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

learn more… | top users | synonyms

0
votes
1answer
56 views

LC Low Pass Output Filters for Inverters

I need an output filter for UPS inverter. I am using 9.6kHz PWM and 60Hz frequency. Can anyone help me with the right filter as I am new with filter design?
0
votes
0answers
52 views

Problem with PWM Output - PIC24F

The following is my code: ...
0
votes
0answers
26 views

Uneven distribution when using a mosfet for LED PWM drive [duplicate]

I'm using a set of NX3008NBK mosfets to drive a set of mid-range LEDs (~3.3V, ~20mA-60mA) with a microcontroller to apply PWM to control brightness. I am finding however, that the conversion between ...
0
votes
1answer
59 views

PWM-stimulated N-channel MOSFET unexpectedly always on

Electronics! I would appreciate help with the following problem: Goal: Get 12V PWM-modulated from a microcontroller-generated 5V PWM. Elements: • IRLML2502, n-channel FET - Datasheet ...
8
votes
4answers
347 views

Controlling heater with PWM through MOSFET

I'm trying to control a heater coil (resistance ~0.9 Ohm) with PWM using a MOSFET. PWM modulator is based on LM393, MOSFET is IRFR3704 (20V, 60A). If I place 1k resistor in place of heater ...
0
votes
0answers
21 views

LV halogen transformer for dimming via PWM control

I am looking for some advice regarding my plans to assemble a circuit to dim a halogen bulb. I am planning to use the principle of switched mode power to control a halogen bulb. I intend to ...
5
votes
2answers
76 views

Voltage spikes when driving DC motor with N-channel MOSFET

I'm trying to drive a DC motor (12V, 100W) with MOSFET IRFP054N. PWM frequency is 25 kHz. Here's the schematic: I know DSEI120-12A is not the best diode for this but I don't have any better right ...
0
votes
0answers
36 views

ATmega PWM frequency resolution

I am using an ATmega328 for generating a PWM signal. But I need a specific frequency. So I tried to use "PWM Phase Correct" mode (mode 10) for Timer 1. It says, the TOP value should be ICR1. It ...
0
votes
1answer
30 views

PWM AVR Atmega16

How can I use PWM in atmega16 with another ports (for example: PB0, PB1, PA0, etc.) and show the LED fade in and out slowly? I tried to do it but the LED only duffenly turn on-turn off, not fade ...
0
votes
1answer
37 views

High Side PWM motor driving circuit

I have two theoretical question about my circuit (that I have tested with a breadboard and it works, but I want to understand better some design choices): 1) As far the flyback diode is concerned, I ...
1
vote
2answers
53 views

Mosfet PWM signal not square

I'm a beginner learning about electronics, currently trying to control a DC motor using a PWM signal. I got it to work, but want to understand what I'm seeing using an oscilloscope and optimize it. ...
0
votes
2answers
55 views

Mosfet time and PWM frequency relation

what is the relation that I have to take into account when I select a mosfet(or a transistor in general) for pwm driving about rise/fall/turn off delay/turn on delay and the PWM frequency? How to ...
0
votes
0answers
35 views

Driving high voltage MOSFET H-bridge

I am looking for suggestions on MOSFET transistors and logic for driving high voltage full H-bridge from a 5V PWM signal. I have a microcontroller that outputs a PWM signal 0V->5V. And with this ...
1
vote
1answer
85 views

Scaling 12V PWM signal to 0-10V

I'm trying to translate a 3.3v PWM signal through an optocoupler to the 12V side of a circuit, filter it to obtain a relatively clear DC voltage, and scale that to 0-10V for a control element. So ...
-1
votes
1answer
76 views

PWM with MOSFet- make it linear

there maybe wrong assumption in my question , so forgive me, i am here to learn . So controlling a light(LED) with MCU that outputs PWM, into a MOSFET N-CHANNEL, as described in this little image: ...
2
votes
2answers
105 views

PWM an AC pump using MOSFET

I'm currently stuck on my project as I'm not sure what to do with PWMing my pump as I want to adjust the pressure. I will be using an Arduino for PWM. The pump is 60W @ 230V 50Hz mains and is a ...
0
votes
1answer
56 views

Why would someone use an amplitude modulation ratio lower than one in a power inverter?

We had a test the other day, and there was this question: What is the minimum DC voltage required to drive a PWM, half-bridge, three-phase, power inverter to 4160Vrms. It should be possible to vary ...
-3
votes
2answers
66 views

RGB control with MOSFets

I would like to control RGB leds , or other PWN channels , using a micro controlelr, and ...
0
votes
2answers
115 views

Delay introduced by transistor

I have the following circuitry: PWM-2V8 is a square 50% 40kHz signal as this (R37 not populated on this capture): On P8, I get the following signal which is distorted and the duty is more like ...
0
votes
1answer
38 views

LED Backlight driver output current

Our LCD has 10 series white LEDs for backlight with total Vf of 15V and current of 40ma. The backlight circuit is designed with SC4509. As per the datasheet its recommended output voltage is 20V and ...
0
votes
1answer
41 views

PID control using halogen dimming?

I am looking for some enlightenment with regards to a project i am working on. I aim to use a halogen bulb as a heating element to implement PID control. I intended to dim the halogen bulb (using ...
0
votes
0answers
51 views

Design considerations for internal PC parts

I'm designing a PWM fan controller. It will be interally mounted inside a PC and will take power from the normal 4 pin Mate-N-Lock ("molex") connector. The on-board MCU and LCD will draw power from ...
1
vote
0answers
25 views

Problem with Constant Off-time PWM/Variable Frequency on dsPIC30F2020

I'm using the Microchip dsPIC30F2020. I've been trying for the longest time to get some sort of PFM signal for my project. I see in Section 12.4.7 there is the ability to have constant off-time PWM ...
0
votes
1answer
28 views

Torque control with H-Bridge via direction pin

Using the LMD18200 (H-Bridge) and the LM3524D (PWM regulator) I should design a torque regulation. I've found a circuit in the LMD18200 datasheet which uses the current feedback to adjust the PWM. ...
3
votes
6answers
298 views

MOSFET PWM switch jamming on - why?

The circuit presented here is sized to switch 100W at a minimum pulse width matching 250Hz. But actually it's currently only being asked to switch around 10-20W. The load is an array of LEDs. Q1 ...
0
votes
2answers
49 views

Using 3 Channel Video Switcher Module with Arduino

Hey all I am wondering how to go about switch from camera 1, 2 or 3 using this 3 Channel Video Switcher Module on ebay here. Since there's only V+, V- and signal for the "switch" it looks to take a ...
0
votes
2answers
56 views

Can you set the PWM output of an Atmel AVR to a specific frequency and have control over duty cycle?

I'm trying to drive an LED at 38kHz with a low duty cycle like 10% from an Atmel ATTiny88. The chip is currently running at 8MHz, but could be adjusted for this portion of code, if need be. Using ...
0
votes
1answer
58 views

How to calculate frequency for PWM design

I would like to create a PWM controller for an open loop galvo-mirror. The similar questions involve motors and I can not directly use that approach to galvo-mirror which only deflects, not rotates. ...
0
votes
2answers
110 views

Is there a difference between 100% duty cycle PWM and continuous current?

I was thinking that 100% duty cycle PWM always keeps output HIGH ( just like a continuous current ) but according to Proteus simulation the output still falls and rises in a very little time Is that ...
0
votes
1answer
79 views

Increase toggling speed of PNP for PWM

I got a shift register which I use to PWM LEDs. Since I multiplex this toggling I noticed some "afterglowing" if the next LED is not active of the same color. (RGB cathode) Multiplexing by the MOSFET ...
1
vote
0answers
42 views

can I drive 100 or so LRAs with WS2811 controlling DRV2603?

I would like to make a suit with 100 or more individually controllable Linear Resonant Actuators. Texas Instruments makes this http://www.ti.com/lit/ds/symlink/drv2603.pdf which take a PWM as an input ...
0
votes
1answer
105 views

PIC - 4-20mA (Duty cycle formula)

I am implementing a 4-20mA current loop to my PIC. I have everything working. I am measuring the distance away from an object. When I hardcoded the distance as 300 the output voltage is 4V and when ...
0
votes
1answer
72 views

Beaglebone Black PWM Driver for 12VDC 1.05A Motor | Drive from Positive Side

I have several 12VDC 1.05A pumps I am using in my hombrew system which I would like to drive via PWM on my BBB. Each one will have a hall effect flowmeter attached so that I can get flowrates, totals, ...
0
votes
0answers
51 views

PWM for my air-compressor 15 Amp dc-motor

I have read some similar questions but didn't get the answer for mine. I want to make a viair 12v compressor run at a low pace to fill some tires very slowly drawing as few amps as possible. Could I ...
0
votes
1answer
57 views

Current usage with multiple PWM controlled motors

I have a circuit that can use 25 A of current max, it is on a 25 A fuse. I am looking to control 4 DC brushless motors using ESC's. The trouble is that the motors are rated at 7A max current. I know ...
0
votes
1answer
116 views

Transistor amplifier circuit for triangular wave

I've made triangular wave oscilator as shown in Fig. 1 and it works perfectly at frequancy 10 kHz with peak voltage +3 Volt to -3 Volt. I intend to generate SPWM. But when I feed this circuit to ...
0
votes
2answers
40 views

Inverted PWM with ATTiny10

On a 10MHz ATTiny10, the following code generates the same 40kHz 50% duty PWM on both pins 0 and 1: ...
1
vote
3answers
71 views

HEXFET PWM motor driver does not work

I'm trying to drive a motor for an academic project, using the circuit in the image. The STM32F4 Discovery board that I'm using in this phase of the project produces a 30Khz PWM at 3V, that is correct ...
0
votes
0answers
72 views

PWM and brushed DC motor - AC input? Limiting RPM?

I'm looking to replace the 20-year old poorly-performing speed control in a MIG welder. It allows the user to adjust the speed of a small brushed DC motor, which drives thin welding wire of of a ...
0
votes
3answers
87 views

Detect a missing PWM signal in the smallest possible board space

I have a motor control board that basically has zero space left, and the customer wants to add a fault flag to tell if their 2 kHz PWM input signal is lost. So basically, I need to detect a lack of ...
0
votes
1answer
38 views

Voltage wave form across a DC motor driven by a transistor with pwm

Above is the simple implementation for a DC motor control with pwm. I was expecting to see a square wave with a Vmax when Q1 is ON and zero when Q1 is OFF like the one here: standard pwm But ...
0
votes
1answer
51 views

How does this motor drive circuit work?

The Drive terminals are connected to a PWM signal generated by an arduino micro controller. The purpose of this circuit is to isolate the arduino from the motors to avoid too much current being drawn. ...
2
votes
0answers
114 views

STM32 - Multiple channel PWM input

I am using an STM32F405 based board , (OpenPilot revo ) to receive PWM signals from a joystick receiver . i have to xapture 5 PWM signals using only two timers , the timer 8 and the timer 12 . I've ...
2
votes
2answers
187 views

Convert positive square wave to positive-negative

I am looking for a way to convert a square wave coming from a microcontroller with voltage range from 0V to 5V, to a voltage range from -12V to +12V. The frequency of a square wave will vary from few ...
0
votes
3answers
78 views

How to up-convert PWM frequency without using a microcontroller?

I am trying to drive a motor H-bridge, but my control system can only support a 400 Hz PWM signal (black box, can't change it) which gives the motor an extremely loud 400 Hz whine as you would expect. ...
0
votes
1answer
115 views

Temperature stabilization with PWM , PID controller with delay system

I am doing a project to control the temperature with PWM. I use peltier, thermistor,mcu and h-bridge mosfet. I want to reach a temperature with an error less than 0.05 and stay at that temperature ...
0
votes
2answers
69 views

DC - DC Amplifier for Piezo Buzzer

I have a Raspberry Pi outputting a 3.3v DC square wave that I'd like to be able to amplify to just under 20v, the maximum the piezo can handle. Just to clarify, the piezo does not have an internal ...
0
votes
0answers
35 views

Pulse frequency for a pulse width modulation application

How can I determine the pulse frequency for a DC motor speed control or an LED brightness control. I have no data about the DC motor and led frequency dependence they both do not provide anything ...
0
votes
2answers
83 views

Basic h-bridge motor driver circuit for audio PWM waves with possible negative voltage

I need to control a DC motor with the PWM audio waves coming out of the audio jack of a device. The device will send a positive PWM to drive the motor forward and a negative PWM signal for driving it ...
1
vote
1answer
89 views

What is PWM Dead Band and when should I use it?

I'm having trouble understanding this concept, here is what the documentation in my microcontroller says about it: dead bands are defined as the number of PWM clock ticks from the rising or ...