September 04, 2007

Modification to the Wacky Sound Generator

Here is a little drawing of a modification you can add to the music from outer space wacky sound generator.

This was one of the first noise making units I built. Its a really simple fun little project that produces lots of cool strange sounds and has the potential to be modified in lots of interesting ways. Here is a post we did earlier regarding our own WSG housed in a cardboard enclosure.

How does this mod work? Well one of the first things you learn when studying electronics is that capacitors in parallel have their values added. So when the transistor in my circuit is open the value of capacitance that determines the frequency of the WSG's square wave is increased by 0.01uf. This translates into a lower tone being produced every time the transistor opens and a higher tone every time it closes. The frequency of open / closed cycle is determined by the inverter connected to the base of the new transistor. So instead of your noise maker making just two distinct tones there are now three or more tones to be heard. Below is a sound clip of the mod in action.

The cool thing about this modification is that you can add several of them to the WSG creating a device capable of even greater sonic madness. Just built the above circuit several times using whatever inverters are free on the CD40106 and connect them all to Q1's emitter. Vary the values of the capacitors and see what sort of noises are produced, experiment.

The only change to the WSG circuit I would recommend that you make would be to change the value of C5 to 0.01uf or 0.015uf so the values don't get so high that no audible sound is generated.

You can set it up on solderless breadboard first and connect it to your WSG using patch cords with crocodile clips.

Parts List:


130K Ohm 1/4 Watt

10K Ohm 1/4 Watt

1M Ohm Linear Potentiometer




1uf Ceramic

.01uf Ceramic

.015uf Ceramic

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