PWM Generator

This project is an updated version of a PWM generator I found here. The original schematic had a few problems. Firstly, there was no connection between pin 2 (Trigger) and pin 6 (Threshold) of the 555 chip, and the PWM signal was labeled as being output from pin 7 when it actually outputs from pin 3. After asking online for some help diagnosing the issues with the circuit, I tested the recommended changes and updated the schematic. Note that I used a 5k potentiometer in place of the 100k potentiometer that was recommended as that's all I had available, however, the potentiometer value shouldn't make much of a difference when using the circuit. Additionally, I powered the circuit using 12 volts, just as the original Instructables post recommended. That seems to work fine, although I'm sure that you could power it with a range of voltages and still achieve the desired PWM output. 

1. 1x 555 Timer IC
2. 1x 100K potentiometer (I'm suggesting a 100k potentiometer as that's what the original post suggested, although the resistance shouldn't matter)
3. 1x 100nF capacitor
4. 1x 10nF capacitor
5. 2x 1N4148 (Or equivalent) diodes
6. A 12V DC power source
7. Breadboard
8. Jumper wires

First, connect pin 4 and pin 8 of the 555 timer to the positive rails of the breadboard. Next, connect pin 1 to the negative rail of the breadboard. Lastly, connect pin 2 and pin 6.

First, connect the potentiometer to the breadboard, then, connect the center wire of the potentiometer to pin 3 of the 555 timer. Next, connect the diodes. Pay attention to the polarity of the diodes when connecting them, and to make wiring easier, insert the leads (Opposite the potentiometer) into the same row. Lastly, connect a wire from row you just inserted the leads into to pin 2 of the 555 timer.

First, connect the 10nf capacitor from pin 5 on the 555 timer to the negative rail of the breadboard. Next, connect one lead of the 100nf capacitor to the row with the leads of the two diodes, and connect the other lead to the negative rail of the breadboard.

Connect the positive (red) rail on one side of the breadboard to the positive (red) rail on the other side of the breadboard. Repeat this process for the negative rails.

Connect your positive wire to one of the positive rails of the breadboard, and the negative wire to one of the negative rails of the breadboard.

I attached the positive lead of my oscilloscope to pin 3 of the 555 timer, and the negative lead to the one of the negative rails on the breadboard.