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

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35 views

help with 555 timer to dim led driver

I am trying to build some DIY LED fixtures to light my saltwater aquarium. They need to be dimmable, and I want to dim them with Pots for convenience versus a controller. It will probably be clear by ...
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1answer
46 views

Control LEDS with PWM and transistors

I have three transistors that are each connected to 5 LEDs like so. I am attempting to increase and decrease the current through the LED's in a linear fashion by increasing the current in the base ...
0
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2answers
47 views

How to add the two output of a PWM IC?

I need to sum output A and output B of a PWM (UC3526AN) because each output have a maximum duty cycle of 0.45. I try with 2 diode and a limiting resistor(R1) for the led inside the optocoupler ...
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0answers
13 views

voltage level shift at the input of PWM IC (UC1526 )

I am using UC1526 in open loop configuration (pin2 and 3 connected) and I am inputting a voltage to pin 1 to control the duty cycle. I notice that pin 1 which control the duty cycle need a minimum ...
0
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0answers
44 views

code mickro C for CLosed loop control for switching boost converter not working

i try to write a code in mikro C for closed loop control for boost converter for get the stabe output voltage inputvoltage : 12V output voltage =26V bellow the code ...
0
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1answer
34 views

Driving 5 RGB LEDs using a microcontroller

I need to run 5 differnet rgb LEDs from a microcontroller. All the LEDs will be producing the same color so there will only be 3 separate PWMs (1 for each channel of rgb.) My problem is most ...
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2answers
103 views

can a voltage regulator circuit be modified to put out PWM? [on hold]

can a voltage regulator circuit be modified to put out PWM? i'm putting a full-wave rectifier circuit and voltage regulator circuit on a pcb. i'd like to modify the vreg circuit so that it puts out ...
-4
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0answers
24 views

Program to Generate pwm output varying Dutycycle from Analog Input 0-5V using LPC 2148 ARM [on hold]

i want to generate the pulse based on analog input giving to ADC and convert ADC value to PWM signal using LPC 2148 ARM processor.Please help me with code in c
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1answer
51 views

30x Incandescent light bulb in parallel ? + dimming

I'm trying to connect 30x small incandescent light bulb in parallel (1.5v / 300mA). But I'm having some issue designing the supply and dimming circuit. Does it just work like LED's for the ...
0
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1answer
18 views

PWM in 8051 with PCA counter

I read in documentation of AT89C51RC2, that I can make one of 5 ports to generate PWM signal if I set properly some registers. Some things I don't understand. I don't know what PCA counter is and how ...
2
votes
1answer
46 views

FIltering a PWM signal?

The first box is my modulating signal and the last box is my demodulated signal (filtered signal) I used my signal to change the duty Cycle of a PWM modulator (fix PWM frequency and variable Duty ...
0
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0answers
30 views

Control Output Power using PWM from Arduino

I am trying to make a simple control loop to power up a lamp and with that control the temperature, for that I am using an Arduino as microcontroller. The lamp I am using is a DC 12V 20W, so we ...
0
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1answer
43 views

PWM speed control for 90vdc motor

I built this circuit and it seems to work if i use a the same power supply to the motor that is powering the IC. I am using an LED in place of the motor for testing. But the circuit does not work ...
0
votes
1answer
55 views

What's the relationship between ESC pwm input and output?

I'm using ESC(Electronic speed controller) to control outrunner brushless dc motor. As you know ESC detects ppm signal between 1ms and 2 ms approximately. So my ESC detects signal between 4% and 9% ...
0
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2answers
53 views

Space vector PWM signals

I have done few BLDC motor controllers with trapezoidal modulation and they work fine. Now i'm trying to build another one with space vector modulation but as it doesn't work well i'm getting more and ...
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0answers
48 views

Inductance to capacitance ratio in LC filter for PWM

When using parallel LC filter for smoothing out PWM, I'm using the following equation to calculate its frequency: F\$_C = \dfrac{1}{2\pi\sqrt{LC}}\$ Here is a schematic of an LC filter I'm talking ...
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2answers
95 views

Why Op Amp circuit not behaving as desired

I want to convert PWM output of microcontroller to 4-20mA. I use below circuit for this work : But voltage on pin + and - Are not equal in this circuit!!! for example when pin + is 1.2 volt with ...
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1answer
47 views

PWM bahaving OPPOSITELY as expected on dsPIC33EP256MC506

The PWM module on my dsPIC33EP256MC506 is behaving opposite as it should. When I set the duty cycle equal to the PWM period i.e. 100%, the duty cycle is treated as ...
4
votes
3answers
267 views

Why is PWM used to control LEDs even when they're only used On or Off?

I've noticed on cars with LED tail lights that they have a flicker to them - I presume because they're PWM controlled. But I've seen it on vehicles where brake lights and tail lights are separate ...
0
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1answer
38 views

Using an AC speed controllet with an rectifier and dc motor

I salvaged a 12 amp motor from an AC lawnmower and wanted to use a motor controller to reduce the speed. This is the controller I used http://www.amazon.com/gp/aw/d/B00GMBYFRK. The motor is a dc ...
0
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1answer
35 views

Question on dsPIC33F PWM Period and Duty Cycle Calculation

On the Microchip dsPIC33F family, the PWM period PTPER is calculated as: PTPER = (FCY/FPWM)*(PTMR Prescaler Value) - 1 where PTMR is the input clock to the PWM and FCY = Fosc/2, FCY being the ...
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2answers
95 views

P-type MOSFET is not turning off

I am designing a buck converter as class assignment as shown in figure. I have calculated all the value of inductor and capacitor. I am applying PWM to the input of MAX627 MOSFET driver through ...
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2answers
82 views

5v piezo (micropump) with arduino

edit -added pin 9 as output in setup and now HIGH/LOW code works. -When the pump is set to LOW it turns on, when it goes HIGH it is disabled. So when I plug the arduino in, by default the pump turns ...
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2answers
345 views

Resistors with arduino

simulate this circuit – Schematic created using CircuitLab I'm using Arduino Mega Pro 5V. Pins use a max of 40-50mA. I'm connecting 3 RGB super bright 5mm LEDs. Currently wired in ...
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0answers
26 views

STM32F205VC - What causes this short impulse in one-pulse mode of TIM1?

Hi! Why am I seeing this short impulse? This is my code: ...
0
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2answers
68 views

Checking my understanding of how hobby servo motors operate?

Can someone tell me if my understanding is correct please. The control signal to a hobby servo motor that is connected to an arduino operates by : In every 1 s there are fifty windows each of length ...
0
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2answers
59 views

running AC synchronous motor with DC

I have a gadget that does contain a 12V AC synchronous gear motor (2 Terminals) that i want to hack. I want to supply the gadget with 12V DC (among other changes). Up to now i use tiny AVR and a ...
0
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1answer
42 views

How to connect PWM output from a dsPIC MCU to 12V LEDs?

How to connect PWM output from a dsPIC30F MCU channels to 12V LED diodes? 4 x PWM channels will be used. For use with following voltage: LED Voltage: 12V Total operating current: 5A 1W ...
0
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1answer
46 views

PWM vs Analog Signals

Oftentimes in EE classes we learn about AC analysis and phasors and other stuff heavily based on analog signals. I also know that many digital applications approximate analog signals using PWM. But ...
2
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1answer
61 views

Avr multiple ADC and PWM channels

I've been trying to make a program that would continuously read analog values from 3 different pins and then make a PWM signal corresponding to each of those 3 pins. So basically, 3 output PWM ...
2
votes
1answer
60 views

Why Some SMPS use Tiny Switch, Some use Top Switch and Some use Link Switch and Other use PWM IC. Please guide what is the criteria to select?

I saw many smps design , Some use Tiny Switch , Top Switch , Link Switch and other user PWM Control IC only. What is the difference and how to choose right one??
0
votes
1answer
68 views

Buck converter not working

I designed a buck converter on breadboard as shown in the picture. I am applying PWM from my microcontroller. I am not sure why this circuit is not working, I have spent so much time on it. Is there ...
0
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2answers
80 views

Applications of PWM?

I know the application of PWM is controlling the brightness of led or DC motor speed, but I don't understand it, why when we change the duty cycle, it change the brightness or motor speed ? Can you ...
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0answers
99 views

AC fan speed control (using Arduino)

I wanted to control a 220V, 50Hz AC ceiling FAN using PWM output from an Arduino microcontroller and I have referred to several resources regarding this. Resources I referred ...
2
votes
2answers
58 views

Replace transformer with PWM control

This is my first question on stackexchange so if I do anything wrong, please let me know :-) So my situation is the following: I am working on a power supply module where I need 7 separated +28V DC ...
1
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2answers
82 views

Change RGB leds intensity?

Sorry if this is too basic but I don't understand this issue. Right now, using an MCU, I change the RGB colours of an LED strip with 3 PWM signals. All colours works great . The thing is, when I am ...
0
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1answer
57 views

Low cost H-Bridge circuit for PWM

I try to design a (relatively) low cost H-Bridge on N channel MOSFETs. I need to drive 8.5A peltier device with 12V and (roughly) 20kHz PWM. (after reading some of the comments I changed this ...
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votes
2answers
67 views

pwm and pull up/down [closed]

I am an electrical engineer and feel I should know this, but I for the life of me still cant quite get this concept. I understand conceptually the idea behind a pull up or a pull down, in that we ...
4
votes
5answers
68 views

Staggering PWM waveforms for servos to minimize current spikes

If I'm controlling multiple hobby PWM servo motors, is there an advantage to staggering the pulses sent to each servo? By which I mean, each servo needs to see a pulse of width ~1ms every 20ms. Let's ...
1
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2answers
35 views

555 timer control voltage

I'm trying connect the 555 timer as a pulse wave modulator. Notice from the diagram below, the - input of Comp1 is internally connected to \$2/3V_{CC}\$. The control voltage is applied at pin 5. The ...
1
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5answers
102 views

Generating a PWM ramp signal using logic gates

I have a microcontroller outputting a ramp signal on an I/O pin in PWM form. i.e. the duty cycle steadily increases from 0% to 100%, then drops to zero and repeats. After smoothing I end up with a ...
1
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1answer
58 views

Problems with using 20Mhz crystal withPIC18f2420

I am using PIC18f2420 to generate PWM. I am using Timer 2 with 4MHZ crystal, which works perfectly by giving me PWM. I need to get 100KHZ of frequency for PWM, for which, 4MHZ crystal is not enough as ...
0
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0answers
30 views

Voltage-mode or Current-mode PWM controller?

I am trying to decide between a voltage-mode and current-mode PWM generator to connect to a gate driver IC to drive my power MOSFET. The PWM will be generated based on a current input to the ...
0
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2answers
44 views

Current-controlled PWM Generator with variable duty cycle?

I need to implement a variable duty cycle PWM generator with constant frequency (100kHz) to help drive a MOSFET. Is there such a thing out there in the market or is it something I need to build with ...
0
votes
1answer
39 views

Drive 12V load with 5V PWM

I want to control a 12V heater coil with 5KHz 5V PWM using the below circuit, but the load voltage does not goes higher than 5V. I made a similar circuit with a MOSFET and the result does not changed. ...
0
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1answer
33 views

Boost PWM Signal to 12 V LED strip?

A little background: I'm hoping to take the PWM from the Disney Parks Made with Magic Ears in order to drive a short 12V strip of LEDs (Here's a teardown.) After taking a pair apart and testing, I ...
1
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1answer
39 views

What voltage reference is the pwm signal using in the QUADRUPLE HALF-H DRIVER SN754410NE?

I have a QUADRUPLE HALF-H DRIVER SN754410NE, and i saw online that the 5V from the arduino goes to pin1, pin 9 and pine 16 and on pin 8 you attach a separate 5v supply that has at least or more than ...
0
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2answers
58 views

RPM of two 300rpm motors is not equal, what to do?

I have two 300 RPM motors. But one moves slightly slower. Hence the robot does not move exactly straight. I tested various PWM values and now I am getting very less angle of turn. i there any other ...
0
votes
1answer
38 views

Controlling an ESC for Brushless Motors with an RPi

Originally posted on Robotics, but guess it's not active enough. I'm looking to build a new (first) quadcopter without the conventional flight controller and radio, with an onboard RPi and applying ...
0
votes
1answer
81 views

What happens when you rectify phase cut current?

Forgive the simplicity of the question, since I'm not a professional, just a tinker with a soldering iron. Just dancing with the idea in my head, I believe that if I rectify a current that's been ...