Handmade Electronic Music the art of hardware hacking by Nicolas Collins looks like a great resource. When I get back to London I want to modify the contact mics so that they can be placed on the body without the getting a humming sound this means i may need different wire or simply to use Plasti-Dip as described bellow:
Rule #11: Don’t drink and solder.
- When you are sure you have an electrically functional contact mike, cover the ceramic side with a piece of electrical tape—you can trim it around the circumference with scissors or a knife, or you can wrap the edges over to the other side of the disk.
- Find a well-ventilated space. Open up and stir your can of Plasti-Dip. As per the instructions on the label, slowly dip the contact mike end of your cable into the goop until you have covered the wire past the electrical tape (see figure 7.5). Slowly with- draw it and hang it up (preferably outside) to dry. Go away and take a break—this stuff is stinky. You can dip a second layer after the first one dries thoroughly, which can take a few hours. More than three layers tend to muffle the sound, so don’t overdo it without listening carefully after each new layer.
The tape and Plasti-Dip treatment serves several functions:
- It strengthens the connections between the wires and the piezo disk.
- It insulates the disk from electrical shorts, and prevents hum when you touch it.
- It waterproofs the contact mike, so you can use it to record underwater sounds, freeze it in ice-cubes, dangle it in a drink, etc.
- It deadens slightly the pronounced high-frequency resonance of the disk similar to the effect of gaffing tape on the head of an unruly snare drum.)