texts: How do you Calibrate 32.768kHz crystal for PIC24 RTCC

texts:
I'm trying to figure out the best method for PIC24 RTCC crystal calibration.
Their application note states two methods: using a lookup table and using a reference system clock.

According to them the reference system clock method is best, but they recommend a system oscillator that is a multiple of the RTCC crystal oscillator, like 16.777MHz.

Has anyone actually tried this RTCC crystal calibraiton process for PIC24?
I would appreciate some practical guidelines.
I'm using PIC24FJ128GA006.


texts: Difference between PuTTY Serial and Modbus

texts:
I am trying to communicate with a PM810 power meter using Modbus-RTU protocol with the RS-485 standard over 175 meters of CAT5e STP cable. It's less than ideal, but it's the situation I'm working with.

To facilitate testing, I have installed two laptops at either end of the transmission cable. The idea is that one is setup as a Modbus master, the other runs a slave server to emulate communication with the PM810. I wanted to post a block diagram for clarity here, but I'm only allowed two links.

  Laptop -> USB to RS-485 Converter -> 175m of CAT5e STP -> USB to RS-485 Converter -> Laptop

The problem I am facing and can't wrap my head around is as follows:

Laptop_PuTTY -> 175m CAT5e -> Laptop_PuTTY serial communication (9600 Baud, 8bits, no parity, 1 stop) is fine. It works in both directions without any issues.
Modbus Master -> 175m CAT5e -> Modbus Slave (9600 Baud, 8bits, even parity, 1 stop) fails.
Modbus Master -> 1m CAT5e -> Modbus Slave (9600 Baud, 8bits, even parity, 1 stop) works fine.

So here is my question. What is the difference between PuTTY's serial communication protocol and Modbus protocol that could be causing Modbus to fail and PuTTY to work fine over the 175 meter length? They both work over the shorter distance, the physical medium is the same for both over the longer distance, in yet only PuTTY serial works. I tried googling information about what exactly PuTTY's serial communication protocol is, but I couldn't find any satisfying answers. This is from the PuTTY manual, but I don't really understand what it means.

  In this mode [serial], text typed into the PuTTY window will be sent straight out of your computer's serial port, and data received through that port will be displayed in the PuTTY window.

Any advice on how to address this problem, or is Modbus communication out of the question?


texts: What replaces MobiTex for sporadic low bandwidth usage?

texts:
Back in the day I would use MobiTex for low bandwidth usage for devices that simply needed a few simple commands sent or received.

It now seems next to impossible to procure or use MobiText devices and it's possible that the whole network is being phased out.

For devices that simply need to report information (oil pumps, sprinklers) or things that need authenticated control (remote locks, pump controllers etc) what network has the ubiquity and low bandwidth requirements that MobiTex once dominated?


texts:
Would it be safe to replace a ferrite bead that had a rating of 47 ohm @ 100MHz 5A  with one that is 70 Ohms @ 100MHz 6A?

I can't seem to find an exact replacement.

https://www.amigawiki.org/dnl/schematics/A4000_Rb.pdf - fb177 for example.


texts: Current-limit circuit for 78XX voltage regulators

texts:
I need  to find the value of Rsc and R1 in the following circuit:

In this circuit, Q1 is the high-current pass transistor.  Its emitter-to-base resistor has been chosen to turn it on at a given load current.

In the circuit, Q2 senses the load current via the drop across the resistor Rsc cutting off drive when the drop exceeds a diode drop(i.e 0.7V.)

Now I want to calculate the value of Rsc and R1.

But how can I solve this problem for a linear voltage regulator?


texts: How A/C board works on an air conditioner

texts:
I have a question.

I got a Panasonic CU-C24GVK (24000 BTU Air conditioner), and the A/C board relay is burnt. If I'm not explaining myself, the A/C board is the thermostat itself, the board receive the 240V, and after some minutes it send a signal to a relay that connects those 240V to the outdoor unit's compressor, that board have the following diagram:

The question is, I want to know how this exactly works, because the relay that connects the 240V line with the COMP output is bad, so I cut the wire and connect the line directly to the COMP, so the compressor will be ON all the time, however, what is happening is that the compressor turns on, and after like 20 min, it turns off and never go back on again, it only turns on if I let it rest a while cutting the electrical supply to the thermostat. A technician told me that because of what I did, the run capacitor might be getting overheated, I ran a test, I waited for night, and as the outside temperature is lower, the compressor doesn't turn off.

But that have no sense to me, how a capacitor will get overheated for constant electrical supply if in a normal run it also have a constant supply unless the thermostat wants to shutdown the compressor? Can anyone explain that to me?


texts: ModelSim wave window showing zero time transitions

texts:
I'm new to verilog and so ModelSim. There's a problem or actually may not be a problem that I have noticed.

It seems to me that ModelSim wave window imposes by default a transition at time zero on any signal. Depending on the initial value of the signal it's either a 1 to 0 or a 1 to 0 transition. This may not cause problems for most cases but it might, say with negative-edge triggered circuits whose clock is initially set to 0 and do not expect a zero time triggering. To show the problem consider the following verilog code describing a falling edge triggered DFF:

module dff(d,clk,reset,q);

//define DFF delay
`define DFF_DLY 5

input d,clk,reset;
output reg q;

always @(negedge clk or posedge reset)
   if (reset)
      q=#`DFF_DLY 0;
   else
      q=#`DFF_DLY d;

endmodule

Based on the following test bench code the output signal q is determined 5ns after an early triggering occurred at time 0ns (the zero time transitions are also visible in the image):

Test bench code:

module dff_tb;

reg d,reset,clk;
wire q;

initial begin
d=1'b1;
clk=1'b0;
reset=1'b0;
end

always #10 clk=~clk;
//always #27 reset=~reset;
always #18 d=~d;

dff ff1(d,clk,reset,q);

endmodule

One solution that I think of is modify the module dff in such a way that the negative edge triggering happens soon after a positive edge is detected. This prevents an early, unexpected negative triggering. The part of modified code is shown below.

always @(posedge clk or posedge reset)
   if (reset)
      q=#`DFF_DLY 0;
   else
      always @(negedge clk) q=#`DFF_DLY d;

While the above trick solves the problem this is not actually what I'm looking for. I don't want to modify the code, which works fine in case of no initial transitions. The question: Is that a problem with my test bench code or that's the ModelSim that comes the issue with? In either case how to solve the problem?

Best,


texts: Can you reuse FCC certification from a pre-certified RF chip and antenna for a new product?

texts:
I am in the process of designing a board that turns a Gameboy into a Bluetooth controller. Due to size constraints, I would like to use the ESP32-PICO-D4 standalone chip by Espressif instead of one of the larger modules that has an integrated PCB antenna like the ESP32-WROOM-32. In Espressif's dev kit for this chip, they use a 3D chip antenna as shown in this image of the board.

This antenna is the PRO-OB-440 by ProAnt AB as shown on their page here and the Digi-Key product page here.

As I would like to eventually sell this product, I know that there are certification requirements that should be taken into consideration. After reading up on this through the FCC's Title 47 CFR Part 15 under Subpart C - Intentional Radiators as well as an article from EMC FastPass about pre-certified RF modules, I saw that they were wanting to cut down on the number of products that needed certification by encouraging the re-use of pre-certified modules.

If I was to use the same chip and antenna together, would this pre-certification for the dev kit carry over to my product?

Note: The dev kit's certification documents can be found here.

(Also, I feel that my question is different from this one as that board uses an integrated PCB antenna while my question focuses on an RF chip combined with a surface mount antenna.)


texts:
I have a ceramic disc capacitor that got cooked in a power surge due to a faulty generator.    The capacitor was between the fuse and transformer of a circuit board for a pellet stove.

It is RED with and though damaged, I can make out two lines of text

50L10
0933

I believe the first line its a 250volt with 10% tolerance.
But not sure how to read the 0933  because everything I found on the web talks about 2 and 3 digit codes.

Any help would be appreciated.


texts: Why does this BJT work as a switch in this logical-NOT circuit, no matter how I orient the emitter and collector?

texts:
I have built the following circuit (obtained from Electronics All-in-One For Dummies (For Dummies 2nd Edition))

It works quite well. When the the momentary button (normally open) is not pushed the LED is on.
When I push the button, I see the LED turn off.

However, for a bit I accidentally had my 2n2222a NPN BJT transistor (datasheet) oriented backwards so that :

the emitter was connected to the LED
and the collector was connected to ground

The circuit still worked exactly as expected.
Can someone explain why it would still work the same with the transistor in the incorrect orientation?


texts:
I know mixing SPI and I2C is a bad idea, but, when using a microcontroller short on pins, is it safe to share clocks between both buses, provided both are running at bus-tolerable frequencies?

In my application, I plan on using one bus at a time, but I suppose this question applies even if that was not the case.


texts: Is it possible to calculate the Time of Flight between two Bluetooth devices?

texts:
I want to calculate the distance between 2 Bluetooth tags (still need to be developed so no restrictions in components).

The tags will not be time synced so we would like to calculate time of flight by checking the time it took to go from A to B and back.

The error margin should be around 5 cm. Typically the tags are placed 10 to 30 meters apart.

Is it possible to calculate distance between the devices?

If Bluetooth is not suitable for this, do you have any suggestion for which transmission protocol would be better?

Thank you


texts: Howland current source with voltage reference

texts:
I need a precision current pump for small ac signals(50uA) and i tried it in multisim with a howland topology. It works however i need the load to not be grounded but bound to a bias voltage.

Here i show the layout.I want a non- inverting topology. Also,i have already biased the input AC signal to this DC and i have this DC available as a low-impedance voltage source. For me, the DC bias is 2.5V, with the load tied to this voltage, and Vs is 5V.


texts: SPI communication between PIC24FV32KA301 and MS5611 won't work

texts:
I am new to microcontrollers programming and I am trying to establish SPI communication between PIC24FV32KA301(Datasheet) and MS5611(Datasheet).

After a week of searching and learning about SPI I am still not able to communicate between those two and I would appreciate if someone could help me.

Am I missing something?

/* Device header file */
#if defined(__XC16__)
    #include <xc.h>
#elif defined(__C30__)
    #if defined(__PIC24E__)
        #include <p24Exxxx.h>
    #elif defined (__PIC24F__)||defined (__PIC24FK__)
    #include <p24Fxxxx.h>
    #elif defined(__PIC24H__)
    #include <p24Hxxxx.h>
    #endif
#endif

#include <stdint.h>        /* Includes uint16_t definition                    */
#include <stdbool.h>       /* Includes true/false definition                  */

#include "system.h"        /* System funct/params, like osc/peripheral config */
#include "user.h"          /* User funct/params, such as InitApp              */

#include "uart1.h"

#include <libpic30.h>        // __delayXXX() functions macros defined here

/******************************************************************************/
/* Global Variable Declaration                                                */
/******************************************************************************/

/* i.e. uint16_t <variable_name>; */

/******************************************************************************/
/* Main Program                                                               */
/******************************************************************************/

void SPIinit(){
    //Master mode, 8bits
    SPI1CON1bits.MSTEN = 1;
    SPI1CON1bits.MODE16 = 0; //8bit
    SPI1CON1bits.DISSCK = 0;

    //SPI mode 0
    SPI1CON1bits.CKP = 0;
    SPI1CON1bits.CKE = 1;

    //1:1 prescale
    //SPI1CON1bits.SPRE = 0b111;
    //SPI1CON1bits.PPRE = 0b11;

    //Enable SPI operation
    SPI1STATbits.SPIROV = 0;
    SPI1STATbits.SPIEN = 1;
}

char SPIsend(char command){

    unsigned int buffer;

    //wait until the device is available
    while( SPI1STATbits.SPITBF);
    // Initiate the exchange
    SPI1BUF = command;

    // Wait for the exchange to complete (or handle things via an ISR)
    while( !SPI1STATbits.SPIRBF);

    //Read from buffer
    buffer = SPI1BUF;

    //return first byte
    return buffer & 0xff;
}

int16_t main(void)
{

    /* Configure the oscillator for the device */
    ConfigureOscillator();

    /* Initialize IO ports and peripherals */
    InitApp();

    //OSCCON = 0x11C0;   //Use primary, no divide FCY = 10Mhz/2 = 5Mhz
    OSCCON = 0x11C0;
    CLKDIV = 0x0000;     //do not divide

    ANSELA = 0x0000;
    ANSELB = 0x0000;

    //UART
    TRISBbits.TRISB2 = 1;
    TRISBbits.TRISB7 = 0;

    //SPI
    TRISBbits.TRISB12 = 0; //SCK
    TRISBbits.TRISB13 = 0; //SDO
    TRISBbits.TRISB14 = 1; //SDI
    TRISBbits.TRISB15 = 0; //CSB

    LATBbits.LATB15 = 0; //CSB

    //Disable Watch Dog Timer
    RCONbits.SWDTEN = 0;

    UART1Init(12);   //Initiate UART1 to 19200 at 8MHz OSCI
    SPIinit();
    __delay_ms(1000);

    SPIsend(0x1E);
    __delay_ms(3);

    //pressure command
    SPIsend(0x40);
    __delay_ms(9);

    //read
    UART1PutChar(SPIsend(0x00));
    UART1PutChar(SPIsend(0x00));
    UART1PutChar(SPIsend(0x00));

    while(1){

    }
}

I am using UART1PutChar to send results back to my computer and I am always getting the response 0xFF from MS5611, but if I connect SDO and SDI on board I get back the same data I am sending to MS5611 which means my code works but sensor(MS5611) is dead?


texts: Do I need to add power filter capacitors to a blue pill?

texts:
May I ask somebody to have a look at my schematic? It's rather not complicated.
M1 - fan motor, controlled by IRL540 Logic level transitor. I'm decided whether the fan will be controlled using pwm.
M2 - motor used to control door. Controlled by mosfet driver TC4420.
D1 - the purpose of this diode is to prevent reverse polarity.
SW1, SW2 - magnetic sensors used to check the door position.
I am wondering about MCU power supply filtration, because during my tests MCU was powered either by JLink or USB, but now I need to take care about power supply on my own. Does the blue pil already has some internal capacitors and adding addional ones won't be nescessery or should I add them?


texts: How can I change step-down my variable input voltage?

texts:
Ok so here's the deal:

I have a variable DC Voltage source from 0-10V.

I need to step that down to a variable source of 0-3V.

This 0-3V DC will be fed to an Analog to Digital converter in a microcontroller.

I know I can potentially use a Voltage Divider (using resistors) but apparently, that's not a good solution.

Op-amps don't provide a gain < 1.

So I'm just struggling as to how I can accomplish this.

The microcontroller: https://www.microchip.com/wwwproducts/en/PIC18F47K42


texts:
I am attempting to make a battery powered alarm clock with an Arduino, and I would appreciate some help on the circuitry part. I am very inexperienced with electrical engineering.

I am using a voltage divider in parallel with the rest of my circuit so that I can feed it into a pin on an Arduino and read the battery life. I am using a two 100k resistors to lower my 4.5v power source to 2.25v (the maximum input voltage for a analog pin on an Arduino mini 3.3v is 3.3v). The three AAAs ran out of battery much quicker than expected, and I figured it might have something to do with the voltage divider. Is power constantly flowing through the voltage divider, even when I'm not reading any data from the pin? If so, does this reduce battery life?

Side question: I noticed the voltage divider was very inconsistent, is there a better way to lower the voltage going into the Arduino's analog pin?


texts:
I am designing a boost LED driver using LT3761

Using the datasheet examples I designed and ordered PCBs, assembled them, but every time I connect the power one of four things explode: fuse, driver, boost MOSFET or sense shunt. I tried many different LEDs, calculated and populated different sets of components, but the result is the same. I tried the exact values from the datasheet's first example, boost driver for 1A led, the result is the same.

I do not know what is wrong here.

For explode part of the question, I understand, that I give the energy from my battery which is sufficient for explosion and if I would use current limited power supply it would behave differently. But, the IC has all possible protections. How it goes into drawing so much energy for explosion...

I am designing the driver to be used from 20V to 50V. Tried 24V and 48V, both do same damage. Tried to power with a 24V battery and 48V power supply. Wires from source to the load are 20cm.

When I limit the power using a series resistor it does not blow. I do not have current limiting power supply.

Please see the attached schematic and the PCB.

It is in boost mode.
The Inductor is 10uH.

I tried MOSFETS FDMS86201, NVMFS6B14NLT1G, FDMT800150DC

All parts sourced from Arrow.com

Thank you.

This is top layer from official evaluation board design. Usual design with small gaps and copper regions.


texts: Understanding the flow of the application with UART interrupts

texts:
I am trying to think of a design to make better use of UART interrupts. Currently, what I have involves calling a function that enables the UART interrupt control bits,  and continues to poll till a specific char is received from the terminal.

void start_serial(usart_handle *usart) {
   while (true) {
     receive_data();  // calls uart's custom HAL function for receiving data via interrupts, and storing into rx buffer
     parse_data();
     execute_data();
}

int main(void) {
  // init
  start_serial(&usart);
  // do something else...
}

That's sort of what I have, and is clearly not using interrupts as it should be but that was something to get started with. To make use of interrupts, is it usually done by calling a function to enable the control bits, and then you continue doing something in your application and everytime there's a new byte, it triggers the ISR, stores the byte into the rx buffer, and depending on your application perhaps process the input once a specific byte is received, say, \n.

int main(void) {
  // init...
  enable_uart_it(&usart); // enables uart control bits
  // ...do something in your application
}

// called once \n is received by the ISR; for processing the bytes received (for e.g: gyro\n),
void application_callback_uart(uart_handle *uart) {
   parse_data(rx_buffer);
   execute_data();
   enable_uart_it(&usart); // for next set of data
}

tldr; to make use of uart interrupts, you enable the control bits, which continues to store data into your rx buffer, and then at one point your process it, and do something with what was requested, and continue doing what the application was previously doing. Does the idea sound okayish? Is this how uart interrupts mainly used in applications? any interesting use cases for better visualization or perhaps resources?


texts:
I'm kind of new to this and was wondering how I would go to draw a block diagram for a differential equation that I've recently calculated?:   y[n] = y[n-1]+ [1/4] ([x[n]-x[n-4]])
There is no problem for me to calculate these types of mathematics, but I do have problems to visualize/sketch it in terms of block diagrams etc, so any help would be appreciated!


texts:
I intend to interface an ADC that supports JESD204B (subclass 1) with the Zynq Ultrascale+ MpSoC. I currently switched to Vivado 2020.2 version and realized that the Xilinx IP block JESD204 (which implemented JESD204B in Vivado's previous versions) is no longer supported in this version. It seems like I can only work with the JESD204C IP block in Vivado 2020.2.
If the above information is correct, I have only one way to interface my ADC with the MpSoc: Use JESD204C (subclass 0), which has backward compatibility with the JESD204B standard, on the MpSoc to interface with the ADC. However, I also notice that subclass 0 does not have deterministic latency.
Is there any better way to implement JESD204B (subclass 1) on Zynq Ultrascale+ MpSoC in Vivado 2020.2 environment?


texts: Help Identifying Non-Standard USB Connector

texts:
I need help in identifying a part and finding a source (if possible) for a non-standard USB connector... at least I believe it to be non-standard. I've attached a few pictures which are focused to the best of my abilities.

The connector measures approximately .200" x .085" and has 8 positions. The 6 inner most positions are recessed maybe .030" further back than the two outside positions. This particular connector mates with a Nikon camera. It seems to be for USB and AV.

Any thoughts?


texts:
Suppose we're given the position  \$x\$ , velocity  \$\dot{x}\$ , and acceleration \$\ddot{x}\$ at \$t_1 \$.

We need to approximate the position \$x\$ at \$t_2\$.

In below picture, I understand how \$x_1\$  represents the vertical black length, and how  \$ \color{blue}{\dot{x_1}(t_1)}h\$ represents the vertical blue length. However I don't get how \$\color{green}{\ddot{x}(t_1)}\dfrac{h^2}{2}\$ represents the green length. I'm wondering if there a simple derivation for proving that the green vertical length equals \$\color{green}{\ddot{x}(t_1)}\dfrac{h^2}{2}\$ . Any ideas ? Thanks !


texts: What value to use to find complex impedance of a motor?

texts:
Output of motor is 3000 W with efficiency of 0.8, so The input power is 3750 W. when I want to find the complex impedance of the motor Z = X + jY i get fail answer when I use P = 3750 W to calculate the answer.
The equation I use is Zm = E^2 / Sm, where S = P-jQ. Q=2250 VAR and E=230V.

I get the right answer with 3000 W though, but still need some explanation. Anyone?
thnx


texts: Pic18F67K40 unable to read 7940 RTCC over I2C

texts:
I'm trying to integrate the MCP7940N RTCC into my design. The MCU is the PIC18F67K40 and I'm using I2C to communicate. I created a new starter project to make sure that it works there before I add to my larger design. My IDE is MPLab X v5.4 with MCC 4.02, core v5.0.2. I can't get even this basic project to communicate correctly, I believe the problem is with the timing of the pulses. For this prototype I'm using the Explorer 8 and Mikroe's RTC6 Click board. I started with the RTC Example and I2CSimple Foundation Service. The RTCC Datasheet says it can handle I2C clock up to 400 kHz.
Initialization
...
    #pragma config FEXTOSC = OFF    // External Oscillator mode Selection bits->Oscillator not enabled
    #pragma config RSTOSC = HFINTOSC_64MHZ
...
    SSP1CLKPPS = 0x13;   //RC3->MSSP1:SCL1;
    RC3PPS = 0x19;   //RC3->MSSP1:SCL1;
    RC5PPS = 0x1A;   //RC5->MSSP1:SDA1;
    SSP1DATPPS = 0x15;   //RC5->MSSP1:SDA1;
...
    SSP1STAT = 0x80;
    SSP1CON1 = 0x18;
    SSP1CON2 = 0x00;
    SSP1ADD  = 0x03;
    SSP1CON1bits.SSPEN = 0;
...
    // NOSC HFINTOSC; NDIV 1;
    OSCCON1 = 0x60;
    // CSWHOLD may proceed; SOSCPWR Low power;
    OSCCON3 = 0x00;
    // MFOEN disabled; LFOEN disabled; ADOEN disabled; SOSCEN disabled; EXTOEN disabled; HFOEN disabled;
    OSCEN = 0x00;
    // HFFRQ 64_MHz;
    OSCFRQ = 0x08;
    // TUN 0;
    OSCTUNE = 0x00;

I can open the I2C channel just find, but when I try to read a register on the RTCC it hangs waiting for
PIR3bits.SSP1IF to be set but it never is. I'm using MCC to generate the RTC and I2C code for me. Thank you.
Edit 1:
Here is the schematic for the RTC click board.


texts:
I want to understand the way this circuit works. The following are diagrams of the transmitter and receiver of a wireless iPod charging circuit. I have added a link to the instructable that describes this project.
From what I have understood, the transmitter takes the DC input voltage,and turns it into an oscillating signal that can be transferred to the receiver circuit through the inductor.
The recieving circuit then rectifies, filters and regulates this signal to give DC output?

Is that how this is working?

Also, are the resistors in the receiver circuit put there for the female USB? Why?
Also when I bought the diodes for the transmitter circuit, I could only get 1 UF4007 and the other is a 1N4001. Will that affect the functioning of the circuit?

Thank you for your time!

This is the transmitter circuit.

This is the receiver circuit.

the instructable where I got these diagrams from


texts: Validation required for wiring of a 3 pin illuminated rocker switch

texts:
I'm trying to reproduce a setup for an induction heater. This is the one I am looking to do, but I ended up buying a rocker switch that has an integrated led, and it has 3 pins. Now I did find a guide to wire this kind of switch, but I'm not entirely convinced I applied what I learned there to the setup I want to reproduce, since it has to be wired to a mosfet, which is not the case with the guide.
Here's the (non technical) schematic I made. If any one can help me by pointing if either I am right or wrong with the rocker switch, and if I'm wrong... What did I got wrong ?


texts:
I would like to simulate a circuit which uses LM324 operational amplifier.
The complete schematics of the circuit is like that.
It is taken from an article written by George Steber in the 2004 issue of Circuit Cellar magazine.
U1A and U1B generates triangle wave. U2A and U2B form a power buffer for the triangle wave.

I've understood most of the circuit's working principle. But I couldn't figure out this part.

As you can see there is a CD4066 CMOS switch and a voltage controlled switch.
I am not sure whether this switch is between, CD4066's VDD and VSS pins.
This is the same circuit in MicroCap simulator software.

When I look at the transient analysis result, I see some kind of noise instead of step wave.

May you provide a working example which doesn't use switches?
Any ideas would be apreciated. Thanks.
Update :
According to a similiar article step generator provides a slow voltage when S1 switch closes.


texts:
I'm looking for a modern memory product or solution which can hold at least 256 bits but has a destructive readout, the hardware must be reusable without requiring intervention. The only thing I have been able to find is an Arduino Project which uses core memory. No preference regarding its interface or volatility, beggars can't be choosers. Keep in mind we're not EE guys so it would be difficult for us to construct something from scratch.
Any information would be appreciated.
The purpose is to be key storage for an encryption solution.


texts: Proper inverter VAC output when tied to grid

texts:
I live in a US state which encourages home-owners to install their own renewable system and feed the power back into the commercial grid. The inverters take their phase clock from the line and actually shut off if the line goes down.

I'm assuming (please correct me) that the VAC output from the inverters needs to be higher then the line VAC in order to push power out to the grid and spin my meter backwards.

How much higher should it be?

My grid power is nominally 240, but I'm not sure what it measures (I suppose, since I have solar, that VAC after sunset would be the supplier's). The inverters report 252 VAC when the sun is shining.

This has come up because circuits in my household heat pump have blown and the installer thinks the house voltage is too high.


texts:
I have a device I'd like to hack. The manufacturer has provided JTAG through-hole connector in the PCB:

Due to various personal reasons I currently cannot use/access a soldering iron.
I am looking for clippable/snappable/solderless header pins similar to the ones listed on sparkfun here.

What are they called? I cannot find others with these terms.
EDIT: Anything that serves a similar purpose will also work. I just need a way to connect the programmer to the pins.


texts:
I'm trying to identify a fault on a printed circuit board in a consumer product. So I tried to find a pin-out diagram, specifications, etc. for this surface mount component designated AA3 03:

There are two of them. I imagine they are ~3V voltage regulators for some small krypton light bulbs wired up in series. But I don't know for sure.

Can anyone definitively identify this component, or cross reference the part number with a more common one; so I can hunt for the specs? Thanks.


texts:
So here is what I'm trying to make I need a portable UPS for my portable DVD player 12VDC in 12VDC out.  The reason for this is my car's 12VDC outlet looses power whenever the ignition is switched off, even switching it to accessory will kill the power.  This plays havoc with the portable DVD player.  Try telling a five year old that her show died because you needed gas.  Rather than rewiring the outlet direct to the car battery what I want to do is build a small UPS out of some Lithium ion 18650 cells that I have left over.  Now I'm planning to connect them with one of these:

(http://www.batteryspace.com/protection-circuit-module-pcb-for-11-1v-li-ion-battery-pack-triangle-3s-4a-limit.aspx)

Which should protect them for charging.  Then use a dc-dc up converter to get me the 12VDC output I need and put a voltage regulator on the input to ensure I've got a stable ~12VDC on the input to supply the charge.  That should I believe give me up to 4A to draw for my DVD player which should be more than enough for it, the excess is then available to keep the batteries topped up.

I just want to make sure I'm not missing something that will start say a bad lithium fire.  I've done something similar with some sealed lead acid batteries but they are far more forgiving than Lithium ions.  However, they are big and heavy I want to keep this small and light for travel it's not like it has to run the DVD player for hours just keep it running when we need to make pit stops.  Because trying to find the exact instant that the show stopped because children only care about that sort of thing when it's their shows.....

I would love some feedback to let me know if there are some considerations I have missed.

Thanks


texts:
I have this schematic, with an power supply of 24V and I want to read this voltage with my arduino so i need a voltage divider, the formula for voltage divider is Vout = (Vin * R2)/R1+R2, so with my data, Vout is 2.824V (24 * 10000)/75000+10000.

So what is the reverse formula to convert 2.824V to 24V, for printing on my serial monitor?


texts: How do I design my very own ARM based processors?

texts:
I have several questions about how I would design my own ARM-based CPU?

How does one start with an ARM license and end up with a package ready to be soldered on to a board?
What do I get from ARM (I am sure they have multiple license options to dish out - Architecture License (Qualcomm Snapdragon style) and Core License (TI OMAP style))?
What tools do I need to proceed once I have 'that something' from ARM?
What do I send to the fab?
I believe only certain foundaries are licensed to etch an ARM core on to a silicon wafer. Am I right?
As a student, can I afford to do this on an FPGA? How do I get hands on experience for something like this?


texts: Using a DB3 diode as a flyback for a 24vdc relay

texts:
Can I use the DB3 diode as a flyback for a relay that works on 24v dc?

[![enter image description here][3]][3]

This is a new photo :

[3]: https://i.stack.imgur.com/Snv9f.jpg


texts: How is the data transferred from smartphone app to ESP32 using BLE? (flutter)

texts:
I am trying to send data to an ESP32 using a smartphone app. I am using the flutter_blue package to do so. I am having issues understand the whole communication process between the 2 devices. So I am looking to better understand the way BLE communication functions.
I understand that the GATT contains a profile, which contains service(s). Each service contains a characteristic, and each characteristic has properties, a value and a descriptor.
Assuming I program the ESP32 such that whenever it receives a string signal "1", its onboard LED turns on. Where would that string be stored? in the descriptor? or the value?
What is the Profile? Service? Characteristic?
What is the role of the UUID in all of this ?
Any help/explanation would be greatly appreciated! Thank you!


texts:
My vehicle alarm consists of a control box containing some vibration sensor and relays, and a buzzer that creates an ear piercing sound upon triggering. I've recorded this alarm sound.

After pulling off the buzzer, I'm trying to replicate this sound on my Arduino Uno with it. Here is what my 'buzzer' looks like: High Decibels Alarm XHD SFB-55 DC6 12V Acoustic Alarm Buzzer Horn Siren.

To find the frequency function of the alarm sound I used Spek  – Acoustic Spectrum Analyser:

This plot shows something that's close to saw tooth wave between the frequencies 2kHz and 5kHz.

After playing around with Wolfram Alpha to find a function description I get the following code:

for(double x = 0; x < 0.92; x += 0.01){
  tone(3, sinh(x+8.294), 10);
  delay(1);
}

for(double x = 0; x < 0.183258; x += 0.002){
  tone(3, sinh(-5* (x-1.8420681)), 10);
  delay(2);
}

This is how I connect the buzzer.

I suspect it's a piezo buzzer because when there is no R2, I only hear a click sound. I have read about capacitive  behaviour of piezo buzzers, so adding R2 should be unload the buzzer.

This is the result:

The sound I get is quite close but it's far from ear piercing, but more like a sound of a bird.

I suspect the frequency function is not 'sharp' enough, does the function have to rise and drop quicker to create the original effect?

Could anybody help me with this function, or is there a better way to sound an alarm?


texts: How to use a cap in parallel with power supply to help start a motor

texts:
I have two motors in parallel and a battery with a switch in series with both motors to stop and start them. They are DC brushed motors and the inrush current is huge. While my 3S LiPo handles this with no problems, I would like to use a capacitor to limit the initial burst, and take it easy on my battery. I am also using MOSFETs to keep the high current away from the tiny switch, but that isn't relevant here so I've left it out for simplicity.

I have learnt from my research that putting a capacitor in parallel to the battery and leaving the rest of the circuit as it was means it will get charged when nothing is happening and then I can use that stored charge to help the motors get going when I close the switch.

Does this mean there will always be current flowing when I plug in the battery? Is there anything fundamentally wrong with how I plan to wire this? When the capacitor is charged, and the switch is open, is anything happening, or is it idle, waiting for me to close the switch? And finally, what happens if the capacitor is charged, and I remove the battery?


texts:
I'm using a attiny2313a, and I'm having a lot of trouble figuring out what's going on with the timer. It's very simple, yet it simply refuses to work.

I have a 16Mhz clock.
When I put in a 1024 prescaler, then the TCNT1 clock will increment at the frequency 16Mhz/1024= 0.0156MHz, This means that I get an increment every 64uS.

So, for one second, I should expect 1000000/64 = 15625

This is ok, because TCNT1 is a 16-bit counter.

However, when I set up a testing program, what I get is a very long beep somewhere closer to 15-16 seconds.

When I set the prescaler at 64, then 15624 gives me exactly one second.

In my mind, my crystal is behaving like I would expect a 1Mhz crystal to. Is my thought process wrong, or is there something else that might be wrong?

Here is my testing code, the important parts:

#include <avr/io.h>
#include <avr/interrupt.h>

#define Echo    PINB0
#define Trig    PINB1
#define Buzz    PINB4
#define Led PIND4

int main(void)
{
DDRD = (1<<Led);
PORTD = 1<<Led;

DDRB = 1<<Trig | 1<<Buzz;
DDRB &= ~(1<<Echo);

TCCR1B = (1<< CS10) |  (1<<CS12); // prescaler = 1024

    while(1) {
        beep();
        wait(1);
    }
}

void wait(int t){
    TCNT1 = 0;
    while(TCNT1 <= 15624*t){

    }
}
void beep(){
    TCNT1 = 0;
    PORTB = 1<<Buzz;
    while(TCNT1 <= 15624){

    }
    PORTB &= ~(1<<Buzz);
}


texts: Explanation required for xperm.n, xperm.b, in RISCV bitmanip

texts:
I am currently implementing a single core RISC processor. I have successfully implemented the base rv32 instruction set. I want to know what the instruction xperm does and how it works.
For instance:
I have given the instructions,
FFFFF808
00000001
I got the output as 0801F808.
FFFFF808
00000002
I got the output as 0802F808.
FFFFF808
00000003
I got the output as 0803F808.
I am not able to infer anything from this. Also I have tried the xperm.n (nibble), but I wasn't able to understand it as well.
Thanks for your help in advance.


texts:
So I'm wondering if anyone has any information about the Dell power supplies which have 3 contacts on the barrel.

I know the 3 are power, ground, and some sort of communication link. Does anyone know what the communication line is for and/or what kind of protocol it uses?

Thanks

EDIT The reason I ask is I'm considering trying to build my own semi-advanced charger (not for a laptop but something else... it's a long story) and while I'm sure I could figure out a charging circuit given the internet as a resource, I was wondering what they use the communication line for and if it's necessary for my purposes. It seems the answer is no since I will be the only one using my device and thus don't need to worry about people plugging in not kosher chargers...


texts: How do I create a 50ohm input impedance into this RF power measurement IC

texts:
I'm trying to create a basic RF power meter using the LTC5532.

I want to add a SMA connector, and termination, so that the device has a 50ohm input impedance. I'll be using it primarily at 2.4Ghz, but if I can make it work down to 900Mhz, or up to 5.8Ghz that would be nice.

I'm having trouble figuring out what termination parts I'll need for the impedance matching. There's a table of input impedance with columns for reactance (-70.13ohms at 2.5Ghz), and resistance (34.82ohms at 2.5ghz).

How do I use these to choose a termination resistor?

There is a schematic for the dev board available here.


texts: Using a 13.8 VDC 30-50A switching power supply on a 15A house circuit

texts: Want to use a bench top power supply to run 2 - 40Watt motorola radios. What is the max amp rating to use safely on a 15A home circuit?


texts: Microphone saturation avoiding desired signal from being detected

texts:
I'm trying to detect a known signal under heavy interference. I'm working with 2 smartphones and an interfering speaker. I'm sending a signal from one smartphone speaker to the other smartphone microphone while the speaker emits an interfering signal. The bandwidth of the useful signal broadcasted between the 2 smartphones is 2.5 kHz (from 18 to 20.5 kHz), it is a "broadband signal" (imagine something like a spread spectrum) not a tone and the signal emitted by the interfering speaker is a tone at 19 kHz. The distance between the smartphones is 10 cm and the speaker is located 10 cm apart from both of them. I have noticed that as I increase the volume of the interfering tone the signal sent between the smartphones is less accurately detected. I have the following doubts:

Why would this happen if the signal bandwidth is much broader than
the interfering tone?

This process also happens when instead of in band, the interfering signal is off band, lets say a tone at 16 kHz. So more questions:

Why does a loud input signal at a given frequency interfere with the performance of another signal (which uses other bandwidth)?
Is microphone saturation a process affecting the whole frequency band in which the microphone is supposed to operate? So that any signal saturating the microphone even if it is at an specific narrow frequency impedes the microphone from working at other frequency ranges?
Is there a technical parameter for a microphone saturation at ultrasound frequencies? Does it have a name?
How does saturation at an stimulus at 1kHz relates to saturation at other frequencies? Which physical process at the microphone relates them?

Note: I would appreciate if every of the 5 questions was answered


texts: Why do multimeters show values at the lower parts of a given range the way they do?

texts:
Suppose I have a 20,000 counts multimeter, and I am measuring a 220k resistance with it.

The multimeter can only display a resistance below 200k as 200.00k - supposedly because of the counts. For higher resistances, it has to switch the range and starts displaying the result as 0.2200M. But this makes no sense to me: switching range doesn't require the display to change in a major way like that.

Granted, by switching range the meter loses one digit of precision, and conjuring it up would be wrong. But why not simply hide that non-existent digit, and display 220.0 k (see how the last digit is missing) instead of the less readable 0.2200M - they both have the exact same precision!

Why don't multimeters do this seemingly very sane thing, not even the very expensive ones? Am I missing something important?


texts: What is this marine type water proof connector?

texts: Does anyone know what this connector is by any chance?


texts: Is a node always considered to be 0 volt when it's connected to a ground?

texts: Can we directly say that a voltage at a node (voltage at point A) that shares a ground is always equal to 0 Volt? (I'm assuming right-side of the point A doesn't affect the solution as long as the rest of the circuit is completed.) or could it be greater than 0V, too?


texts:
All I read online is that in a Y-Δ connection of a 3-phase transformer the voltage(phase and line if I'm correct) on the secondary side leads the primary one by 30 degrees phase.

Does that happen regardless of which connection is the primary? I mean does it matter if the star is the primary and delta the secondary? Will the secondary always lead by 30 ? Or could it lag 30 behind depending on the connection?


texts: Lowering pitch sound of a piezoelectric buzzer

texts:
I have tried to drastically lower the pitch of a piezoelectric buzzer, but to no avail. All the piezo buzzers I have emit a very high pitched whistle-like tone. I've tried changing all the parameters of my pulse generator, i.e., frequency, duty width, spacing, amplitude, etc. but the pitch of the tone remains the same, very high! Is it even possible to make a base tone from a piezo, or is the high pitch an intrinsic characteristic of all piezo units?
The piezo I have is just a plain transducer, no internal circuitry. That's why I am using a pulse generator. What I am trying to do is move as much air as possible with a vibrating membrane unit that is extremely light and simple, which rules out heavy magnet/cone speakers of any size. I figure that a low bass sound would be the key. If not with piezo buzzers, what else could I try?


texts:
I know how the non-inverting configuration actually looks but I wonder why it can't be identical to the inverting mode (regarding connection of resistors). The feedback is the major issue I can see here but just for mathematical calculation of gain, this modified circuit would still produce the gain same as that of the inverting mode(with negative sign of course).

Why is the non-inverting configuration producing inverted output like in inverted configuration? What are the factors that differentiate the non-inverting and inverting configuration of the op amp?

simulate this circuit – Schematic created using CircuitLab

original image


texts: Can I guess 5/3-wire RS-232 pins from voltages?

texts:
Objective: interface to an HPLC pump via the RS-232 interface described in the manual. Communication protocol is well described. Pinout is not described at all. Can I guess the pinout based on voltages?

Information: I have a LKB Bromma 2150 pump, and am trying to use an Arduino to control it. The manual states that it has the following RS-232 parameters, and has an entire page of simple enough commands.

I have numbered the pins on the 6-pin connector in the following way, and by measuring their pair-wise voltages, was able to figure out the voltage of each pin while the device is on but not communicating.

The voltages are as follows:

Pin 3 (4.93V)
Pin 1 (1.26V)
Pin 2 (0.04V)
Pin 4 (0.00V)
Pin 5 (0.00V)

What I need help with: does someone with more RS-232 experience think they can guess which pins are what? I am assuming its a 5-wire RS-232 protocol with gnd, tx, rx, cts, and rts. I really only need to determine the gnd, tx, and rx.

Note: the Arduino is communicating through a Sparkfun Level-Shifter designed for RS-232 communications--no need to worry about blowing up the Arduino.

Additional Information: the instrument has a BNC connector that goes to a chart recorder. The ground on this connector is shorted with Pin 5 on my diagram.

Another commenter also pointed out that the manual states the communication protocol is RS-232C.

Update (15 AUG 2016): Still messing around with this pump, but haven't been able to get it to work yet. Switched to a MAX232 based TTL logic shifter, and that got another piece of instrumentation going, but this pump is still a puzzle.

Update (16 AUG 2016): Scope in hand, still trying to figure it out. Using PIN 5 as ground and PIN 2 as probe, I see that PIN 2 appears to be a 0-5 VDC signal going high only when the pump is in "Run" mode. Having trouble figuring out how to prompt the pump to send data over the Tx line (whichever pin that is) that I can detect with my scope.

Update (16 AUG 2016 Later): I think I've got it. This pump can be operated in standalone mode, or using a LKB Bromma 2152 controller. I found the manual for the next generation controller (LKB Bromma 2252), and it gives a pinout for the connections to the "LKB Bromma 2250" pump. Uses a 6-pin connector with a NC pin for control, and a 6-pin connector with 2 NC pins for the 'recorder' leading me to believe the pinouts are the same.

Further, the manual states that the LKB Bromma 2252 controller is compatible with my LKB Bromma 2150 pump--meaning the connection has to be the same. The confusing bit is that the pin labeled "PULSE"--what I had thought was ground--would be tied to the ground of the BNC connector. Strange.


texts:
Given the below circuit (at regime) I have to calculate the voltage \$v_u(t)\$, by knowing that.

\$I_0=3\$ mA, \$I_s(t)=I_m sin(2\pi f t)\$, \$I_m=2\$ mA, \$f=1\$ kHz, \$R=1 \$k\$\Omega\$, \$C=100\$ nF.

simulate this circuit – Schematic created using CircuitLab

I solved it with the uperposition principle: \$v_u(t)=v_u'+v_u''=v_{u_{\Big|I_0}}+v_{u_{\Big|I_s}}\$

\$v_{u_{\Big|I_0}}=I_0\frac{R}{1/(j\omega C)+R}\cdot \frac{1}{j\omega C}=I_0\frac{1/(j\omega C)}{1/(j\omega C)+R}\cdot R=Z\cdot I_0\$, where \$Z=\frac{R \cdot 1/(j\omega C)}{R+1/(j\omega C)}=\frac{R}{j\omega RC+1}\$
\$v_{u_{\Big|I_s}}=I_s\frac{R}{1/(j\omega C)+R}\cdot \frac{1}{j\omega C}=I_s\frac{1/(j\omega C)}{1/(j\omega C)+R}\cdot R=Z\cdot I_s\$, where \$I_S=I_m\$ (by assuming the phase of \$I_s\$ as reference phase).

Thus the phase taken as reference is \$\angle I_s=\angle sin(2\pi f t)=\angle cos(2\pi f t - \frac{\pi}{2})=-\frac{\pi}{2}\$

\$Z=|Z|e^{j\angle Z}\$, \$|Z|=|R|/|1+j\omega RC|=...=846.73 \Omega\$, \$\angle Z=\angle R - \angle (1+j\omega RC)=-arctan(\omega RC)=-arctan(2\pi fRC)=0.561\$ rad

By substituing the values, I obtain: \$v_u(t)=(3+2)Z=5\cdot 1.69 sin (\omega t - 0.561)\$ V,(s,rad)

Afterwards, if I calculate the module and phase, I can write \$v_u(t)\$ as somethinng like \$v_u(t)=A\cdot cos(\omega t + \phi)\$

Is the whole process right?

Just in one thing I'm not so sure: my book calculates \$v_{u_{\Big|I_0}}=R I_0\$. Why?


texts:
Many point-to-point communication protocols are designed to have an electrical interface with data/clock/whatever signals along with the ground signal for reference. For example, CAN is composed of +Hi, -Low, and ground. Minimum RS232 usage is TX/RX/Ground, its balanced counter-part RS485 A+/B-/GND. With exception of unbalanced interfaces, in which the GND is obviously needed to reference the signal, I've always seen the GND as needed to equalize the potentials between both ends, such that the potential difference between the equipment could be kept in safe regions. I wonder why such problem doesn't occur in ethernet (or maybe it does), where there's no GND. Here's the problem I see:

simulate this circuit – Schematic created using CircuitLab

The incoming signal TX_D1+/TX_D1- arrives and is connected to an ethernet transceiver through a transformer XFMR1. As there's no GND, an unknown potential difference exists, for instance, between TX_D1- and GND, as represented by Vpot. Well, how one guarantees that a large Vpot won't damage the transformer?


texts: How to make a basic DC fan circuit with an on/off switch (source from batteries). I will be more than happy if I have the schematic and the component needed.


texts:
In some applications I have seen a group or small bundle of wires wrapped with a black nylon and wax covered string.

I am making some small bundles of wires and would like to make the wraps instead of using small zip ties.

What is this wire wrapping called and where can I find instructions for this technique.

Thanks


texts: Connecting transformers in parallel.Will this be a problem?

texts:
I am creating a power supply as a small project. I am planning on using two transformers (in parallel) to create a positive rail and a negative rail. Will this cause a problem ?

I have researched online and found that the transformers can be connected in parallel given that they have the same number of turns and are in phase.

Both the transformers will be connected to the same AC outlet thus I assume they would be in phase ?

Also both the transformers are 220VAC to 12VAC , but one of them is rated for 1 A(planning to use that for +ve rail) while the other is rated for 500mA. Will this cause a problem ?. I assume not since they would both have the same no of turns (the 1 A transformer may have thicker windings ?)

If there will be a problem , is there any way to connect two transformers to the same AC source ?.

I have attached the schematic below if it helps.

Thanks for your help :)

simulate this circuit – Schematic created using CircuitLab

PS : Is my schematic correct? I think this is how to create a negative voltage rail.

Edit : Fixed typos, reworded a part of the question


texts: How to choose proper size of high power DC cable connections

texts:
I can't understand how to properly calculate AWG of a cable working in DC at high current: I found several tables for AC, but I don't know if/how they can be applied to DC.

My system is rated 70V/100A; I think I should use at least 16mm2, but how to be sure?

Example tables:

http://www.carnevale.bz/wp-content/uploads/2012/cataloghi/Cavi_Speciali/BERICACAVI/BERICACAVI2011_CaviSpeciali.pdf

http://www.bericacavi.com/site/index.php?option=com_content&view=article&id=59

I read about "ampacity", but it too is applicable to AC and I can't understand if it is also useful for DC.

I also can't understand on which length are awg/ampacity tables calculated: shouldn't AWG also depend on line length?!?

On my specific system I have cables long at most 1 meter, and I want to be sure they don't get hot, as they are enclosed in plastic with no air cooling and they must tolerate safely 100A continuously for several minutes.


texts: Is the quantization error and random error included in the of-range error for multimeters?

texts:
When I am looking at a datasheet for a DMM (Digital Multimeter) to calculate the accuracy of a measurement it specifies two error sources: of-range and of-value (also called of-reading). For example this datasheet for the Keysight 34470A: https://www.keysight.com/us/en/assets/7018-03846/data-sheets/5991-1983.pdf

I understand that the of-range error is mainly the offset error and the of-value error is the gain error.

But I don't get two things:

Is the quantization error included in these of-range specifications or do I need to account for it separately? The examples always seem to suggest that the quantization error is in fact included.
Is the random error included in the of-range error? If not, then how can I account for it, because I have never seen a DMM datasheet specify the noise (except for AC measurement)? If yes, than what is the confidence interval (2 sigma -> 95%, 3 sigma -> 99%, 4 sigma -> 99.99)?


texts: Controlling the number of devices manufactured by a licensed manufacturer

texts:
Problem

A small company is trying to outsource manufacturing to a small 3rd party factory. The products are consumer grade electronic devices and do not require any special certification besides CE and FCC class B (although I don't think it's relevant to the problem).

The factory is required to pay a certain fixed royalty to the company per every manufactured device.

In order to collect the royalty, the company needs to have a reliable way of telling how many devices have been manufactured in a given amount of time.

Conditions

Manufactured devices run non-trivial firmware provided by the company.
The devices are also equipped with a trivial custom bootloader.
Devices have no means of communication with the company on their own (not connected to the Internet, cellular networks, etc).
Every manufactured device undergoes a certain automated testing procedure, which involves the device to be connected to a PC that runs a special-purpose software developed by the company. This software also flashes the firmware.
Device's microcontrollers have globally unique 96/128-bit ID. Actually, the microcontrollers are STM32F0, STM32F1, STM32F4 and LPC11C24, if that helps.
Projected quantities are up to 500 devices monthly in total.
Shipping any hardware between the company and the factory is not feasible.

Assumptions

The factory is a legal and reasonably honest business, they will not go at great lengths in order to exploit the process for their benefit.
Number of manufactured devices equals the number of sold devices; amount of defect products is negligible.

Solution

One of the first solution that comes to mind is to extend the testing software mentioned above so that it follows the following algorithm:

Once the device is connected and before the main firmware is flashed, the application requests the company's web API (possibly via secure protocol), sending it the unique ID of the device.
Upon reception of such a request, the company's server stores the unique ID in a database (with some metadata such as date/time, etc).
Once the confirmation is received, the firmware will be loaded.

This seems to provide the company with required data.

The drawbacks are obvious: the application can be patched in plenty of ways, the host PC can redirect the queries to a third-party server, the factory can disregard the testing application completely and implement their own alternative instead, etc. Not to mention that the manufacturing will halt if the company's web API is down, although it shouldn't be a frequent problem nowadays.

Questions

What approaches to the problem exist in the industry?
Can a more reliable solution be implemented with OTP memory (some of the listed MCU have it, other products can be equipped with a dedicated OTP chip, although it is undesirable because of cost efficiency reasons).
OTP/cryptography aside, is there an obvious way to improve the described solution that I'm missing?


texts: Thermal pads, their thickness and conductivity

texts: I would like fo know how do thermal pads work, more specifically why does their thickness matter so much even more so than their actual conductivity numbers sometimes and how do I choose the proper thickness, or rather how do manufacturers choose it for the various products/applications.


texts: Order of circuit decomposition to find thevenin circuit

texts:
In the circuit below, Vs=18V, R1=100Ω, R2=100Ω, R3=100Ω, and R4=100Ω.!  Determine RTh for the Thévenin equivalent circuit.

I know to find the thevenin resistance, all independent voltage sources are converted to shorts and current sources are converted to open circuits.

In the diagram above, if the circuit is if the voltage source is replaced with a short, then R1 // R2.  My confusion is in part II of the diagram.  I thought in part II of the simplified circuit, it doesn't matter how the final circuit is decomposed--but apparently it does.  When I simply for the circuit as I did in green, I get the correct solution, but in the the blue ink, its incorrect... why?

In part II, I thought R3 and R4 are in series and (R1//R2) is in series with R3.  Why is (R1//R2) //(R3+R4) incorrect?


texts: Multisim : Wrong Output for 1 way traffic light using 555 timers

texts:
I made a curcuit using the given diagram in Multisim but my output is of the order Green->Yellow->Green->(Yellow and Red) . Pls tell what should I do to get the output of the order Green->Yellow->Red
The link of the circuit is https://www.multisim.com/content/bXVdiYwFbtRPj7UKASFCaj/traffic-lights/ and the circuit diagram is :


texts: Is there such thing as a 9V NiMH battery with 600 mAh?

texts:
I want to buy some NiMH batteries for a meter, the stocked NiMH that comes with the meter is 9V 300 mAh NiMH. Looking on eBay I found several NiMH batteries which appear to be 600 mAh, here is a link of the batteries : 9V  Battery

Or this link (in case the other is broken):9V Battery

However, reading on Wikipedia and other sources I found that NiMH batteries have a maximum capacity of around 300 mAh, so my question is : Is a 9v NiMH  battery  with 600 mAh possible?, or are they just a Chinese gimmick that claims 600 mAh without actually delivering such capacity?

P.S. I cant use Li batteries on my meter.


texts: Web connection through Arduino with WiFi

texts:
I'd like to be able to make an HTTP request on the web to a specific server from my Arduino. I already have a Wireless SD Shield, and I am wondering if what I want to do is possible / what I would need to buy to make it work. From what I understand, I can plug an "add-on" shield to that with an antenna, like an XBee Wireless Transmitter. However, all examples I find on the web of such things use two Arduinos, one as a receiver and one as a transmitter. What I want is to use a single Arduino to connect wirelessly to the web and make an HTTP request.

It doesn't matter if HTTP itself is not supported, I can always create a basic client using TCP. But at the very least I need to be able to create a TCP connection and send data to the web through Wifi. Basically exactly like an Ethernet shield, but through Wifi.


texts:
Can the pinch-off voltage be equal to zero?
In my opinion no, because the JEFT would be off all the time, isn't it?


texts:
According to wiki, an electrode is an electrical conductor used to make contact with a nonmetallic part of a circuit (e.g. a semiconductor, an electrolyte or a vacuum). Examples of electrodes are the cathode and anode.

Given this definition, does this mean that every electric component that has electrodes (i.e. anode or cathode), is a nonmetallic part? And what exactly is the use of an electrode? Is it just used to indicate polarity? Are there other types besides anode or cathode? Can I use electrode as a synonym for pole? I hope someone can explain this without getting too technical.


texts: Relaxation oscillator with two time constants

texts:
I have the following circuit and I have to find the duty cycle of the output signal and its frequency:

I figured out that if \$v_{cond} > 0\$, then D4 will be forward biased and D3 reverse biased, so it's basically a relaxation oscillator with the time constant \$T_{b} = R_{1b}*C_{1}\$, and if \$v_{cond} < 0\$, then D3 will be forward biased and D4 will be reverse biased and the time constant will be \$T_{a} = R_{1a}*C_{1}\$.

The threshold value is 4V, so if the capacitor is fully charged at 4V and it begins to discharge, then it does so with the time constant \$T_{b}\$ until the voltage reaches 0 and then it continues to discharge with the time constant \$T_{a}\$ until it reaches -4V, then it starts charging again and so on.

If my way of thinking until now is not flawed, then on half of the period of the signal I have a capacitor charging/discharging at different speeds and so I'm stuck at finding the duty cycle. It would be quite easy if I could find out how much time is elapsed from the moment the capacitor is fully charged until it reaches zero, but I cannot use the usual relationship \$ V_{cond} = (V_{c_{stop}} - V_{c_{start}}) * (1 - e^{-\frac{t}{R C}})\$, so I'm obviously missing something. After I clear this thing out I think finding out the frequency of the output signal will be quite simple.

Any help is greatly appreciated.


texts: What is the best way to make a speaker louder

texts:
What are the pros/cons of adding more coils or getting a stronger magnet for a speaker?

Are there other methods to make them louder keeping the power supplied to the speaker the same?


texts: Find the flux leaving the surface of the sphere: What will the position of line charges look like diagrammatically?

texts: I am not able to understand how the two uniform line charges will look like in space. It would be of great help if someone could draw the uniform line charges in cartesian coordinates and upload it here.


texts: Determine the voltage drops across the capacitor

texts:
I am having troubles with one type of tasks when preparing for an exam. I think I get the way to solve it when t = 0, but I don't really know what my approach should be when t>0.

Task:

That is how I solved it:

//Edit
Updated version for t>0. I think it might be correct now. Is it?


texts:
I want to clarify the statement on LM2596 Datasheet.
It states one of its feature is Ensured 3A Output Load Current.

My question is related to the Adjustable version of LM2596
Vin: 4.5V-40V
Vout: 3.3V-37V

Does the above statement means:
No matter what voltage the input is (as long it is still in Vin range and higher than Vout), the LM2596 will still regulate with 3A output load current?

Extreme cases:
Vin: 40V and Vout: 3.3V, and
Vin: 40V and Vout: 37V
Can LM2596 regulate both cases with 3A output load current? If not, please provide me info or chart that show varying load current based on Vin and Vout.

Side notes: My reason to ask these question is because I think LM2596 should have max power rating (I can't find one yet from Datasheet), thus 37V@3A would be more than 100W. And I think the power is too big for such small IC.

Thanks for your time!


texts: Shaping negative pulses to positive ones pt2

texts:
I asked a questing a few weeks ago, and asked a follow up question as a answer to that post? Apparently that's not allowed, so I am making this post instead.

The question is based on this thread:
Shaping negative pulses to positive ones

Question:
The op amp that I chose has sufficient properties. However, I can't get my schematic to work. See the picture below for my schematic.

The output I am getting is my Vcc+, which is odd. I am not getting the pulses that I was looking for. I think I did something wrong, does anybody have any ideas?

Thanks!


texts: What is the best way to connect different LEDs?

texts:
I'm working on my first PCB for horticulture lighting and wondering what is the best way to connect all LEDs. The idea is to use both white LEDs (using Samsung's LM301H LEDs that require 2.75V@65mA datasheet) and red LEDs (using Samsung LH351H LEDs that require 2.2V@350mA datasheet) but since those require different currents I'm not completely sure if I'm connecting them appropriately, and I've been struggling to find any tips on the subject. The current wiring is as follows, in total there are 72 white LEDs and 4 red LEDs. The white LEDs are connected in series of 12 times 6 in parallel, thus this block should require 33V@390mA. Then the red LEDs are connected in series after this block, hence the entire PCB should require 41.8V (33+2.2*4) @ between 350 and 390mA. I'm not using any resistors since the PCB will be connected to a constant current driver. My questions are:

Are there any problems in having the first block draw a slightly different current than the following red LEDs, if so what do you suggest me to change?
Are there any samples of resources that explain/simplify the process of connecting different types of LEDs without using resistors?

Thank you!


texts: Run actuator at higher voltage and with lower dutycycles

texts:
I have an actuator which is rated at 12 VDC input voltage (0-15) with a maximum allowed duty cycle of 20%. The already existing voltage levels in my system are 5V and 22V, and since I am weight constrained I would rather not add another step-down converter.

What would be the implications of running at a higher voltage (22 Volts) and a lower duty cycle, say 11%, resulting in the same average voltage and current? My PWM-frequency is about 20kHz and the motor is a simple brushed, dc motor.

More specifically, would I get away with it, without damaging my motor and severely reducing its Lifespan?


texts: PWM modulator in voltage mode buck converter

texts:
I am referring to datasheet of LM3743 block diagram in Pg no. 5

The EA and PWM Comp is in leading edge modulator configuration. According to my understanding SR latch which comes after PWM Comp must be R (Reset) must be triggered by Clock and S (Set) must be output of PWM Comp.
Example below gives better understanding.

Which determines duty cycle on time of Vx or off time in figure b ? What are these configurations called in industry (keyword) ?
Should IL (Inductor current) should have raise during off time of Vx (Figure b) or fall from peak value during off time Vx (Figure b)
Further latch output Vx (Figure b) is given to gate driver high side and low side.


texts: Does wire diameter affect the electricity bill?

texts: Does thickness of wire affect the electricity bill, for same load? Thicker Wire has lower resistive losses ,does this reduce power bill? Does a longer length of the same diameter wire increase bill by the same reasoning?


texts: Measuring power consumption of VHDL code

texts:
I am trying to find power consumption of my vhdl code.I am going to use the power estimator in xilinx 9.2.Do the power analysis results vary in xilinx 9.2 and xilinx 14.7??

Also will xilinx provide accurate power analysis results ??

Is there any other tool to find acccurate power consumption of vhdl code??


texts:
I'm currently working on designing a circuit that will utilize two piezoelectric stacks (5mm x 5mm x 20mm Parker stacks) that are loaded into a housing in parallel mechanically.  The circuit I'm trying to design will be a pressure sensor that utilizes those two stacks the way to measure the dynamic pressure and I have examined some circuits that utilize piezoelectric diaphragms (eg: Piezoelectric Sensor and the ADC), but I am unsure of whether or not the same kind of circuit would be applicable to piezoelectric stacks.

Some of the other circuits I've seen utilize diodes, while others utilize capacitors, and all of them utilize some type of op-amp (I was thinking of using the TLV2771) so I am kind of at a loss of what the best way to design this circuit would be.


texts: Reading a simple diagram, how to practically implement this on a breadboard

texts:
So yes, I'm brand new to circuitry, and I'm looking to implement a very simple diagram in order to boost a 3.3v output to 12v output.

I've picked up a lm317T from the local electronics shop and I'm currently supplying my breadboard with 3.3v.

What does the practical application of this look like?

I realize this is super simple for most of you, but I'm not totally up on how it works.

Is R2 (resistor 2) connected to the ground?
How do I figure out which resistors I need?
How do I calculate the formula to take a 3.3V input and dump out a 12V output?

$$V_{out} = (1 + \frac{R2}{R1}) +  ADJ_{R2}$$

note: R2 is not adjustable in my scenario, but rather it's going to be a fixed resistor in order to give a consistant output


texts: Why is the maximum efficiency of a push-pull amplifier 78.5%?

texts:
One of the practice questions for my upcoming test is this:

After some googling, it seems like the correct answer is A. But why?


texts:
Is it possible to get the Fourier transform in LTSpice? For example I'd like to plot the Fourier transform of the following signal:

$$s(t)=A \space sin(2\pi f_0t)$$

Can you attached a LTSpice example file please?

Thank you for your time.


texts: ERC error "ErrType(3): Pin connected to some others pins but no pin to drive it"

texts:
The following simple circuit gives the following error message
when running ERC check:

ErrType(3): Pin connected to some others pins but no pin to drive it
@ (2.5000 ",4.0000 "): Cmp #PWR01, Pin 1 (power_in) not driven (Net 5)

The CONN_2 component is supposed to receive external power. I have not made any changes to any pin configuration of it which I probably should. How do I
correctly do that?


texts: Systick interruption doesn't trigger when handling another interrupt

texts:
I am experimenting with the STM32f4 discovery and i tried to use a delay (based on SYSTICK) in an EXTI_IRQ handler but i figured out that while the EXTI handler is triggered the the systick handler doesn't trigger , here's my code :

extern volatile int del ;
void EXTI0_IRQHandler(void) {

  if (EXTI_GetITStatus(EXTI_Line0) != RESET ) {
        /* Do your stuff when PD0 is changed */
         del=1000 ;
         while(del)
       {
       //do something
       }

       /* Clear interrupt flag */
        EXTI_ClearITPendingBit(EXTI_Line0);
    }
  }

And the systick handler :

void SysTick_Handler(void)
{
  if (del--)
 ;
}

So how can i solve this problem .


texts:
I'm attempting to design a data logger and the AD7193 seems to fit my requirements. I'd like to drive it by an external clock in a GPS-disciplined loop while sampling at an integer rate, as this would simplify comparing signals from distributed sensors. I am looking at choosing a SiT5358 oscillator which eliminates the need for a DAC as there's a digitally-controlled version. I'm new to designing hardware systems and have (at least) two questions about this pairing:

The sample rate of the AD7193 is proportional to the f_CLK/A where A is a constant depending on many configuration options. Supposing A is fixed, then a desired sample rate could be achieved by varying f_CLK. Are there limits to how far from the internal 4.92Mhz clock rate we can vary f_CLK and still have stable operation?

The datasheet states, "[The] internal clock has a tolerance of +-4%." This seems to imply that operation would be unaffected by a deviation up to +-4%. Is a greater deviation advised with an external clock?

The SiT5358 comes in LVCMOS and clipped sine wave output flavors. The AD7193 datasheet suggests either is tolerated by the AD7193, though they are attached slightly differently. Are there reasons to choose one over the other?


texts: Choosing a Relay to Operate Solenoid Valve

texts:
I'm working on a project in which a solenoid valve needs to be triggered when a sensor detects a passing object. I have the concept and general design down, however I need some help with the specifics.

Essentially, a photoelectric retro-reflective sensor will detect an object, send its signal to a relay which in turn will trigger a 24 Vdc solenoid valve.

The sensor's signal voltage is listed as approximately Uv / < 3V and output current Imax is 100 mA

Sensor Datasheet

The solenoid is 24 Vdc and 8W, with an inrush VA of 25 and hold VA of 14.5

Solenoid Datasheet

24 Vdc power supply is to be used

Question 1: What data do I need to consider (from that listed above or otherwise) when choosing a relay? Specific relay suggestions are welcome :)

Question 2: Once the relay has been chosen and provided its specs suit the sensor and solenoid, is any further circuitry required i.e. a diode for the inductive load etc?

As is probably evident from my questions I'm quite inexperienced in this area so sorry for any ambiguity but thank you, your help is much appreciated!


texts: does SPI master always receive data in same time he send data

texts:
I try to communicate with EPPROM using SPI. the image illustrate the read status register sequence.

the program I'm using checks the receive data register each time SPI finish sending (send data register empty).

my question is, did SPI master receives data on MISO when he send the instruction data as shown in image below. and in general did SPI always receive data on MISO in same time he send data on MOSI?

in other words, to get status register out data, should I send other NULL data (0x00)??


texts: Old Record Player Motor Doesn't Have Torque To Start

texts:
I am restoring a jukebox from 1953 (AMI E-120).  Everything is going fine except the main drive motor, an A/C induction motor, cannot start under the load of the platter.  It starts fine when the belts are off, but under full load, it won't start. And once I start it with my hand, it runs fine.
That makes for a pretty worthless jukebox.

(The pics above are of another one that looks like mine)
I've taken the motor apart, and cleaned and oiled everything.  It looks spotless, but it still doesn't have the guts to start the player.
What steps would you do next?  Have the magnets gotten weak?  Or do the coils need re-wiring?
Thank you in advance.


texts: Time step Error In Multisim Using 555 timer

texts:
I am trying to simulate a circuit in multisim and I keep running into the following error. (new to multisim) I attached a picture of the circuit and error. Any advice on how to fix this?

The purpose of the project is to activate the green LED (left) for 12 seconds when the buttons in series on the left are pressed simultaneously. If any of the buttons in parallel on the right are pressed, the red LED should light for 4 seconds and reset the the 555 timer on the left. This was how we thought the circuit should work but we could be wrong.


texts: I'm curious as to the ability of an antenna designed for a specific wavelength, to work on another wavelength. For example, I have a half wave antenna that is 1.5m long, which would be ideal for a 100MHz signal. Now would that same 1.5m antenna work well on a 150MHz signal, or an even higher frequency? At what point would it no longer work? Are there any quantities that are minimized?


texts:
I am completely new to electrical engineering.
For a school project I am making a crank-electricity generator. My idea was to attach a crank to a stepper motor and when I crank the shaft, use the electrical output to power an LED.
I want a smooth flow, so I was going to attach a capacitor to the motor so the LED wouldn't flash because of the inconsistent turning motion. However, when I did so the capacitor didn't work.  Moreover, the shaft became hard to turn. I tried many different types and capacities of capacitors, but that didnt' solve the problem, so I tried switching to a DC motor but it still didn't work.
When I hook my capacitor and LED to a battery it functions properly.


texts: Overcurrent protection won't let motor spin up

texts:
I'm using a TLE5205 H-Bridge to drive a small DC motor.
The setup works just fine with small load (an LED for example), however once I connect the motor, it won't spin, only flicks slightly each time the direction of the output current is changed.

I'm pretty sure this is caused by the integral overcurrent protection feature of the H-bridge, since the error flag pin state behaves according to this situation. The OC protection is set to trigger at I = 10A (As seen in the datasheet). When the motor spins continuously, this is more than enough space, since it draws a steady current of 0.7A at 7V, however, while stalled, the motor draws up to 21A which is a lot more than what the OCP tolerates.

The IC doesn't seem to have a current limiting feature aside from the OCP, which shuts it down completely. I could potentially connect a resistor in series with the motor to limit the current it draws, however this would also limit the overall power of the motor, which I don't want. Is there a way to solve this issue, preferably without having to redo the whole PCB which has already been manufactured?


texts: Can someone explain and help me with this circuit?

texts:
This is a board that controls a circular knitting machine, this machine has 108 MPF feeders, those feeders controls 108 yarn, when a yarn breaks the feeder lights its bulb the machine decelerates to stop, at this moment, the worker must fix the yarn and run the machine again, I want to take 2 wires from somewhere to activate a relay when the switch of one or more is closed I want to use this relay to operate a bulb I'll put it on the top of the machine so the worker can see it easily and come to fix the yarn again:

please see the pictures below:

This question contains a unique parts which differentiate it from my other question, I'am asking for the function of the components in this circuit and how can I benefit from them.


texts: Tripping Power supply but no short circuit

texts:
I'm having a bit of a hard time diagnosing a problem with a circuit I have just soldered onto stripboard, the circuit works perfect in simulation.

The scenario is that I have a circuit with a few opamps and transistors and am using a lab power supply in series to provide +- voltage rails.

If I connect positive and ground to my circuit everything seems fine. In terms of the power supply. However if I connect the negative rail to the board then the supply that's providing the negative rail trips and goes into CC mode, the voltage on the display drops from 12v to around 0.1v (I can't remember the exact but its low), if I remove the negative rail connection the supply restores and comes out of CC mode.

This happens with both just ground and negative and positive and negative connected. So the problem is with the negative rail / connection.

However, when I test with my multimeter on the continuity setting, there is no beep when I touch the ground and negative or positive and negative. So this to me means there's no short?

So I'm not sure what I'm looking at or what the problem is...I assumed the power supply going into CC mode meant there was a short somewhere but I can't find anything and I'm not sure why its happening for both ground and positive rails.

This still happens when I remove all the opamps from the chip holders so theres no shorting happening through a potentially dead opamp.

EDIT: added schematic photo. Also another thing I discovered is that when I do a continuity test from the black dot and the ground rail I get a beep.

Testing is so done with pin 3 of the first opamp disconnected.


texts: What is the difference between GPS and GNSS?

texts:
I'm looking for a GPS module for my project but I've found some modules with GNSS what is the difference between GPS and GNSS?
What module do you recommend I'm using BLE?

Thanks


texts: Derivation of formula for temperature coefficient of resistance

texts:
https://www.electrical4u.com/temperature-coefficient-of-resistance/
Referring to this article, I'd like to compile two key formulas for the temperature coefficient of resistance.
First is the formula at zero temperature.

Next is the formula at a specific temperature.

To put it more simply, the reciprocal of the temperature coefficient of resistance in the second formula is equal to the inferred absolute zero temperature, $ t_o $. So the second formula can be interpreted as, if you want to get the temperature coefficient of resistance at a given temperature that isn't zero you have to add that value to the inferred absolute zero temperature.
I'd like to know, is there a derivation for these formulas? I mean, I totally get how you could define the first formula to just be a reciprocal of that quantity. But with the second, I don't get the intuition behind just adding in the denominator. I mean, it doesn't have to be a derivation but at least some intuition on why it is like that so it would help me remember it other than just straight up memorizing.


texts:
I try to learn the theory of Transistors and there came up several questions, I can’t find an answer for.

I’ve read that in order to use a transistor as a switch the base current should be high enough to fully saturate the transistor. If the base current is too low it could destroy the transistor. Why does the transistor get destroyed with less current?
There was a sample where they switched a solenoid (5V, 1.1A) with a TIP120 transistor. When I check the datasheet the PC is 2W@TA=25°C, but isn’t 5V*1.1A already way too much for the TIP120? Does it have anything to do with VCE?

I’m sorry for these basic questions but I’m pretty confused right now.


texts: What is the common cause of short circuit in PCB design

texts: In PCB design there is some clearance and creepage distances to respect according to the UL 60950 standard for example, I want to know why this distances need to be respected in PCB design, what is the risk in DC circuit if the distances is not respected.


texts: I got this receiver. Its output power is 2 x 30W on 8 ohms. My question is: is it possible to combine the power from these 2 channels and connect both channels to a single 60W speaker? And if it's possible what will I need. My goal is to connect just 1 bass speaker to the whole receiver, using its whole power.


texts: Why does my summing mixer max out at 5.39V when my rails are roughly +/- 11.7V?

texts:
I've been working on this project to sum and scale DC voltages from 2 sets of four 0-5V variable voltage dividers, into two separate mixes with identical circuits. In my previous version, I fed the voltages straight off the dividers without buffers and ended up having lots of problems with voltage droop, as the mixer was forming a parallel path to ground for each divider.
I added voltage follower configured op-amps to buffer each stage and that solved my issue. Now I get the correct maximum voltage when all stages are turned up fully, (about 5.09V) but I've run into another perplexing problem. Each summing mixer also has another input from an external source that is clamped to a voltage range of +/-3V, and is not scaled. When the signal coming into the mixer from the dividers is at it's maximum, (5.09V), and I apply a 3V external signal to this non-scaled input, the voltage at the mixer output doesn't respond as expected, only increasing a total of roughly 25mV from the 5.09V instead of the full 3V. If I attenuate the voltages at the dividers to offer more headroom then the circuit reacts normally to external voltage, adjusting the output as expected in response to the 3V input.
My question is: Why is this circuit preventing the output from going higher than 5.35V?
It feels like I'm reaching the limit of the op-amp swing, but the supply is +/-12V (minus 0.3V Schottky diode drop on each for reverse voltage protection). The op-amp is an LM324, so unlike the TL074, it should be capable of going to the negative rail, and I can't imagine the upper voltage limit being 5.5V below the positive rail. Is there something I'm missing with regards to this op-amp's output range?
Here is a picture of the schematic, is there anything else clearly amiss?


texts:
I am trying to simulate a load in two different instances. In first instance i want the load to have a constant dc value of 2A, and in the second instance PULSE(2 11 1.06 100n 100n 0.30 0.8 1).
I know that using the command .step param X 1 2 1, i would be able to run the simulation twice. I want to know how to write the command to run both the load instances..

simulate this circuit – Schematic created using CircuitLab


texts: Formula for how much power a motor generates

texts:
I'm interested in the formula for how much power a handcrank motor can generate.

I dont know much about electrical engineering but I'm assuming it's related to a few factor.

The speed on which you are cranking
The amount of copper wrapper

But what I'm confused on is the exact formula.  E.g.

What would generate more power more wrapping of the coils or thicker wire? Is it based on total mass?


texts: Crystal PCB Layout Design on Re spin Board

texts:
I'm trying to redesign the layout with a 8 MHz crystal(XT1) for atmega328p micro controller. Since this micro controller uses internal oscillator,UART Communication does not work reliably on current design.So I decided to go with external crystal for the production.

Since this board works fine with all the other functionalities except UART,we need to re spin the board with minimal changes.The red represents the top PCB layer and blue is the bottom PCB layer (it's a 2-layer design).Due to the placement constraints on the bottom side of the PCB,I placed the Crystal and its Load capacitance on the Top side whereas the micro-controller sits on the bottom side.

I've been reading through several recommendations specifically for crystals layout design.I am sure that design does not meet most of them(ex.Avoid vias). I am concerned about the functionality of the PCB, especially from EMC problems.There are really no high frequency signals on this board except 8 MHz. Can anybody give some suggestions on how the PCB can be improved?


texts:
I would like to build a big AC-DC SMPS. I built a little one based on ST's VIPer22A. This is a nice little IC that can give up to a couple watts (my design was 5V 1A). It was easy enough to design using ST's online tools: it calculates all the required component values (especially the transformer).

But, for a 400W supply (50V 8A) it goes a little out of spec for the tool. The IC they recommend is L6566B. The transformer is much larger than what the tool is able to handle (EE60 core), and it requires litz type wire for all coils. I'd prefer if litz wasn't a requirement.

What IC is there that can handle this kind of power AND offers some sort of tool to calculate the required transformer?

I know anything mains-related is dangerous by its nature, but I have the tools for this (an isolation transformer, for starters).


texts:
It is almost the reference design from the DS. The only differences are those quite large inductances I had to add to remove the noise.

The neg voltage is used to power RR OPamps feeding the ADC the current is never larger than about 20mA

What can cause the problem? At some point (after a day, sometimes month or mostly 5-6 months) the pump dies and stops generating negative voltage.


texts:
I'm trying to wire as per the following wiring diagram.

I completed wiring as below, and timer is switching on, but at the programmed time, light is not switching on, anything wrong with wiring.

See the wiring that I did, shown below..

Please tell me what I'm doing wrong, why my bulb is not glowing at the specified time in timer?

For user manual click below

https://www.google.com/url?sa=t&source=web&rct=j&url=https://cdn.shopify.com/s/files/1/0819/3759/files/Euro_Controls_EDT811_822_digital_programmable_timer_Instruction_eManual.pdf&ved=2ahUKEwi3h6HfrbTpAhUafSsKHTCdBfIQFjAAegQIAhAB&usg=AOvVaw0dRTUlIxtpP0U4aJpsoM1g


texts: How do I control a brushless DC motor without an ESC with Arduino

texts: Is there a way to control brushless DC motor removed from a CD-ROM drive without using an ESC by using an Arduino.


texts:
I am looking for a 32-channel ADC (24-bit resolution) which can simultaneously sample all the signals. But I could find only 8-channel ADC with the above requirements.

So, is it possible that I can use multiple 8-channel ADC's to interface with FPGA at the same time?


texts: IMU (ADXL345 & ITG3200). Triple Axis Filter

texts:
I am building a TriCopter based on the FEZmini .Net Micro Framework.

I have an ADXL345 triple axis Accelerometer and an ITG3200 triple axis Gyro which I am interfacing via I2C.

I am able to get data from the two sensors and they seem to be working fine. What I am having a hard time with is finding a filter that can successfully fuse the two sensors data together into useful IMU data.

I have converted the Kalman Filter presented by Varesano.net to c# but without any useful results. The filter simply does nothing when the IMU moves.

I also converted the complimentary filter presented by nuclearprojects.com to c# with more success, but not complete success: Although the X and Y values are stable, the Z axis keeps rotating fairly constantly, which means I have no good data for Yaw of my TriCopter.

If you need more background on my project, please let me know or have a look at my project on my site at: http://bit.ly/TriRot

Any help would be much appreciated.

Thanks in advance

Gineer


texts:
I've coded this state in VHDL, but I am having problem getting into a certain state.

    architecture Behavioral of game is
type LIST  is ARRAY (11 downto 0) of std_logic_vector(3 downto 0);
Constant LISTEN: LIST := ("0010","0100","1000","0001","0100","0010","0010","0010","1000","0001","0010","0001");
begin
process(CLK)
variable prescaler: integer range 0 to 50000000;
Variable control: std_logic := '0';
variable pointer: integer range 0 to 11:=0;
variable test: std_logic:='0';
variable error: std_logic:='0';
variable top_pointer: integer range 0 to 11 := 0;
variable buttontimer:  integer range 0 to 50000000 := 0;
begin
if rising_edge (clk) then
            if control = '0' and error = '0' then
                winLEd <= "01";
                    if(prescaler < 49999999/1) then
                        prescaler := prescaler + 1;
                    else
                        prescaler := 0;
                        top_pointer := top_pointer + 1;  -- Top pointer increment
                        control := '1'; --- trigger event to get to new state
                        --test := '0';
                    end if;
            end if;
                    if control = '1'  and error = '0' then
                        winLEd <= "11";
                    --  test := '0';
                        if pointer > (top_pointer) then     -- If pointer is higher than toppointer, it means the sequence has to be incrementet.
                                LED <= "0000";
                                control := '0';
                                pointer := 0;
                                test := '0';
                                error:= '0';
                        end if;
                        --if switch = "0000" then
                                if switch = LISTEN(pointer-1) and pointer<= top_pointer  then -- Checks if the switch match the sequence.
                                    test := '1';
                                    buttontimer := buttontimer + 1;
                                    errorLed <= "01";
                                        if switch = "0000" and test = '1' and buttontimer < 49999999/1 then
                                            pointer:= pointer +1;
                                            test := '0';
                                            errorLed <= "10";
                                            buttontimer:= 0;
                                        end if;

                                end if;

                                if switch /= LISTEN(pointer-1) and switch /= "0000"  then  -- if it doesn not match, error will be set high => trigger an new state.
                                    error:= '1';
                                end if;
                                        if switch = "0000"  then
                                        Led <= LISTEN(pointer-1);
                                          errorLed <= "11";
                                            error:= '0';
                                            control := '1';
                                        end if;

                        --end if;
                    end if;
                    if error = '1' then  -- stays here infinetly until board is reset.
                                winLED <=  "10";
                                errorLed <= "00";
                                Led <= switch;
                    end if;

end if;
end process;
end Behavioral;

I am having problem incrementing pointer here. Listen is an array, containing  different 4 bit patterns. The Switch is the switches on my FGPA, I've used errorLED to see where I am in code, I see that I am entering this if statement, when the switches mathes the 4 bit pattern.


texts: Development kit for learning USB device driver development

texts:
I want to learn writing device drivers for USB devices (on linux kernel or microcontrollers, if that matters). Hence, I am looking for sample USB development kit.

e.g. when I wanted to learn I2C, I could find hundreds of I2C based sensors, LCDs, switches, etc. Now I am looking for similar simple beginner level USB devices that can be used to learn USB driver programming. It could be a small thumb-drive shaped circuit board with LEDs and buttons, that I can blink or receive button press events over the usb.

Can someone please point me to such device or kits, if they exist. I searched a lot but always ended up with wrong search results, probably I need more fine-tuned search keywords. I do not want to begin with a USB mouse or USB keyboard to learn USB driver programming. I would love it to be simple to begin with.

EDIT
I am just adding the examples here which I found, it may help someone in future. However, I am looking for kits intended for USB development that are developer friendly (with documentation). The devices below are not.

Consider this example : https://www.linuxjournal.com/article/7353 (a USB based LED lamp). I am looking for such kind of devices.

Another example : here is another article which makes of similar device : http://matthias.vallentin.net/blog/2007/04/writing-a-linux-kernel-driver-for-an-unknown-usb-device/


texts: I need a quad NOR gate that is pinned out like a quad AND gate? Is there a good way to search for this?

texts:
So I have the footprint for a 2-input Quad AND gate (SN74LV08A) on a PCB. It is a 14-TSSOP and is pinned out like this:

However, I want to change the logic to four NOR gates. The problem is, all of the NOR gates seemed to be pinned out like below:

Is there a database for this kind of thing or is going to digikey or mouser and playing the guess and check game my only option?


texts:
Could somebody please explain the two logic gates with only the one input, A and B, respectively??

It is a NAND gate, with a box just before it.

What is this box?

Why only one input?


texts: When is a reverse current diode protection needed for linear regulators?

texts:
I'm mainly having trouble with the wording in datasheets.

So I know diode protection can be useful in a situation where you're using a large capacitor at the output of a regulator and the fault case of the input shorting to ground occurs. The diode keeps the current from going through the regulator(correct?)

So when looking at regulator datasheet, if it's not explicitly stated that it has reverse current protection, does that usually mean I should use diode protection there?

The datasheet mentions it has protection against reverse output voltage and reverse input voltage. I'm not sure if those mean the same thing as having reverse current protection.

  In addition  to  the  normal  protection  features  associated with monolithic regulators, such as current limiting and thermal limiting, the device protects itself against reverse input voltages and reverse output voltages.

But then I also see this:

  A parasitic substrate diode exists between OUT and IN of the LT3015. Therefore, do not drive OUT more than 0.3V below IN during normal operation or during a fault condition.

I'm guessing that statement is enough to say that diode protection will be needed from output to input?

The datasheet in question would be the LT3015.
http://cds.linear.com/docs/en/datasheet/3015fb.pdf


texts:
How can I choose between the two?
When can I use single and When I must use double? ( speaking of simple circuits).
Do I have to use a double layer when using ICs?
When u
If I have a circuit consisting of an arduino, a motor driver and a Bluetooth module can I use single? If no , why not?


texts: Can I load program a micro with a .out file like I can with an ELF or HEX?

texts:
I have a binary of the form ".out", from a project that was generated by an IAR development suite. The release directory does not have an ELF or HEX file. This is for the STM32F103 ARM based micro controller. I need to program the binary onto a board off site an so I will not have an IAR development suite.

Can I use a JTAG debugger like the Segger J-Link or Atollic's ST-Link to program the board with the .out file? I know I can program .ELF file in this way. Is it possible with .out files? Can I convert it to an ELF file?

Thanks!


texts: Trying to identify MOSFET - top markings DAX620 1411

texts:
My RC car ESC MOSFET is burnt. I'm trying to find a replacement for it, but I can't find the number or specs anywhere. The MOSFET has these numbers: DAX620 and below is 1411. Can someone help me identify it?
And the MOSFETs are burnt so bad I can't see what is written inside the little circle on top. On the others it reads p1r or j13, j14, j15,j16. Does this matter?
I want to be an electronics engeneer, if you could explain, so i can learn new ways of finding component, it would be nice.