texts: Speed and Position Control for high-volt Elektro Motor with AVR

texts:
Is there anything that one can purchase to control speed and position of a high voltage electro motor?

I am quite a bit of a noob at this but I could think of a circuit using photo-sensors or hal-sensors to estimate speed and position of something that's being moved by this motor.

Is there anything that fulfills my needs or would I have to create something like this from scratch?

I know there are servo-motors that can be controlled very precisely but they are also quite expensive - additionally I don't need that much accuracy a servo-motor can provide.


texts: Signal Integrity with Parallel Switch Control

texts:
Please excuse what is likely to be a very basic question, but I am an ME, and this stuff is somewhat magic to me. First, I'll provide a minimal, generic question, and then, for those interested, I'll provide all of the application details.
I have a signal wire, and when a switch is flipped from its normally closed position (along with a normally closed safety switch), I want the signal to be broken. So, any condition where any switch is in its resting position should allow signal flow.
I intend to spit the signal line into 2 parallel lines, with a switch in the middle of each branch.
My question is this, can I reasonably expect the signal integrity to remain adequate after doing this, even if the branches aren't the same length, and/or if the length is nominally the same? Also, can I expect the signal integrity to remain adequate when signal is flowing through both switches, and one switch gets opened, or when signal is flowing through 1 switch, and the other gets closed?
I am not concerned about the transient response going from no signal flow to one or both switches being engaged, which will make more sense for those who care to read the application, described below.
The application is for a Jeep (2015 Wrangler). The newer Jeeps have an ESC system that remains intrusive offroad, even when "off". This is less true for a stock Jeep, but some aftermarket mods make the system a problem. There is a common mod that involves a momentary, NC switch which is placed in an accelerometer signal wire. Interrupting that signal kills the ESC system. Earlier, I said I wasnt worried about the transients that could occur from signal restoration, and that is because restoration of ESC function requires the ignition to be cycled after signal is restored. What I want to do differently from most Jeep owners is to have a main safety switch, which will need to be opened in order for other switches to do anything, to prevent accidental engagement. My concern is in the signal integrity at steady-state single and dual switch closure, considering a potential difference in lead lengths, and also in the potential for there to be noise in a 2-1 or 1-2 switch engagement.
Also noteworthy is that I intend to make the main safety switch a DPDT switch, which will also be used to switch ground (NO configuration) for other nearby circuits. I'm not sure what cross-contamination I may experience from this, but I think it will be minimal, as the other circuit is just signal ground for 2 relays.
Edit...more details:
I've added some drawings and photos to help clarify.  The diagrams are my attempt at illustrating the factory circuit, the most common modification, and what I want to do.  I've also attached a photo of the actual switch panel in my Jeep.  The switch labeled main will be a DPDT switch, where the normally closed terminals will be used for the circuit in the diagram.  There is a blank spot for a switch (where the little plastic cap is), where I will put an SPDT switch, and again, I'll use the normally closed terminals.  The idea is that ESC will be disabled by "engaging" (opening) both switches, as seen with 2 switches in one of the attached photos (where we pretend the top switch is the one I'll be adding).  My concern is that this will introduce noise in the signal, and cause the stability control system to behave erratically when it's on, and/or when only one switch is being opened/closed.


texts:
I am trying to figure out how to interface a A2235-H GPS module.

The datasheet says that one pin(nRST) must be connected to open collector or open drain output of uC while an other one(ON_OFF) must be connected to push-pull output of uC.

I am using an AVR uC. Is it wrong to connect directly in AVR pins or should I build some circuit between?


texts: Are voltage and current the same when it comes to device protection?

texts: Perhaps I'm not thinking about this correctly, but I've never understood if there is really a distinction between voltage and current being harmful to an electronic device of any kind. Obviously, current is the the actual moving electrons which we know can transfer energy in the form of heat which can be dangerous in large amounts. Voltage on the other hand, is just a potential difference, but the force that causes current. So yes, without a voltage there would be no current; but if we could apply a voltage across some electronic device and stop all current, the device would be fine no? Isn't it ultimately the current that causes damage or can destroy some electronic device?


texts:
I am building a project which requires a very fine servo resolution (<=.1 degree). I understand there is a lot that goes into servo resolution like digital v analog, dead-band, # of poles, etcetera. However, all other things being equal, is there any reason to think that a micro servo would not be as precise as a standard-size servo?

Edit: Let's assume I have two servos of different sizes. Both are digital, 5 pole, geared servos and I have programmatically set the dead-band to 0. Are there factors I am not considering, like the electronics or manufacturing process, that would make the larger one more accurate than the smaller (or vice-versa)?

Edit2: I am building a drawing robot as a hobby project so I'm interested in model servos (ideally < $100) and my question is specifically for that market. I am more interested in resolution (making very short lines) than accuracy (the absolute positioning of the pen on the page) as long as the accuracy is fairly consistent for the whole drawing


texts: Will a CC1120 IC be burnt during transmission if antenna is removed

texts:
I am using a TI CC1120 evaluation kit which is working in the 800MHz band amplified by a C1190 to a 27dBm output power.

I would like to know if it would damage the board to be used with no antenna connected to the SMA adapter.

I am curious about the reflected power. Would it be reflected back to the chip and damage the same?


texts: GSM/GPRS reach for Class 4 2W 900MHz/ Class 1 1W 1800Mhz

texts:
I'm studying differents GSM/GPRS modules and all of them have two operation modes depending the frecuency (900MHz and 1800Mhz). If I'm not wrong, for the same power higher frecuencies have a lower reach and higher trassmision rate than lower frecuencies.

My question is, how can I know the reach in meters of each range for a power of 2W or 33dBm in 900MHz and 1W or 30dBm in 1800MHz.

Thanks for your time!


texts:
For now, I'm sending bytes from FPGA (verilog) to serial at 115200 bps.
I would like to send at higher speed and connect to a bluetooth module (RN42).

UART (SPP or HCI) and USB (HCI only) data connection interfaces.
Sustained SPP data rates - 240Kbps (slave), 300Kbps (master)
HCI data rates - 1.5Mbps sustained, 3.0Mbps burst in HCI mode

Then, now, I would like to implement a HCI UART in order to get max 3 Mbps.
I didn't find anything clear about how to implement this.
Could you help me? What does change? Should I just send my data at higher bps and it's done?
It's the first time I'm trying to implement another way to send data than serial.


texts: Motor Driver - Microcontroller-less and no IC chips available

texts:
I am looking to control a DC motor with the use of an IR-LED detection circuit.

I am hoping that when the IR-LED circuit detects a wall approaching, the robot will pivot and move towards the other wall in a 45degree angle or so.

However, I need help driving my motor.

I do not have a microcontroller and no IC chips so I can't use a L293 or anything like that.

What is the best way to create a motor driver with the IR-LED used for switching?


texts: Ripple and Ringing from Cheap Chinese Boost Converter

texts:
I'm using a cheap chinese XL6009 adjustable converter module to boost 5 V to 12 V. To test this converter, I used a 5 V supply, a 120 Ω ohm load to draw 100 mA current (100 mA at 12 V is the requirement of my target circuit), hooked up a DMM to monitor the voltage and an analog current meter in series with the load, and connected an oscilloscope across the load. It was drawing about 0.25 A from the source (a regulated lab supply), to give an efficiency of 96%, but the results were not particularly promising (here, V/div = 50 mV and T/div = 0.5 µs):
.

I housed the converter in a metal enclosure, and there was a definite improvement in the ripple characteristics (here, V/div = 10 mV and T/div = 0.5 µs):

Even then, these 40 mV spikes will eventually kill the capacitors in my target circuit.

Just to test, I ramped up the boost converter to 15 V and then hooked it up to a 7812 with 1 m wires running from the enclosure of the converter to the breadboard on which I have my regulator. The input side filter capacitor is 470 µF and the output side one is 22 uF (I tried many combinations but it didn't make much difference). I can't embed more images directly, so it's here (V/div = 5 mV and T/div = 0.5 µs): https i imgur com M43un2W jpg (sorry).

What am I doing wrong and how can I fix it?


texts: Tracking Down a Datasheet for an unknown Optical Sensor

texts:
I scavenged an optical sensor out of a wireless mouse I had, and now I'm trying to track down the data sheet.  Honestly, the pinout (from what I could determine looking at the board in which it was soldered) seems pretty similar to a "ADNS2620" (like this one at sparkfun: https://www.sparkfun.com/products/retired/12907) but I'd like to track down a data sheet to make the process of figuring it out a little easier.  Pictures provided below, direction helpful.

For those curious, the text appears to say "FCT3065-XY" and "16365A6".


texts: Arduino - Weird behavior reading speaker level input

texts:
I'm trying to detect when speaker starts playing audio, my speaker is connected with a 10uF 50v in series with the positive (red) cable coming out of my receiver, and negative to ground.

Speaker (+) ----- || ----- A0
Speaker (-) -------------- GND

I was reading values from around 200 I believe. I had something like input > 210 and it worked(to detect audio). Now at some point and I'm sorry to say I have no clue what changed the reading changed to 100, it looked weird but at that moment I didn't care much and changed my control value to 110.

Now this happened again and I'm reading 36. I'm kinda worried now I'm doing something horribly wrong. Any ideas?


texts:
I intend to design a CMOS voltage regulator that takes 2.5V supply and outputs 1.2V. I am starting off with an opamp+pass transistor design.

Will there be a specific advantage to using an NMOS pullup device vs PMOS pulldown for the pass transistor?

Additional details: The regulator supplies this constant voltage but is also supposed to sink a lot of current (~5 mA)


texts:
How to calculate the input current consumption of the buck converter.
It's seem that the output current only depends on the output voltage, duty cycles, input voltage, and coil inductance. Does the output current have any relation to the input current.


texts: Boost Converter why is the calculation result not the same as simulation

texts:
guys just asking why is my simulation result not the same as my calculation I am not sure why.
My design has the specification of Vin (power supply) = 1.5V , Vout = 5Volt with a Pout(power output of) = 1 watt , running on 10kHz frequency with 0.1V voltage ripple.

My calculation ^

My Schematic ^

The output voltage ^
Using the MOSFET Si7866DP

I am pretty sure that my calculation is correct but I am not sure why is my output not as my calculation. I did a few tests and I am pretty sure it has nothing to do with the mosfet(not sure if I am right). But can anyone tell me what's wrong and how do I fix it so that the output will be 5V instead of what I got?


texts: Does Inverting Op Amp Require Buffer at Output to Prevent Influence from Load

texts: If the final stage of an op amp cascade is an inverting op amp, should its output be sent through a buffer, or can a load be attached directly to the output of the inverting op amp without fear of undesirable effects?


texts:
How to change the range of antenna for non-contact voltage detection?
For example I would like to detect 220 VAC at 1 cm, 2 cm or 5 cm.
Can I make these changes with potentiometer?
I attached my circuit

TNX

if I find 220 volts at a distance of 10 centimeters in normal mode, I want to change the distance between 1 cm to 10 cm with a 2 key or one potentiometer or one keys .
what should I do ?


texts: RC circuit with a constant current source

texts:
I am trying to simulate a series RC circuit excited with a constant DC current source in LTSPICE. The expectation is that it should linearly charge the capacitor with a constant current flowing through it however what I am seeing in the simulation window is a zero or nearly zero(femto ampere) current always through the capacitor. Can you please help to understand where I am going wrong? Attaching images for my simulation.
P.S. I am using basic Capacitor in ltspice, no specific model from it's library.


texts:
I found this circuit from Encyclopedia of Electronic Circuits Volumes 1 by RUDOLF F. GRAF
I used Multisim to simulate.
When switches S1 and S2 are open (U1A@3 and U1B@6 are floating) and I measured by Oscilloscope (and probe) and found that the voltage are 6.6V.
I got the following results after measuring by Oscilloscope:

  U1A@3 = 6.6V,  U1A@2=6.5V, U1B@5 = 5.5V, U1B@6 = 6.6V, U1A = 10.6V, U1B = 0V og U1C@10 = 5V
  U1C@9 = 2.6V, U1D12 = 10.1V, U1D@13 = 1.9V og U1D = 10.6V

I would like to know:

Where are voltage on U1A@3 and U1B@6 (6.6V) from?
C1 are drawn with wrong polarity?
Why R10 and R7 not the same value?

Actually I really don't know about floating input and it seems that all the opamps are operating in Saturation.


texts: I2C communication with LCD2041 using PIC32MM

texts:
I am trying to communicate with LCD2041 using pic32MM using I2C I wrote the following code on MPLAB code configurator but so far the status for the I2c communication seems to get stuck on pending . I need help on how I can proceed further . The default slave address for LCD is 0x50
#include <stdint.h>
#include <string.h>
#include <xc.h>
#include "mcc_generated_files/mcc.h"
//#include "lcd_i2c.h"

#define slave_Adress 0b01010000

void ByteDelay(void){
    // Delay between bytes required by LCD2041 spec
    DELAY_microseconds(625);
}

void ReadDelay(void){
    // Delay between read commands required by LCD2041 spec
    DELAY_milliseconds(3);
}

void TransactionDelay(void){
    // Delay between transactions required by LCD2041 spec
    DELAY_microseconds(375);
}

int main(void)
{
   SYSTEM_Initialize();
   uint8_t data = 0xFE; // host to tell data are output via I2c
   uint8_t lcd_clear_display =  0xA4; // command    to clear LCD
   TRISBbits.TRISB2 = 1; // set B2 (scl) as input
    TRISBbits.TRISB3 = 1; // set B3 (SDA) as input

   I2C2_Initialize() ;
   I2C2_MESSAGE_STATUS status ;
   I2C2_MasterWrite(data, 1 , slave_Adress, &status);
    ByteDelay();
    if ( status == I2C2_MESSAGE_PENDING) {led_3_SetHigh();}
    return 1;
}


texts: Using single microcontroller PWM output for 2 h-bridges

texts:
I am using ATMega16L and I'm using two DC motors to build an autonomous robot. I want to use an h-bridge to control the two motors. Can I use a single PWM output from say Timer1 on the microcontroller to control two h-briges so that the motors can go forward at the same speed, go reverse at the same speed and change direction by making one motor go forward and the other in reverse?

Can I connect OC1A PWM output from the microcontroller to be an input to 'IN1' pin on both h-bridges while 'IN2' is low so that robot goes forward and vice-versa to make the robot go backwards. I am not sure how to connect the circuit to share OC1A output to control these h-bridges.


texts: i dont want to change voltage but only regulate input voltage

texts: It is my first power supply project. I will supply 300 watt vehicle audio amplifier with this supply. I will use nominal 24V and 14A at my system Vehicle input 24V and my amlifier 12V-30V but when i measure vehicle input, i see surge and spike some times and exceed the limits. I need to know that, if i design only surgey and input protection circuit. Is it protect my amplifier or am i need buck/boost converter?


texts: What is the difference between the circuits?

texts:
I found the trigger (latch) circuit:
When no button is pressed, the LED does not light, if you press SW1, the LED will light up, and will light until you press SW2.

This can work for different values of the resistors (R2, R3, R7, R8).

What will be the difference, if we put for R2 and R7, instead of 300 Ω, 5.1 kΩ, and R3 and R8 instead of 5.1 kΩ, 1 kΩ?

I added both circuits. The LED (D1) is used as an example of a load.

simulate this circuit – Schematic created using CircuitLab

simulate this circuit

P. S. Q1, Q3 is KTC945P (2SC945P):
https://alltransistors.com/pdfdatasheet_nec/2sc945.pdf

Q2, Q4 is 2SA1273:
http://rtellason.com/transdata/2sa1273.pdf


texts: Current limit of switch mode power supply

texts:
I have a premade SMPS, it is 12V and maxes out at 8.5A. I have a TEC1-12706 on one pair of terminals and there will be a fan on the other terminals (I only have a total of 4 terminals for out). I would like to limit the current for the fan. How would this be done?

The PWM controller inside of the SMPS is the OB2269AP along with a coupler ic.


texts: How can an SR Flip Flop be made using a D Flip Flop and other Gates?

texts:
An SR flip flop is a flip flop that has set and reset inputs like a gated SR latch. How can an SR Flip Flop be made from using a D Flip Flop and other logic gates?

I've done several searches online and nothing really explains this. I believe a latch can determine values based on inputs and/or the clock? And flip flops are dependent on the inputs?

I've sketched several circuits and the SR FF always seems more basic than the D FF.. So I'm confused as to how this can be shown. My book is terrible at explaining things and the questions are basically irrelevant to the explanations in the chapters.


texts: Galvanic DC-DC isolation without inverting/rectifying

texts:
Is this possible?

I have a 12V regulated supply that I need a 36V and 5v (100W total) supply from to power a peripheral and power the control circuit for said peripheral. This peripheral uses a piezo self resonating oscillator so I need to isolate it from sensitive analog measurements on the CPU that'll be the master of the peripheral. The control circuit will send/receive RS232 commands to/from an isolated RS232 transceiver IC on the CPU.

To repeat me question, is DC-DC galvanic isolation possible without inverting/transforming/rectifying? I want 1:1 isolation for the 12V supply which I'll then buck/boost with a double ended switching converter. I want to avoid creating a flyback converter since that'll destroy my BOM cost and transformers are BIG.

Thanks!

EDIT: I think I am over-complicating things and wasn't completely understanding the task given to me. Even so, I am still curious what the community has to say about DC-DC isolation since it's much more of a rabbit hole than AC isolation.

EDIT2: Closing this question since it is no longer applicable to my work and I believe Bimpelrekkie answered in sufficiently. Thanks Stack Exchange Community!


texts: What is the purpose of RIN in this schematic?


texts: Is this different to a short circuit and if so then how? Because some circuit breaker protect from both short circuits and ground fault thanks, so when do u need to protect from them and when don’t you ?


texts:
The desirate goal here would be to apply a current throught a weak inductance (< 60µH) at at least 500kHz and producing as much as possible a square current figure.
To do so I have to dissipate the energy of the coil quickly when the power is cut in order to inject again the current later.

I took a look on the "flyback diode" placed in derivation of the coil and it works great (under 20V test voltage), but the inductance current fall time seems to be slower than using 51V Zener diodes mass-connected on the low side of the inductance.

But the Zener solution gives much more fluctuation (rest of the inductance energy trapped?).
Are TVS diodes another solution in this case?

Here is the (simplified) final expected design without the dissipation circuit.

simulate this circuit – Schematic created using CircuitLab

Is a H bridge to invert polarity on the coil when the power is cut (in order to discharge faster the coil) could be a solution?


texts: Measure electrical consumption from electric panel

texts:
I want to hack my electrical distribution board a little, to measure the energy used by each circuit.

Thus, I want to use a little arduino or maybe a raspberry pi and plug it to my circuits to take measures (I assume I should use things like ampmeter or voltmeter). Then I could make charts about what use energy the most in my home (and eventualy point energy leaks).

Unfortunately, I have less-than-basic knowledge about electricity, so I don't have a clue about how to measure energy.

So here are my questions :

where and what should I plug to my circuits ?
how many measures would be enough to be valuable ? (one every millisecond ? second ? hour ?)
would this system consume a non-negligible amount of energy ?

EDIT : as Will Dean stated, I should start with something small. Please consider this question to apply to a simple plug, and not an entire electric panel :-)

FINAL EDIT : I have to admit this seems way too dangerous for me since there is too much information I don't know about the electricity way across my home. So the final answer is : I give up for now. Any advice to how to teach myself is really welcomed


texts:
I have a 3 cell lipo connected in series and I want to charge them without removing them from circuit.

I only have single cell chargers so I can only charge one at a time or charge them in parallel but if I don't remove them from the circuit, charging them in parallel will short the contacts. but what if I use 3 single cell lipo chargers? Is it possible for me to charge these lipos while they are still connected to the main circuit (while circuit is open)


texts: Software vs hardware-defined GNSS receivers

texts:
I am conducting research into the accuracy of smartphone positional fixing accuracy. I have come to understand that smartphones use software-defined receivers rather than hardware-defined receivers. Is this correct?

Furthermore, would it be correct to make the following statement:

"Traditionally, GNSS receivers are implemented in hardware in comparison to modern software-defined receivers where processing of the satellite signals are performed by a low-cost microprocessor. The latter, common in smartphone devices, has the added benefit of flexibility with easily modified and updated features."


texts: How do I simulate an audio amplifier in Multisim?

texts:
I'm new to Multisim and am using the 12.0 PowerPro version. I have designed the circuit in the question TDA2002 Audio Amplifier using Multisim:

The Multisim circuit may be found here. Instead of a function generator or AC signal, is it possible to input an audio file and see its output in an oscilloscope?


texts:
I'm tasked with implementing a DRM on an embedded system. The device would have a limited number of times which it can run, after which it would be disabled, until it syncs with a computer with an internet to be allowed to run again.

For inspiration, I would like to know of embedded device that have similar DRM security and the way they implement it. I have found examples, but would like something on the market.


texts:
I'm new to pic and uart. Just trying out simple uart transmission. I'm using mplab IDE and coolterm for serial monitoring. I'm getting serial framing error.
I also used PuTTY and it was printing junk value. Below's the code that i'm using and i want to print hello world on desktop.

config.h

#ifndef CONFIG_H
#define CONFIG_H

// PIC16F886 Configuration Bit Settings

// 'C' source line config statements

// CONFIG1
#pragma config FOSC = HS        // Oscillator Selection bits (HS oscillator: High-speed crystal/resonator on RA6/OSC2/CLKOUT and RA7/OSC1/CLKIN)
#pragma config WDTE = OFF       // Watchdog Timer Enable bit (WDT disabled and can be enabled by SWDTEN bit of the WDTCON register)
#pragma config PWRTE = ON       // Power-up Timer Enable bit (PWRT enabled)
#pragma config MCLRE = ON       // RE3/MCLR pin function select bit (RE3/MCLR pin function is MCLR)
#pragma config CP = OFF         // Code Protection bit (Program memory code protection is disabled)
#pragma config CPD = OFF        // Data Code Protection bit (Data memory code protection is disabled)
#pragma config BOREN = ON       // Brown Out Reset Selection bits (BOR enabled)
#pragma config IESO = ON        // Internal External Switchover bit (Internal/External Switchover mode is enabled)
#pragma config FCMEN = ON       // Fail-Safe Clock Monitor Enabled bit (Fail-Safe Clock Monitor is enabled)
#pragma config LVP = OFF        // Low Voltage Programming Enable bit (RB3 pin has digital I/O, HV on MCLR must be used for programming)

// CONFIG2
#pragma config BOR4V = BOR40V   // Brown-out Reset Selection bit (Brown-out Reset set to 4.0V)
#pragma config WRT = OFF        // Flash Program Memory Self Write Enable bits (Write protection off)

#endif  /* CONFIG_H */

uart.c

#include <xc.h>
#include<stdio.h>
#include<stdlib.h>
#include<string.h>
#include<conio.h>
#include "config.h"

#define _XTAL_FREQ 20000000
#define baud 9600

void usart_init();
void usart_send_byte(char);
void usart_send_string(char*);

void usart_init(){
    TRISC6=0;
    TRISC7=1;
//    SPBRG=_XTAL_FREQ/(64*baud) -1;
    SPBRG=31;
    TXSTAbits.BRGH=1;
    TXSTAbits.SYNC=0;
    RCSTAbits.SPEN=1;
    TXSTAbits.TXEN=1;
    RCSTAbits.CREN=1;
    TXSTAbits.TX9=0;
    RCSTAbits.RX9=0;
    RCSTAbits.FERR = 0;     // Disable framing error
    RCSTAbits.OERR = 0;     // Disable overrun error
}

void usart_send_byte(char bt){
    while(TXIF==0);
    TXREG=bt;
}

void usart_send_string(char* str) {
    while(*str!= '\0')
        usart_send_byte(*str++);
}

void main(void) {
    char* str = "Hello world!\n\r";
    usart_init();

    while (1) {
        usart_send_string(str);
        __delay_ms(500);
    }

    return;
}


texts: How do PCB fabrication houses make PCBs?

texts: I know the different ways of making PCBs at home, but I can't seem to find a lot of information on how board houses professionally make their PCBs. Is this how they do it?: http://www.youtube.com/watch?v=8-WGaAmpfOU&feature=related


texts: Is it safe to keep on using AC adapter with a damaged output capacitor?

texts:
I was experimenting with my universal laptop adapter (Meind 100W) and when I switched it to 34V mode (while official max is 24V) the capacitor (25V) popped (the top opened and some white fibers spread over the nearby parts).

The capacitor is glued to the board and is not easy to remove. When using the adaptor it slowly heats now.

When under load the output voltage of the adapter drops (and probably recovers after some seconds), so I have to set it to voltage that is higher than needed.

Questions:

Is it safe to continue using that adaptor? Can it degrage further with time or it will remain stable?
How to unglue the damaged capacitor from board?
Should I use some additional safety measures (for example, external capacitor connected to output) to reduce the risk? (I'm not going to just buy another adaptor)


texts: What are some insights from looking at Bode plots

texts:
After studying this in school, the entire concept of a Bode plot still seems to be as a bit of a let down for me given how much emphasis is placed upon it, how often this tool is rumored to be used in the workplace and how little it actually seems to offer. Much ado is placed on how to analytically draw the Bode plot, but very little is said about its interpretation. How does this thing relate back to real life?

Most Bode plots look like this:

I honestly have to say I am not in the least impressed by this plot. All that the Bode plot is telling me is that as frequency go up, at frequency of 1 Hz, there is a peak in system response, then it goes down afterwards (surprise surprise). The phase is a bit more enigmatic, it seems to tell me that the signal experiences a larger delay as frequency goes up.

What are some conclusions that an experienced engineer is able to see from looking at these Bode plots. Are there things that are not obvious that is blocking me from seeing the utility of these bodes plots?

Since I have not done much real life engineering work with Bode plot, can someone please show me an example of a bode plot of a real system that actually provides some more interesting insights?


texts: Can I charge my AC rechargeable hearing aid batteries via USB PD with converter?

texts:
I hope you'll be able to help. First of all this is a bit of a complex one that I'm struggling with. I wear hearing aids, both of which use removable, rechargeable batteries, charged only by a charger plugged into an AC outlet.

Short version: I'm looking to try and see if it's possible to charge my batteries using a USB outlet, presumably USB C or USB PD (meaning I can use a battery bank to do so, and I don't have to spend my life tethered to an AC outlet).

Long version: I'm profoundly deaf, (basically, without hearing aids I hear sod all) and I'm an outdoor person. I love to spend long periods of time outdoors, exploring and doing things that involved a prolonged period of time away from regular AC outlets. This means that I don't always get to recharge my hearing aid batteries due to their power supply being AC (UK plug). Hearing aid manufacturers aren't renowned for being modern and keeping up to date with modern charging capabilities. I'd love to know if it's possible to charge my current set up using a USB C/USB PD battery bank, with the help of an adapter/converter; I just simply don't know enough about electronics to feel comfortable in making the decision. I swear to God, if anyone is able to help me understand this or make it possible, you will have honestly changed my life and I'll be forever grateful to you.

The specifications on the plug for the charger to my hearing aid batteries reads as follows:
Switching Power Supply
Model: S018BAM1200100
Input: 100-240V ~ 50/60Hz 500mA
Output: 12V - 1000mA

If there's any more information you need, just let me know. Again, I appreciate anyone's help with this in any way.

Many thanks!


texts: pcb-4-pin passive crystal is soldered to a 2-pin crystal PCB package

texts:
I would like to know whether it is suitable (not harmful) to put a 4 pin passive crystal in a 2 pin footprint.

Thanks in advance.

I have a 2 pin footprint in my PCB board,however,I only have a 4 pin passive crystal (8M). I have to solder like this: connect 1# to 2#,connect 3# to 4#;


texts: Volume control with DS1807 digital potentiometer?

texts:
I'm making a digital synth for a project and I need to wire in an Arduino-controlled volume circuit.

Right now I'm outputting a 0-5V audio signal and cutting it down to a pure AC 0.5V signal with a voltage divider (1kohms and 10ohms) and a capacitor. I would like to tack on a digital potentiometer to this circuit to control the audio volume so I bought a DS1807.

The datasheet is here but I'm still not totally sure how to use this -- it refers to the resistor settings in db rather than ohms, but it feels like I should be putting in a second resistor to form a voltage divider with it. What should that resistor value be? I don't see a reference to what the actual resistance of the DS1807 varies between. Or am I thinking about this circuit completely wrong?

(p.s., the speaker we'll use is a powered computer speaker)

Here's the circuit I was thinking of-- is that correct and how do I choose R3?

Thanks!

simulate this circuit – Schematic created using CircuitLab


texts:
I am looking for an LED driver circuit that would illuminate when a voltage is at zero, and which would gradually shut off as a voltage rises to 3.3v, with a (somewhat) direct relationship between brightness and voltage level.

I have already designed this circuit using an inverting op amp to invert and offset the control voltage signal with a negative reference, and then a second op amp to drive the LED using the feedback path.

I am hoping that someone might know of a simpler design, that would be lower cost and fewer parts. As it stands, this will cost me about $0.30 and uses 5 parts (not counting the LED itself). I need 16 of these in a single circuit, and I was hoping to be able to reduce the cost to below $2 total, ideally below $1

And here is the signal analysis, where the Green line is the 0-3v3 control signal, and the Blue line is the current used by the LED itself.

UPDATE 1:

One additional constraint I forgot to mention is the control input must be high impedance, as that signal will be needed for other purposes as well


texts: Propagate data bits with 8 BIT register in ISE SR8RLED

texts:
I had some issues propagating the input from the 8 BIT register to the output using the SR8RLED 8 BIT Register in Xilinx ISE.

The register has the following parameters:

SLI   - Shift Left Input

D[N]  - Input bus

L     - Load enable

CE    - Clear

C     - Clock

R     - Reset

According to the data sheet in the symbol info given by ISE, it suggests that If you want to propagate data from the Input bus to the output bus, this procedure should be followed.

R - LOW
L - HIGH
CE -   X
LEFT - X
SLI -  X
SRI -  X
C   -  Falling Edge.

But after playing around with some settings I fail to get the data on the output bus. The rest of the settings which aren't in the code are hard wired in the schematic (CE, R, SLI, SRI,).

 tb : PROCESS
   BEGIN
        input_bus <= "00001111";
        wait for 20 ns;
        clear <= '0';
        wait for 5 ns;
        load_enable_1 <= '1';
        wait for 5 ns;
        load_enable_1 <= '0';
        WAIT; -- will wait forever
   END PROCESS;

    tx : PROCESS
   BEGIN
    for i in 0 to 20 loop
        clock <= '1';
        wait for 20 ns;
        clock <= '0';
        wait for 20 ns;
        end loop;
      WAIT; -- will wait forever
   END PROCESS;


texts:
I am doing a project about a windmill.
I have to make a controller system for this windmill
The first thing I want to know is what is it generating?

So after the 3 phases there is a rectifier and after this I want to measure.

The windmill can generate at average about 50 Volts DC and 10 Amps of current.
So this will make a power generated of about P = U * I > 50 * 10 = 500 Watts
Right?

Now the problem is I want to measure voltage and current.
And there are a lot of ways like a voltage divider with a voltage follower with a opamp that creates high impedance and will let little current through.
That's for the Voltage.

But then I thought may be if there is a chip/board that can measure both and calculates this and then sends this data to a i2c line.

Now I found a LTC2946 chip
I actually don't understand how to set this up.
The problem this chip needs a sense resistor. On that page they have chosen a 0.02 Ohm sense resistor.

So let's do a little math.

So I know the value of the resistor right? >> 0.02 Ohm
Say my current is 10 Amps >>

Ohms law = V = I * R right?
So my voltage will be 10 * 0.02 = 0.2 Volt or 200 mVolts
So can I say then that I need a > 0.2 * 10 = 2 Watt High Power Resistor
Is this right?

Say my current will be 15 Amps. That make 15*0.02 = 0.3 Volts
This will make > 0.3 * 15 = 4.5 Watts of High Power Resistor right?
I don't know if I am doing this right !

If so then the next problem will occur.

How can I measure voltages with this chip?
I don't understand.

If you guys know anything, help is appreciated.

PART 2

Now I found something the LTC2947. The last one was LTC2946 and this one needed a external sense resistor. Take the LTC2946, which has a full-scale voltage of
approximately 100mV. If the LTC2946 is used to measure a 30A rail, a 3.3 mili Ohm sense resistor is required. This is readily available but will have to dissipate 2.9W of power !!!!.

Now that is a lot of dissipation of power for a simple measurement.
Furthermore the package is not "standard" and therefore expensive.

Then I saw the LTC2947 chip. Datasheet

This chip has a integrated sense resistor of 300µ Ohms.
So this is a very efficient chip with high accuracy.

I have looked in the datasheet and found a the section
"48V Bidirectional Power, Energy and Charge Monitor with Isolated I2C Interface and High Side Sense"

So I don't think I am gonna use the LTC2946 because of the high power loss.

But the next problem occurs.
Does this chip measure voltages beyond 48Volts ?
Because the windmill can generate higher than that, it depends on the wind.

If not how can I make this work? In which way?


texts: Why does this DC motor controller use relays and also MOSFETs?

texts:
I've a motor control board here for controlling the motors that move a caravan. The board wasn't working properly so I thought I'd take a look at it. I'm definitely a newbie when it comes to electronics, but I'm not bad at understanding the electrical aspect of simple circuits..
I traced out the relay connections as that seemed most logically how the motors would be controlled. The circuit looks like this, and the relays all function as I'd expect - a main power feed is switched on/off by two relays and from there feeds to a bank of 4 relays that are all off, and energise alternately depending on whether the relevant motor is to go forward or backward. The red boxes denote relays- i've left the coil rendition and the coil connections out because it's not needed for my question:

Main Question
Chiefly I'm curious why the ground/negative is supplied through (board can take six but only features four in parallel, only one shown in diagram) IRF3205 MOSFETs? Why does there need to be anything that switches the negative?
3 of the MOSFETs seemed dead - the D-S was OL regardless of whether the G had been prodded with the multimeter probe to activate it, and the 4th had some odd non-OL readings whether activated or not. I found a lower power MOSFET in a PC power supply and soldered it in as a tester, and the board neems to work sensibly now (on the bench) so I've ordered some replacements for the IRF3205s but I was puzzled as to why they were necessary
Pictures of the board in case they help:

Also, bonus question. When the controller is used, the sequence of events is:

Push "turn clockwise motor 1" button on the remote
Relay A for motor 1 energizes, supplying +ve to terminal 1 of the motor
Relay B for motor 1 remains inactive, supplying -ve to terminal 2 of the motor
If the button on the remote is released, Relay B briefly energises, meaning that both motor terminals are connected to +ve, then they both deactivate to the final resting state, meaning both motor terminals are connected to negative

What was the purpose of this brief "connect both motor terminals to positive" ?


texts: Why can I not format my USB mass storage device?

texts:
I'm working with an STM32F3DISCOVERY board.
I want to provide USB mass storage functionality over the user USB plug on the board (not the one of the ST-LINK).
I'm following ST's video tutorial as closely as possible, with only the following distinctions:

I use a different chip/board
I use STM32CubeIDE, Version: 1.3.1, Build: 6291_20200406_0752 (UTC)
I use a smaller buffer/media size (16K)

When I plug it into windows, it asks me to format the disk just like in the video.
However, the formatting process does not complete.
I get the same message as Youtube commenter "Rtek100":

Windows was unable to complete the format.

Trying to format with windows disk management, I got the error message:

The cluster size is too large for the file system

I tried the same thing under linux with the disks utility and got the following result:

What causes this problem?
Is it related to the settings of the high and low speed clock settings?
When he assigns "BYPASS Clock Source" to the High Speed Clock, he mentions that it will come from the ST-LINK. Does this mean that I need to power the ST-LINK USB plug?
update
I watched the tutorial again and found that I have missed to increase the heap size. The problem is still the same. On linux the error message changed (see below), although I'm not sure if this is related to the heap size.
comments

On Linux, after it fails, run dmesg | tail -n100 and look for I/O related errors and post them here.

To my surprise, the error message is now different (for possible reasons, see update above):

I tried dmesg and the following is what I get for unplugging, replugging the device.
The attempt to format the disk added no further entries to dmesg.
[  968.463379] usb 2-1.2: USB disconnect, device number 9
[  971.502067] usb 2-1.2: new full-speed USB device number 10 using ehci-pci
[  971.613248] usb 2-1.2: New USB device found, idVendor=0483, idProduct=572a
[  971.613253] usb 2-1.2: New USB device strings: Mfr=1, Product=2, SerialNumber=3
[  971.613256] usb 2-1.2: Product: STM32 Mass Storage
[  971.613258] usb 2-1.2: Manufacturer: STMicroelectronics
[  971.613260] usb 2-1.2: SerialNumber: 206636734136
[  971.614248] usb-storage 2-1.2:1.0: USB Mass Storage device detected
[  971.614759] scsi host0: usb-storage 2-1.2:1.0
[  972.619001] scsi 0:0:0:0: Direct-Access     STM      Product          0.01 PQ: 0 ANSI: 2
[  972.619599] sd 0:0:0:0: Attached scsi generic sg3 type 0
[  972.620374] sd 0:0:0:0: [sdc] 32 512-byte logical blocks: (16.4 kB/16.0 KiB)
[  972.621077] sd 0:0:0:0: [sdc] Write Protect is off
[  972.621080] sd 0:0:0:0: [sdc] Mode Sense: 00 00 00 00
[  972.621701] sd 0:0:0:0: [sdc] Asking for cache data failed
[  972.621707] sd 0:0:0:0: [sdc] Assuming drive cache: write through
[  972.653486] sd 0:0:0:0: [sdc] Attached SCSI removable disk

I ran fdisk as well:
$ sudo fdisk -l /dev/sdc
Disk /dev/sdc: 16 KiB, 16384 bytes, 32 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes

16 kilobytes? Is that the correct size of your device? I think mkfs is telling you that it can't create a filesystem that small.

Yes, that's correct.
The tutorial uses 64, but my chip does not have that much SRAM, so I went with a smaller size.
I checked FAT size limits:

FAT32 minimum : 1 sector per cluster × 65,525 clusters = 33,548,800 bytes (32,762.5 KB)

This might be the cause of the problem, but if 33,548,800 bytes is the lower limit, why do the 64k work in the video?
What am I missing here?


texts:
Can I use CPU heat-sinks for cooling transistors?

CPU heat-sinks are low volume and they have been made to cooling a sensitive hot Chip and if the datasheet has said that it requires to hold on the transistor less than 150 C,I thought maybe it will be possible and good way instead of massive heat-sinks. the CPU heat-sinks are always available in the markets But maybe finding the heatsinks with special shape and enough size are slightly difficult.
Are these fans and heat-sinks suitable and normative for transistor?
If so, How should I choose heat-sink?(for example:for one 100 watt transistor Is the 100 Watt CPU heat-sinks suitable and enough?)


texts: Displacement current generation in dielectric and in vacuum? How is it different?

texts: I understand how the displacement current work in dielectric such as in parallel plate capacitors but don't know how they would work in a vacuum where there is no dielectric present. Can someone please explain.


texts:
I need one clarification regarding ESD,EFT and SUrge protectors.
Different manufacturers have architectures of diodes+Zenar diode combinations for different protection levels for different interfaces.

I am attaching a figure which shows 2 architectures of ESD suppressors.
What factor determines how manufacturer connects these diodes and zenar's in a specific way.
 in the figure attached 2 components
1. 2 zenar's with anodes connected to each other and cathode terminals are exposed outside -
CDSOT23-SM712 for RS485 Protection
2. same 2 Zenar diodes with 2 cathodes connected internally and anodes exposed outside -  PGB1
for USB protection.

for analysis if any ESD event occurs , if voltage is > Forward voltage of one zenar+ reverse  voltage of zenar, then device will protect.

I am really curios to know why these architecures done in this way.
Please correct me if i am wrong. my intention is in both cases breakdown will happen in same way, how we can we say which architecure is good for RS485 or USB.


texts: Direct connection or using capacitor when shorting PSU's DC negative terminal to earth terminal?

texts:
I have read and then observed that for reducing the 50Hz related noise, tying the -DC terminal of an SMPS supply to the earth terminal woks well in some cases when. Below shows a direct path by a wire between the negative DC terminal and the earth terminal of the supply:

But I have also seen some uses 100nF capacitors instead of wiring directly. Is there a particular reason for using capacitor instead of directly tying these terminals by a wire?


texts: Converting 3.3V signal to 5V with tri-state

texts:
I need to buffer and tri-state a 3.3V 8 bit signal, and shift the output to 5V (when the buffer is not in tri-state).

I am using a CD54HC373 buffer and 2 BOB-12009 logic level converters, but I can't find a way to output a 5V signal.

I have tried to route the signal in 2 ways:

[3v output from the board] -> 2 [BOB-12009] - > [CD54HC373].
In this way, I can enable/disable the tri-state of the output using the OE pin of the CD54HC373, but i get a 3.3v output (I need a 5v one).
[3v output from the board]-> [CD54HC373] -> 2 [BOB-12009]. Tri-stating using OE does not work anymore, because of the logic converters.

I am powering the CD54HC373 using a 5v input!

Any advice?


texts:
I am inexperienced in the field of electronics and don't yet understand diagrams and things alike, but I have a specific need and would appreciate any help you can provide.

I am constructing a "fortune teller machine" like Zoltar from BIG. The mechanics are simple and I do not need help with that part. What I would like is the ability for the user to push a button on the front of the unit, and the fortune teller doll to begin moving (via a 12v motor), along with lights and sounds (which again, I have figured out). After a certain period of time, I would like the fortune teller to stop, and a card dispenser to activate, dropping a card into the retrieval bin below.

I need to set it up so that this happens in order with one single push of that button.

So the setup is:

Push a button
Fortune teller activates (12v motor runs)

Lights come on
Sound plays from mp3 repeater module
then:

Card dispenser activates

If anyone can help explain how this would be wired and what components I need I would be so grateful!


texts: Should I use li-ion CR1220 cell or a different chemical type?

texts: I have bought an RTC module that needs a CR1220 coin cell, but is supplied without one. Should I use a Li-ion cell or a different chemical type, and what advantages or differences are there between them? I cannot find any guidance at all so far on-line.


texts: Why we need clock pulse in sequential circuits?

texts: I need to know why do we need clock pulse in sequential circuits but not in combinational circuits?


texts: Why cannot I use the USB port directly to communicate via PC with STM32F4-DISC

texts:
I will keep it short and clean, if it won't be enough please let me know and add more details.

When using an Arduino UNO, a serial communication can be achieved by the same USB connection which is also used to load the code or power the board.

But when using another board for ex. stm32f4-disc, I also power the board and send the code into the board via a USB port on my board. However to get a serial communication between pc and board, I specify some pins as UART Tx/Rx and use a TTL-USB converter.

So why using the USB port on Arduino UNO for serial communication is possible while it is not the case with STM32F4-DISC?


texts: How should power be supplied for in-system programming?

texts:
I'm trying to program an ATmega328 with an AVR-ISP-MK2 from Olimex. The programmer has a setting for whether to supply power to the target board or not. The connector has +5V and GND pins. I wanted to make sure that I've understood this correctly before breaking anything:

If the programmer does not supply power (OFF): should I connect the +5V and GND pins from the programmer to the same +5V and GND as the target board, which is powered by another source?
If the programmer does supply power (ON): should I power the target board completely from the programmer, so that I pull the +5V and GND on the connector to VCC and GND on the target board? If so, the programmer would be the only power supply.

That is: in both cases, +5V and VCC would be connected, and programmer-pin-GND and target-board-GND would be connected. The only difference would be whether an external power supply is connected.

  TARGET jumper controls the powering of the target board. If it is in position ON (check the diagram on the back of the plastic cover) it will provide either 3.3V or 5V to the target board (depending on the position of the POWER jumper) The default position is OFF.


texts: How do I sniff this RF Transmitter Gate Opener Circuit?

texts:
What piece of hardware am I looking for to observe the transmitted radio signal? Would an oscilloscope come in handy here? is this a 2-channel RF remote, a 3channel RF remote, or something else?

My goal is to build my own circuit that emulates this circuit. Would I require a bus pirate for this? I realize it might be much easier just to buy a new remote but I'm using it as a learning experience rather than a cost saving endeavor.

googling the IC, a message board mentions its probably a custom IC. The IC has the following printed on it:
0412
SEMEFAB
051-8728
0821-D (LF)  D[big letters, on right]


texts: Controller Area Network (CAN), high speed and low speed

texts:
Is the difference between high- and low-speed CAN only with respect to baud rate values?
Is the CAN transceiver programmable for a range of speeds or is it fixed for a specific value? For example, can a high-speed transceiver can be programmed for 500 kbit/s or 1 Mbit/s?
What happens when a high-speed node is connected to a low speed node in the same network? Is it possible to get the data? Does it cause error frames?


texts: In many datasheets clock tolerance is in ppm and in some other it is in ns or ps. What is the difference in giving clock tolerance in ppm and ns/ps. How it can be converted from one unit to another?


texts:
can you please help me identify this connector?

It is used on the Clearpath Husky to connect the battery to the robot.
The top image shows the male (from the charger) and the bottom one the connector female part attached to the battery. Both have a tiny letter A printed on the mating side. They seem to be modular and single modules can be slided on or off.

I want to buy some spares and make my own cable.
Thanks!


texts:
I want to create an controllable output voltage from -2.5 to +2.5 on the R8 resistor.
My circuit is:

simulate this circuit – Schematic created using CircuitLab
So my microcontroller controls the DAC, which outputs from 5V to 0V. This output goes to Differential amplifier (AMP2), which should give me max:
2.5V-0 = +2.5V
and min:
2.5V-5V = -2.5V
Across the R8
Did I use the reference voltages (VGND and GND) correct?
I have a slight confusion:
Will the AMP2 see the 5V from the DAC as 5V and subtract it? Or it will see the 5V from DAC as 2.5V?
I think, because DAC is connected to GND (and not VGND) , the AMP2 will see the 5V from the DAC


texts:
I am working on a PCB that is powered by a 12 V DC source, in the circuit I have a 12 V DC motor (drawing about 4-6 A continuous), as well as other digital CMOS elements powered by a 5v step down voltage regulator (12 V -> 5 V).
I need to create an ON-OFF (non momentary) mechanical switching mechanism which switches the circuit on and off.
The thing is, that looking at SPST switches and other types of high current mechanical switches, they are all quiet expensive for what they do, so I came up with a simple solution that uses a single 30 V, 50 mA ON-OFF pushbutton and a suitable N-channel MOSFET, where instead of connecting all of the source terminals of the components in the circuit to ground, I connect them to the drain of the MOSFET, and the gate of the MOSFET is connected to the 12 V supply through the pushbutton.
Here is the schematic of what I came up with (question below):

I know this would work with something like powering a single LED, but would it be ok to do in a mixed voltage circuit, CMOS components and dc motor driver circuit? (assume everything works ok when the switch is removed and every LOAD source is tied directly to ground).


texts: What is the function of these resistors in the power supply circuit

texts:
I'm trying to really understand the choice of components in this power supply circuit, which i got as a reference design for a 3-phase energy meter from MAXIM.

VA_IN, VB_IN and VC_IN in Black on the far left, are the mains input for the 3phase AC lines at  220V each, while the VA_IN,VB_IN,VC_IN on the right (marked with red arrows) go the a voltage divider that feeds the voltage measurement circuit.

Apparently, D12-D14 are used to prevent feedback to the line from adjacent phases, while they all feed the power supply.

My major issue is with the purpose of R141 and R140.

I was told that R141 is there to limit the rise of surge current during a spike, but i don't really get that.
and i'm assuming R140 is there because of the D12, but i'm not sure.

I would appreciate some clearification, thanks.


texts: How to create a nested for-loop in Verilog?

texts:
I try to create a CRC module on Verilog.
The CRC calculating use an LFSR and can be fully-sequential (with two cycles), semi-sequential (with one cycle) or parallel. I have already made sequential module. And I try to create a fully-parallel. There is some code-generators for fixed methods (like "CRC-16 modbus" or "CRC-32 Ethernet"). But I want to create an universal parametrizade parallel module.
With for-loop expression I create a prametrized LFSR.
module main
#(
parameter LFSR_SIZE     = 16,
parameter START_VALUE   = 'hFFFF,
parameter POLYNOME      = 'h8005)
(
input           clk,
input           n_reset,
output reg  [LFSR_SIZE-1:0]lfsr);

integer lfsr_index;

always @(posedge clk) begin
    if(n_reset) begin
        lfsr[0] <= lfsr[LFSR_SIZE - 1];
        for(lfsr_index = 1; lfsr_index < LFSR_SIZE; lfsr_index = lfsr_index + 1) begin
            if( ((1 << lfsr_index) & POLYNOME) == 0) begin
                lfsr[lfsr_index] <= lfsr[lfsr_index - 1];
            end
            else begin
                lfsr[lfsr_index] <= lfsr[lfsr_index - 1] ^ lfsr[LFSR_SIZE - 1];
            end
        end
    end
    else begin
        lfsr <= START_VALUE;
    end
end
endmodule

Is it possible to generate number of shifts of the LFSR with a nested loop (two loops, one inside other)?
If answer is "no" does the nested loop usefull expression in some case?


texts: Charging phone battery with a lower voltage, coming from a bike charger?

texts:
Since travel by bike a lot, and use my phone very often during those trips, I tried designing a USB phone bikecharger that would use my bike-dynamo that also powers my lamp.

Yesterday, I did my first tests. Without load, the circuit would give me 9,3V (even when the wheel was not spinning, which was a surprise to me :) ). With a 47 Ohm load, it would still give 9.3V. This is way too much for USB ofcourse, but 47Ohm is still quite big I think.

When a 10Ohm load was applied (I assumed 5V USB-voltage, 500mA charge current --> 10 ohm), the voltage dropped to 3,5V (it kept quite stable, it didn't fluctuate all that much. It seems the wheel speed doesn't influence the output voltage, except for when it spins too slow and the voltage is cut off entirely. I assume this is some kind of protection mechanism in the dynamo?).

So here's my question: what would happen is I were to attach a phone to this charger?

My guess is that 3.5V is not enough to overcome the internal resistance of the phone battery  threshold for the charge circuitry of the phone, so it will be blocked a few ms, but because of the open circuit, the voltage will rise to 5V and that will eventually be enough to charge. So in practice, it will just charge with a lower current (same as charging your phone on the USB-port of a netbook. Those often can't provide enough current, and the phone just charges slowly).

Is my guess right?

What are the risks of charging a phone-battery with too little voltage?

Should I worry about the charger outputting 9V when the phone battery is full? Because there won't be any load anymore then.

Thanks in advance!

ps. I also checked the signal with an oscilloscope to check the purity of the DC, and it was pretty clean. There were no big spikes and the level was quite stable. (I didn't try to pitch pennies on noise-supressing capacitors ;) )

Edit: added my schematic

EDIT2: J3 in the schematic is an LM2596 Buck module, using a MP1584 step-down regulator module.

EDIT3: I was doing some tests a few minutes ago, and I guess I had misconfigured the LM2596 (doh...). I think the 9.3V issue is not existent anymore (I've only tested it on a bench power supply right now, but I assume it'll be the same when I test it on my bike again).
So now the only question that remains: Is there any risk to applying a voltage too low to the phone? And will my above assumption hold true?

EDIT4: Currently testing it with some old phones, with my bike on a treadmill. 5V is constantly stable now for every speed above 6km/h, and charge current is 300mA, also pretty stable (100mA on an older phone). The phones themselves also indicate that they're being charged
At first glance, everything seems to be working, but... the charge percentage is barely going up. I'm not sure yet if this is because the batteries are very old and haven't been used in ages, or if there's still something wrong with the circuit. More testing will be needed ;)

EDIT5: as pointed out by @Ale...chenski the path between the rectifier bridge and the two elco's is wrong and will be removed.


texts: Bi color led with tri-state pin (high->D1, tri-state->D2, low->off)

texts:
I have a tri-state pin and I would like to use a bi-color led:

Pin     Low     High    Hi-Z
D1      off     on      off
D2      off     off     on

There are a lot of examples around but none in the combination of the above table.

How can I do that with minimum components?


texts: Why voltage increase when current flows backwards into a non-ideal voltage source?

texts:
I observed this when I was doing laboratory for one of my courses: when current flows back into my voltage source, its voltage output suddenly increases.

This is my experiment circuit. I set the voltage source on the left to 5volts and then connected it to the circuit. But as the current is flowing backward into the 5volts voltage source, the reading on my voltage source says that its actually output is 5.7volts.

Could anyone tell me why?

The voltage sources are Tektronix PS280/PS283 lab power supplies.


texts:
Im going to be using XBees in my project to wirelessly communicate between things, one of the devices is going to have a set of switches and 1 output - the xbee has enough IO to handle it. Is it possible to program the XBee to do the processing instead of having to interface a microcontroller with it? As I'd like to reduce the need of these extra microcontrollers.

The idea of the system is that if a switch that is attached to the xbee is pressed the output is toggled, and then if it is toggled on the remote device, the output is toggled on the device. Is this possible or will I have to use microcontroller as well?


texts: Getting started with an Arduino Ethernet board (not shield)

texts:
I got an Arduino Ethernet board for Christmas, and I can't figure out how to start using it. This is NOT an Ethernet shield without an Arduino board, this is their board/shield combo (link).

I've tried to follow their instructions in Getting Started w/ Arduino on Mac OS X, but nothing seems to explain the specifics for uploading projects to the Arduino Ethernet. Do I need to configure a new bootloader? Do I need to get it connected to an Ethernet connection (not my computer directly)? Do I need to wire something up or get a serial-to-USB device of some sort? Do I need something like USB FTDI TTL-232 cable - TTL-232R 3.3V?


texts: Do 10V 100μF and 16V 100μF capacitors have the same capacity and output?

texts: I vaguely remember that 100μF represent the capacity of a capacitor, but I also kinda remember that it has to do with the voltage. So my question is, do 10V 100μF and 16V 100μF capacitors have the same capacity and output (meaning does the 16V 100μF capacitor is the same as 10V 100μF capacitor only capable of working in a higher voltage system)?


texts:
I'm designing an analog synthesizer, which is controlled by an STM32 -microcontroller. In several parts of the circuit, I intend to use a GPIO pin to control switches in the circuit, and in two different parts as parts for generating audio. I'm worried about noise from the uC leaking in to the circuit, and my question is should I be worried, and if I should, what should I do to minimize the problems?

Some details: my PCB is laid out such that the right hand side is entirely analog, except for the said signals from the pins, and the left hand side contains the digital part, with DACs and an analog MUX (multiplexing the uC's built in DAC's) sitting on the dividing line. I have a ground plane on one of the inner layers of the 4 layer board.

The signals controlled from the GPIO's are:

two analog SPST switches switching signal flow
four on-off switches made from a single MOSFET, with the GPIO pin controlling the gate and switching unipolar analog signals on or off
a leaky op-amp integrator integrating a narrow pulse generated by the PWM of the uC, which is used as an analog signal and processed further.
and finally, a step transition in a GPIO is fed into the filter as a test signal for calibration.

The final output of the circuit has a one-pole lowpass filter around 70kHz to reduce spurious high frequencies.

It would be very difficult to try to place all the switches and such at the analog/digital boundary of the board, so they are placed rather deep inside the analog area of the board. On the other hand, being switch control signals, they carry very little current. Also the current into the integrator is quite small, some tens of microamperes during the pulses and otherwise essentially zero.

So, how much should I worry about inducing digital noise into the analog side here?


texts:
a Friend have a problem with the fridge&freezer - it does not produce coldness anymore.

Company : AEG Electrolux

Model :  S 75348KG5

Typ : CBFF340 EL

We would like to know why, and what we can do about it.

It is connected to the grid,
light and sensor indicators are on,
fan/ventilator(?) in freezer is working,
Compressor on the bottom back is vibrating,
No wet leakage are found - however on one pipe there is a bit rust.

Still the heat exchange grid, keep being cold,

later on i can provide some proper electrical sketch.

Thank you,


texts: Question on inductors with initial current

texts:
Question:
Initially the switch position is aa', 3 H is connected across a 3 A supply and 6 H is connected across 6 A supply. After some time the make before break switch is actuated to the new position bb'. Determine the steady state current, fluxes associated with each inductor in the new position. Assume there are no switching losses.
Fig 1 : Initial condition (switch in aa')
Fig 2: circuit while operating the make before break switch
Fig 3 : switch in bb'

Pre switching period is fine, each inductor having a current of 3 A and 6 A respectively. Inductors don't allow a sudden change in current when disconnected from supply as in fig 3, their magnetic field collapses and allow a decreasing current to flow in the same direction as previous and their  voltages are reversed. But how does it behave when two inductors having different initial currents are switched together? It shouldn't be 9 A otherwise total energy associated with the series inductors is more than pre switching violating law of conservation of energy. Is this case similar to connecting two current sources in series which is not allowed?


texts:
I am checking PCB board of a commercial device that has W25Q256JV 32MByte SPI Flash on it. The device is in use for more than a year now at more than 2000 client locations. It has internal backup battery that is put on charging at night and then at day time the device is used without the mains charger.

The Flash is being written and read continuously all the time for more than 1 year now. It's write cycles are surely reaching to its limits now.

Now faulty devices have started to come for repair from the client and mostly flash is the culprit in these devices. Once it is replaced with a new chip then the device again becomes functional.

It is observed that the event of faulty flash occurs at the instant when the connector of its power adapter is removed from the device.

How can the flash getting corrupt avoided at the instant when its power jack is removed?

How can we detect in the firmware that the flash has become corrupt and consequently display this message on device screen.. so that no guess work is done to re-live the device?


texts: Active phased antenna array for Wi-Fi efficiency compared to a directional antenna?

texts:
I'm interested in mesh networking of poorly controllable autonomous aerial vehicles (like blimps), so i wonder whether it is viable to use a phased antenna array versus a few traditional directional antennas (say, Yagi-Uda) directed with RC servos, to communicate between ground and other aerial vehicles, that use solar+battery power. AFAIU, GHz-range amplifiers aren't really efficient, and phase shifting may be challenging, but i'm getting lost in the marketing speak when i'm trying to understand whether there are new developments in this area.

The question is not about the theoretical limits of the phased arrays, but about the state-of-the-art hardware and technologies available to a hobbyist.


texts: Ambiguous labels for AA battery insertion

texts:
I have a consumer device that accepts two AA batteries.  The battery chamber is designed such that the batteries are inserted from open end of the chamber rather than the side (i.e. along the axis of each battery).  The '+' and '-' labels are also located on the end of the chamber next to the "holes" that accommodate each battery.  The positioning of the labels is ambiguous -- it depends on the conceptual model of what you think the labels are asking:  1) "insert the battery such that the end of the battery matching this symbol goes into the hole first", or 2) "insert the battery such that the end of the battery that is visible after insertion matches this symbol".  A little research on this revealed that one can almost always determine the correct orientation by making sure that the negative side of the battery goes against the spring contact, but I have seen some references that state that this is not universally true.  In this case, the answer is option 2.

Is there a standard for labeling such "vertical" battery containers to resolve the ambiguity?  Has anyone seen a product that accepts AA or AAA batteries that did not follow the design noted above?


texts:
I was given the next assignment, but I dont know what to do.
From the system showed there must be a regulation at the PQ node (3rd). But the course is starting and I have no idea what to do, it is supposed to be equations that regulate this, but I wasnt given none.
The system is

The conditions are :
the tension must be regulated at the PQ node,so it can support:
a)  100 MW, 60 Mvar (at the load)
b)  140 MW, 90 Mvar (at the load)
So, intuitively, this can be done via playing with the controls and running the solve system, but whats the math behind it.
Im asking for advise of what to do, not the solution of it.
When using 100MW/60MVAR the generators run well

but when the 140/90 load is applyed the gen2 wents off.

So besides of cutting off load, what more can be done?
Is there a way to balance the load so the generators can support it?
Thanks in advance
PD.I have seen this can be done in matlab/simulink but what are the values/parameters usually taken?


texts: Strange issue on Raspberry Pi UART (with FTDI USB  RS-232 adapter)

texts:
I'm trying to establish a high speed UART communication on Raspberry Pi board. Since internal UART is not quite good at 1+ Mbaud, decided to use FTDI adapter (based on FT232RL chip) instead.

I've tested an adapter on my laptop running Debian 8 and reached stable transmission speed at 3 Mbaud (with a cat * >> /dev/ttyUSB0).
Then plugged it to Pi2 doing exactly the same, and noticed this:

(at 3 Mbaud)

(at 1 Mbaud)

There are wide (up to 1 second at 3 Mbaud) gaps in transmission at regular time intervals. Transmitting data is not corrupted, just delayed.
Any suggestion on how to overcome a problem? Thank you.


texts: How does this transistor radio mixer work?

texts:
I recently picked up a transistor radio, a Unitra Nova 206.  I've been studying the schematic with an interest in the AM operation for now.  Most of it makes sense and I've included an annotated snippet below.

Looking at the transistor pair T3 and T4 you can see that the RF signal arrives at the base of T3 with the LO signal applied to the emitter of both T3 and T4.  T3 seems to be producing the IF products typical of a super-het, but what about T4?

T4 has a fixed DC bias produced by detection IC UN1211/R11/R12 (about 3V at pin 2).  The LO signal gets applied to the emitter, but no RF signal.  What then is the purpose of T4?

More extensive schematics, etc. below.

Full schematic (apologies for image quality!)

http://www.elektroda.pl/rtvforum/topic1690084.html

http://www.datasheetcatalog.com/datasheets_pdf/U/L/1/2/UL1211.shtml


texts: 5 seconds power supply backup for 12V 0.5A router

texts:
My country has a problem with the mains electricity supply, which cuts off and comes back straight away. My router restarts every time that happens.

What I like to know is: What would be the most efficient way to have a 5 seconds power supply backup on my router?

Router: ASUS RT-N12+
Power Supply:

AC Input: 110V~240V (50~60Hz)
DC Output: 12 V with max. 0.5 A current

A schematic would be amazing since I am totally new to this subject.


texts: Detrimental impact of magnetic field on PCB and battery?

texts: We are developing a small consumer electronics product consisting of a small 4-layer PCB along with a few PDM microphones and BLE chip/ an antenna, as well as a LiPo battery. We are locating a small but pretty strong magnet next to these components in the enclosure. It is an N52 (Surface Field: 3032 Gauss, \$B_{r_{max}}\$: 14,800 Gauss, \$B_{H_{max}}\$: 52 MGOe). Are there any long term effects of the magnet which may be detrimental to the battery or PCB electronics?


texts: Convert 36 V lawn mower from Lead Acid to Li Ion batteries - charging / danger

texts:
I have a 36 V lawn mower with a battery container with three 12 V SLA batteries in series.

I am thinking about switching to LiIon batteries for more run time (and hopefully more recharge cycles). I can find batteries that fit physically, and putting them in series is easy.

I don't think the SLA charger will charge LiIon batteries correctly.  I found 36 V LiIon charges online. But...it is safe?

I thought LiIon batteries packs need a thermal sensor input to the charger to prevent overheat/damage during charging.  All the LiIon charges I found are 2 pin output.
Is it safe to charge 3 LiIon in series?  Or do I need to charge each 12 V individually?

I found someone doing exactly this project but using small cells (YouTube).  However, he does not discuss if/how he changes charging circuit or running circuit.


texts:
There are several open-source general-purpose CPUs, and the most advanced of them seems to be OpenSPARC T2 (correct me, if I'm wrong).

I want to find out, with what effort I can build a machine, which uses this processor and runs some of the common operating systems (e. g. Ubuntu).

That it, I want to build a motherboard with that CPU, connect it to 4 GB of memory and a hard disk (or SSD) and then try to run Ubuntu on that device.

This device will be created for prototyping purposes only (there will be only 1-2 copies of it).

Question: If I want to do this, are there any alternatives to using this evaluation platform?


texts:
I am designing a system where a DSP (like the TMS320VC5501) processes some video data and outputs it to a PSP screen (the ones sold on sparkfun). The issue I'm having here is designing the video output interface. I'm thinking that I should have a video buffer and maybe a CPLD to read data and spit it out to the PSP screen, but the exact details haven't been completely worked out.

My main concern is timing. The DSP will be writing image data to the video buffer as fast as possible which might not leave enough room for data reads on the output side. I've looked around and it seems like GPUs these days use fast SDRAM which suggests that I should use it (since it's obviously working for them), but if I do then I'm blanking on how to read from it to output to the display. (The DSP has an SDRAM controller, but I don't want to load it with constant display requests. I want to use it's processing power for actual processing as opposed to memory games) Another alternative is VRAM, but this is a really old method and seems to be going out of style. Might be my best option though...

As another thought, I can use DMA to burst-write 11520 bits (480pix x 8bits x 3colors) to a shift register during hsync via an interrupt (hsync/vsync will be PLD controlled). From there, the PLD will control that shift register to output the data using the correct timing. I have to double check the numbers, but this seems like a plausible solution.

Anybody have any insight on this?


texts: dc brushless motor shuts off automatically

texts:
I'm trying to see whether my electric bike's dc brushless motor controller (input 24 V) is repairable. The problem is that when I adjust the throttle to the highest power and release, the motor controller clicks and power stops going to the motor. I have to turn the power off and on to get it working again. (I am able to maintain medium speeds without the controller automatically turning off.

Would this be due to a safety mechanism preventing too much current from damaging the motor? I measured input voltage to the controller by putting my multimeter in series with the hot wires and got a reading of 50V (motor controller input is 24V). Please let me know if I diagnosed the problem correctly and what can be done to resolve it. I've attached pictures of the wiring diagram, motor controller specs and multimeter reading below.


texts:
I have read the Wikipedia article Three-state logic, but it is not clear enough. What is a more simple explanation for what a three-state circuit is?

When and where do we use it? What has CMOS to do with three-state circuits?


texts:
I am designing a Geiger counter which measures radioactivity. I am planning to this using the photoelectric effect.

The band gap of insulators is pretty big and only gamma particles are energetic enough to jump an electron from the valence band to the conduction band.

Where can I find a photo-resistor made of material with a band gap of 30+ eV? Can it be ordered online or is this a special case and it needs to be ordered from a factory?


texts: Why do people get electrocuted by cell phones

texts: I heard people electrocuted (death caused by electric shock) while charging their cell phones and using them same time. But I can't figure out why. I understand that the secondary coil of the transformer inside the charger has no electrical connection with the primary coil. The changing magnetic field induces emf across the secondary coil. So, my question is how do people get electrocuted when using their cell phones and charging them simultaneously.


texts: One of the two brown wires to my shower isolator switch is not live. What has caused this please?

texts: My electric shower stopped working. The shower power button didn’t turn on the shower. I then checked the isolator switch on the ceiling. Its red light didn’t turn on when the switch was on. I checked the cabling to the switch. Of the two brown wires, one of them was live (the furthest one in the image) but the other wasn’t. What has caused this please?


texts:
I’m working on a university project that involves switching a relay using an ILD213T optoisolator. The optoisolator is driven directly by an ATmega328p.

I had calculated the required current limiting resistor to be 220 ohms at 3.3v but it absolutely refused to switch.

I tried quickly connecting the optoisolator without a resistor and it worked great, the relay switched, however I don’t want to burn the LED out.

I gave 27 ohms a go just because I had a few of those to hand and it would switch the relay, but barely. It really struggled.

I’m at a bit of a loss as to what to do here. Any thoughts or ideas would be greatly appreciated.

Note that the Relays are driven by 5V as per the spec.

Schematic below:

The data sheet for the optoisolator is at: http://www.farnell.com/datasheets/2045803.pdf


texts:
I'm really curious to know what are these holes on this mobile PCB:

Are these vias? I doubt they are vias. If these are not vias then what are they? What's the usage of these holes?


texts: Analogue signal generation: Which is better Standalone or PWM DAC?

texts:
Most controller/processor come with PWM output and integrated standalone DAC module....

My need is to generate 50/60Hz analog signal for testing purpose! Which would be the good choice PWM DAC or Standalone DAC?

Better in terms of:
* Simple electronics
* Simple coding
* Quality signals (lesser distortion)
* Sine wave generation


texts: Software for workshop - electronic components stock management

texts:
Im looking for reliable software that will help me to manage electronic components, tools, drills, wires in my workshop.

Currently I have probably more than 1000 diffrent components. My brain can't manage this anymore.

My "wishlist":

preferable free or low cost software
not too complicated
locations feature ("where is it" eg. Shelf 1 -> Box 1)
stock/shopping history - where and when I purchased part and how much I paid
categories with tree structure
some functionality to assign part to projects (example: I want to note somewhere that im using MCP3424 in "Acurrate voltometer v2" and "Raspberry Pi Solar Energy Logger" projects, also I want to see full part list for "Acurrate voltometer v2" project)
client-server architecture would be nice
(optional wish) functionality that allows me prepare shopping lists (sometimes I forget to order something, I don't want to order just 1 part an pay for the shipping, so I'm planning buying it next time)

EDIT / BOUNTY COMMENT

So far nothing really interesting appeared in answers. Excel or PHP based solutions are not productive enough (too much clicking). zParts is too simple, I can write something like this myself in 2 hours :)


texts: MUX for receiving 1MHz ultrasonic signal from multiple transducers

texts:
I have one ultrasonic transducer that is connected to high voltage Pulser (1-2MHz), I want to detect the ultrasonic signal generated by this transducer with other multiple transducers (~16). I have an electronic device that is able to receive analog signal (amplify+filter+ADC) from only one transducer. I am looking for a MUX that will allow receiving the analog signal (typically <500mV) from the 16 transducers sequentially (ADC is set at ~10MHz, pulse repetition is set at ~1-20kHz).
What are the design considerations and MUX parameters that shall be taken into account while selecting a suitable MUX for this purpose?

Please note that I am looking only for a low voltage MUX, as the high voltage circuit is separated from the receiving circuit.


texts: How to analytically find node voltages in a voltage doubler?

texts:
Given a voltage doubler circuit:

simulate this circuit – Schematic created using CircuitLab
You can figure out what should happen in stead state if \$R_L=\infty\$ and \$R_s=0\$. In that case, \$V_{out}=2(V_P-V_{diode})\$.
What is it when \$R_s>0\$ or when \$R_{load}<\infty\$?
I don't think you do a simple Thevin equivalent with complex impedances because the diodes screw things up. What I've been trying, but haven't found a simple answer yet, is the following:
At steady state, the charge stored in \$C_1\$ (i.e., the change in voltage across \$C_1\$) during the negative part of the cycle has to equal the charge (or voltage) lost by \$C_1\$ in the positive part of the cycle. The same for \$C_2\$.
You then get two circuits (shown above). Is this something you just have to solve the differential equations for for each half of the wave, and setting the \$\Delta V\$ of a capacitor equal to the negative of the other side of the phase? Is there an easier way that I'm missing? Thank you!


texts: Boost DC voltage converter for wireless temperature sensor (1.5V to 5V)

texts:
I'm trying to design a wireless temperature sensor powered by one (or maybe two) rechargeable NiMH AA cell(s). The sensor should read and transmit the temperature every couple of seconds and remain in low power consumption mode the rest of the time.

I'd like the sensor to be built with the following components:

ATtiny85-20PU or ATmega328P-PU as MCU (1.8-2.7 to 5.5V)
TWS-DS-6 433.92MHz RF Transmitter (1.5 to 12V)
The obsolete LM35DZ Precision Centigrade Temperature Sensor (4 to 30V)

To power these components with the batteries I chose, I suppose I'll need a boost converter that generates 4 to 5V out of 1.2 to 1.5V input (or 2.4 to 3V if I use two cells).

My problem is that I can't find the right boost converter that is simple and cheap enough for me to build, and that I can easily get parts for. For example, I've found these really cool resources online:

Maxim's Switching Regulators for Battery-Powered Applications - a quick guide to choosing switching regulators for battery powered applications, with links to parametric searches on Maxim's site.
Linear's App Note 30 - Switching Regulator Circuit Collection

From App Note 30 above, I could select a couple of circuits that I think could meet my requirements, such as:

Figure 9. Boost Converter (1.5V to 5V)
Figure 11. Single Cell Up Converter (1.5V to 5V)

The problems I have with those circuits is that I don't have easy access to some of the components, such as the LT1018, LM10 or the TRIAD SP-29 (I don't even know what that is), for example.

So, my question is what would be an appropriate boost voltage regulator circuit for my specs?


texts:
Is there a way to store a signal in LT spice and then plot it on the next simulation run?

I find myself either plotting two runs in an external program all too often, or even using a screen capture to compare different signals.

My tek scope does this, I can store a signal and then compare it with another signal from a different capture, is there a way to get LT spice to do this?


texts: Connecting logic gate input pin with pull up resistor to another driver input pin doesn't keep the voltage

texts:
I have a circuit with logic gates that implements a function in order to get 3 logic control signals. This logic works with 12V or 0V for high and low states. Logic input pins will be connected to other board pins through a connector. This board connector pins can be at GND or high impedance (no connected) states/levels. Last stage needs more current that logic outputs can offer, so driver will be used.

In order to "translate" high impedance state to high logic state ('1') I have connected a pull up resistor to 12V. So I can get 12V when input board pin is at high impedance. In case that input board pin is at GND level, GND also is at logic gate input pin, so this will be a '0' logic state.

I have done some protoboard tests doing it at two stages. At first, I connected the input board pin with pull resistor to the logic gate input pin and this pull up configuration is working correcly.

At second stage I need to bring the same input board signal pin directly to an input driver pin but also keeping this pin connected to the input logic gate pin. At the picture an only one connector pin is drawn, it's called D.

This stage is not working well because I'm not able to keep 12V at logic input gate (VIN1). I may have the explanation for this, due the driver is built with two transistors. They both are off with 0V input, but they are ON with bigger voltage, as ie: 12V. So the net is carrying current throught resistors.

I use restistors for current limitation. But I have noticed that removing driver resistor, the input gate voltage is reduced from 12V to less than 4V. So, logic is not working well. But if I put a 30K resistor voltage is only reduced until 10V. As R = 40K is a value that offers the input current that my application needs to keep 70mA at driver output, I keep this as my solution.

I need the pull up configuration for logic gate input, but the same signal must arrive to the driver input. I need to keep 12V, there (logic gate input pin). Now I have get 10.5V using R = 30K.

My question is how would you solve the situation I have?
Is there a way for improving this solution?

Notes: I'm using ULN2803A device for driver and cd4072B device for NOR.


texts: How to calculate output voltage of a non polarized capacitor?

texts:
How to calculate output voltage of non polarized x-rated capacitor (230VAC 5A 50/60Hz)? (which depends on input voltage) as like as the calculation of output current here tutorial

table here tested values how do they obtained it?

  I want to design Capacitor Power Supply for household LED lamp
  (high luminosity also needed) applicable for different input voltage
  levels which dimmed for corresponds. -- LED Driver


texts:
I'm reviewing the schematics for an evaluation board, which uses an LC filter on the DC input as shown here:

PWR_IN is defined for the evaluation board as being 7-27V. The issue I'm facing, is where the evaluation board is defined for current draw less than 7A, my device is designed for up to 15A draw (external 15A fuse on the PWR_IN positive lead). Ferrite beads aren't typically available above 10/10.5A rating, so I need an alternative means for providing a similar level of EMI filtering.

Can I put 2 10A ferrite beads in parallel on each of the positive and negative traces, or would a dedicated automotive EMI IC (such as the BNX02301L) be the best option?


texts:
I am trying to build my own DDS.  I want to make a lookup table (eeprom)that controls steps of a counter and  then feed it into a DAC to make a wave form ( something like that Direct Digital Synthesizers do).

It seems all parts are straight forward except the counter. Normally, counters start counting from 0-2^n-1.  For example a 256 step counter starts from 0 and counts one by one to 255. Now I need a counter that can count with controlled steps (jump). For example 0,10,20,...,250  or 0-4,8,..    And these steps are selected programmatically with count speed around 100MHz.

Anyone knows an IC that does the job?  I heard Analog Devices has parts like that but I don't know under which product group should I look for that?


texts: D+ and D- not working. Can We STILL Use Q.C. charger?

texts:
I have a MOTO G4+.
I recently changed the charging port from a repair shop. After that my device does not detected on PC not OTG detection and when plugged mobile into charger shows charging over USB. After checking with multimeter one of the data line is shorts to ground and other data line not. Before this happened I measured the voltages to know at what voltage my device charge with fast charger and it charges at

v+ 9v
d- 0.9v
d+ 3.6v

So know as I know data lines not working. My question is what if I supply 9 V on V+?
What will happen?
Will it charge or destroyes? Should I supply voltages on D+ and D- ?
Sorry for bad English, thank you.


texts: Hooking up two voltage regulators for more power?

texts:
I have two LM317's, which I am wiring up as a current source for two high power, 10 watt LED's.

The 317 can operate @ 1.5 amps maximum, so I plan to build two of these circuits.

The problem I am running across is the output pin has continuity with the metal casing, and I wanted to use one heat sink. The metal casing touches the screw, so there is no way I can put an insulator in between, the screw will still make it short.

So can I have both output pins touching, and run everything together, assuming each LED takes the same amount of current?


texts: How to design GUI for my embedded design

texts: I have designed my embedded software and it is working fine. I was thinking about making good GUI so that it is easy for others to interface with my software.


texts: Let's say I have a PIC and an EEPROM memory IC. I store sensitive data in the EEPROM. If I want to encrypt the data what is a good encryption algorithm? It should be executed by the PIC but that does have time for that. So I want to store ~100 bytes and the encryption shouldn't take longer than ~5s on 40MHz.


texts:
I'm building some slides for my class about how we should document the hardware we are developing.

I'd like to list the documents we should make when building some hardware. I was inspired at UML software documentation, which brings lots of document types for almost every situation.

From my experience and research, lots of projects only have the schematics, the layout and the bill of materials. I think that we should also add information about the motive (requirements) that lead us in choosing one microcontroler and not the other. There are also some information regarding the layout that we just don't write, as special component position that should not be changed.

That being told:

How we should document our hardware?
Which are the important document you wanted to have if you need to make some improvements/alteration on someone else hardware you have never seen?
How organize these information in a clear way?


texts: N-channel MOSFET in low-side switch allows current to pass when off

texts:
I am attempting to replicate the circuit below on a through-hole breadboard  and am not getting the expected results. The "Bed-Heat" input on the far right of the schematic is a digital signal from a logic board of 0V or 5V to turn the transistor on. The two 'VBED' inputs up top correspond to my +24V in from a DC power supply, and the GND node contains both the ground from the Bed_heat input (logic board) and the ground from the power supply. The output is on the left (X11J and X11I), and should yield +24V when the input signal is on and 0 when the signal is 0.

As of now I can get the output to show +24V when on, but it's never at 0V when I turn off the input signal; instead I get a value between +14 and 16V. I've experimented with a couple different mosfets and diodes, and tried a 10 Ohm in the place of the 100 Ohm resistor going to the gate.

The transistor in question I'm using is PSMN2R2-40PS, and the Schottky diode is SB3100E-G. I'm not using the LED shown so that part is an open circuit in my case.

The circuit drives a heated bed for a 3D printer powered by a Rambo board (arduino). I have a power supply unit just for the heated bed and the electronics fans, separate from the power supply for the logic board.

Appreciate any pointers!

Edit: see two pictures at the top of this post for the breadboard I'm trying to make this circuit on. Red wire at top right is VBED (+24V in), thin red wire at the bottom is Bed_heat +5V input signal. The grounds of both inputs (white wire at top, black wire at the bottom) are shorted to each other via the orange wire on the board. The terminal at the bottom right will have the outputs X11J and X11I respectively left and right.


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Germanium transistors would sometimes become very noisy despite the in-circuit DC bias voltages testing normal. This failure was cured by replacing the offending BJT. I have found this as a teenager and now when fixing classic car radios.

What is the mechanism for this type of failure? Si transistors don't fail this way in my experience, why? It has been said that a particular batch of Ge transistors failed this way. Is there any truth to this or is it an urban myth?


texts: What is the minimum voltage requited to charge a cell phone?

texts: When charging a cell phone, what is the minimum input voltage to the phone required not the battery directly, but the actual phone?  Is it actually five volts that the wall charger puts out, or can it be less like 4.4 volts?


texts: Wireless Audio Transmission with NRF24L01

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:)

I have been planning to do a project on transmitting audio through arduino using NRF24L01 RF Modules at the same time sending data commands. I am really a beginner in terms of audio circuits so I just want you, experienced people, to check if my Schematic diagram draft is correct. Thanks!  :)

The project is based on the RF24 and RF24audio library for the arduino by TMRh20
https://github.com/nRF24/RF24Audio.

My references for this project:

a research paper PDF https://www.academia.edu/37370105/A_LOW-COST_WIRELESS_TV_AUDIO_TRANSCEIVER
and an arduino walkie talkie instructable https://www.instructables.com/id/Wristwatch-Walkie-Talkie/?fbclid=IwAR3ygIxQ04RkGxoig-NLiG63_Dy67fn-ugK_Q-e1ZIqhI5EkollqOw6UfOc

These are my Schematic diagram for the project:

Transmitter Circuit

The input circuit for the 3.5mm jack was based on the given circuit I found on the internet.

Receiver Circuit

The receiver circuit for the was based on the given circuit I found on the project reference paper https://www.academia.edu/37370105/A_LOW-COST_WIRELESS_TV_AUDIO_TRANSCEIVER.


texts: Active Filter and Sine to Square Conversion Issues

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Background: I am currently using a SparkFun Electret Microphone and am needing to both filter and amplify the signal before turning it into a square wave to be interpreted by a FPGA. The mic itself has a ~1.65V DC offset and the signal amplitude is in the range of 200mV. The mic is powered off of 3.3V. For amplification I am utilizing a LM324 powered off +/-2.5V. For the conversion of the signal, I am using a LM339 comparator with a low pass "averaging" circuit and it is powered off of 3.3V.

Issue: Both of these circuits work just fine independently of each other. The active filter does a pretty good job of attenuating room noise below the 8kHz cutoff I had specified when I built it. The LM339 with the "averaging" filter works just fine to convert the sine wave from the mic to a square wave as well.

The problem I am encountering however is trying to integrate the two of them. When the output from the LM324 is fed into the comparator, I cannot seem to get any output out of the comparator.

I have simulated the circuit in LTSpice and the output is what I would be expecting to see in reality, but I cannot for the life of me get this to work. Images of the simulation are attached below.

Red trace is the simulated mic input
Green trace is the output from the active filter
Blue trace is the output from the comparator

Thanks in advance, any help is appreciated!


texts: Can I run a 12v fan off of a 9v power supply for LED lights and are there any side effects

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I have multiple (9v 1500mA to 9v 3500mA) LED light fixtures that I have tested chaining a single fan (12v 5.2w and 12v 0.16A fans) and they seem to work under the brief test with enough air flow for my needs.

Anything I should be careful about while doing this and any direction to better understand if there are concerns or how to calculate? I am a software engineer, just getting into electronics via raspberry pi projects, so still learning as I go. The actual project right now is regulating / climate control of multiple dart frog terrariums.


texts: I get that the frequency is zero hence the voltage is consequently zero according to the the equations, but any current through a conductor should produce a magnetic field. I also understand that there's no rate of change of flux and EMF induced should be zero. So does that basically mean that normally when AC current is passed, the voltage VL is because of the emf self induced by the inductor? If so, how does this happen? Should not the coil be a closed path for EMF to be induced? Is this closed path the entire circuit which the inductor is a part of?


texts:
I can easily switch on and off a 220V source using an electromechanical relay. But I am now looking for a much more versatile solution. Something that can not only switch the source on/off but also use them as dimmers. I had no idea how to do this so a friend of mine (from electronics background) said I could use SCR circuits to this, but he had no idea about what ICs could accomplish that. So a visit to a local store and now I have a couple of TYN612 IC which is an SCR capable of controlling upto 600v AC at 12amps.

Now, Using TYN612 how can I build a dimmer circuit, that can be controlled using arduino, which could also control on/off at 220V AC. Or any other alternative is welcome.


texts: Calculating load resistor for maximum power

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How would I go about solving this? I cannot even begin solving this.
EDIT 1:
Thank you all of you I got it:
\$R_{Th}=(\frac{1}{6k}+\frac{1}{12k})^{-1}+2k = 6kΩ\$
Find the potentials at both the nodes connecting the \$12kΩ\$ resistor to the rest of the circuit. \$6V\$ at the top node and \$2V\$ at the bottom. Their difference gives \$V_{Th}\$:
\$V_{Th}=6-2=4V\$
The maximum power transfers to the load resistor when \$R_{Th}=R_{L}\$
Using \$P_{L}=\frac{V_{Th}^{2}}{R_{Th}}\$ the power is found to be \$1.5mW\$
Edit 2:
Sorry, the power is actually found to be \$0.6667mW\$