Friday, October 8, 2010

Guitar Hero Controller Synth

This is a modified Playstation 2 Guitar Hero controller. Just about everything is left the same with only slight modifications to the actual controller. The circuit that drives the oscillator is based on the LM386 amplifier chip. Here's the schematic. You can download the full image here.

Controller Schematic

In this image, I actually inverted the resistors. The 50k ohm should be at the top and the 10k ohm should be at the bottom. That way, the lower tone is connected to the higher up keys and the higher tone is connected to the bottom keys, the way a real guitar is. Here is another picture which corrects this.

Controller Key Layout

Because of this layout, you still get a low tone if you strum without pressing a key because the potentiometer is also a resistor. When one key is pressed at a time, you will get a different tone but if you press two or more at a time, you will get a high tone. This is because the resistors will be connected in parallel. Here are a few photos of the key board along with the resistor board.

Controller Keys

Keys (Full View)

Resistor Key Tuner

Resistor Tuner (Bottom)

Resistor and Pot

The strum bar was a little tricky. I wanted to use an entirely different board because I was worried that the components on the board would cause some kind of short circuit. I was unable to find a board big enough to fit across the strum bar so I ended up using the original board. I had to cut several traces to ensure the current from the square wave circuit wouldn't run anywhere else.

Strum Bar Mod

The switches are connected to the output jack. I also accidentally inverted the wiring here as well. I connected the Ground to the switches and the switches to ground rather than the signal to the output. This is okay if you use it on a small amp but if you using a real guitar amp, the Ground on the amp will replace the ground on the circuit, which would give a constant signal, and bypass the switches for the strum bar.

If you connect the output signal to the switches (like I was supposed to) you effectively disconnect the signal from the amp until the switches are pressed using the strum bar.

I hope this helps you out if you decide to make this. If you need any help or clarifications email me at Thanks.

All images embedded on this post are Attribution-NonCommercial-ShareAlike Creative Commons licensed.

1 comment:

Anonymous said...

very nice, always wanted to look inside a gh controller.