texts: Does developing on ARM Processors from different vendors differ much?

texts:
I have started developing applications on XMC 2 go evaluation board. I, more or less, got the idea. But what if I try to go for, lets say, STM32?

For XMC1100 setting pin 00 as output is

PORT1->IOCR0 &= ~PORT0_IOCR0_PC0_Msk;
PORT0->IOCR0 |= 0x0 << PORT0_IOCR0_PC0_Pos;

But I don't think stm32 has a IOCR register. So, should an engineer learn all these different register names?


texts: Can I use a source follower to read the floating gate voltage then add a fixed tunneling voltage, then feed it back to the tunneling electrode?

texts:
So I was reading this research paper:
H. Kosaka, T. Shibata, H. Ishii, and T. Ohmi, “An excellent weightupdating-linearity
synapse memory cell for self-leaming neuron MOS
neural networks,” in IEDM Tech. Dig., Dec. 1993, pp. 623426

https://ieeexplore.ieee.org/document/370025/

Here's a link to view the document:

https://tohoku.repo.nii.ac.jp/index.php?action=pages_view_main&active_action=repository_action_common_download&item_id=53595&item_no=1&attribute_id=18&file_no=1&page_id=33&block_id=38

For (b) the nmos1 source follower reads out the floating gate voltage, Фf, minus the nmos threshold voltage, vth: Ф- vth
This is conducted into the tunneling electrode in the middle, right below the floating gate. Then, in (c), nmos2 turns off and the tunneling electrode holds onto this voltage (Ф- vth). Why?? Wouldn't it leak away slowly thru the nmos off resistances?

What bothers me is this seems like an endless feedback loop. The floating gate voltage is the sum of the weighted capacitive inputs and the effect of the charge in the floating gate:

Increasing the tunneling electrode potential Vinj will increase the floating gate voltage Vfg or Фf. then the source follower will pass it to the tunneling electrode and will add back to the floating gate voltage and so on.....

I need to clarify the above questions because what I want to do is to feedback the floating gate voltage and add a fixed tunneling voltage Vt before feeding it to the tunneling electrode. This will make the difference between the floating gate and tunneling electrode potentials constant, so that a constant tunneling current will flow and the floating gate voltage will increase linearly with time.


texts:
This might not be a heat sensor at all. I bought this at a swapmeet and the bag in which this came had the words "Heat Sensor - Hitachi" written on it. The sensor is mounted on an aluminium piece by some form of epoxy. The sensor itself seems to have a white ceramic substrate with zig-zag traces on it.

The resistance of between the leads is around 1K and does not seem to change with temperature when I heated it on an electric stove. Light also does not make a difference(so its not a photocell)

Can somebody please let me know what this is?

edit: I read about PT1000 sensors. It said that they are quite accurate. So I decided to put the sensor in a ice/water bath to get 1000 Ohms at 0 degC. Over time the resistance actually increased and it went over 2000K(multimeter limit). I then decided to heat it a little more than last time over an electric stove. The resistance dropped to about 700 Ohms before the epoxy melted and the sensor came off the aluminium. For a PT100 sensor the resistance should increase with temperature so this behaved opposite.

Another thing I noticed is that the two traces actually do not form a long connecting trace. They are actually intertwined fingers without touching.


texts:
The question is asking to find ID1 and ID2 of the two ideal diodes in the circuit below:

I solved it as follows:

The correct solution is as follows:

I would like to know where is my mistake. Also, why did he assume that the voltage at the anodes to be zero? why not 3 or 2 volts? How did he arrive to zero?
The source:

I know the question numbers are different,however, they are the most relevant to the question asked.


texts: I am working on building a computer with a Motorola 68030. The one I got my hands on is the 40Mhz version. In the electrical specifications pdf they list the minimum clock frequency for the 40Mhz version as 25Mhz. I would prefer to at least at the beginning run it slower so I don't have to worry about memory timing. What will actually happen if I run it too slow?


texts: Significance of Vf terminal in Li-Ion Battery

texts:
i was going through some propriety schematics that i can't post

the battery used in the schematic is a li-ion battery of 3.8V/2.1Ah/ from samsung, which gives out three pins + - vf

i have seen batteries in my previous experience trying give a thermistor output which conveys the temperature value of battery

but what exactly is vf here, i came across some one calling it a forward voltage of diode which is used inside the battery, the vf from battery was going to an ADC in my design

some useful link i have found is here which speaks about internals of a nokia bl5c, as the design is of a smartphone itself i assume this battery would be similar to mine

in short i know this is been used for battery detection but i want a clear cut idea on how is this helping


texts:
I'm doing an internship where we are connecting all kind of sensors on a CAN-network for an automated datagathering.
There is one sensor that sends a 50% duty cycle frequency signal between 1 and 11 Hz.
So 1 Hz stands for 1l/hour and 11 Hz stands for 1500l/h.

Does anyone know which kind of converter can be used? preferable to DC
The converter should come in a room of 70°C (160°F)
For the prototyping I used an Arduino Due with an own-made shield. counting the time between each interrupt.
But we have like 300 sensors, so creating 300 shields would be a plan B option.


texts:
I'm working on a ultra-low power application and want to enable and access only one pin as output and one pin as input. I'm using the MSP430 microcontroller and CCS for programming. I have two questions.

The MSP430 allows accessibility of a whole port. Is it possible to access only the required two pins as input and output (which is possible in PIC)?
Doesn't accessing (and enabling) the whole port (8 pins) consume more current compared to accessing (and enabling) a single pin?


texts:
I'm assigned with creating up/down counter in quartus II, but I can't find a way to do it properly. In simulation it always ends in transient state, so I guess there are some metastability issues that I don't understand, but I spent long hours on it and couldn't make it work.

This is my base design, are there any obvious issues at this stage that I'm missing?

Then I tried to ensure that counter is cleared only when we count up (104->0) and when it counts down, given value is loaded when it underflows (0->104).
What do I need to do, to make it work correctly?


texts: Where are details regarding peripheral configuration for STM32 controllers in datasheets?

texts:
I have recently begun working more with STM32 processors coming from the more simple Atmel 8bit variety. The Atmel datasheets are very nicely laid out -- specifically speaking to how they provide information relating to hardware configuration registers.

However, I am having a difficult time finding similar information in the ST datasheets. How, for example, do I find information about configuring the alternative options on a pin, or the sampling rate of the ADC? I can find only general information about this hardware for a given processor, but never as much detail as provided by Atmel shown above.

Am I just looking at a condensed datasheet? I pulled one available directly from mouser: see an example.


texts: ESD Protection for flyback diode - Relay circuit

texts:
I am designing a board to accommodate relay and flyback diode with IO connector in a PCB. The low side driver of relay will be present in another PCB. Both the boards will be connected through wires(12V supply and Drain of low side driver). Please refer attached image to understand the schematic.

I understand that when the relay board is not connected to anything, and when human interfaces with relay board, there are possibilities for ESD event across flyback diode which can damage the diode.
But I do not understand that when human touches the input connector, how ESD high potential develops across flyback diode since anode and cathode of flyback diode is floating when the board is not connected anywhere.
If the anode of flyback diode is connected to GND, then it is easy to assume that high potential developed across flyback diode. When both the pins of flyback diode is floating, how high potential develops across diode?
If high voltage developed, will the TVS diode across flyback diode protect the circuit?


texts: Circuit short circuit capacitor question confusion

texts:
I am really unsure about how to go about this question and which circuits to consider.

Here's the question:

Determine the value of the current labeled \$i\$ and the voltage labeled \$v\$ at \$t=0+\$, \$t=1.5ms\$, and \$t = 3.0ms\$.

The circuit is as follows:

simulate this circuit – Schematic created using CircuitLab

Relevant equations:

Ohm's law: \$v = iR\$

Decay in source free RC Circuit \$v(t) = v(0)  e^{-t/RC}\$

The attempt at a solution:

\$i(0-) = 0.1 A.\$

Therefore,

\$v\$ across 200 ohm: \$200 * 0.1 = 20 V\$

Since no current flows through capacitor with constant dc current,

\$v\$ across capacitor: \$20 V @ t < 0\$

\$v\$ across capacitor cannot change immediately as it would require infinite power so \$v\$ across capacitor @ \$t = 0\$ is \$20V\$

Here's where the confusion is: Should I include the 200 ohm resistor in my RC circuit? Why or why not? Also, will my circuit be a source free RC circuit?

Also, what will be the current i through the 200 ohm resistor when t>0?

My last question is a theoretical one: Can a current through a resistor change immediately at one instant of time?


texts: I'm doing a project on live audio streaming through xbee. The baud rate we are using is 115200. Audio transmission works perfectly through wired UART connection. But when we performed wireless communication through xbee, audio got distorted. I think the problem is within the xbee data rate. How can i solve this issue?


texts: I was looking at the AD8403 A1 Digital potentiometer to use in a circuit where the voltage on the brush would be 12V and the voltage on the extremities would be 11.9V. Whilst this is way outside of the specification of 5V, since the difference across the pot is only 0.1V can it still be used?


texts: How to ensure an off-before-on transition for an H-bridge?

texts:
I want to control a H-bridge using an ATMega2560. The goal is to produce output with +-18V for driving a Merklin H0 digital train set.

Given the voltage and current needed for the trains it is crucial that the H-bridge never ever goes into a shortcut state. And since software is always buggy I don't want to rely on the ATMega to switch the pins correctly. Instead I want to add some hardware between the ATMega and the H-bridge that does the following:

turn the H-bridge off on illegal inputs
when transitioning from one state to another ensure that the H-bridge first gets an off signal before an on signal for the opposite switch.

I have a lot of 74HTCxx chips around so I can implement logic functions with them.

My question now is: How do I make the H-bridge foolproof? How do I ensure the off-before-on transition for the output signals? Can I use gate switch times to delay on signals sufficiently? Or do I need a clock signal and flip-flops to implement discrete transitions from one state to another?


texts: Does transformer humming cause notable waste of energy?

texts:
AFAIK transformers hum because alternating magnetic field causes pieces of laminated core to slightly deform and vibrate and that is simply a byprocess of how transformers work. However for the same model, the same power load and the same age some transformers hum more than others. The latter is sometimes claimed to coils being winded slightly less tightly so that over the transformer lifetime it first vibrates less and that vibration causes coils to stretch a little bit and allow for more vibration. Another scenario is when a transformer ages and laminated pieces slightly grind the thin insulation between themselves.

I'd guess that increased vibration should require some power to work and that would decrease transformer efficiency.

Does transformer humming cause any notable waste of energy?


texts: What is the minimum clearance I need to set between two tracks with voltage difference 36 V

texts:
What is the minimum clearance I need to set between two tracks with voltage difference of 36 V.
External traces, given that solder mask is applied on the board if it matter in calculation. And is there any other variables that we have to take into consideration?


texts: Store uart incoming data in sd card interfaced with CC2652RB LP

texts:
I am using TI Simplelink CC2652RB LP for my project.
I have to store UART incoming data in text file created in SD card interfaced with cc2652RB LP via SPI.
Can I use the following logic along with other  declarations?
char str = uart_read(uart, &input,1)
fwrite(str, 1, strlen(str), src)


texts: voltage gain and current gain in a common emitter

texts: How can I calculate the voltage gain and current gain of this circuit? The voltage gain is giving me -204.49, but with the oscilloscope gave me a gain of approximately 10 (positive). I do not understand where I was wrong.


texts: What is the 1000V - 200mV AC range for on my multi meter?

texts: This question draws upon elements of using a DVM for AC.  My multi meter has a 1000V - 200mV AC range.  Since there seems to be a consensus that multi meters can only reliably read 50Hz AC wave forms, why would you have this range on a meter?  Very few are going to use a 50Hz signal for testing their kit.  It might not even get through some small coupling capacitors.  It doesn't really get to /from my sound card which I'm using as an oscilloscope.  So unless you're measuring the mains, what's the point of such a huge AC range on my meter?  In what circumstance would you be needing to measure for example 100 mV AC @ 50Hz?


texts:
For a uni project I am tasked with programming embedded C onto an ATMEGA 8 uC, and there aren't enough development boards for everyone to use at uni, so I have an ingenious solution. I have several arduino uno's lying around, and I've replaced the ATMEGA328P chip on the Uno with an ATMEGA 8 chip.

Now I want to program the chip while it is on the arduino uno board, using Atmel Studio instead of Arduino IDE in Embedded C (not C++).

From what I hear, first, I'll need to burn a bootloader onto the ATMEGA 8 chip before I can do anything else. But which bootloader do I burn? Will the Arduino Bootloader work for the ATMEGA 8? or do I need the bootloader made specifically for the ATMEGA 8 in embedded C? I need to program it in Atmel Studio afterwards as well, instead of using the Arduino IDE.


texts: Designing PID to reject load disturbances of dead-time process

texts:
I am using the PID Tuner for the PID Controller Block in Simulink. I am particularly interested in the output disturbance BODE plot. I am trying to achieve an acceptable output disturbance with the follow requirements:

Attenuation of at least 10 dB with frequencies less than 0.5 Hz
Flat response (0 dB) at higher frequencies with no overshoot.

By raising the bandwidth of the controller, see image below.

I am able to achieve the appropriate attenuation at < 0.5 Hz, but I am getting a nasty overshoot at 4 Hz, which is unacceptable. Lowering the bandwidth, see image below, removes the overshoot but then I have poor attenuation.

My plant is:

\$G(s) = \frac{4.1s + 59.5}{s^2 + 34.1s + 385.7}×e^{-0.05s}\$

Other than adjusting bandwidth and phase margin, is there anything else I can try to achieve both of these requirements?

If it isn't evident. I am not an expert in controls engineering. I apologise in advanced if this question seems novice.

Thank you,


texts: Finding wavelength from infrared LED in a photodiode sensor

texts:
w
I have a dust sensor that emits LED light, scatters the light of the material and records the light intensity via a photodiode. I know the LED will emit light in the infrared range. I want to know the (approximate) wavelength since the infrared range is quite large.

Is there any way I can find the wavelength of my IRED LED (page 2) based on the spec sheet, particularly pages 4 and 5.


texts: Tips for improving this PT100 sensor amplifier circuit?

texts:
I'm designing a circuit to read a PT100 temperature sensor using an OP-amp and the ADC of a PIC 16F1788. I've designed the following circuit:

The PT100 sensor is labelled PT100. The basic idea is a non-inverting OP-amp configuration with a gain of approximately 300, and an offset, such that signals of 100mV and 116mV are amplified to 0V and 5V respectively. This is to give the sensor a range of approximately 0 degree C to ~40 degree C, for sensing indoor temperatures. I've derived the exact formula for converting nominal ADC voltage to temperature, but I'll spare you the details in this question.

After the output of the OP-amp I've put a simple low-pass filter.

I've built this circuit on a PCB, but without the low pass filter, and then the total noise is equivalent to 0.5 degree C. This is approximateley 0.0625V at the ADC, and 195 microvolt at the OP-amp + input. I'm now spinning a new PCB, with space for the filter, and a lot of improvements unrelated to this question.

The circuit works, and using filtering in software I can sense very small temperature differences (such as a few 0.1 deg C from turning on a lamp a meter from the sensor). However I'd like to not have to do all this filtering in software.

Is the low-pass filter a reasonable precaution to getting lower noise? Am I right in thinking it is more effective from a noise perspective to put it at the ADC compared to trying to put it over the PT100?

Anything else that could be improved in this circuit (since I'm ordering a new PCB anyway)?

I've been thinking about putting a ~680 ohm resistor right after the voltage regulator, so that it together with C2 creates a low pass filter, and then to connect the ADC Vref+ of the PIC ADC to the positive terminal of C2. Would this be more effective to reject power supply noise, compared to just using the PIC's internal 5V as positive reference? The PIC is powered from the same power supply as the op-amp.

PIC16F1788 datasheet: http://ww1.microchip.com/downloads/en/DeviceDoc/40001675B.pdf

OP-amp AD8629ARZ datasheet: http://www.analog.com/media/en/technical-documentation/data-sheets/AD8628_8629_8630.pdf

Voltage regulator LM340LAZ-5.0: http://www.ti.com/lit/ds/symlink/lm140l.pdf


texts:
I'm having some troubles with setting up a 1 second timer on STM32F103 mcu.

I have set Timer 2 to have a prescaler of 1099 and a period of 65514, so I'm expecting to have a 1 second interrupt rate: 72MHz/1099/65514 = 1Hz.

Yet in reality I get the first interrupt before even finishing the timer configuration routine (not a big concern at the moment), the next interrupt occurs after 1000ms as expected, the next interrupt occurs after 322ms, and the next after 32ms and the next after 590ms. (these were measured according to the systick timer which I have running at 1ms).

It seems pretty random, what's going on ?

Here is part of the relevant code:

void RCC_Configuration() {
RCC_APB2PeriphClockCmd( RCC_APB2Periph_GPIOA |
                        RCC_APB2Periph_GPIOB |
                        RCC_APB2Periph_AFIO  |
                        RCC_APB2Periph_USART1, ENABLE);

RCC_APB1PeriphClockCmd( RCC_APB1Periph_TIM3 |
                        RCC_APB1Periph_TIM2, ENABLE);
}

void Timer2_4_5_Configuration() {
TIM_TimeBaseInitTypeDef  TIM_TimeBaseStructure;

TIM_TimeBaseStructure.TIM_ClockDivision = TIM_CKD_DIV1;
TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;
TIM_TimeBaseStructure.TIM_Prescaler = (1099-1);
TIM_TimeBaseStructure.TIM_Period = (65514-1);

TIM_TimeBaseInit(TIM2,&TIM_TimeBaseStructure);
TIM_ITConfig(TIM2, TIM_IT_Update, ENABLE);

TIM_Cmd(TIM2, ENABLE);
}

void NVIC_Configuration () {
NVIC_InitTypeDef NVIC_InitStructure;

NVIC_InitStructure.NVIC_IRQChannel = TIM2_IRQn;
NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0;
NVIC_InitStructure.NVIC_IRQChannelSubPriority = 1;
NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;

NVIC_Init(&NVIC_InitStructure);
}

void TIM2_IRQHandler() {
TIM_ClearITPendingBit(TIM2, TIM_IT_Update);
GPIOA->ODR ^= GPIO_Pin_2;
}

EDIT: I managed to get this to work, I did a silly mistake in the rest of my code. I have used the same pin for something else forgot to comment the line, oopsy.

The led on pin 2 toggles at 1Hz as intended, but a new question arises:

I have set a breakpoint at the pin toggle line in the TIM interrupt handler and it seems it fires up at random times as stated above. But when I remove the breakpoint the led toggles as intended.

What's going on ?

P.S - I'm using CooCox IDE.


texts:
I am having an issue with my motor control code.
The aim of the code is to control a motor which has a built in encoder.  Now, I wrote a simple test code that makes a user enter the value between 1-255 which makes the motor move clockwise  a certain svalue. But I am having an issue in terms of the encoder.
I used a encode library that works exceptionally well as seen in the diagram. However, when the motor moves, it does not give a real time position also seen in the diagram.

I was wondering how I can make the encoder send the Realtime position of the motor when the motor has moved.
I have attached the code below.
#include <Encoder.h>
//Pin Constants
#define motorDirPin 12
#define motorSpeed 3
#define encoderA 2
#define encoderB 8

Encoder myEnc(encoderA, encoderB);
long oldPosition  = -999;

//Clockwise Or Counter Clockwise
const int CW  = 1;
const int CCW = 0;
volatile long int encoder_pos = 0;

void setup()
{
  //Start Serial monitor
  Serial.begin(9600);
  //Motor Inputs
  pinMode(encoderA, INPUT);
  pinMode(encoderB, INPUT);
  //motorSetup Handles the I/O
  motorSetup();
  attachInterrupt(digitalPinToInterrupt(encoderA), encoder, RISING);
}

void loop()
{

  //Allows user to enter speed value between 1-255
  if (Serial.available() > 0)
  {

    int val = Serial.parseInt();

    //motorMove is the method that handles the motors movement.
    //Requires direction (CW or CCW)and speed paramater (Entered in Serial Monitor)
    motorMove(CW, val);

  }
}

void motorMove( int dir, int speed)
{
  int motor;
  int motorPinSpeed;

  motor = motorDirPin;
  motorPinSpeed = motorSpeed;

  if (speed > 1)
  {
    digitalWrite(motor, dir);// direction
    analogWrite(motorPinSpeed, speed);// speed

    Serial.print("speed: ");
    Serial.println(speed);
  }
  if (speed <= 0 || speed > 256)
  {
    motorStop();
  }
}

void motorSetup()
{
  //Motor Outputs
  pinMode(motorDirPin, OUTPUT);
  pinMode(motorSpeed, OUTPUT);

  digitalWrite(motorDirPin, LOW);
  digitalWrite(motorSpeed, LOW);
}

void encoder()
{

 if(digitalRead(8) == HIGH)
  {
    encoder_pos--;
  }
  else
  {
    encoder_pos++;
  }
  if (encoder_pos == -50 || encoder_pos == 50)
  {
     motorStop();

     encoder_pos = 0;
     delay(5000);
  }
  Serial.println(encoder_pos);
  }

void motorStop()
{
  int motorPinSpeed;
  motorPinSpeed = motorSpeed;
  analogWrite(motorPinSpeed, 0);
  Serial.print("motor has stopped");

}


texts: How to wind a toroid for 170 uH Inductor

texts:
I am planning on buying a toroid core from Digi-Key. I want to be sure that this is the right type and that I can achieve 170 uh inductance with 22-18 AWG wire. How can I wind this and what is the formula so I can calculate this myself in the future. If this doesn't work which one can I buy from Digi-Key to get the right inductance. (my budget is 4 dollars or under for the toroid core) Last, I want this to handle up to 10 amps of current so tell me if I can't use 18 AWG wire.

edit-fixed broken link, i guess it was just because it was linked directly to my shopping cart

From a comment It said to buy my own I can't find any already pre-wound 10 amp 170 uH toroid and the only thing close was like 10 dollars so I would like to wind it myself!!!


texts: Why Does My PMG Generator gets Locked Up?

texts: I tired to connect a 60 W 240 V resistive load to a 1000 W generator which was running at 200 V immediately after the load was connected the voltage drops to 60 V and the generator stops spinning. By the way it is a three phase 415 V delta generator.


texts: About CT secondary winding on toroidal transformer

texts: I am done primary winding today of my toroidal core. Attached photo of transformer below. 755 turn of 0.914 mm magnet wire. Core size before winding OD-100mm, ID-60mm, Ht-50mm (M4,CRGO). Sir when I test for secondary voltage I get 2.7 volt on 10 turn of magnet wire. why I get less volt per turn. Because before making the primary winding I done partial test on core, wind 10 turn for secondary, I get 3.2 volt. And I am winding center tap for this transformer of 35-0-35 using dual winding method (2 wire at same time, bifilar.) If I want lower voltage from same winding can it be done? e.g for 25-0-25?


texts: Does MPLAB IDE v8.92 show Page Breaks anywhere in programmer

texts:
In the MPLAB assembly code window is their anyway to show or indicate where page breaks are I am using 50 PClath Calls.
 If I add or remove code it changes the position of page breaks. I would like to know where the page breaks are, if shown in any of the windows provided in MPLAB.  Page refers to memory allocation block boundaries. In code their is no defined points where they start are end.


texts: What exactly are harmonics and how do they "appear"?

texts:
From reading so many sources online, I still cannot grasp why a different waveforms have harmonics.

For example: when designing a silly amplitude modulation (AM) circuit that puts a square wave from a microcontroller in to an antenna, how are harmonics generated? The signal is just "on" or "off", how are there first, third, and fifth harmonics and why do they get weaker?

I've heard oscilloscopes being able to measure up to the fifth harmonic of a square wave (or something similar) is important, but why would that make the reading different? Are these harmonics irrelevant in things such as data transfer (high=1, low=0) and only matter in situations such as audio or RF?

Why do sinusoidal waves not have as many harmonics? Because the waveform is always moving and not flat going up (triangle) or horizontal (square), but circular with an always changing value?


texts:
Dig through a junk drawer, I find a long cable with RJ-45 on each end.  Definitely not RJ-11.  It has only four wires.  What might it have been used for?

I'm not expert on wired ethernet, but in forty years of tech work, I've seen only six and eight wire connectors, mostly eight.  This is the first time I've seen four on RJ-45.


texts: How to configure STM32 with two different clock speeds

texts:
I'm using STM32F103RE for implementing a time-consuming operation. This device is connected to the PC via a USB port. I'm not expert in configuring these MCUs, but it seems when it configures to communicate via USB, it can't use maximum possible processing speed which is 72 MHZ.

Is there a way to configure my STM32F103 with two different frequencies (one for USB communication & the other for internal proccessing at 72MHZ)?

This is part of the USB configuration code:

RCC->APB1ENR |= (1 << 23);                /* Enable clock for USB */

/* Enable USB interrupts */
NVIC->IPR [5] |= 0x00000010;              /* Set priority lower than SVC */

NVIC->ISER[0] |= (1 << (USB_LP_CAN_RX0_IRQChannel & 0x1F));

/* Control USB connecting via SW */
RCC->APB2ENR |= (1 << 5);                 /* Enable clock for GPIOD */
GPIOD->CRL &= ~0x00000F00;                /* Clear port PD2 */
GPIOD->CRL |=  0x00000700;                /* PD2 General purpose output open-drain, max speed 50 MHz */
GPIOD->BRR  = 0x0004;                     /* Reset PD2 (set to low) */

And this is my smt32_init clock configuration:

#define __CLOCK_SETUP              1
#define __RCC_CR_VAL               0x01010082
#define __RCC_CFGR_VAL             0x001D8402
#define __HSE                      8000000

I guess some change in RCC_CR or RCC_CFGR should solve the problem, but I think there are also some other configurations for flash to work with high frequency.

How can I do that?


texts: Understanding Circuitry from a Datasheet

texts:
I'm having a little difficulty understanding this section of a circuit from the datasheet for an MC33035 BLDC Motor Driver.

Some info:

Pin 7 is enable, send pin high to enable motor
Pin 8 is a 6.25v source
Pin 14 is a fault pin, active low during a fault (at VCC (pin 17) not during a fault)

I'm assuming during a fault "Latch on Fault" is closed, pushing the reset button would therefore send pin 7 high, re-enabling the motor.

However, following this logic then "Latch on Fault" would be open when the motor is running - but how is pin 7 sent high?

Or is it default high, closing the switch next to it pulls it down, or if "latch on fault" closes it pulls it down?

What is the 47uF cap for?

Any help greatly appreciated.


texts:
I have wondered this on and off for years, and was prompted to find out the answer:

Any time I've seen capacitors, they're listed with milli- or pico-Farad ratings. I understand that, nowadays, we have special purpose supercapacitors that package "whole" Farads into single components.

But, why on earth did "they" use such a large base value that for "most" applications you'd need something in the milli- to pico- range? It just seems ... unnecessarily skewed.


texts: What is the technically right thing: the function of a battery cell in a battery in a phone is to maintain certain voltage or provide certain current?

texts:
I need to write the precise functions of an individual battery cell in a li-ion battery of a laptop.
I am not sure whether one of the functions should be to provide voltage or provide variable current.
This question arises because I think that primarily the battery cell creates a voltage across its ends and the current is a by-product of its connection to a load and so the function of the battery cell should be to provide voltage and not the current but I am not sure.
Also, the cells provide constant voltage/current right (whichever it does)? Is it then the battery management system or something like that, that modulates the voltage or current to suit the laptop’s needs such as when high power is required for gaming?
I realise I may have implicitly assumed wrong things while framing these questions so I apologise for that and request you to correct me.


texts: Which type of registers is used in CPU: serial or parallel? And how to implement them in VHDL?

texts:
I'm making a CPU in which the memory is represented as a two-dimensional array, using FPGA. I've come to the implementation of registers, and I need the answer to this question. I'm new to electronics, and the answers I've seen were that it depends on the bus type: whether it's a single wire or their collection.
When I choose one, can you please give me a hint on implementing it in VHDL?


texts: Question about LC Filter - Critical Inductance Lc

texts:
In the following screenshot from this video:

Why in the proof to find critical inductance, \$L_C\$, is the following equation used:
$$ I_{dc} = |I_{ac}|_\mathrm{(peak)} $$


texts: How to connect single-phase power source to 3-phase motor

texts:
My 3-phase, wye wound, 9-lead motor has:

wires 1 & 7 connected to wire L1
2 & 8 connected to L2
3 & 9 connected to L3
and 4, 5, 6 wired together.

I put a plug on one end of a cable, that is plugged into a 220 V dryer outlet. How are the three wires in the cable, connected to the motor wires?


texts: American wire gauge - why exactly this ratio?

texts:
Wikipedia on American wire gauge reads:

  Any two successive gauges (e.g. A & B ) have diameters in the ratio (dia. B ÷
  dia. A) of \$\sqrt [39]{92}\$ (approximately 1.12293), while for  gauges two
  steps apart (e.g. A, B & C), the ratio of the C to A is about 1.12293² = 1.26098.

My question is: why exactly this ratio? What's the background behind it?


texts:
I bought a new LED aquarium light and the driver that came with it is not working. I want to buy a replacement driver but I need a better understanding of the driver requirements before I can make an informed purchase.

The driver that came with the light has an output of 48v/700mA and it's dimmable via a 1-10v input, all that's written on the light is that they are 45W (15*3W).

The original driver only outputs 33,6W, isn't it best to have a driver that is working at no more than 80% capacity?
If I wanted dimmer light could I buy a driver that has say an output of 48v/500mA or would that stress the driver? Isn't that how a driver with a dimmer works anyways; lowering the amps?
I connected the light to the strongest power supply I have at hand which is 12v/5A, when I connect this the light only barely lights up. In terms of wattage this power supply should be sufficient so obviously voltage is important here, why is that?
Do I need 48v minimum?
I found a driver with dimmer that outputs 30-36V/0-1,5A does that mean the knob will adjust both voltage and ampere simultaneously?
If I want a dimmable driver do I need one with constant voltage that only adjust the amps?

Feel free to only answer the question(s) you want.


texts: Splitting a +5V rail into 2 isolated +5V lines

texts:
I have a 5v 10A power supply that I am using to power my project. The project consists of a raspberry pi and 3 servos that are controlled by the pi through a PWM driver. The 3 servos and the Pi are powered from the same power supply.

The problem is that when I move all 3 servos I see the low voltage indicator pop up on the Pi. I don't have an oscilloscope to test how much current the servos are using but peak current is 600mA so the power supply should be sufficient to power everything.

Is there a way to split the incoming +5v into 2 isolated +5v rails that share a common ground?

That way I can use one rail to power the Pi and the other rail for the servos without the voltage drops triggered by the servos affecting the Pi.

I need to have a single power input that goes into the housing so I can't use two power supplies to power the Pi and servos separately.

Edit: Here is a an image of the circuit. I've marked out the important parts to make it clearer:


texts: What can the reason be to choose this specific op-amp as a Comparator/Schmitt trigger?

texts:
A rotating instrument is outputting AC sinusoidal wave where both the frequency and amplitude of the output is proportional with the rotation speed.
This output then goes to a converter box, which converts the sinusoidal signals
to pulses.

I opened the circuit case and saw the following opAmp is used:
MCP06
I noticed that our old signal conditioning box which does the similar job cannot function at very low rotational speeds. Which means the opAmp in our circuit is not somehow triggering at low voltages. The min/max amplitude of the sinusoidal signal is from around 10mV to around 150mV. It seems to me that for very low sinusoidal signals with amplitudes around 10mV or up to 50mV our conditioner does not function. But the new converter with MCP607 works fine.

Why do you think this opAmp is used for this purpose?

Cant one make a comparator/schmitt trigger and set the limits of triggering with any opAmp?


texts: 8051 to I2C backpack/4 bit LCD Byte Construct Probelms

texts:
Been feverishly writing bit bang code in assembly for this I2C backpack/4 bit LCD and dont quite understand the binary constructs I need to display text. Im trying to learn this the real way, not the Arduino way where everything is handled for you in the background by library's. Please correct me where I am wrong. Thank you.

I start out in 8-bit mode initializing the 20x4 LCD because it only really recognizes the high order 0010 and disregards the low order 0000 because it is wired for 4 bit anyway:

Send 00110000 (30h) 3 times to LCD in 8 bit mode because thats what the Hitachi controller says to do before 4-bit setup.

Then Hitachi says to send 0010000 (20H) in an 8 bit send and this really puts it in 4 bit mode.

This all works fine. The problem is when in 4 bit mode Im getting confused as to how the nibbles should be constructed for sending commands and text versus interfering with the "RS" and "EN" pins.

So I know the LCD control pins are in the low byte. "EN" is tied to bit 2 so to turn it on I would need to send 00000100 and "RS" is tied to bit 0 so to turn on RS I would send 00000001

Lets use the letter "H" 01110010 (72H) as letter to send to screen.
In 4 bit mode I need to break this up into high nibble 0111 and low nibble 0010.

So knowing that in 4 bit wiring mode the LCD only recognizes the high order for data and expects the upper order of the letter "H" first for data, then the lower order of the letter "H" for data.

So I would need to send out in 8 bit format 01110000 and then 00100000 for my letter "H" and the LCD would take the high order only of these 2 bytes sent separately and reassemble them correctly for letter display.

Now I know for the LCD to actually know this is data I need to make "RS" high so I would first need to send 00000001 in 8 bit mode, because the "RS" is in the lower order no matter what LCD mode I am in? Or would I need to send it twice because I am in 4 bit mode and that would complete a 4 bit transaction and still keep "RS" high?

Then for the letter "H" I would send my upper 01110000 part. Now the high order of letter "H" is in the LCD RAM, waiting for the low order of letter "H" to appear in the next incoming 8 bit high order.

But by sending this haven't I just wiped out the "RS" from being high? Would I need to send 01110001 to keep "RS" high? Wouldn't the 4 bit LCD only see my high order and the low order would still go to the control pins?

Now I need to make "EN" high 00000100 but here is my problem. If I send this I have now just made "RS" low as well. So Wouldn't I need to send 00000101 ? To make "EN" high and KEEP "RS" high?

Then I would need to make "EN" low 00000000, but that would make "RS" low now, so wouldn't I need to send 00000001 to make "EN" low and keep "RS" high?

Now I need to repeat this using the low order nibble of the letter "H" but in the high order position of the 8 bit send 00100000.

When sending data to 4 bit LCD via I2C, would I still have to include the "RS" bit in the low order of both 8 bit nibble sends just to maintain the state of "RS" should it need to be kept at 1 high?

This is SUPER CONFUSING and so far has demanded a lot of assembly code just to get this to try to work.


texts:
reference to internal leds
What voltage is a 3-LED light from a LED-TV?

As above the gentleman is asking for operational voltages etc, my question is (refer to my pic)

The apparent white circles may be due to overcharge given short the several dead LEDs.
Is it possible the dead LEDs are having a negative (aesthetically) effect on the panel?


texts:
I have created the following circuit.

simulate this circuit – Schematic created using CircuitLab

I have a few questions regarding its function. I've seen that D1 stays constantly on while D2 flickers on and off during the cutoff and saturation region respectively.

When the transistor is functioning in the cutoff region (\$ V_{in} < V_{threshold} \$), it acts like an open switch and we have current flowing from \$ V_{CC} \$ through LEDs D1 and D2. I think my previous statement is correct.

I want some help on what happens when the transistor is functioning in the saturation region. Thank you in advance.


texts: How to calculate total current, power, energy consumption from device?

texts:
I have a circuit/device that using ESP32 as microcontroller. I want to calculate how much total current and power that my device drawn.

So, the current draw will be like this:

My question is:

The total current drawn in 1 minute by my device is 1.62 A (i just summing all of current draw * time), is it correct?
How long my device last if i powered it with battery 4000 mAh, device is using 5 V, and ON/active time is 12 hours a day?

EDITED (1):

OK, now I have measured the current drawn using 1 ohm resistor series with load/device. Then connected my digital oscilloscope. Now what i got is like this:

So, to calculate total current drawn i just have to multiple current draw with period, is it correct?

EDITED (2):

Okay, now i got the average current consumption. But i got another question, i need to calculate the power consumption and energy that consumed by 1 hour. To get the power consumption i need to multiple current with voltage, like this:

P = V * I = 5V * 12.25mA = 61,25 mWatt.

Is it correct?
Is this average power drawn each day?
Then to calculate energy each hour, i just multiply it by 3600. E = 0.06125 * 3600 = 220.5 Wh. Is it correct?

Thank You


texts: Air core transformer with multiple secondaries

texts: If I were to construct an air core transformer with multiple secondaries. Would the magnetic coupling be better if the primary was wound around the secondaries or the secondaries positioned around the inner primary. I'm thinking it wouldn't make much difference.


texts: Im playing with electroluminescent paint, i want to change frequencies

texts:
I'm playing with electroluminescent paint. I can make the paint go paramagnetic and change colors by changing my power source from 240v 50Hz to 240v 1400Hz. Is there a device out there I can make or use that will create an AC voltage of 240v at 0.2-0.3A and be able to change frequency that much?

I can't design circuits but I'm capable of building them. Any assistance would be great. Thanks in advance.


texts: Is quality China manufacturing possible without being there?

texts:
I'm looking for some help with manufacturing in China with respect to PCB fabrication and assembly, plastic injection molding and metal forging/brushing.
Common wisdom in our days is that one HAS to be in China otherwise you WILL get screwed.
But then there is an option of hiring an independent inspection company to do initial factory audit, to check parts before shipping them, etc.

Is this inspection company any good?

Is there a list of reliable PCB, plastic/metal production factories in China?
Is there a list of trusted inspection companies?

The main question is: is it possible to manufacture something of good quality in China without personally being there all the time or at all?


texts: Viewing verilog enums in iverilog + gtkwave

texts:
Say I have a state machine in verilog implemented with enums instead of parameters. I'd like to  simulate this design in Icarus Verilog (iverilog) and look at the results in GtkWave. Is there any way I can get Icarus to dump out the enumeration text values and have them displayed in GktWave? For example, instead of 0, 1, 2 , I want to see "STATE0", "STATE1", "STATE2", etc?
In states.v:
module states ();

typedef enum logic [1:0] {
    STATE0,
    STATE1,
    STATE2
} state_t;

state_t state;

initial begin
    state = STATE0;
    #10;
    state = STATE1;
    #10;
    state = STATE2;
    #10;
end

`ifdef __ICARUS__
initial begin
    $dumpfile("states.fst");
    $dumpvars(0, states);
end
`endif

endmodule

Commands:
iverilog -g2012 states.sv
vvp a.out -fst
gtkwave states.fst

Then, after I've added the bus state to the waveform view, I'd expect Right-Mouse -> Data Format -> Enum to change the numbers to the state text values. But it just seems to change the values to a binary representation.
Tools:

Icarus Verilog version 11.0 (devel) (s20150603-612-ga9388a89)
GTKWave Analyzer v3.3.107 (w)1999-2020 BSI

Thanks!


texts: How to recieve data over SPI as a master device?

texts:
Working on Serial data protocols using STM32 (bare metal coding, not using any HAL libraries).

So far I've configured the board to act as master and send data to an IC and also configured two different stm boards (one as master and other as slave) to exchange data. So all that included using the MOSI line. Now I wish to use the MISO line so that I can have a duplex connection between the two boards.

For the master side of things, the CS (chip select) is configured as output pin so I can pull it high or low after as many as bytes as I like, and thus I have enable 'Software Slave Management' in the registers.

On the slave board side, CS is configured as Alternate Function and disabled 'Software Slave Management' so the CS pin gets pulled low whenever master wants to send data.

Keeping this in mind, how do I control the CS pins on the two boards when using the MISO line?

Do I just swap the 'Software Slave Management' enable and the Alternate Function on both boards?


texts:
TL:DR Using CANopen, don't see CANopen IDs on the bus.

I'm very confused. I have a semi-functional CANopen network set up between a PLC and a motor controller. Those two items are the only two nodes on the bus.

I say semi-functional because only some of the features work. The sync message is going out from the PLC who is the bus master. This is verified by the motor controller, that will fault if the sync message goes missing like when unplugging the CAN bus.

Information seems to only move on the bus via TPDOA and RPDOA. The motor controller accepts data on CAN ID 0x201 RPDOA. The motor controller transmits data on CAN ID 0x181 TPDOA. This aligns with the CANopen standard.

I'm trying to move other data from the motor controller to the PLC vis TPDOB, TPDOC, and TPDOD. The addresses should be 0x281, 0x381, and 0x481 respectively. This is not functional and the PLC does not receive anything. This also aligns with the CANopen standard.

To try and figure out what's wrong I sniffed the CAN network. The sniffing was done With an Arduino and a CAN shield with an MCP2515. The MCP2515 uses an 8MHz cristal and the bus is running at 500k. The problem is that when looking at just the IDs I don't see anything that I was expecting. The two most common IDs are 0x269 and 0x4A9. These don't match any CANopen IDs. There are some other IDs that I'm also seeing but far less frequently 0x26A, 0x4AA, 0x262, and so on.

To make sure that what I'm seeing is not some artifact I've poured over the library that I'm using. I did not find any faults with the way the IDs are detected and presented. I also looked at how the library configures the CAN bus baud rate. I did not entirely agree with their implementation and tweaked it. Unfortunately, even with the tweak, all I see is the aforementioned IDs.

The thing I have yet to try is to filter out the two most common IDs to make sure that they are not somehow obscuring the other IDs because the buffers of the MCP2515 may be overloaded. It only has two buffers and I don't think the Arduino can read them fast enough.

Are there any reasons why the actual CAN IDs look funny? Am I misinterpreting the CANopen ID standard or is there some other coding in play?


texts: Interpreting the differential resistance of a Zener diode

texts:
I have this Zener diode - 12V rated C part.
I just want to understand how to read the differential resistance column on table 8 for Zener current of 1mA and 5mA.
Suppose I give an input voltage of 16V across the 12V rated Zener diode. Let's assume that the series resistor is of appropriate value so as to focus on this understanding of the concept.
Let's also assume that the circuit is designed with proper series resistor for a certain load current.
My questions

How to read the differential resistance column on the table 8 with respect to the working voltage column?
Like when to use the 1mA zener differential resistance column value and when to use the 5mA zener differential resistance column value?

For example, let us assume the 12V zener is in the breakdown region by applying 16V to the 12V Zener. What happens if I supply a Zener current of which is between the mentioned Zener currents in the differential resistance column of the datasheet , say for example a Zener current of 3mA or 15mA? How to find the Zener voltage when I supply these Zener currents?

In certain Zener diode datasheets, they provide the minimum Zener current required to make the Zener enter into the breakdown region. But in this datasheet, no such minimum current is provided. Why have not provided and how to find the minimum current at which the 12V Zener will enter into the breakdown region if I have applied 16V?


texts: What is the 'continuous standard load' of a battery?

texts:
I'm currently integrating a coin cell power design into an electronics project. I am trying to verify my understanding of the 'continuous standard load' rating given for a battery (datasheet)

When looking through coin cell data sheets, I am typically looking at the mAh rating. This is a a measure of how much current can be supplied for a given time period (sort of). Now, I also understand that this number is typically provided given that you operate at some spec'd current. That is, if you decide to draw more current than the spec'd current, the battery will not be able to last as long as the mAh rating suggests.

So my question: Is the 'continuous standard load' the coin cell current that will provide the spec'd mAh rating? Furthermore, if I run above this current, will that translate to a much lower mAh rating?

The reason I'm confused is due to the fact that the 'continuous standard load' is such a small number in the datasheet I'm referencing. When looking at the CR2032 coin cell in the datasheet, it has a mAh of 225, but it only has a continuous standard load of 0.2mA. If I operate at say 10mA, will that translate to something much lower than 225mAh?

Thanks!


texts: I2C communication between MPU6050 and MSP430FR2433

texts: I'm trying to communicate in I2C between a MSP430FR2433 and an MPU6050. I can send the start bit then the slave address (0x68) followed by the write bit (0) but the slave send me a NACK. I'm using the GY-521 board and there are two pull-ups of 4k7. The clock is at 100 kHz which is under the maximum. I could once make the communication but since I always get a NACK


texts: Parametric Equalizer with State Variable Filter

texts:
I'm new to this forum but hope to get some answers to a project I'm working on.
I'm trying to build an parametric equalizer with several bands (5 Bass-Bands, 3 Middle-Bands, 3 High-Bands). In the first picture below you can see the Middle-Band. I use a state variable filter design. It's based on the Urei 545 parametric equalizer.
I would like to connect all the bands parallel to each other. I tried but in the simulation I get a loss of cut and boost, almost 5dB. Is this the right way to connect those two filters parallel together (see second picture)? Why do I loose the cut and boost? Thanks in advance for your help.
And in general I think my impedance level is to high. I think I need to lower the values of the resistors in order to reduce noise, is that right?

Thanks for your help.

Ian

Here I'm connecting the two middle-bands parallel.


texts:
I'm using the Adafruit Feather nRF52 to build the HIDScan sketch which essentially allows completed circuits to transmit keys over bluetooth.  I have a switch that connects from pin A0 to GND, and when I trigger the physical switch, it sends a signal.

I want to swap out the circuit to use a pressure switch for a Sip & Puff 'trigger' which would complete the circuit when I either blow or suck on a connecting tube.  I don't have this trigger, but think maybe I need a Pressure transducer, and  I'm looking at something like http://www.ebay.ca/itm/0-40kPa-Atmospheric-Pressure-Transducer-Sensor-Module-3-3V-Power-Supply-/401405291040?hash=item5d759eaa20:g:15cAAOSwcUBYSNSp but I have no idea how to hook this up, or if it will do the job.

I think I understand that the transducer will give a variable voltage, but what I really want is just to detect any voltage (eg. puff or no puff) and complete the circuit.  I don't care about intensity.

Am I missing something, or is the wrong piece for the job?  Do I need some kind of relay?

I don't have a lot of experience understanding data sheets, and am fairly new to circuits in general.  Any help would be appreciated.


texts: Oscilloscope differential measurement for battery powered circuit using single probe

texts:
I want to measure the voltage across a resistor in my circuit. The circuit is battery powered. I don't want to use the two probe method and calculate A-B to get the results. Can I use one probe to measure the differential voltage as shown in the figure below?
No other point in the circuit is connected to the oscilloscope GND except one of the test points.


texts: How to convert a floating point number to integer, using VHDL?

texts:
I want to convert a floating point number to a integer number. Basically I have a floating point number between 1 and 0, with three decimal places, and I want to pass it to a integer number as if multiplied by 1000. I suspect there should be a more optimal way to do it than using the arithmetic multiply operation x1000.
I'm looking for a piece of code preferably.


texts: Why do I see no voltage drop in this circuit?

texts:
What is the voltage drop of a 1N4001 when current is very low?

I am constructing a game that uses an Arduino ADC pin to measure the voltage produced by a person spinning the shaft of a 3V DC motor.  To protect the Arduino from damage if the human player spins the motor shaft in the reverse direction, I placed a 1N4001 diode in between the positive motor terminal and the Arduino ADC pin.  I am surprised to find that there seems to be no voltage drop when the diode is present versus not present.  This is great, but I do not understand why.  I see the same behavior when I use a voltmeter in place of the Arduino.  Is this because the current draw from the Arduino and the Voltmeter are so low?  The data sheets for the 1N4001 show a 0.6V drop, but the chart doesn't show the behavior below 0.1A.

simulate this circuit – Schematic created using CircuitLab

simulate this circuit


texts: Why exactly does peaking of magnetization current occur in a transformer?

texts:
Initially assuming that the input current is sinusoidal.
In a practical transformer, flux \$\phi\$ produced in the primary is not linearly proportional to the current \$I\$ through it. Due to saturation, the flux flattens

It's said that this flattening implies the presence of a dominant 3rd harmonic in addition to the fundamental

Questions:

Why does the presence of the third harmonic in the flux, alter the current (by adding a third harmonic out of phase by a 180\$^{\circ}\$)?

Why is it out of phase?


texts: I am building a smps that brings 120 vac to 5v dc and have it all designed so far but am having trouble on what to do for the pwm on the buck converter portion. I was wondering if a pwm controller is something that I could use? How do they work exactly? Would need like 18V at 400khz at ~42% duty cycle to drive the gate of my nmos according to my simulations on multisim.


texts: In a vacuum triode (positive terminal to anode, negative terminal to cathode), how do the electrons flow from the control grid to the anode?

texts:
In a vacuum triode (positive terminal to anode, negative terminal to cathode,) once we apply the positive charge to the control grid it will start to attract free electrons, which are released from cathode due to thermo-ionic emission.

How do the electrons flow from the control grid to the anode , since both of these terminals are positively charged?
What is the driving force that helps in moving the electrons from the control-grid to the anode?
How come placing the control-grid is effective, when there is
voltage required to move free electrons from the cathode to the anode? Zero voltage on control grid = voltage required to move free electrons from the cathode to the control grid + voltage required to move electrons from control grid to anode.

Please help me to understand better.


texts: GPS PPS signal corresponds to data time?

texts:
I currently have an Adafruit Ultimate GPS connected to an Arduino that outputing GPS data (nmea sentences) once per second.  There is also a pin on the GPS outputting 1 PPS signal.

My question is whether the pulse of the PPS suppose to match the time that the GPS data is coming in i.e are they are coming in at the same time?

Also does PPS pulse come in at the beginning of a UTC second or is it random and simply once a second?


texts: Noise resistant microcontroller used in high power inverters for PWM generating

texts: In order to generate PWM pulses for driving switches of a high power(80 kW) three-phase inverter,which microcontroller family(and which member) is suitable? ,taking into account the noise effects on microcontroller operation due to switching.


texts: Would it harm a LiPo to charge it in several periods?

texts:
I have a 3.7V 5000mAh Lithium-Polymer battery cell, which I'm charging with the MCP73831, using the typical application circuit on page 1:

I have \$R_{prog}=2\text{K}\$ and \$V_{in}=6.0\text{V}\$. Normally, I'd charge the cell during the evening and night, since it takes 10+ hours.

However, I'm testing this circuit, so I want to be near to check if everything's fine and to do what's needed when something goes wrong. Problem: I don't have 10 consecutive hours.

So would it harm the cell to load it in several short periods? Does it depend on the length of the periods or the time in between?


texts: Single-ended to differential conversion and ADC application

texts:
I am not quite familiar with the things I am going to describe. So, I need some help over here.

I want to integrate an AD4001 ADC at a board I currently design. The thing is that my analog signal is single-ended and I need it to be differential to enter the ADC. The datasheet of the AD4001 proposes an application circuit, the one at the figure I attach.

Based on the AD4001 datasheet, I selected the ADA4940 differential amplifier for converting my analog signal to its differential one. I downloaded the SPICE model from its site and ran it using LTSpice. Attached is its circuit.

My analog input signal is 0-5 Volts, so I used a voltage supply with 2.5V DC offset and 2.5V magnitude. Then, 2.5V as VOCM and 5V as VS. The ouput signals I get are the following:

Is the blue-red differential output the right one of the green input? How is it connected to the VOCM? I cannot understand how the initial signal can be formed based on its differential one.

Is it the correct input for the ADC for my analog input? I have read that the ADC converts the difference between positive and negative signals, but their difference never reaches 5V.

Also, I would like a single supply system (5 V DC). But my analog signal is 0-5V. Does this mean that it is not feasible to implement such a circuit since Vref reaches ~4 V or I could connect 5V to Vref and V+ of the amplifier?


texts: NPN transistor doesn't work when base gets more voltage

texts: I'm working on a project to control my tv with voice commands. I disassembled the remote control and i want to replace the physical switches that are beneath the buttons with transistors, so that i can turn them on and off without physically pressing buttons. When i connect the base to one of the other buttons of the remote to try it, it lets current through and the button is "pressed", when i connect the base to a battery, either with or without a resistor, it doesn't do anything at all.


texts: Is normal SPI device compatible with SPI I/F?

texts: Audio controller AK5374 that I use requires EEPROM with SPI. However, in the specs it is written, that it communicates with EEPROM via SPI I/F. Will normal EEPROM be compatible with this interface?


texts: Scaling PID (Proportional Integral Derivative) Output

texts:
I have implemented a PID function using the formula,

correction = Kp * error + Kd * (error - prevError) + kI * (sum of errors)

What should I do to keep my output between a certain range? say 0-255 If I disregard any value not between 0 to 255 it produces a jiggly behavior?


texts: How to get an accurate LTSpice model of a real inductor after impedance analysis?

texts:
I want to get an accurate model of a real inductor in LTSpice. Therefor I used an Bode 100 Network Analyzer und measured its impedance in a range of 100 Hz to 20 MHz. My idea was to calculate the capacitance of the inductor from the resonant frequency of the inductor like this (rearranged formula from wikipedia for a real parallel resonant circuit):
$$ C=\dfrac{1}{L\omega_r^2+\dfrac{R_L^2}{L}}$$
However, I have not been that satisfied with the results, when using this model in LTSpice. The inductor will be used in a resonant circuit, whose resonant frequency is approximately at 7 MHz. Can this inductor be modelled more accurately?
Impedance of the inductor (measured in inductance and serial resistance, the narrow one is the serial resistance):

Comparison of the impedances in LTSpice and the Bode 100:


texts:
I have a question regarding a level shifter schematic that I've implemented. I need to connect a 1v8 logic UART device to both an arduino and a TTL232-3V3 cable. The Tx side works as expected and I can step down the 5V logic from the arduino to 2V which is accepted by the 1v8 device. The 1v8 device gives a response which I can read just fine using the TTL cable. However I can not read it using the Arduino.
This is because for some reason the drain of the Rx level shifter is not pulled up to 5V when the bus is idle but rather stays at 2.2V and I have no reason as to why it is doing this. It was working fine before when I was using a simple resistor divider to create the 2V that is on the gate of the MOSFET. I changed this to a zener diode configuration to create a more stable voltage. I already swapped the MOSFET once but the same thing happens
Why does the MOSFET do this, it seems like the zener is damaging it somehow?? When LV side is high the Vgs voltage is 2V - 1.8V = 0.2V which is lower than the minimal voltage required to switch the MOSFET (which is 0.8V according to the datasheet), so this can't be it.
Ps. don't mind the BOOT button, it is designed to short the Rx line like this without damage. Also I tried disconnecting the arduino Rx line and it's still 2.2V (instead of 5V) on the drain when the LV side is high
Any help would be much appreciated!


texts: Why are electrically insulating heatsinks so rare? Is it just cost?

texts:
Edit: It seems my initial question (Why are there no insulating heatsinks?) was based on a false premise, and there are in fact insulating heatsinks--I just wasn't able to find them with a cursory search. So instead, I'm changing this to ask about their rarity instead.

Heatsinks seem to be almost universally made of aluminum, copper, or some combination thereof. This makes sense; aluminum and copper are easy to work and have high thermal conductivity. But diamond has one of the highest thermal conductivities of any known substance--it's obvious, of course, that diamond of the type suitable for use as a heatsink would be inordinately expensive to say the least, as it would probably have to be a single gem-quality crystal, but would it not be possible to use, for example, cubic boron nitride, which has a similar thermal conductivity?

And yes, the manufacturing difficulties with making a large single crystal of c-BN would probably be about the same as making a large single crystal of diamond, but I expect the end price wouldn't be as much because there's no De Beers group to come after you for boron nitride. And there are surely other nonmetallic compounds that have good heat conductivity, and some of them would presumably be better suited to manufacture. I doubt they'd be able to even approach the price point of extruded aluminum, but sometimes you do need higher performance.

So, in summary, my question is: Is it only cost that makes nonmetallic heatsinks so rare, or are there some other drawbacks that make them less desirable outside of the most esoteric of applications?


texts: Finding the laplace transform of a wave?

texts:
I was going through the solutions of a past paper and came across this question where it is asked to determine the laplace transform of a transient waveform. I'm a bit confused with how it balances the waves and getting 10000 slope. Can anybody shed some light on it?

The equation obtained is as follows

$$i(t) = (5000 slope ramp at t=0) -(10000 slope ramp at t=2)+ (5000 slope ramp at t=4)($$
$$ I(s) = \frac{5000}{s^2}(1-2e^{-0.002s}+e^{-0.004s})$$


texts: PID tuning single input two output with changing setpoint

texts:
I am operating the process in the image below, where I am using a recirculating heated/cooled bath (RHCB) (Polystat 12122-56) that externally circulates hot water through a heat exchanger (HX) and back to the bath.

The RHCB has a refrigeration coil (800 W) and a heating element (2 kW) immersed in the bath to control temperature, with the ability to edit “heat PID” settings and “cool PID” settings. I have the RHCB hooked up to LabVIEW, which I use to change the setpoint temperature every 5 minutes according to the variable setpoint temperature profile below. I tried using the RHCB to track the variable setpoint temperature profile using the factory PID settings of P=1, I=0.6, and D=0 for heat PID and cool PID but the RHCB had trouble achieving the higher setpoint temperatures (see the "Actual" temperature profile in the image below).

I think the refrigeration cycle is preventing the heater from reaching the higher setpoint temperatures, and that I can stop that from happening by choosing the appropriate PID settings. So, my question is:

What is the best way to tune two separate PID settings (heat PID and cool PID in this example) when both of those are controlling the same variable and the setpoint changes frequently?


texts: What does "seamless power transfer" mean?

texts: In power electronics context, is there any technical definition of "seamless power transfer"?. Does it mean a smooth power transfer without a transient variations regardless the disturbances in the input, or it has some other meanings?


texts: Interpreting results when IC temperature fits all categories

texts:
I have recently downloaded a datasheet for one of the chips I am using in my project, the familiar 74HC164 shift register. The datsheet URL is here:

https://assets.nexperia.com/documents/data-sheet/74HC_HCT164.pdf

So I then look inside it to try to figure out how long the chip needs to process various states, and it provides three temperature categories as circled in the picture:

Since my circuit never overheats, and runs in a normal room temperature environment, I find this particular datasheet confusing. It's because my scenario fits two temperature categories and possibly three. To me, room temperature is 21 degrees, so the only category that MIGHT not apply to me is the 25 degrees celcius category.

Let's say I wanted to determine Propogation delay based on the information given. What value should I use?

The worst case of 255ns (because the temp range is -40 to +125 degrees)?

OR

Do I need a special (tell me its not expensive) thermometer to measure the degree range of my chip while its running and get results based on the temperature range that special thermometer reports?

OR

I should assume these temperatures mean the maximum rise temperature of the circuit when it is running and follow the 25 degrees column?

Or is there another way to calculate the value based on the chip not warming up at all even with the correct power applied to it and the whole circuit being in a room at room temperature?


texts: SinePWM - Modulation Index calculation for a 3phase igbt inverter with ac load

texts:
For a project I have to create a simulation of a 3 phase IGBT inverter with SinePWM (in Plecs) with a AC load
Udc = 650V; cos(phi) = -1; I_ph = 500A; Uun/Uvn/Uwn = 230V;
So I calculate my SinePWM modulation index like this 2*230V*sqrt(2) / Udc whitch should be like 1.0008 a little bit overmodulation. Is that right?
Someone in my group noted that we have to use sqrt(3) aswell as its a 3 phase system and wants to multiply it so we get like 1.73 wich is waaaay to overmodulated.
Thanks!


texts:
I wondered if it were possible to accelerate in hardware the Python dict? Dicts are mappings between a key and value that form a large part of the backbone of how Python works. Everything is an object; objects are built with dicts.

I have heard of CAMs (content addressable memories), but apart from a similarity in the name, I don't know if they could help in any thought experiment to create a computer optimised to run Python. (An equivalent to Forth, Java and Lisp optimised machines).

Any ideas and references appreciated.


texts:
Do passive backscatter devices fall under regulations of FCC/ETSI?

Suppose a system emits a 4W EIRP tone in the ISM band (conforming to FCC/ETSI regulations). A fully passive device backscatters data not only on its fundamental but also on its harmonics.

Is this passive backscatter "emission" on the harmonics regulated by FCC/ETSI?
If a complete system were to be certified, would that only check if the transmitter satisfies the standards or would it also take into account if passive tags backscatter at different frequencies?

The information I found is unfortunately fairly vague.
For FCC, I found https://transition.fcc.gov/oet/ea/presentations/files/may05/New_Policies_Pt._15_SD.pdf which states that passive tags do not have to be tested individually and since its emissions are much lower than that of the reader, only the reader has to be tested. However, this is vague and is not an official document.

For ETSI, I found Draft ETSI
EN 302 208, which states fairly clear limits in section 4.5.2.3. However, it is unclear if this applies to active tags or also passive tags.


texts:
Hi I've been trying to solve this problem on finding the voltage out by using the Laplace transform. I know it's pretty basic but I can't get the solution after trying many times. I'm starting now to study this, and I'm a bit confused because it's a bit different to the way I'm used to solve this kind of circuits.

This is the problem:

Solution: $$v_{o}(t) = (20e^{-2000t} - 10e^{-1000t})u(t)$$

I have tried to associate Ls and R in parallel and then associating (R||Ls)+(1/Cs) but I don't get to the solution I should obtain. Can someone help me and tell me what should I do to solve this kind of circuit? (I don't want you to solve it, just need you to give me a hint on what's the operation I should do to obtain Vo(s) ) Thank you very much.

EDIT: So this is what I have to develop?

$$V_{o}(s) = \frac{10}{s} \cdot \frac{\frac{RLs}{R+Ls}}{\frac{1}{Cs}+\frac{RLs}{R+Ls}}$$


texts: Feeding Arduino from 220v AC with dual primary coil transformer

texts:
I'm starting an Arduino project that need to get is power from a 220 Vac line. It's a thermostat project (I know, an another one!) so this need to go on the wall and replace actual commercial thermostat. So here's the primary specs :

10 Vdc to power the all module (board, LCD, Wireless receiv., temp. sensor, etc)
160 mA maximum current draw
Small footprint

So when I start to look around for how to feed this thing a got in two problems:

1) Getting 160mA from 220v with minimal parts

2) Getting power for the thermostat terminal alone (more on this later)

So 1) concern was to get the less possible parts and provide me with 160mA @ 10 Vdc. I look into transformerless design but the problem get obvious rapidly. Getting more than 50mA from this design required either big resistor (>10W dissipation) or big capacitor with high voltage tolerance (X2 type). And those don't come in small package. So transformerless is not the way for me. Now I'm back to a transformer design. I found this model that fit my specs (dual primary/secondary coil). With a rectifier bridge and a couple of component I'm all set!

Now for the second problem, getting 220Vac from the actual thermostat lead. As you know, you have two way to run cable around your house to connect a electric furnace. You either bring the power line to the thermostat, get your thermostat in the middle and run another cable to your electric furnace. OR, you bring the power directly to the electric furnace and bring a cable to the thermostat. There's no difference in both approach, both work (obviously!) but there is one minor difference. In the first approach, you have "direct" access to the power line so I can connect, in parallel, my "new" thermostat. In the second approach, you just have access to a simple switch lead. So the only way to get power in this configuration is to be in series with thermostat. I think now you see the thing coming... since the thermostat need to work in both approach, it's always in series, acting as a simple switch. And since I want my design working exactly as a commercial device this is the ONLY way I want to connect. Now the problem : when the thermostat is open a need to be in parallel to get power from line. When the thermostat close, this get shorted so now I need to be in series to get power from my line. So how I do that!? My answer for now is again my dual primary transformer and here a "crude" schematic to illustrate it...

So my question (it's about time!) :)

Is this design workable? Having one primary in parallel of the anodes of the thriac and the other one in series. This way I'm always getting power independent of the state of the switch (triac). I'm not an expert in power supply so I'm not sure if wiring my transformer this way will works? Is there any kind of bizarre out of phase or stuff like that that can destroy my transformer?

Thanks for you advice!

Edit 1:

Sorry for the child look alike schematic but I was in transit and all I had in my hands was time and my iPad... Here's a better version :

Edit 2:

This is a new iteration of my design, that build on the suggestion to use a battery (9v). So my main power is still a transformer connected in parallel of the triac that is control by my arduino board (thru a opto-coupler). I add a charging circuit to this power supply for the 9v NiCad batt. I also add a LTC4412 to control switching the source of power (9v Batt or power supply). Since my thermostat use a PWM algorithm and is more often off then on, the battery life should be quite good.


texts: New PowerVR Support Introduced to ARM Cortex-A Embeded Processors

texts:
I understand that ARM Cortex-A and their graphics processing is a highly problematic section in GNU/Linux world I have heard due to the fact that Open-GL is not so much developed to the extent it is required to and for other reasons I haven’t heard of.
Due to all of this reasons I believe video processing on a Cortex-A chip is always not so much easy and is troublesome. But, we must appreciate the Open-GL community and the people who are developing the stripped down version of open-gl for Cortex-A devices a lot, as it is because of such generous people we do have the tools to process video in embedded ARM devices that run GNU/Linux.

Question 0:

I head that Texas Instruments (TI) released a new ARM Cortex-A device series recently that claims to have PowerVR graphics. I believe it is newly released through  AM437X series after ARM Cortex-A AM335X series.

Question 1:
Is this proprietary hardware inside the SOC just like nVidia?

As a newbie, I do not understand how this is different to the previously introduced AM335X series graphics processing (used in the beagle-bone black,etc). I think the previous chip series too had HDMI graphics. So what caused this upgrade in the SOC? What is new with this new hardware attached toe the SOC?

Did TI completely ditch the previously used SOC part used for the graphics processing or is this only an addition?

Question 2:

How about the open source software support for this newly inteduced part of  the TI SOC?


texts: using .meas during .op for list of values

texts:
I am using LTSpice and I am trying to run a simulation for multiple resistor values in a DC op pt simulation. I need to measure the resistance at a node as well as the current through the varying resistor. I am using:

.step param VAR list val1 val2 val3 ... valn

to simulate the resistor but I cannot seem to find the proper way to get the measurements I need from that. I have tried using

.meas op RESULT find V(myNode) at VAR = val1.

to find the voltage for the first value val1 but I can't figure out how to make it run the list or to measure the current through VAR


texts:
I bought an LTC3780 step-up/down converter:

(https://www.aliexpress.com/item/DC-5V-32V-to-1V-30V-10A-LTC3780-Automatic-Step-Up-Down-Regulator-Charging-Module/32662632572.html)

It is working fine but the LM358 on it is getting pretty hot. It seems no matter what I do with the LTC3780 the LM358 is always pretty hot. Like I have to remove my finger after 3-4 seconds hot.

I have put (non-permanently) a small heatsink on it (held by gravity) and when I remove it and touch the chip again I am able to touch it for pretty long without having to remove my finger again.

Is it normal?

I have applied a 2.5A current @ 5V during 4 hours and everything remained stable. The LM358 was not particularly hotter.

EDIT:
Input voltage 12v from a switching power supply.

Thank you!


texts:
I got school project and I was trying to make counter that will count in this order: 1,3,6,5,2,4 and again but there is
forbidden numbers 0,7(I assign 7 to 3 and 0 to 1 see border on table). So I used 3 JK flip-flops(C, B and A).
There is table for counter:

After minimization I get following results:

Jc = B      Jb=A       Ja=~B+C
Kc = A      Kb=~A      Ka=C~B+~C+B (XOR C+B)

And when I get it all together in Multisim (clock input of all JK FFs merged all together and connect to the CLOCK_VOLTAGE and 3 PROBE_DIG_RED to 3 ~Q outputs to see if it works) it just lights first two and turns off.

I also did another version in different sequence( to count up from 1 to 6 but not to show 0 and 7) and it displays 1,2,3,4,5,6 but in strage way. I was using 7 SEGMENT display and it shows me numbers 1,5,3,6 if I connect decoder to Qs of Flip flops but if I connect to ~Qs of FFs it shows 6,2,4,1. Is this how it works in Multisim or I have done something wronig ?

And what I have done wrong in current version of counter ?


texts: Details regarding PMOS and NMOS transistors used as gates

texts:
My lab instructor explained very briefly what transistors are and started by naming them NPN and PNP then switched to PMOS and NMOS and I (as well as my classmates) am very confused, I need someone to explain to me these points because I am not finding clear explanations anywhere:

is PMOS the same as PNP? (and NMOS same as NPN)?
How do they actually work as "gates"? how does it relate to the input given and the actual properties of these transistors?
What do Logical 0 and 1 really represent? (as voltages)

PS: Sorry if these questions are wrong or badly formulated I really am very confused about everything.


texts: First DDR2 Layout - How much of a data lane must have the same reference?

texts:
Doing my first DDR2 layout and I'm hitting some conflicting requirements.

I have dogbones to an internal ground-referenced layer, and then short top layer traces at the other end going from the other via to the DDR2 pins.

I my second data lane (DQ15-8,DQS1, DM1) is looking really good except for two of the data lines I can't seem to figure out how to keep the top trace on the DDR2 side <2mm. I have to make it longer to allow the other traces to pass through with the proper spacing.

So my question is: How much of this data lane do I need to keep on the same layer? The bottom layer is reference a different ground plane (same ground but different plane), so could I put those traces there because they are all referencing a ground plane?

Picture attached. Length matching hasn't been done yet.

.


texts: USB C device termination without controller

texts:
I was wondering about a minimal device (sink) design with USB C connector. In this case, where the device will only accept 5V and not further, I think a USB C controller is not mandatory. But I dont know how to terminate the CC1 and CC2 lines in order for the host (power provider) to know that the only available pdo level is 5V/2A. I have found this source but its not straight forward to me: https://www.silabs.com/community/mcu/8-bit/knowledge-base.entry.html/2016/09/26/what_s_the_role_ofc-kQYe

I would appreciate all help.


texts: How Does Trapezoidal BLDC Have Constant Toruqe

texts:
I'm trying to understand how a BLDC with trapezoidal back EMF can have constant torque when driven by a 6-step commutation as some literature suggests.
Let's consider the case of a single winding pair per phase. In this case, each commutation drives the motor through 60 electrical and mechanical degrees. This 60 degrees takes the rotor-to-stator magnetic field angle from 60 to 120.
I would expect that peak torque is achieved in the middle of each commutation at exactly 90 degrees, and would expect that the resulting torque profile would be a triangular wave rather than flat.

Edit:
To clarify, I understand the source of the torque ripple referred to by the article and am not asking about that. I think the 10 seconds of video starting here explains my question the best: http://www.youtube.com/watch?v=gNpoTPzEkco&t=8m20s: "However, in BLDC motors we never achieve 90 degrees with 6-step commutation". If that's true then how do we in theory achieve constant torque?


texts: Cost effective way to convert 12v DC to 7.6v DC @2A

texts:
I'm working on a hobby project that involves continuously powering a 5 watt handheld radio for long periods of time off a 12v automotive electrical system (in reality the input will be more like 13-14v).  The battery that comes with the radio is 7.6v and the radio draws ~2 amps during transmission.

The radio is designed to be charged while the battery is attached, however the final solution does not need to include the battery at all.  I plan to connect the output of whatever circuitry I build/buy directly to the contacts on the radio where the battery would normally interface.

What would be the best way to build a voltage regulator for this application relatively cheaply?  I'm not against buying something off the shelf, but I've found very little that is rated above 1000 ma.

EDIT: The original body of this question said the radio drew 7.6 amps.  This was a typo, the peak current draw is ~2 amps. Sorry for the confusion.


texts: What is the best way of implementing ethernet over a custom pogo pin connector?

texts: I'm designing a custom hot swap connector with pogo pin contacts, similar to that of an electronic camera lens. I am wondering if there are any special considerations I should be taking if I want to implement ethernet across these pins: I plan to have a hot-swap controller for protection, but is there anything I should be weary of in terms of noise, routing, shielding etc?


texts: What is the best way to play music through speakers

texts:
I have these speakers I recovered from an old iPod dock.

I want to hook these up to a big remote control truck I have but I have never worked with playing music. What is the easiest way to get music to play through them? I was looking at this breakout board but not sure if it's as easy as simply connecting the speakers to the board through their ground and vcc wires or what.


texts:
I'm looking for a neat off the shelf solution to halving a voltage via a resistor network. Some kind of small module, (probably GND, signal in, signal out) that can be wired inline with a sensor that delivers 0-10V for feeding into a 0-5V ADC.
I do NOT want to make my own PCB, enclosure etc. This should be something that can be dropped straight into production equipment.

I have tried googling the title desription but nothing comes up. Do such devices exist, and if so what are they called?

Thanks for the replies - the term I am looking for is "precision attenuator"


texts: Voltage drop of a non-ideal voltage source

texts:
I am having a problem with calculating the amount of current flowing through a branch, after deriving potential of its nodes using the Node Voltage Method.

I understand how to calculate voltage drop on a resistor and the voltage of an ideal voltage source as well:

The branch I am having problems with is sketched below:

The current I2 should be equal to $$I_2 = \frac{U_{02}}{R_2} = \frac{(E_2-V_2)}{R_2}$$ but I do not understand why this would be the case.

In the expression $$I_2 = \frac{U_{02}}{R_2}$$ I tried to calculate the voltage U02 the way I thought was correct:

$$U_{02} = U_{0A} + U_{A2} = -E_2 + I_2R_2$$ substituting in the previous equation:
$$I_2 =\frac{(-E_2 + I_2R_2)}{R_2}$$

If we multiply this with R2 we will get:
$$I_2R_2 = -E_2 + I_2R_2$$
$$-E_2 = 0$$ ???

and if we don't substitute anything, but rather continue with the expression for U02 we get:

$$U_{02} = U_{0A} + U_{A2} = -E_2 + I_2R_2$$
$$I_2 = \frac{U_{02}+E_2}{R_2}$$, which would bring us to the suggested solution if it was true that:

$$U_{02} = V_0 - V_2 = -V_2$$

which shouldn't be the case, since the voltage between 0 and 2 isn't determined only by potential difference between the nodes, but also the voltage generator that contributes as well.

I do not understand this at all and I feel like everything I've learned so far is not valid anymore. Things are literally making no sense. Where did I go wrong?

EDIT: To rephrase and recap: How to calculate the current I2 (second sketch) if values R2, E2 and V2 are known (V0 = 0) ?


texts: I get what PWM is and how it can be done using a 555 astable circuit. However I feel I don't completely get what PPM is how its circuit works. I understand the VCO circuit, but I don't see how it can be used as PPM modulator simply by varying UTP and LTP using the pin5. I don't see much difference between PWM and PPM in below circuits. Both seem to produce varying width pulses. Shouldn't the pulse width be fixed in PPM and just the position change ? Could somebody please help me understand how the VCO in second figure acts as a PPM modulator ?


texts: How does LED matrix circuit work in the following example?

texts:
The circuit below shows how to build an LED matrix with shift register multiplexing.

From what I understand, R1-R8 is the column vector setting the LEDs high or low and the shift register will pick one row at a time.

What is the output of the shift register Q0-Q7?

In order to light up bottom left LED, I Would need to set R1 3.3V and Q0 grounded (or 0V I guess?) whilst Q1 - Q7 must be floating. However, in this circuit, I don't see how to float the Q1-Q7.

Or are Q1-Q7 actually 3.3V so that all other LED in the first row have zero potential with the Q1-Q7?

In the example below, it's more understandable as the shift register is switching the transistors, therefore, multiplexing the rows to the ground.

A - How does the first circuit work?

B - What are advantages and disadvantages of the first and the second circuit?


texts: Circuit to cut one audio input into another

texts:
I have a project I've been scratching my head over for a few days.
I work a lot with 2-way radios and like to listen to music while I'm doing it. I wear an earpiece for the 2 way radio.
I want to build a circuit box I can plug the audio for the 2-way radio into along with the audio from an MP3 player and have them coming out of the same earpiece but the 2 way radio to cut out the MP3 signal when someone talks over the radio to me so I can hear it.
I thought a resistor on the radio wire but that doesn't seem to help with the problem that I have I need the music to cut out when the radio signal comes through and come back once the radio signal has stopped.
Ideally would also like to add vol controls (variable resistors) for both on the box
Anyone got any ideas or probably something horrendously simple I haven't thought of/overlooked would be greatly appreciated.


texts: Connecting batteries in parallel (concerns)

texts:
I have been trying to understand if it is possible to connect two identical batteries in parallel (same: number of cells, manufacturer, capacity, CRate, usage).

I want to create a circuit to select between the battery pack (two batteries in parallel) and a DC input. With a relay and diodes I manage to select this.

However I'd also need to be able to charge the batteries. I don't know if I need to split them before charging and if they both have to be charged at the same time (so they both have the same voltage after charge). This part I could do with just a manual switch.
And if I put them in parallel and introduce a diode in series with each battery for protection - this diode wouldn't let the battery to receive current (won't be charged).

Could anyone explain if it is possible to do this?

By the way, I'm planning to use this LiFe batteries or this Lead Acid batteries.

update:  Ah ok.  So in this schematic I don't need the ON/OFF charge button?


texts: What governs the output voltage of a three-phase generator?

texts:
If you have a three-phase generator (or motor run as a generator), what part of it governs the output voltage?  For example the speed at which you rotate the shaft governs the output frequency, but what governs the output voltage?
The reason I ask is that I'm looking for cheap ways to produce three-phase power in an off-grid scenario, and electric motors from damaged EVs are relatively cheap.  Many of these seem to be three-phase permanent magnet motors, but finding out what voltages they produce when driven as generators is very hard to come by.
I am wondering whether it's a function of some part of the motor design (e.g. the strength of the permanent magnets) or whether it's something you can control as part of driving the generator, as you do with frequency by varying the shaft speed as required.  For example does the output voltage go quite high if there is no load, and enough of a load must be placed on the generator output to drag the voltage down to the desired level?  I'm not sure if that's right because I thought the load was related to the frequency (and how hard it is to turn the shaft at the correct speed in order to maintain the desired frequency).
In other words, if you are designing a three-phase generator from scratch, what (if anything) do you change in the design to adjust the output voltage it produces?


texts: Is there any reasoning behind making capacitors go to 105°C?

texts:
Electrolytic capacitors are often rated -40°C to +105°C. I've always wondered about the extra 5°C. This also seems to be the temperature range for some types of microcontrollers, and is marketed as an "extended temperature range", although in reality extended usually goes to +125°C.

Is there any particular reason for this temperature - was it chosen to be 5.0161°C above the boiling point of water at 1 atm (99.9839°C or 100°C), or is there another reason?

Curiosity question - not going to be running any components at 105°C any time soon!


texts: How should I take out (or fix) this broken potentiometer?

texts:
First of all, please excuse this super simple question. I know nearly nothing about electronics, and just want to make sure my understanding of this is correct.

So I ordered two of the same audio amplifier board (from different sellers), and the first one's potentiometer just sort of fell apart as soon as I inserted a screwdriver. I tried but couldn't but it back together.

I think, I don't need to mess with the amplifier's volume for this project, and I was planning on having it turned all the way anyway.

The exact model of the pot on both of them, I believe, is RM065-103 (datasheet here).

I have no idea how to read schematics, but I'm guessing that to replace it, (after desoldering and removing the pot,) the 1 and 3 pins (in/out?) should just be connected directly, and the 2 pin (gnd?) just be left alone, like this:

Is this the right approach to take? I tried researching a little bit and I think I might need to have a resistor between the connection, but I'm not sure.


texts: Analysing an op-amp circuit and I do not understand a specific resistor value

texts:
Hi was reading this article and I read:

There is written: Here, the feedback resistor Rf provides a discharge path for capacitor Cf, while the series resistor at the non-inverting input Rn, when of the correct value, alleviates input bias current and common-mode problems. That value is the parallel resistance of Ri and Rf.

  Question: What is the reason for this statement, why does the resistor \$\text{R}_\text{n}\$ has to equal: \$\frac{1}{\frac{1}{\text{R}_\text{i}}+\frac{1}{\text{R}_\text{f}}}\$


texts: Controlling a 1000W radiant heating element with dimmers

texts:
First I would like to mention that I am a stranger to electrical components and I come from a mechanical engineering background so please keep that in mind when answering my question.

I am trying to use 1000W ceramic radiant heaters to heat up an enclosed container and I would need to adjust the heat emitted by the heater frequently. In the future I would like to implement a closed-loop and use a PID but for now, I just need to be able to do the "controlling" part manually.  I found that TRIAC dimmers and typical light dimmers (with suitable wattage) could be considered for my application but I am not sure how to implement these dimmers in a circuit. I could use some help to make the circuit!

Also, please suggest other types of dimmers if you think the ones I mentioned will not be suitable.


texts:
In winding a coil for a generator, does the organization of the wires have an effect? Should I be very careful to lay each turn of each layer side by side in a neatly packed line, or can I be quick and messy and as long as the same number of turns fit into the same volume, I should be fine?

If it does matter...how significantly can it affect the power generation? A slight loss in power production, or a major hit?


texts: Order of resistor/capacitor in bandpass/highpass filter

texts: Is there any particular reason to prefer one of these filter designs over the other? Theoretically, they are the same. Practically, does changing the order of the resistor and capacitor have any effect (except, perhaps, on physical layout)?


texts:
I am always confused between varying voltage versus current in a circuit. Why cannot we keep a standard voltage source (say 12V) and simply change the resistance to vary the current accordingly.

What are the advantages of varying voltage? And what are the advantages of varying the current?


texts: Why would a buck converter IC fail and blow up?

texts:
I have a deployed design in which we are experiencing a high (~4%) failure rate in the 12V to 5V step-down buck converter portion of the PCB.  The buck converter's role in the circuit is to step down 12 V input (from a connected lead acid battery) to 5V, which is then fed to a USB-A receptacle for battery charging purposes.

All returned units have the same characteristic blown-up buck converter IC.

The IC is a TPS562200DDCT from Texas Instruments (reputable manufacturer, so I hear)

Here is the datasheet.

Here is a picture of a failed unit:

Here is the schematic:

Here is a look at the PCB design file for that section of the board:

In analyzing the failure of the buck converter IC, I think that you can ignore the low battery cutoff circuit.  That portion of the circuit simply uses a reference voltage and low-side pass FET to cut off the battery's negative terminal from the rest of the circuitry when the battery's voltage drops below 11 V.

It seems to me that an external short circuit on a device connected to the USB receptacle would not be a culprit, since the TPS562200DDCT has overcurrent protection built into it:

  7.3.4 Current Protection
  The output overcurrent limit (OCL) is implemented using a cycle-by-cycle valley detect control circuit. The switch
  current is monitored during the OFF state by measuring the low-side FET drain to source voltage. This voltage is
  proportional to the switch current. To improve accuracy, the voltage sensing is temperature compensated.
  During the on time of the high-side FET switch, the switch current increases at a linear rate determined by VIN,
  VOUT, the on-time and the output inductor value. During the on time of the low-side FET switch, this current
  decreases linearly. The average value of the switch current is the load current IOUT. If the monitored current is
  above the OCL level, the converter maintains low-side FET on and delays the creation of a new set pulse, even
  the voltage feedback loop requires one, until the current level becomes OCL level or lower. In subsequent
  switching cycles, the on-time is set to a fixed value and the current is monitored in the same manner. If the over
  current condition exists consecutive switching cycles, the internal OCL threshold is set to a lower level, reducing
  the available output current. When a switching cycle occurs where the switch current is not above the lower OCL
  threshold, the counter is reset and the OCL threshold is returned to the higher value.
  There are some important considerations for this type of over-current protection. The load current is higher than
  the over-current threshold by one half of the peak-to-peak inductor ripple current. Also, when the current is being
  limited, the output voltage tends to fall as the demanded load current may be higher than the current available
  from the converter. This may cause the output voltage to fall. When the VFB voltage falls below the UVP
  threshold voltage, the UVP comparator detects it. Then, the device shuts down after the UVP delay time
  (typically 14 μs) and re-start after the hiccup time (typically 12 ms).

So, does anyone have any idea how this could have happened?

EDIT

Here is a link to a reference design that I used to come up with component values and operating points for the buck converter using TI WEBENCH Designer:
https://webench.ti.com/appinfo/webench/scripts/SDP.cgi?ID=F18605EF5763ECE7

EDIT

I have done some destructive testing here in the lab and can confirm that I get a very similar-looking pile of melted plastic where the Buck converter used to be if I plug in the battery with reverse polarity.  Since our choice of battery connector does provide a relatively high chance of accidental reverse polarity plug-ins (say, 4% chance --> wink wink), it would seem likely that this is responsible for the majority of the failures we observed.


texts: 5VDC output converter going to 10V when IC is connected

texts:
I have a pcb which uses ICs including two MCP3008. The voltage provided by the DC DC converter is to be 5V, and it is 5V when the two MCP3008 ICs are not inserted in the sockets. But when I place either of them in either socket (two ICs, two dip sockets) the voltage on that rail shoots to 10V.

What can I try to diagnose the problem.

I tried pulling both ICs, testing one at a time, testing each in each socket. Same problem happens.