Simple 555 PWM

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Introduction: Simple 555 PWM

About: I like finding new uses for things, making things, and improving things. I'm a student who is currently looking for a better job, one where I can make an actual difference.

This circuit sets up the common 555 timer IC to output a PWM pulse that can be varied by the position of a connected potentiometer. PWM (pulse width modulation) is commonly used to control the speed of motors or brightness of LED's. With just a few common electronic components this is one of the simplest PWM circuits you can make.

Step 1: The Circuit

I've included the circuit schematic and PCB layout, the PCB layout may have to be altered based on the transistor you use. The transistor determines how much current you can control, I used a 2n2222a which can supply up to 800ma. The voltages that can be controlled range from 5-15 volts. I used my 555 PWM to control the speed of 3 12volt DC computer fans that use 180ma each.

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    7 Comments

    This looks like a really old circuit. Did you just have a bunch of really old components, or is this a really old project?

    4 replies

    I actually have a surplus of electronic components, that were passed down to me. Some components are more than 30 years old. The project is new and was put together and posted around the same time.

    Cool! I wonder if any are worth something for collectable or repair valuye?

    I haven't gone through everything but so far I've come across some valuable vintage transistors that are brand new in packaging. I plan to eventually post most of the collection onto eBay.

    Neat! Good luck selling!

    what diodes did you use? is it important to use ones with low voltage drop like a shottky or doesn't it matter an normal si can be used like 4148?

    1 reply

    Normal regular diodes work well, the one on the load is there too protect from an inductive spike from a motor. They should be scaled based on your current needs.