_PIN(name, port, bit) \
static CC_INLINE void name##_SELECT() {P##port##SEL &= ~(1 << bit);}

and so on..

to make programming the port easier but I can't figure out how this enternally gets
executed.

For example, how is this " name##_SELECT()" called?

I know it's a newbie question but bear with me. Thanx


texts: MOSFET gate driver used without series capacitor

texts:
I'm planning on using this drivers I bought MD1213 to drive BUK7M45-40E MOSFETs and achieve fast PWM switching. Yet the drivers datasheet states the outputs are "Intended to drive the gate of an external MOSFET via a series capacitor." Would connecting this drivers directly to the MOSFET gates work right or are this series capacitors present on the reference design compulsory?

Edit: This is the schematic, the driver output is connected directly to the MOSFET gate, with no other component in the same net.


texts: Can I use 2 RJ45 magjacks (PCB mounted) used for pass through..on my PCB?

texts:
I need to put a pass through ethernet on my PCB. (rj45 to rj45).
My circuit is similar to this guy..
I want to use my existing components. I have space on my chipplacer(yes I have a chipplacer line) for this magjack here.
I would like to use 2 of these magjacks instead of 2 standard rj45s. back to back.
Will this work? (10baseT is OK for me).
Or will the magjacks back-to-back destroy the signal?


texts: How to set the resistor value for INA219

texts:
I managed to understand how to write/read data from the INA219 directly, using just linux/i2c-dev.

When I was planning my PCB and Bill of materials with my supervisor he suggested I should use a 0.002 Ohm - 1W shunt resistor for this module.

I tried to research on different forums on how to set this value in the registers. I also read the datasheet here: http://www.ti.com/lit/ds/symlink/ina219.pdf, but I am finding it very difficult to understand.

My battery can output at most 12.6V and I want to measure voltage/current every 20 seconds.
Maximum current drawn will be 20A.


texts:
I want to use a MOSFET as a switch driven by my microcomputer.

The original circuit using N-channel MOSFET is on the left side.  Honestly, I do not understand the choice of the IRLZ44.  The circuit is designed for Arduino, which has 5V logic.  Which means that for GPIO=True=5V, MOSFET opens and lets the current into the load.

However I have two problems:

I am using Raspberry Pi, which has 3.3V logic.  According to available information 3.3V is not enough to fully open MOSFET.
I want my load to be connected to the ground (I had to do some voltage measurements).

I know enough electronics to assume that using P-channel MOSFET, as shown on the right side, might solve both of my problems at one stroke.  For GPIO=False=0V MOSFET will be fully open, while GPIO=True=3.3V puts -1.7V on the MOSFET gate and practically close it down.  If that does not suffice, I could also put GPIO into the listening mode and therefore pull the MOSFET gate to 5V.

Could you please tell me if the idea will work?  And what IRLZ44-equivalent P-channel MOSFET should I use?


texts: What does the horizontal bar indicate in the DMM display?

texts: What does the horizontal bar indicate and how to use it in my measurement?


texts: Protecting opamp inputs when powered down

texts:
I'm designing a circuit with an opamp buffer at the input, which runs of batteries.

As the input does what it likes, the input of the opamp can see voltage even when the opamp is powered down. As the opamp inputs are rated at +0.5V V+ (rail) and -0.5V V-(rail), it is common practice to bolt diodes across the inputs of the opamps to the rails.

My question is, where does this current go? Say the positive rail is at 0V and 5V is applied to the input, so the diode (seen in the diagram below) clamps at 0.7V. Well, this makes sense but it's a positive rail so it's not grounded, its just sitting there floating, so where does this current flow? Surely this will just cause the positive rail to flow to Vin-Vdrop = 4.3V. Same goes for the negative rail just vice versa. Can anyone explain how this works?

I have attached supporting works below.

simulate this circuit – Schematic created using CircuitLab


texts: what is the V_IO Pin for in a SPI header?

texts:
I built a small PCB board that runs my HMC833 phase lock loop using the reference design provided by analog devices, and it works.
The pll is controlled using spi to set the frequency, so I placed a 12 pin header on the board to directly program the pll from my computer, a USB to SPI converter is used along with the provided pll programming software by analog device.
Below is the schematic of the HMC833 Eval board, and my design is almost identical to the eval board except that I customized the reference frequency input part for my own purposes:

WHAT IS CONFUSING me is the purpose of the V_IO voltage. V_IO is a 3.3V supplied by the voltage regulator U4 to the SPI header J7, and that is it. V_IO is not supplying voltage to anything else on the board.
This concerns me because when I tested my PCB board, I connected my usb-spi interface to the spi header on the board. I turned the power on, program the registers and it indeed produced my desired frequency. BUT when I unplug pin 4 at the header (U7), it looks like everything is then turned off on the board. See photos below:

When all spi pins and V_IO pins are connected, power source has current output and spectrum analyzer has the desire frequency (power amp wasn't power in the pic but it did produced frequency when I turn the amp on)

when pin 4 is unplug, no current output from the source

and this is the usb-spi converter I am using, it is provided when I purchased the eval board from Hitties(analog device). There isn't much information I can find regarding what exactly does this programmer do...

Right now I need to draw a second version of my own board but this time I am putting in an MCU to drive the PLL instead of using a PC. I am stuck at what to do with the V_IO pin because I don't know what does V_IO actually do. From the schematic it looks useless because it is not connected to anything else on the board but everything seems to turned off if I don't connect them.
Anybody has any idea?
Regards,


texts: Protect ADC input from over-voltage with Schottky diodes

texts:
Alan Walsh on this article has suggested using Schottky diodes to protect ADC input from over-voltage, the circuit looks like below:

simulate this circuit – Schematic created using CircuitLab

But it seems that the 3.3V regulator should have current sink capability in order to this circuit work, and the regulator I've chosen(LF33CDT) has not. One way I can think of is to add a load resistor on 3.3V rail to make a path for Schottky current to ground, But how can I make sure this path conducts enough current for Schottky to pull ADC input voltage down? (The Schottky is a BAT54).


texts:
This question might possibly be answered somewhere, but as I'm googling the particular phrase in the title, I couldn't find anything. I'm fairly new to designing development boards. I use the STM32F303 and came across a certain description in the manual that I don't understand.

I want to connect my battery with the V_Bat pin of the STM32 and I don't understand what is meant by the second line "Ratio on V_Bat measurement: 2". Can please somebody explain this to me with a possible circuit example. Thank you in advance.


texts:
I have built an audio amplifier using TDA2030. The amplifier works fine with very low noise, the input is given through 3.5mm jack of my phone. Everything works fine until I touch or pick up my metal phone, as I touch my phone the speaker starts giving out a loud noise until I place it back on the table.
Please tell me what is the cause of this noise, and how can I fix/reduce it.

Note: C1= 20uF in my circuit
Edit: It's a continuous buzz sound. It is the same type of noise we get when we touch an unplugged 3.5mm jack. I am providing power through a 12V 2Amp rated adapter (which is giving 18V output when not connected to load). I am using long wires to build the circuit. Actually, I used a breadboard to build the circuit and test it.
Many of you are suggesting that it's because of improper grounding. Please explain this because I am not getting your point, I will be happy to learn a new concept. And suggest a method to fix the noise.


texts: Need a 48v relay but I don't know the terminology

texts:
I need a little terminology help so I can search for and obtain the correct relay.

The relay will control a 48v 32a circuit.  It should be normally open unless a signal is present.  If the signal is present, the relay will close to complete the 48v circuit .  The signal current level is 175mA maximum.

The relay will not be on a PCB or rack of any kind, but probably mounted on a plywood board.

Does such a relay exist? How would it be described? Someone said I'd need to amplify the small signal in order to control large contactors.  Is that true, and if so, how would I configure (or describe) that?

If someone has a specific brand or part to recommend, that would certainly be welcome.

EDIT: I have a 48v battery bank of LiFePO4 cells.  The SOC cannot drop below a certain percentage or it will damage the cells.  The battery management system (BMS) has a method to send a signal if the pack is okay to use.  Here is what the BMS manual says:

An open drain digital on/off signal (is) used to signal to a load that the load can discharge the battery.  This would normally be used to control a discharge contactor or to signal to a controller that discharge must be stopped if this signal is not present.  This signal can be used as a backup to digital CAN communication with a controller.  This is a signal current level (175mA max) and should be amplified for controlling large contactors or relays.

So it would seem that I need a relay, but there are so many types I'm having difficulty knowing how to narrow the search to what I need.


texts: 10K Potentiometer with Arduino Uno and 5v works but same pot with ESP32 and 3.3v floating values

texts:
How does the voltage measured by a microcontroller from the output of a 10K potentiometer differ between a 5v circuit and a 3.3v circuit? How does a change from an Arduino and 5v circuit to an ESP32 and a 3.3v circuit affect the analog values from a potentiometer as seen by a sensing analog pin on the microcontroller?
With a past project using the Arduino UNO and a 10K potentiomter connected to an analog pin on the Arduino in a 5v circuit, the Arduino provided readings in the correct range of 0 to 1023 as I turned the knob. When I changed the set point by rotating the knob, the values reported by the Arduino through the Serial Monitor would also change to follow. When I stopped rotating the knob the reported value would stick without floating.
Attempting the same project with an ESP32 and the same pot but using a 3.3v circuit, the behavior is quite different. The range reported by the ESP32 is greater since it is a 12 bit value so should be between 0 and 4095.
However what the ESP32 is reporting when I turn the knob to a new point are values that will vary, floating about some point in that range even when the knob is not turning. The variation or floating values vary by as much as 40 or sometimes more. With the Arduino the values would change when I rotated the knob and then stick and not float when I stopped twisting the knob.
I've also just removed the 3.3v connector and the ground connector from those pins of the potentiometer leaving only the lead from the sensing pin of the ESP32 to the middle pin on the pot and I still see the reported values change when I would expect them to be zero and stay zero.
I'm referencing this article https://randomnerdtutorials.com/esp32-adc-analog-read-arduino-ide/
The source code for the pin is:
int  myPin = 34;
static int  iPotValSave = 0;

void setup() {
    Serial.begin(9600);
    delay(500);

    Serial.println("begin setup()");

    pinMode (myPin, INPUT);
    iPotValSave = analogRead (myPin);
    Serial.print (" pot value initial ");
    Serial.println (iPotValSave);
}

void loop() {
    int iPotVal = analogRead (myPin);
    if (iPotVal != iPotValSave) {
        Serial.print (" new pot value ");
        Serial.println (iPotValSave);
    }
    delay(500);
}

My question seems to be similar to the following:
esp32-wrover ADC, incorrect values?
How to convert 10K Pot raw output ADC data to voltage and resistance from arduino uno? with an answer which seems to indicate that the ESP32 needs a reference voltage for the ADC built into the pin.
Notes
Espressif documentation Analog to Digital Converter, https://docs.espressif.com/projects/esp-idf/en/latest/esp32/api-reference/peripherals/adc.html#adc-api-adc-calibration

The ESP32 ADC can be sensitive to noise leading to large discrepancies
in ADC readings. To minimize noise, users may connect a 0.1uF
capacitor to the ADC input pad in use. Multisampling may also be used
to further mitigate the effects of noise.

and see also this section:

esp_err_t adc1_config_channel_atten(adc1_channel_tchannel, adc_atten_tatten)

Set the attenuation of a particular channel on ADC1, and configure its
associated GPIO pin mux.
The default ADC full-scale voltage is 1.1 V. To read higher voltages
(up to the pin maximum voltage, usually 3.3 V) requires setting >0 dB
signal attenuation for that ADC channel.

How to use ADC of ESP32 – Measuring voltage example https://microcontrollerslab.com/adc-esp32-measuring-voltage-example/
ESP32 Pinout Reference: Which GPIO pins should you use? https://randomnerdtutorials.com/esp32-pinout-reference-gpios/


texts:
Let me start with a disclaimer. I am a software guy who can write regular c++ or .net programs. I also write programs for arm based hand held devices using QT and C. But my idea on this electronics and ARM hardware part is very poor.

I am just trying to put together a toy handheld hardware for myself using arm kits. I have been looking up & searching google for some stuff like "Arm Development board" , "arm stamp module" etc.,

I understand that arm stamp module is something like a final production PCB. The development board is for some evaluation software development kit.

Just tried looking up stackexchange for

Good ARM development board for bare-metal development
What's so great about ARM?

But I want to know how to build my own reader with the following.

arm processor
usb, rs232/UART, LAN, power adapter
keyboard facility
some kind of TFT monitor etc.,

Please do understand that I do not want the entire design or whatsoever. But need an idea of

How a arm development board (viz. mini6410) will help me in achieving this?
or do I need to use something else to design my own arm hardware?
or is it like regular circuit design with resistors/capacitors/arm processor/transistors/diodes etc.,?

Am just trying to put the puzzle pieces together and they are not matching to me yet..

Any pointers to good resources to understanding the whole picture would be appreciated.


texts: Using differential line drivers for digital signals

texts:
I need to send a slow (steady state most of the time) TTL signals over 10m - 1km (max) distance.

Shielded CAT6 wire will be used and I can't use radio based solutions.
Wire is only used for that purpose (eg. not shared with anything else, all 4 pairs are available)
Electrical isolation is needed because sender and receiver side may have different ground potentials.
I want to avoid protocols/standards that needs additional complexity at receiver side. A receiver IC that outputs the signal is OK but I don't want to have a uC for decoding packets over something like RS485/CAN etc.

Since I have twisted pair cabling, using differential line drivers seems to be most appropriate solution for these requirements. Here is my confusion begins..

Most of the line drivers I found labeled as "RS485 transceivers". The thing is, I don't intend to use RS485 protocol. Is there any side effect for using these in my application? I can't see any but I want to be sure.
Again, many line drivers works with single 5V supply. That means it can only generate ~+-2V differential signals. With long wires like I'm using, this can be a problem. Is there alternatives that can generate/receive higher Vpp signals (for example +-12V for improving signal), if any what is the keyword for finding them?
All these solutions will also need a shared ground between sender and receiver. Since I'm going to have multiple receivers, even if I isolate ground from sender side (seperate logic / line driver supplies with optocouplers in between for signals), the sender board will need to connect all receiver grounds to a common point. How can I improve this situation and electrical isolation?

Thanks.

Note: In an other question, I stated to want control a relay with that and got related answers. This question focused on transmitting signal over the wire.


texts:
I have basic understanding of FETs and studied Integrated electronics course at college. I want to calculate delay time in H bridge circuit. Any links or tutorials or if any one can explain?

This is the H-bridge I have in mind:


texts:
i'm still a biginner in using eagle .... well everything is almost fine but i keep having this error .... although i cheked a 100 time

Only INPUT pins on net 25
Only INPUT pins on net RXCAN
Only INPUT pins on net RXCAN

Please can some one help me .... it's urgent


texts:
Or is flip flop noisy at all? would you simluate its noise as you would do with a strong arm comparator?
Why is strong arm comparator noisy but not a flip flop?


texts: How to properly ground chassis containing AC/DC switching power supply?

texts:
I'm planning to build a Digital Audio Converter as a hobby device and I had some questions regarding safely grounding the chassis.

I want to purchase a power supply like this one:

MicroMall(TM) NEW Universal Regulated Switching Power Supply DC 5V 3A 15W

and place it inside a metal chassis. I'm going to ground the power supply to the earth ground. I want to minimize any interference with the audio output (RCA jacks in the case).

I have a couple questions:

1) should the V- of the DC circuit be connected to the earth ground?

2) How can I ground the external chassis?


texts: FT245RL - device descriptor read/64, error -32 on connect

texts:
I'm trying to get the FT245RL chip to work but am running into an issue where it is not successfully connecting to my computer.
I also have a separate device which also uses the FT245RL chip which connects correctly so I know that it is not an issue with my computer.
When my device is connected dmesg spits out

[1174250.282775] usb 2-1.3: new low-speed USB device number 108 using ehci-pci
[1174250.347768] usb 2-1.3: device descriptor read/64, error -32
[1174250.518754] usb 2-1.3: device descriptor read/64, error -32
[1174250.685755] usb 2-1.3: new low-speed USB device number 109 using ehci-pci
[1174250.750753] usb 2-1.3: device descriptor read/64, error -32
[1174250.919744] usb 2-1.3: device descriptor read/64, error -32
[1174251.085730] usb 2-1.3: new low-speed USB device number 110 using ehci-pci
[1174251.501718] usb 2-1.3: device not accepting address 110, error -32
[1174251.565708] usb 2-1.3: new low-speed USB device number 111 using ehci-pci
[1174251.981689] usb 2-1.3: device not accepting address 111, error -32
[1174251.981787] usb 2-1-port3: unable to enumerate USB device
[1174325.139540] usb 2-1.3: new low-speed USB device number 113 using ehci-pci
[1174356.370191] usb 2-1.3: new low-speed USB device number 114 using ehci-pci
[1174356.435191] usb 2-1.3: device descriptor read/64, error -32

When plugging in the working device (that wasn't designed by me) that uses the RT245RL it says that it is a full-speed USB device. I know that there is a program which you can use to write the manufacturer and serial number so maybe you can also select wether it's low speed or full speed?
From trying to research I see errors that are somewhat related to this are due from not having sufficient power going to the usb device. Maybe the low-speed issue is some fault with my power line.
I've tried continuity checking all the connections from my schematic to make sure everything is correct.
A schematic of my designs can be viewed at http://gyroninja.net/files/schematic.pdf


texts: Multi-Stage Common-Source Amplifier - When is it no longer a small-signal?

texts:
I have a question about the actual definition of a small-signal signal. We use it all the times in amplifiers. But how small is a small-signal? When does it stop becoming a small-signal?
Take for example, a common-source amplifier cascaded with another common-source amplifier.

[Excuse the poorly drawn sinusoids]
Let's say that both transistors are biased with a 200mV VDS headroom over Vgs-Vth in the saturation region. Let's assume stage 1 has a gain of 5 and stage 2 has a gain of 10.
If we apply a 10mV peak to peak signal at the input, which is our small-signal input. It becomes a 50mV signal at the input of the second stage and a 500mV signal at the output stage.
A 50mV signal at the input of the second stage - how is that a small-signal? Wouldn't we now see distortion because our gm2 is behaving less and less like a constant slope but changing due to this "small-signal" 50mV affecting the bias point? [Q1]
What's the point in calculating output voltage swings if we go anywhere near them, we no longer see a small-signal behaviour. Or are they only important for the output stage, because it doesn't go to any amplifier afterwards [Q2]


texts: circuit to measure positive & negative voltage + Vref resolution

texts:
i would like to make a "voltmeter" to read from +2V to -2V and connect it to an Arduino ADC ( 0V to 5V ).
I found different configurations for do this job:

From this site:

Bipolar to unipolar converter, a summing amp:

Instrumental amp, base on this schematic ( ECG ):

The last approach use:
 - instrumental amp
 - full-wave rectifier
 - low pass filter
 - inverting opamp + gain

The signal i need to read it's "stable", the ECG circuit i suppose it's too complex for this job. But i'm interested to compare the instrumental amp Vs opamp.

What is the best configuration for my porspose?

For the Vref, I have this question:

In this video & this article are show how it works.
In the article he say, for example:
Vref at 5v -> 0-5 V has 4.9 mV resolution
Vref at 3.3v -> 0-3.3 has 3.2mV resolution
But in the video does not say that, he used Vref at 1.1v and apparently does not have any problem.... probably the solution is here in the code.


texts: Current measurment for a circuit with diode and capacitor in parallel

texts:
I have a circuit below.
In this case, the potential difference across the capacitor, Vc, and the potential difference across the the diode(figure2), Vd, would the same, wouldn't they?
So,
Vd=Vc and
Ic= C*Vd/dt.
Ip = Id+Ic
Ic = Ir.

Could anyone confirm if this is correct? If you don't have the time but it doesn't seem right, even a simple yes or no would help a lot.
(Here, Id = I0(exp(eVd/kT)-1 and Ip is a constant)

Figure1

Figure2


texts: Power Supply Design Help- failure at higher currents

texts:
I am trying to design a 60V 6A supply to power a power amplifier.

Here is the circuit I have so far. Feel free to open it in Circuit Lab and play around:

simulate this circuit – Schematic created using CircuitLab

Here's the same thing in PNG form if you need:

I built a prototype and I can get 60V open load no problem. But when I try to connect a 10Ω (500W) load resistor to draw 6A, the output quickly drops to about 30V and the NTC thermistor starts smoking. At one point, when I connected the load before powering it on, R1 failed and read a larger value afterward.

Here is a link to the datasheet for the NTC thermistor I'm using.

I'm having trouble understanding why the thermistor would start to smoke when it doesn't seem like I'm drawing 6A (the max steady state current of the thermistor). It seems to me I'm only drawing 3A since I see about 30V across the 10Ω load.

I have a 3.5A cartridge fuse at the primary as well as a PTC resettable fuse rated for 6A trip current at the secondary. The cartridge fuse definitely hasn't tripped and I don't think the PTC fuse is tripping either.

Here is the datasheet for the PTC fuse I'm using (part number 0ZRB0300FF1A)

Here is the datasheet for the regulator I'm using as well.

Can anyone tell me why the NTC thermistor is smoking and what I can do to get 6A out of my supply? Any advice would be much appreciated.

[Edited to show that my transformer is actually rated for 8.33A and the bridge rectifier is rated for 10A]

EDIT: I have received a lot of helpful advice in the comments. To summarize what I've learned so far:

@JohnBirckhead pointed out that I'm not accounting for large current spikes as the capacitor charges. In my situation they reach close to about 50A even though steady state current is much lower.
@jonk explained further that these spikes are heating up the NTC thermistor causing it to smoke. The dissipation constant in the datasheet provides a way to calculate temperature rise as a function of power dissipation.
@jonk recommended a different approach to inrush current limiting: a series resistor and parallel relay at the primary. The resistor needs to be pulse rated, and the Vishay RS005 series 5W wirewound resistors should be able to do the job depending on the value. A relay needs to be selected with an appropriate pull in and drop out voltage.
@DaveTweed pointed out that my current limiting transistor Q2 is turning on earlier than I expected, limiting output current and leading to the large voltage drop I see when I connect the load.

Now my task is to choose an appropriate resistor and relay to limit the inrush current instead of the NTC, the end goal being to keep my components safe while delivering a maximum of 6A to the load.

According to this paper, a Vishay RS005 500Ω 5W resistor can handle overload power of 250W for 1s. If I were to use this value, I would only need to dissipate about 120W for less than 1s so it should be safe for that resistor.

If I use one of these relays, it will turn on at about 86V which should take roughly .7 time constant with the 500Ω resistor.

I've been reading a little bit about soft start circuits and have found that "The soft start time must be sufficient enough to allow the capacitors to charge, and the transformers and active components to stabilize."

So what I'm not exactly clear on is how long should the soft start take for this to be safe? "Allowing sufficient time for capacitors to charge" makes me think it should take at least 1 time constant. Is that a reasonable assumption?

Trying to find the balance between safe inrush current and long start up times.


texts: Why so much variance in the continuity beeper threshold? How do these beepers work anyway?

texts:
In this answer it is mentioned that the EEVBlog-branded BM235 meter has a threshold of between 30 and 480 ohms for its continuity beeper (as seen on page 25 of the datasheet).

My first thought was "why isn't that an exact value?", but I realized soon afterward that of course it's not exact, as any meter with a good continuity beeper uses analog circuitry to get a fast beep response, and that analog circuitry inherently has tolerances. So I understand why they give a range.

What I don't understand is why the range is so large. I would understand something like 30~60 Ω, but this is more than an order of magnitude! What is it that causes this extreme variation in the beeper threshold?

Is this sort of variance normal? What sort of circuit is typically used for this, and what makes it so sensitive to component tolerances? Is it even that sensitive to component tolerances?


texts: How to connect CAN modules of two STM32 evalboards

texts:
I have two  stm32f407 discovery evalboards and I want to connect them using their CAN modules.

Is that possible without any CAN transceiver?

It comes to me logical but transceiver convert data differantially and it makes my mind confused.


texts: How can I improve this PCB schema for L293D H-brigde?

texts:
I am building a machine that requires a lot of steppers, I've used breadboards until now, and now I plan on getting the driver based on a PCB. I have used Fritzing to design the PCB, and since it's my first design I'm just wondering if it's correctly made.

L293D schema:

My PCB design:

Will this work? The motor supply, do I really need an own connection for it, or can I just send it to 5V and to ground? Are things at an all right distance from each other? Is there anything I've missed? This is my first design I'm actually planning on producing, so hoping to get some feedback on it.

Based on comments, I've implemented some changes. I keep the first image for reference.
Second revision:

I have put the Fritzing PCB sketch up on github.


texts: On a research perspective, do physical layer rules come under the term "wireless protocol"

texts:
My opinion is that the physical layer techniques and routing techniques both come under the term "wireless protocol". In some special cases, I have even seen physical layer protocols that are highly dependant on routing success and vice versa.

Hence, I would like to know if it's right of me to mention the term "wireless sensor network protocols" and expect it to incorporate physical layer technology as well.


texts: Why is my solar panel short circuit rating much higher than in reality?

texts: I have two 6 volt 100mA solar panels. I have connected them in parallel and was expecting to see a maximum of 200ma when I short circuit it. As expected, I got 6 volts, but only 65ma. Does this always occur? The sun was really bright at that time.


texts: Impedance equivalent for oscillating switch in SPICE AC simulation

texts:
I would like to simulate this schematic in a SPICE AC analysis. A regular switch model only works in a transient simulation. Is there an equivalent impedance that I can use in the place of the switches (and the switched resistor)?

The frequency of the switch is 100kHz 50% duty cycle

A better question would be, is there a way to substitute some kind of impedance in for the switch and resistor if the switching frequency is 100kHz?

simulate this circuit – Schematic created using CircuitLab


texts: Is Texas Instrument wrong with their pin number on TO-92 package?

texts:
The official JEDEC standard to number pins on a TO-92 package is the following:

But in many datasheets from Texas Instruments, this order seem reversed. For example, this is a screenshot from the datasheet for the LM185 :

Link to the full datasheet :
http://www.ti.com/lit/ds/symlink/lm185-1.2-n.pdf (page 1)

Texas Instruments's official TO-92 documentation doesn't help since there is an ambiguity as if the drawing is from the top or the bottom : http://www.ti.com/lit/ml/msot002d/msot002d.pdf

In all the datasheets where the pinout is reversed, they used a view from the top or the bottom. In some datasheets the pinout is correct, but they used an isometric view which eliminate all ambiguity. This could be the source of the confusion, but I just don't see how I could misinterpret "Bottom view" or "Top view" for a TO-92 package.

Is Texas Instruments wrong or I don't understand what a bottom view is?

To prove that this is not an isolated mistake in a single datasheet, here are few links to some Texas Instruments datasheets where this happen :

http://www.ti.com/lit/ds/symlink/tl431.pdf (page 4)

http://www.ti.com/lit/ds/symlink/lm285-2.5.pdf (page 3)

http://www.ti.com/lit/ds/symlink/lm4040-n.pdf (page 4)


texts: Are there any issues in using traditional switches with an Arduino?

texts:
I'm using an Arduino Micro for my project.

I'm planning on using two switches as digital inputs. One is for an override switch and a setting switch, but their functions aren't particularly important.

My question is this: is there an issue in using switches? There may be times when the switch is on for long periods of time. I was planning on using the built in pull-ups on the imputs, but I don't want to cause any overheating or issues.

Essentially all of the examples I've seen are with pushbutton momentaries that act as a toggle through software that are only pressed for a fraction of a second at a time, so I didn't know if the lack of examples was indicative of issues with regular switches.


texts: Capacitor discharge: Is gate voltage on IGBT proportional to collector?

texts:
I'm designing a capacitive discharge circuit. I'd like to get some feedback before I buy parts for testing. The output should be around 100v and thought an IGBT would work great in discharging the capacitor. But I'm unsure. What I'm hoping to do is switch the 100v on with a low voltage to the gate from the optocoupler. How much voltage would I need to the gate? I have a couple of question marks on my design below indicating problem areas that I'm unsure about. Please advise.

I'm open to suggestions and criticism.


texts:
I have been trying to understand Bode Phase Plot of RC High pass filter.

I know that from my engineering that voltage lags behind the current passing through the capacitor. So, I assume the current through capacitor will be in-phase with the input voltage waveform and that same current will pass through the resistor. So, output voltage should be in-phase with input waveform.

Can someone explain me the Bode phase plot of the filter when frequency is swept from zero to cut-off frequency via time domain analysis?


texts:
I'm in the process of debugging microprocessor loading of a Spartan 6 image through SelectMap. The HSWAPEN pin has caught my eye. In my design it is pulled low via a 10K resistor. However, when reading the status register I notice that the HSWAPEN pin is read as high, and I've confirmed this with an oscilloscope.

Is this behaviour normal? This user guide (see page 62) explains:

  HSWAPEN is a configuration-related multipurpose pin. When it is grounded prior to
  configuration, it enables internal pull-up resistors in all of the I/O pins of the device

Is HSWAPEN high because the internal pull-up is stronger than my pull-down?


texts: Controlling higher voltage and load via high-side switch from a microcontroller

texts:
I am building a battery-powered uC circuit with an RGB LED. The LED is common cathode, so the circuit for switching the LED elements has to be high-side. The LED is a higher-current LED, so it cannot be driven by the uC directly.

To save power, I was planning to have the uC (AVR ATmega328) run at whatever voltage the 2 AAA batteries will provide (1.8-3.0V), while the LEDs need to be driven at 4.0V to account for the LED vdrop - the plan was to use a boost converter to power the LEDs. I was wondering what is the best way to drive the LED output from the uC. I can think of a few ways:

PNP BJT switch with three diodes

AVR docs state that the chip cannot "see" more then 0.5V above Vcc on any of the pins, so one option would be to use a diode \$V_{forward}\$ to present a lower voltage to the uC:

Perhaps D1 can be omitted? I am not sure if there is a E->B voltage drop in a PNP transistor.

P-Channel MOSFET with an NPN BJT

Another option is to control the P-Channel MOSFET with an NPN BJT

simulate this circuit – Schematic created using CircuitLab

N-Channel high-side MOSFET switch

This requires a charge-pump or something equivalent, so I am leaning against this solution.

Currently I am leaning towards the second solution, for no particular reason. Are there other solutions I should be considering? Are there other considerations that I should be thinking about?


texts: Finding transfer function of this RL circuit

texts:
Have a look at this circuit. I am to find the transfer function which is defined as \$V_L(s)/V(s)\$.

Now I don't understand the solution. First of all, it defines \$V_L(s)\$ at the bottom as \$sI_2(s)\$. Shouldn't it be \$2sI_2(s)\$?

Also, shouldn't the transfer function be \$1/[s + 3 + (1/s)]\$?

Here's how I came to that conclusion. The last part of the solution I agree with is this step:

\$(2s + 2)(s + 2)I_2 - 2I_2 = V(s)\$

Then I get \$(2s^2 + 6s + 4)I_2 - 2I_2 = V(s)\$

Distributing out...

\$2sI_2[(s + 3 + 2/s) - 1/s] = V(s)\$

Now I want \$V(s)/2I_2(s)\$

so...

\$s + 3 + 1/s\$ is equal to that. Now invert that and you get the transfer function I got. What did I do wrong?


texts: Identifying a component with only a partial part number

texts:
I have taken apart some circuitry that no longer works and I accidentally went a bit too far with the dremel. This means I've partially obscured the serial number of a component i'm wishing to identify.

Here is a picture:

There's 3 lines of text as far as I can see on the component in the centre.

The 1st being (I think) EL1738
2nd NY135 (maybe)
3rd SSU

I've tried punching these into google without much luck.

The device itself switches on a coil every other time a hall effect sensor is triggered. My first thoughts are that this might be some sort of flip flop.

What id like to know is what else can I do in order to identify this component?


texts:
Hi what is V_x

I think it's 12 volts.

Computer program does not agree with me.


texts: What's a good way to detect ambient EMF from a distance?

texts:
I am an artist working on a project that, distilled for simplicity, will change the color of LED lighting based on ambient EMF. I've got a prototype built (based on A MAKE magazine project video) which uses seven different colored LEDs instead of a seven segment LED.

Here's my challenge: I will be placing the device in the center of a gallery space (roughly 10x10), and so far, all of my testing with the 6-ish inch whip antenna on the board require me to move the device within inches of devices to get a signal.

So...what next? I know there's EMF from the electrical in the walls. I know that patrons of the gallery will likely have mobile devices that will increase the ambient EMF. But...how do I detect these subtle changes from a sensor mounted on the ceiling? Would a larger antenna help? If so, what are some design considerations for such an antenna? The bigger the better? or is it more a shape issue (e.g., round ball of copper wire vs. a copper wire just kinda hanging there)? Or is it something that ANY antenna will pick up, but I need to use an Op Amp or additional circuitry to amplify the antenna input to detect the subtle changes?

I'm not 100% percent sure this is an antenna issue or a signal amplification issue, so I'm not sure if I'm asking appropriate questions. Any guidance would be appreciated.


texts: Voltage to current converter using transconductance amplifiers, OPA860 and OPA861

texts:
I want to generate an ac current signal of 100 \$\mu\$A(peak to peak) with a bias current of 50 \$\mu\$A  upto 100MHz frequency. This will be the input to a \$20 k \Omega\$ load.

I searched for some wideband transcondutance amplifiers on TI website and I got OPA860 and OPA861 (link). In the link, under the output current, all of the amplifiers feature a minimum of 15 mA. Clearly, these cannot be used for my circuit, so to make myself sure, I checked the datasheets of these two amplifiers if there is any way to control this current...

In the 4th (3rd) page  of OPA860 (OPA 861), it can be seen that for \$R_L = 500 \Omega\$ and \$R_{ADJ} = 250 \Omega\$ (used to adjust the quiescent current) under OTA output performance that `C-Output current sinking/sourcing is a minimum of \$\pm 15m\$A'.

I think these IC's cannot be used, but I am not sure if that is the case. Is there any way to control this current?


texts: How to get dynamic changes on a Philips PM 3253 oscilloscope

texts:
I bought a Philips PM 3253 oscilloscope (and got it working thanks to Electrical Engineering stackexchange, thanks for that).

However, I have a new problem. I probe to the calibration output which gives 2 KHz, 600 mV.

Initially, 0.2 V/div is selected (see yellow circle below), multiplied by 3 boxes = 0.6 V (is ok). See
[1

However, than I change the know to 0.5 V/div (see yellow circle below). However, the electron beam does not change (not ok). See:

When I press the Erase button I see the correct output, meaning 0.5 V/div * approx 1.2 boxes = 0.6 V. Ok again.

Also when I change anything else nothing changes unless I press the Erase button. I'm sure it worked before and tried a lot of switches/buttons, but it is probably a combination.

Do you know how to change the electron beam immediately without having to press the Erase button every time?

Update: After testing a lot, now changes are more or less automatic.
I think the electron beam is really old, and I have to very delicately set the Intens button .... if it is too low, it will not show anything, if it is too high, the old lines will remain (even after removing the probe). To make it more tricky, after the signal change, a bit more Intens is needed, so I have to move that dial a lot (or press the Erase button). I wonder how many problems I will get when looking at a changing signal.


texts:
I'm building an LED lamp and I want it to have no ON/OFF switches/buttons sticking out from the lamp.
The switch function I would like to have is like a pushbutton: You push it and it pops out and then you can turn it as a potentiometer and then push it back in.

I have seen the kind of switch I'm describing, but I don't know how it's called.
One example where this kind of swich is used is in Opel Astra radio panel.

Any ideas how is this switch/button called?


texts: How to disable a single op-amp in dual packaging?

texts: I am using a dual op-amp package in a circuit, however I only need to use one. Is there anyway to disable the other op-amp so it doesn't inject electrical noise in my circuitboard? I think grounding the positive input and setting the op-amp into unity gain might be best, but I am not certain.


texts: Use Kirchhoff's laws to find the currents \$I_1\$ , \$I_2\$ and \$I_3\$

texts:
I would like to find the currents  \$I_1\$ , \$I_2\$ and \$I_3\$.

I have the following equations for the currents between the branches \$AB\$ and \$CFB\$
\$I_{AB} = I_{CB} + I_{CFB}\$
\$I_{CFB} = I_1 - I_2 - I_3\$ based on \$I_1 = I_2 + I_3 + I_{CFB}\$
I have the following questions:

Is the current in the branch \$CFB\$ equal to \$I_1 - I_2 - I_3\$ (junction rule).
How does the current splits in node \$C\$ given the the node is between \$E_1\$ and \$E_2\$, and that they are connected oppositely?
Does the current in the branch \$AB\$ goes to the left?


texts: SPI with differential line drivers, and star configuration problem

texts:
Folks I am helping to design a circuit for a group that uses the odrive motor driver board. The odrive drives two brushless motors and the MCU uses SPI to connect to motor encoders. People using the odrive would like to drive TWO encoders (one for the motor, the other for the gearbox) so it would useful to make a system that communicates with a total of four encoders.

The other thing that we would like is to use differential lines to provide more noise immunity for SPI communication with the encoders. There are no instructions sent to the encoders, so MOSI does not need to be connected. Therefore, the connections to each encoder could look like this:

pair1: link to each individual CS encoder
pair2: CLK ganged across all 4 encoders
pair3: MISO ganged across all 4 encoders
pair4: VCC/GND to all encoders

The idea that is being considered is to use RS485 transceivers on each line, e.g., see this link

where on the encoder side the approach would be this circuit

I'm hoping to make a daughter board to attach to the odrive which would have transceivers for CS pins, CLK, MISO, VCC and GND. The daughter board would also have four RJ45 connectors.

I am requesting comments on this approach, but also provided that using differential RS485 transceivers makes sense, I realize I am heading straight into creating a star configuration - several slaves originating off of a single connection point on the master. This of course is a classic no-no when it comes to RS485 configurations. Unfortunately it is not practical to daisy chain encoders off of the odrive.

Is it appropriate to use RS485 transceivers to create differential lines to transmit SPI?
Are there work-arounds for the star configuration?
Is a star configuration still a problem if lines under 100cm are used to connect to the odrive?


texts: Why is there such a large difference in efficiency in these two boost converter configurations?

texts:
Here is the datasheet

I realize that the converter has to "work harder" to boost a voltage from 2.8V-6V to 48V than it does from 8V-38V to 48V, but I'm curious why there's such a significant drop in the efficiency in the first configuration below 10mA when there isn't a similar drop in the lower configuration. Do boost converters have a certain attribute that doesn't allow high efficiency at low currents? Are some boost converters designed to maximize the efficiency at high boost voltages and low currents?


texts: Auto-start after power off in nvidia TK1 board

texts:
I'm trying to make my Nvidia board (TK1) to boot automatically. i.e., when the power goes off and comes back again i want the board to power up automatically. I have tried the Nvidia forum and found a way to do it, but it works only when i manually pull the charger pin from the jack in the board and re-insert it. When the AC power is turned off (without pulling the plug from the board) and turned on again the board doesn't boot up automatically.

I want to know if it is possible to make a automatic switch circuit that would do the job of push button(which will replace the ON switch)

Note: I was also suggested to use a relay to make the button work, coz of it's bulkiness i cannot use it.


texts: 40kHz Ultrasonic transducer - datasheet gives capacitive load at 1kHz what is it at 40kHz?

texts:
A hopefully simple question, the datasheet for a 25kHz Ultrasonic transducer gives the capacitance load at 1kHz what is it at 25kHz?

I've been calculating the current using

I = fCVpp

where f is driving frequency,
C is capacitance (i've been assuming its the same as 1kHz)
Vpp is peak to peak driving voltage.

Is this a reasonable assumption for designing an amplifier?


texts: PCB photoresist method etching incomplete - only etched around borders of traces

texts:
I'm trying to make PCBs for the first time, but I hit a roadblock and don't know how to fix the problem.
I etched my 3rd developing attempt, but it looks like only the border around the traces was etched, not the open areas of copper between traces.
Here's a picture of the transparency I used and the resulting PCB:

These are the materials and methods I used:

Transparency printed by FedEx - I combined 4 layers
GC Chemicals positive per-sensitized board (from Amazon - product link)
Exposed with sunlight for 20 minutes (clear day, had board perpendicular to sun, sandwiched copper board and transparency between non-UV proof plexiglass which I've used for other photo projects successfully)
Developed board in Lye (sodium hydroxide) solution (1 tsp. lye in 16 oz water, diluted slightly more after first attempt seemed to develop too quickly). The resist looked solid after developing, like expected and similar to examples from the web.
Rinsed in water for a while (minute or two?)
Etched in hydrogen peroxide, vinegar, and salt solution (1/4 cup each peroxide and vinegar) following this guys directions (peroxide was a new 3% strength bottle, vinegar was previously opened old gallon jug, salt was just normal salt: no iodine, but ingredients are "salt, sodium silicoaluminate," whatever that is, and it was kind of old and chunky). Had solution and board in a plastic container in a warm water bath.
I left it in the etch for several hours (about 4). At first I tried swirling the solution every couple of minutes, adding more salt and vinegar in small amounts (maybe 2 tblsp total vinegar) to keep fizzing. I tried brushing the board to remove copper but this started to remove traces, so I didn't do that for the last few hours.

At the end I took it out thinking it didn't work at all, but when I held it up to light, I could see through around the traces, so it looks like the borders etched, but not completely. I tried using a dart point to see if the copper that should have etched would come off, but it didn't. The area that should have etched has a different appearance than the protected traces.
What could have prevented complete etching? I'm wondering if under-developing could have left resist (but then again the borders etched), or if I should spend the cash on ferric chloride etchant. Could the boards have just been bad? There are some kind of textured-looking areas (3rd pic, lower portion).
Edit - problem solved
After trying this again and agitating nearly continuously, as suggested below, I got good results. For the sake of completeness, this is what I did to get a decent result:

Exposed with 4-layer transparency for 20 min in direct, mid-day sunlight (no clouds)
Developed about 2 min in lye-based developer
Developed in 1:1 hydrogen peroxide and vinegar solution (same as above) with about 2 teaspoons salt. Heated vinegar first (not quite to steaming). Nearly continuously swirled/sloshed gently the dish. Brushed gently with foam brush every couple of minutes. I noticed the copper would appear tarnished if the solution was still. Brushing would completely remove this (and copper, I assume), and swirling/sloshing would also, but not as thoroughly, and some spots would remain "tarnished." Finished in about 45 minutes.

Observations:

After about 15-20 minutes, the solution got pretty volatile: lots of bubbles, off-gassing (looked like steam but solution was barely lukewarm)
After about 35 minutes, the solution got very still, tarnishing stopped. Etching was about 90% done. Tried warming in a hot-bath, didn't change much after a few minutes. Added more vinegar and salt, no significant difference after a few minutes. Added more peroxide, solution got more active (not as active as before), tarnishing resumed, and etching finished.
Resist was starting to come off at the end, especially with brushing.


texts: Diy 18650 4s battery pack [How to charge, how to build?]

texts:
I'm building a bluetooth portable speaker.
However, I have some questions about building my first 18650 battery pack.
I have 4 pcs of Panasonic unprotected NCR18650B 18650 3.7V 3400mAh.

My goal is to build a 4s 18650 pack with these batteries, and the battery pack must:
- be inside the portable speaker
- Fully protected
- Safe

My question is, how do I design this battery pack?
I have a idea, but want to know if it is a good way to build it?:

I also have some others questions:
During my searches on internet some people use balanced charge, is it necessary to it use in my case? If yes how?
Do I need to use a power adapttor or lithium li-ion battery charger adaptor?

Thanks for your future help
Cordially,

So i recap, if i have correctly understand,
A BMS board is designed for protect the cells against Overcharge, over discharge, over current, short circuit protection, right?
But for protect the batteries pack life, it need to be balance charge right?
Which board can you advice me for protect and balance my batteries pack? (I have Panasonic unprotected NCR18650B 18650 3.7V 3400mAh)
I found a board on aliexpress, what do you think?

Or i have an other idea,
what do you think if i put a balanced charger in the speaker,
does it possible the wires stay always connected to the charger and the speaker circuits?
Does it is necessary to have a bms for protect my batteries because they are original unprotected ?

Another question,
Please, can you advice me a reliable BMWS for protect my batteries pack?
I'am not there to save money, the safety of the pack is my priority.

I checked the existing BMS on the market, but i noticed that Over-discharge Protection is too low compared to my batteries specs.
The common bms on internet cut the current at approximately 2.55 this is too low for my batteries.
Indeed minimum voltage of my batteries  is 2.75 V.
So i found a new BMS with balance charge function: link

I have several questions, i made a wiring diagram and i want to know if  don't have made mistakes:

However, several questions remain vague in my mind:
The Positive cable and the negative cable are the same cables to charge the battery pack and use it? On the diagram (Output / Input Positive + and Output / Input Negative -)
Can i use the battery pack at the same time as it charging? For me it seems odd to me because I wonder what the intensity and the voltage sent to electric circuit of the bluetooth speaker. On the diagram (Intensity: A?
Voltage Rating: V?)
Those of the adapter or the battery?


texts: Can RADAR cause SEUs or similar transient faults?

texts:
Cosmic rays and terrestrial sources of high-energy particles can cause transient faults like a Single Event Upset (SEU) in Microcontrollers, FPGAs or similar components. This phenomena has been discussed and reported in many sources, for example, https://en.wikipedia.org/wiki/Radiation_hardening

Is Radar known to have similar effects? For example, where a microcontroller and a Radar antenna are close (say < 10 m.) I've searched and cannot locate any sources that describe Radar-induced faults in digital logic devices.


texts: Ho do I convert an "EagleCAD 5.12" project to "KiCad 5.0.2"?

texts:
I have an existing project in Eagle 5.12.  I'd like to convert it to KiCad 5.0.2 (this is the latest I downloaded today).

I have tried using the KiCad File/Import Project.  It failed.  I suspect it wants Eagle 6.0 or later, but I have found no concrete list of what Eagle versions are supported.

I found an Eagle ULP named eagle2kicad.ulp designed for Eagle 5.8.  I tried running that, but it only did the schematic, and failed with many errors.  The resulting schematic was completely unusable.  I suspect this ULP was written for an earlier version of KiCad.

What do I need to do to convert a Eagle 5.12 project (both board and schematic, including all library symbols, etc...) to KiCad 5.0.2?


texts:
I am looking into constructing a small submarine with a Raspberry Pi. This is just for a hobby project but my idea is to have it communicate with the surface wirelessly. I know that normal radio waves will not work very well so I was thinking of using some type of Ultrasound device where a transmitter/tone generator is placed in the water and the submarine has a receiver/microphone that can pick up the sound waves transmitted.

I have read that sound waves are easily transmitted underwater so this is where I came up with this idea. I am wondering if anyone has already done a project like this in the past or knows where I can find more information on it? I have never really worked with sound/wireless transmission so its all very new to me. Any help is greatly appreciated!


texts: Please help with my custom ATMega328 PCB

texts:
I created a PCB for my newest Arduino project and its driving me mad by now. I am through several PCB variations and tried connecting to it (via FTDI first - then) via ISP but I fail every time and in each revision.

Tested all the pads/pins for a short - everything seems ok. On each board I soldered only the barebone components (2x 22uF, 1x100nF caps, 10k resistor, XTAL) to test it. I can often see tiny sparks between the pins when I trying to flash the chip - but I cant find any shots.

I am trying connecting my PCB through ISP with another arduino (ISP sketch on it / + #define old wiring).

I am pretty sure that C2 is not needed - but it also does not work without it.

I am very open to any ideas how to get this done because it is getting very expensive :). Build about 10 different boards now and can't find the issue.

Uploaded the latest schematic and some PCB pics.


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I got a 6-phase DC-DC converter. Fsw=400 kHz, synchronization by external clock(CPLD). I need a spread spectrum 400 kHz. What's the best way?
 All chips what I've seen before worked on MHz and above. Is there solution, based on FPGA?

Maybe someone has faced with that problem .


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I'm trying to define a string in VHDL with a pair of double quotes in the string itself. However I am unable to do so because the IDE (Xilinx ISE 14.7) only recognizes what's in-between the first pair of double quotes as the string. Is there some kind of delimiter or escape character I can use?

Here's the string definition:

constant AT_WKMOD       : string(1 to 15):="AT+WKMOD="SMS""&CR;

If I try:

constant AT_WKMOD       : string(1 to 15):="AT+WKMOD=/"SMS/""&CR;

It does the same thing. The last thing I tried was:

constant AT_WKMOD       : string(1 to 15):="AT+WKMOD=\"SMS\""&CR;

Which gives the following error upon synthesis:

  Non-printing character is not allowed in extended identifier.


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I recently bought an Arduino DUE. I was going through the technical details and realized that the DUE acts a a virtual USB device (COM port). I was wondering whether I could upgrade the Board Support Package to my own custom one. Basically I want to make it act like a true USB device or HID device. This would include rewriting the bootloader and the device drivers (on my computer).

So before I get started with my own bootloader and software, I want to know how the booting currently happens on the DUE. Do they use the same Arduino bootloader? because I read that the SAM processor has an inbuilt bootloader from the factory. Where can I find more information regarding all this? any way how does the uploading of code from Arduino IDE happen if there is no Arduino bootloader on the chip? Any kind of pointers appreciated.


texts: How to test brushed motor rotor coils with a multimeter?

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I have a Blendtec blender that just decided to break on me. The blender has an electric brushed motor that looks like this:

http://www.ifixit.com/Teardown/Blendtec-Total-Blender-Teardown/1128/2

When it broke I smell some "electric smell". The kind you usually smell when electronics break.

I opened up the blender and have taken the rotor out, as I suspect the problem might be in the rotor coils.

My question is I have no idea how electric rotor coils are supposed to be wired. How can I use my multimeter and test if the coils are shorted, connected, or otherwise in proper order or not?

For example if I measure the resistance between two adjecent copper "pads" (the pads that the brushes touch), the resistance is zero. Is that normal?

Half of the pads on one side of a the pad circle seem connected to each other. And half on the other side. Except one pad that doesn't seem to be connected anywhere. So something is clearly not right, but I'm not sure what. Should adjecent pads be connected to each other or not?

UPDATE

After a couple of weeks waiting for the replacement rotor it finally arrived and I measured it for comparison.

The rotor contact points are all connected to each other. Each one is connected to each other with increasing resistance the farther you move from adjacent contacts.

Not sure if this is a special case with this rotor. But that is what I measured.

I put in the new rotor and assembled everything. Now works as good as new. So the original rotor was clearly the faulty component (as measured with the multimeter also - not all contacts were connected any more).


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I have a board with the following connections:

TMS TDI TDO RXD TXD RTCK TRST TCK GND

I am trying to connect my USB UART TTL to it (I have connected the RXD, TXD, GND) but I am not sure which pin I should connect the 5v to?

Any advice would be great, thanks


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I am choosing between schottky for a bridge rectifiers. But I can understand how to choose a SiC based on the parameters for a rectifier application.

I want the fastest 2A SiC diode (for lowest noise). Should I look for a diode with the lowest Qc or should I look for a diode with the lowest capacitance ? or the lowest Ir ?

Cree 3D02060F
https://www.mouser.fr/datasheet/2/90/3d02060f-838501.pdf
Infineon IDH02G65C5XKSA2
https://www.mouser.fr/datasheet/2/196/Infineon-IDH02G65C5-DS-v02_02-en-1225779.pdf
Cree C4D02120A https://www.mouser.fr/datasheet/2/90/4d02120a-838539.pdf

Can you explain this to me please, I have read a lot of whitepapers but it is still blurry.
Thank you.

EDIT : it's for a bridge rectifier for an SMPS power supply for audio equipment (compressor/limiter). I don't have a circuit yet I am just wanting to build a simple SMPS based around the Infineon IR2153. This the stuff I have in mind ; https://homemade-circuits.com/wp-content/uploads/2014/06/smps2B3002Bwatt2Baudio2Bamp2Bpower2Bsupply2Bcircuit.png


texts: VGA controller using FIFO memory, discrete ICs and Arduino Uno/Mega?

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I love the Arduino boards. They're super easy to use and give me access to fairly powerful microcontrollers for all of about $12. Unfortunately, 16MHz isn't quite fast enough to display more than 120x60, 2-bit colour VGA (which is what I have right now on my Uno, using the VGAX library). Even trying to squeeze out 3- or 4-bit colour requires a resolution drop.

I'm making an Arduino-powered games console for the fun of it (I love my Mega Drive and thought it might be fun to see what I could achieve with Arduino). My plan WAS to have an Arduino Mega2560 running the game code and storing all the sprites in its 8KB of RAM, loading and unloading as necessary to/from an SD card or other external storage. The Mega would then send the 2-bit pixel data, 4 pixels at a time, via an 8-bit parallel bus (literally 8 jumper wires with two "acknowledge" lines) to an Arduino Uno, which would act as the display unit and use 95%+ of its processing power just spewing pixels out to the monitor/TV. That was fine, and worked well... but 2-bit colour just isn't quite enough to reach Mega Drive-era games, and is pretty hard to work with. So I decided to try to invent some sort of custom VGA controller...

Ideally, what I would like to do would be have a small SRAM chip (64KB would be HEAPS, even 8KB would be enough, though 16 would be better), which the Arduino talks to. The Arduino would create an array (i.e. the front buffer) in the first section of RAM, then just update the pixels as fast as it can. Then a custom circuit on the other side of the RAM, clocked at VGA-suitable speeds (~25MHz?) would read the pixels from the RAM (using some sort of counter to move through the array?). That way, even if the Arduino couldn't keep up, the VGA controller wouldn't be left without pixel data - rather, it would just be the pixels from the last frame. So you'd get tearing but that's not a major issue.

There's probably numerous reasons that would be hard to do. Different clock speeds, for a start. I don't really know how SRAM works but as I understand it having two different clock speeds trying to write and read at the same time might be bad. So...

I came across this post. In it they mention FIFO memory. Bingo! I didn't even know this was a thing! They refer to the SN74ALVC7804, a 512x18-bit FIFO memory chip. It sounds perfect. It would appear that the chip doesn't care if the clock is consistent or not, or whether the input and output clocks differ, as long as they don't go above 40MHz. It has pins to show when it's nearly full (and when it's full). It's 18-bit, meaning I can spew 3 pixels of 6-bit colour (nice and neat - a 2-bit resistor DAC on each colour wire, giving me 64 colours to play with) into the buffer so as to keep up with the VGA controller on the other side as it reads each of the 6 bits of data... and this is where I'm stuck.

So here is my real question: What would you suggest? I could always just buy an Arduino Zero/Due and be done with it, but that's no fun (and very expensive in Australia). I want some challenge, just so long as it's not physically impossible (i.e. trying to extract 120x60 4-bit colour from an Uno). I would need some way of switching between the first, second and third set of 6 bits from the FIFO. I'd also need some way of actually timing the pixel outputs (probably the hardest part, now that I think about it - not so much the timing itself but rather counting out the sync pulses, front/back porches, etc.). I'm not looking for someone to give me a straight-up BOM, just point me in the direction.

I love electrical engineering, but I don't have much experience with it. Plus I have no clue what kind of ICs you can buy to achieve this kind of thing. And finally, even though I'm a programmer first and EE second, FPGA programming just melts my brain.


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I am working in IR2110 high and low side driver for making H bridge of BLDC motor.

It can be switched low side perfectly but not in high side.


texts:
I have a question regarding a Hall sensor IC.

I cant quite understand how is it possible that it can operate only on 2 wires, instead of 3. The way I can think of it is that 2 wires provide Vcc and gnd, and the 3rd one would be the sensind output on the sense resistor (see app note). Now, I know for a fact that it is used in 2 wire config, like Ccc + sensing wire without gnd. It seems confusing. On the schematic there is something like virtual earth inside the IC- does it mean that what hall effect occur when a magnet is close the loop closes inside the IC? I would appreciate an explanation -- but not about how does the Hall effect work, but how this certain IC does.


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module A (input a, input b)
...
module B (input a, input b)
...
endmodule
endmodule

Is the above allowed in Verilog?