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

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2answers
100 views

The Transistor Menace - Questions regarding an Arduino rgb LED project

I've been browsing this forum and the internet now for a couple of days and what I thought would be an easy side project turned into a (for me) quite complicated matter. I'm planning to build a mood ...
3
votes
1answer
86 views

Help understanding Low side N-Channel MOSFET driver circuit

I took a simple circuit i found and started modifying it for my own purposes and realized i need to understand it's workings better to get where i need to be. PWM+ and PWM- comes from a LED dimmer ...
4
votes
4answers
1k views

How to reduce 28 V to 24 V under load?

I need to PWM control six 24 V DC fans with a total load of 10.6 amperes. That's easy, right? Just PWM to a few MOSFETs. However, my system voltage is 28 V. At 28 V I'm out of ...
0
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2answers
46 views

PWM Drive Simulation

I've been trying to follow an example circuit that does some PWM. First I believe that in a configuration something like this with nor & and that the wave should alternate. Violet line is ...
2
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3answers
59 views

Why does output voltage increase when pwm input frequency to output enable increase?

I'm trying to pulse-width modulate an output from a 74HC585 shift register. To achieve this, I plugged a PWM output from a teensy 3.1 microcontroler into the output enable input of the 74HC595. The ...
2
votes
2answers
71 views

How do I use a PWM unit and/or microcontroller to have transistors progressively all turn on and then progressively all switch off?

How do I use a PWM unit and/or microcontroller to have transistors progressively all turn on and then progressively all switch off? It's for what will most likely be an 18-pulse inverter. ...
2
votes
4answers
71 views

Connecting a galvanometer directly to a microcontroller's PWM output

Is it a good idea to connect a galvanometer (100 µA panel meter) directly to a PWM output of a microcontroller (or any other digital device for that matter)? I set PWM frequency to approximately 10 ...
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2answers
97 views

Arduino + MCP41010

I would like to control two 48V DC motors (500W) from electric scooter with my Arduino. I've bought two PWM controllers from eBay and they work excellent. Issue is that controllers have pot on them ...
0
votes
1answer
57 views

Voltage divider on AC current?

I have a 90V PMDC motor with an triac/diac speed controller. Although, I am not sure, the power output is around 90V, but it may be higher. The torque is fairly constant, but it hiccups at the lowest ...
0
votes
3answers
59 views

Problem : Cmos Circuit

I got a problem related the circuit below. I wanted to make DAC (0-80V) using a pwm input (6 kHz). You might ask why I did not make it with a single n-mos. The reason for it, I used a single as ...
1
vote
1answer
30 views

Circuit with reversing polarity and two microswitches

I am building a time-lapse camera slider with the following components 2rpm DC gearbox motor PWM with reversible DPDT switch to reverse motor 2 SPST Microswitches I am trying to wire the ...
1
vote
3answers
66 views

Best way to read 18kHz PWM signal with wide V_pk-pk (5.5-18V)

I am trying to design a circuit for level-shifting a PWM signal coming from a sensor and reading it with a 5V micro controller in an automotive environment. I will run my design by an EE at the end ...
0
votes
1answer
69 views

How to determine DC motor voltage

I am building a new controller for an existing robot. I need to know the voltage to send the motors. I don't want to remove the motors from the robot, but am able to take measurements while it ...
0
votes
0answers
25 views

PWM Chopping current and Decay Modes of motor drivers

This is my first experience with driving stepper motors, so please bear with me. I was looking again through the datasheet of the stepper driver DRV8811 and came across calculations that needed to be ...
1
vote
1answer
61 views

Battery Discharge

I am making a circuit to discharge an 18V Li-ion battery, with multiple cells, in order to condition it. Each 18V cell has a capacity of 100Wh when fully charged. I would like to control the condition ...
0
votes
2answers
53 views

unexplained short circuit with PWM signal?

Something happened that i haven’t been able to explain , I wrote a program to output a PWM signal, this to activate a transistors base using a PWM which I could change the frequency using a ...
0
votes
3answers
153 views

Controlling a motor using a PWM

Im trying to use a Freescale FRDM-KL25Z, I have been looking at the datasheet to see if I can find the maximum oputput current of the pins with no luck, im assuming its 500mA since its powered via ...
0
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1answer
58 views

multi channel ac dimmer for arduino

I have been looking for a simple ac dimmer circuit to use with my arduino and/or raspberry pi. I have used the TLC 5940 PWM Driver before just to control LEDs and I wanted to adapt this to controlling ...
0
votes
1answer
69 views

Closed-loop gain with source degenerated amplifier

The following circuit needs is modeled with parasitic capacitances to be analysed in frequency. I need to drive it with an MCU that can output a signal that can be some tens of kHz and I need to see ...
0
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1answer
42 views

RaspberryPi + TowardPro MG996R DIGI HI TORQUE +PWM

I am trying to control this servo from a RaspberryPi. https://skippy.org.uk/wp-content/uploads/MG996R_Tower-Pro.pdf I sort of figured out that a servo needs a specific pulse for a specific degree. ...
0
votes
1answer
96 views

Replace an Analog Pot with a digital one?

I have a Boost converter with a constant current mode that allows me power a high power led (Vf 34, 3A). I'd like to be able to control the current potentiometer on this device with an arduino. To do ...
0
votes
0answers
31 views

EMI/EMC filters for different frequency sub-circuits

I am designing a PWM based solenoid controller. The PWM controller works at 23kHz with an average circuit consumption of 23-45mA. The PWM controller is powered by a non-isolated SMPS with 12V output ...
0
votes
1answer
87 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
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0answers
62 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
69 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
422 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
33 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
119 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
54 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
38 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
63 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 ...
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2answers
74 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
3answers
85 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
52 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
124 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
89 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
149 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
76 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
72 views

RGB control with MOSFets

I would like to control RGB leds , or other PWN channels , using a micro controlelr, and ...
0
votes
2answers
118 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
63 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
69 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
49 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
38 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
311 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
57 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
76 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
68 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. ...