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Questions tagged [pwm]

Pulse-width modulation, is varying the duty cycle of a rectangle wave, usually with a constant frequency.

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29 views

Isolated vs non-isolated boost converter for LED (12v to 24v)

I have a 12v system in my motorhome and planning on installing 24v LED strips, however, I'm unsure whether I would need an isolated or a non-isolated boost converter. I'll be using roughly 5 meters ...
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8 views

Arduino pin 13 as PWM output, not possible? [migrated]

I have noted on more than one occasion the comments in sketches "reserving pin 13 for future PWM backlight dimming of the LCD" while using Uno and Nano boards. Am I missing something ? I always ...
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How to wire this double GPU fan connector setup [migrated]

My GPU has two fans connected by 5 wires in total: 2 red, 2 black and 1 yellow. Fan 1 has b+r+y, fan 2 has b+r. Now my connector got damaged and the two wires from fan 2 came lose. I want to ...
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29 views

pwm 5v to 10v with optoisolator

i need to convert pwm 5v to 10v (eventually with an low-pass rc filter) now, the problem here it's that i want to have 5v isolated from 10v, so i don't think that i can use a mosfet. my idea it's to ...
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1answer
45 views

Confusion on Servo and PWM (AVR)

For reference im using an AVR Atmega 328p, and the servo specs i'll be using says this: Pulse Cycle: 20 ms (I assume this means the "period") Pulse Width: 600-2400 µs So from my understanding, ...
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1answer
55 views

Current spikes on rising and falling edge of NPN BJT switch

I am simulating a simple NPN BJT switch for PWM in LTspice, and I observe some current transients on the rising and falling edges that I do not understand. The circuit is here: Picture of the falling ...
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1answer
48 views

Measuring pwm output from low side FET with oscilloscope

I have a n channel MOSFET controlling a high current LED panel. The FET is driven by a FET driver, which is itself driven by a MCU pin. I am using PWM to control the LED brightness. I want to double ...
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16 views

Integrated circuit for phase power measurement of PWM driven motor [closed]

I'm trying to find an integrated circuit to measure power on at least one phase of a PWM driven syncronous or asyncronous motor. I've found plenty of chips that do this kind of job for 50-60Hz ...
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40 views

Calculating the Duty Cycles for the Syren 10A Motor Driver

I bought the Syren 10A to drive a Peltier element using python and a raspberry-pi zero + 12V power supply. After reading and talking I concluded to use the Driver in the R/C Failsafe Timeout Mode ...
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2answers
64 views

Question on Speed Control vs Torque Control

I'm controlling a Permanent Magnet DC motor with PWM for a treadmill. I'm using a reflective sensor with 6 pulses per rev to get a speed feedback. So I'm actually doing "speed control" directly, but ...
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52 views

Attiny45 12V LED Driver

I want a fading effect on a 12V led strip when power is turned on/off. I want to keep it simple and efficient, so I choose an Attiny45. The problem is that for the Attiny to work, I would first need ...
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1answer
45 views

How to drive 4-pin fan

I've been attempting to get this 4-pin brushless dc pc fan working for some time now. It has a red (+) black (-) blue (PWM in) and yellow (tachometer out). I only want this fan running at maximum ...
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30 views

Limit a variable PWM circuit (Using op amps)

I'm working on a variable PWM to control the velocity of a DC motor but i cant delimited the duty cicle of the PWM that never be a DC value (VCC - 0v) and i'm working with LF353 Op amp but doesnt work ...
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1answer
73 views

STM32f103 DMA with PWM repeating values

I have a Blue Pill (STM32F103) and connected to it a ws2812b led strip. I am trying to send data to the led strip via PWM over the TIM2 peripheral (Pin A0). To change the duty cycle of the TIM2 PWM I ...
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1answer
51 views

Inverter with PWM: Modulation Index

I model an photovoltaic inverter in simulink. The Inverter has a PWM, a current control and MPPT. The PWM pulses are generated by comparing the reference sinus signal with a triangular signal. The ...
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1answer
71 views

How to get 50 Hz sine wave from inverter bridge driving PWM pins of MCU

I am using this circuit to see the sine wave coming from a DsPIC Pins to check the shape of sine wave created from my sine table. PWM frequency is 18 kHz But the sine wave does not seem to be ...
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51 views

How to remove PWM noise from my speed sensor wires?

I'm driving a brushed DC motor via PWM at 5kHz. I'm also measuring the speed of the motor. When I try to sample the speed, sometimes I'm getting a value of 5kHz, which is exactly my PWM frequency. ...
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2answers
133 views

500 watt LED PWM

I'm trying to make a PWM'd floodlight with 6 Cree CXA 2540Ns. My setup is a simple 555 timer set up for PWM, driving a 3904, which in turn drives an FDA59N30 N-channel MOSFET, properly cooled to ...
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2answers
73 views

Voltage to PWM Circuit, need to understand frequency

This is an off shelf component that might fit my need. Unfortunately the documentation is terrible. It should convert a 0-5v or 0-10v analog to PWM (0-5v/0-10v is a jumper). The analog voltage signal ...
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1answer
61 views

Microcontroller PWM output volume

So I am designing a cheap and simple sound device using the Atmega32U4 uC and stumbled across one problem. I am using the 10-bit PWM output of the uC to output audio and I want the user to be able to ...
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1answer
56 views

Lowpass Filter and Attenuator

I am designing a circuit to power a brushed DC motor. The motor will be given 24VDC, modulated with PWM. I would like to have an analog voltage sense capability for use with my Atmel ATmega328P @ 3.3 ...
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1answer
62 views

Testing Capacitor in PWM Circuit with Oscilloscope Calibration Signal

I'd like to measure the effect of a capacitor in a PWM circuit with an oscilloscope. The capacitor is engaged on a switch connected to a DC motor. Can I hook the motor up to the 1 kHz calibration ...
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65 views

How to generate two individual signals based on falling/rising edges from two different PWM signals?

I am looking to implement a discrete circuit that can generate two different waveforms based on the rising/falling edge of two individually limited 50% duty cycle PWM signals. See following figure: ...
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2answers
85 views

Which STM32 microcontroller has the most PWM channels? [closed]

I need a MCU with a minimum of 32 PWM outputs and at least 1 analog input. Are there any STM32 MCU which satisfies the requirements? I thought of multiplexing 16 PWM channels to 32 channels, but I ...
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2answers
34 views

Question on brushed DC motor voltage measurement

I'm operating a brushed DC motor via PWM at 5 kHz. It's a big motor rated at 125V/27A. I don't have an voltage acquisition circuit. Just a multimeter. But I want my microcontroller to know what the ...
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2answers
37 views

12V Relay Actuation Depending on PWM or Constant DCV Input

I am looking to actuate a 12V SPDT relay depending on weather or not a 12V PWM signal is received or not. Headlamps use a reduced power PWM signal for daytime running lamps. I want to be able to ...
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0answers
57 views

Current Pump Circuit

I found this circuit diagram in an academic paper, however, there are no values associated with any of the passive components. The authors claim that this circuit can deliver 1-120mA across a load of ...
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2answers
57 views

Select N-Channel MOSFET to drive speaker and LEDs

I have 3 circuits with MOSFET gates routed to MCU's PWM / IO and I would like to drive with them a Speaker, RGY LED and Backlight of LCD. There's a lot of parameters in MOSFET's datasheet. I am not ...
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1answer
113 views

Highest frequency that can be generated with SPWM?

If you use the Arduino low pass filter "trick" called SPWM (sinusoidal PWM). What determines the highest frequency that can be generated like this ?
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1answer
100 views

What is the physics behind width of the duty cycle in Arduino?

I was wondering if someone can tell me how Arduino changes the width of the duty cycle? How it produces an on-off pattern? I am looking for an explanation for modulation in this system.
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44 views

Achieve -12~12V PWM Signal isolate

I have used IL300 to isolate 0~5V PWM signal before and it works great. The circuit is shown below. But now I need to isolate -12 ~ +12V PWM signal. Is there any possibility or suggested circuit to ...
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28 views

PWM Switching and Current measurement

I have the following circuit: This circuit is created in simulink. It has a voltage source (Vs is 36V, Rs is the source's internal resistance, at 0.001Ω). Resistance R is 1Ω. I want to control the ...
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48 views

Designing a constant current pulse circuit

I'm looking for help designing a constant current pulse through a variable load impedance of 10-100k (R4). The ideal response is shown below. This waveform was measured from an off the shelf ...
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85 views

Implementing PID in PWM feedback to lower the settling time

I have created the following simple PWM feedback: The step response is: I have tried to add PID controller and I ran the following code to test it: ...
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1answer
27 views

Single MOSFET motor driver with oscillation on output

I'm trying to drive a small DC motor with a PWM with the circuit below, where I'm using a TIL111 optocoupler and a IRF510N MOSFET. The PWM (50% duty cycle) is generated by a MCU STM32F103C8T6, the +3....
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3answers
60 views

Using PWM instead of real DC for VFD's 0-10V control input

There is a VFD which controls an AC motor through a 0-10V control. I know that this control voltage is DC voltage. I'm wondering would a PWM work for this application? I mean instead of 2VDC, what ...
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1answer
39 views

Question on the right PWM frequency for Permanent Magnet DC Motors

I know that there are some posts in this site about this question. I don't know if there's a way to find out the "ideal" PWM frequency for motor control. Usually they recommend to be safe in a range ...
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23 views

STM32F429 PWM GLITCH

I have set up Timer 1 Channel 1 for pwm mode 1. I used the STM32CUBE to generate code for MDK-ARM. Parameters as below- ...
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1answer
38 views

Controlling DC motors and servos with a single pca9685

I have a Raspberry Pi project (robot with wheels and servos) and I'd like to control both motors and servos at the same time. I'm trying to use PCA9685 + L298N for driving the motors. The problem I'm ...
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2answers
50 views

DC Motor PWM Circuit Implementation

I'm a little new to this, so bear with me: I am working on a hobby-related project that involves the operation of two DC motors in parallel, powered by a NiMH battery. (Crappy circuit diagram ...
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4answers
870 views

Detect ring signal using a low pass filter

I created 2 boards communicating each other like an intercom system. One of them has a button to send a ring signal to the other. The ring signal consists of PWM signals created by an MCU. I want to ...
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2answers
42 views

Current Sensing problems in PWM-switching circuit

I have the following circuit: simulate this circuit – Schematic created using CircuitLab A simple voltage source is connected to a resistor. The current flow is controlled via an NPN switch. I ...
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1answer
110 views

Creating smooth PWM response

By using PWM I have converted some signal to pulses and inserted it into transfer function of 2/(0.01*s+1) I then compared between the result of the original ...
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2answers
382 views

Can PWM affect a brushless DC fan given sufficient time?

tl;dr - Is driving brushless DC fans using PWM unhealthy for the fan compared to variable but steady DC voltage? If yes, why and how? The super simple ...
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0answers
33 views

Comparing Pulse and wave

Im new to PWM and I have tried to generate some pulse. I have made a simulation that generates the command I should send to a servo in order to make a wheel move the direction I want (lower graph). ...
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1answer
51 views

Interfacing with (Two) Full-Bridge PWM Motor Drivers to Control a Stepper Motor

I am working to interface with an existing PCB with on-board Full Bridge PWM motor driver chips, which drive a stepper motor. The interface lacks any kind of standard step (clock) or direction signals ...
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0answers
27 views

Power supply for electro plating

Which DC power supply will be more suitable for electro plating? The PWM type or the normal adjustable V/I type? How many voltage and current will need to be applied. What parameter to decide how ...
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1answer
88 views

What will be the behavior of this circuit?

i have a circuit for which i have simulated its output. But i can't seem to understand how it works. Here is the circuit.. simulate this circuit – Schematic created using CircuitLab For ...
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3answers
99 views

change level of positive square wave signal to negative

A general question: Lets say I have a square wave signal from 0 to 5 volts. What I would like to do is create a circuit that will convert this 0 to 5-volt signal to a -2.5V to +2.5V for example. ( ...
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0answers
42 views

What are the limitations for driving enough servos using PWM drive boards?

I am working on a interactive installation using 16 turrets made by servos and laser. These components are driven by 3 PWM boards connected by I2C on a Teensy 3.5.I am running into some issues now so ...