Circuit bending by ne7 for ZINE 13 (yes, not issue 12)

What is circuit bending?
Circuit bending is the (amusingly silly) name given to hacking electronics (usually sound or video devices) to enable the original device to do something it was not originally intended to do. For example hacking audio output from a cheap kids keyboard or adding pitch control to sound toys, even onto more advanced stuff like adding LFO's and filters or even video output from a non video device! :)

However for the sake of my sanity, in this article I'll be talking about circuit bending for the purpose of sound and sampling for music.

So how does it work?
Well its hilariously simple, a lot of circuit bends focus on interuption of CPU communication - or replacement of static resistors with potentiometers, or draining battery power supply to the circuit.

WARNING:
At this point it is worth mentioning that you really shouldn't mess with anything with mains power (plugged) and stick to battery powered devices til' you really know what you are doing :) unless you are nuts.

What's hot?
Some older toy keyboards are very easy to find bend points on. 
Just open them up - look at the circuit board, lick two of you fingers and try poking around on the board whilst holding down (or taping down) a sound producing key on the toy or keyboard.

Eh?
A good place to start is any resistors you can see on the board or attached to wires coming off the board. More often than not they will be controlling pitch or even envelope length :) use your ears and listen out for subtle (or not so subtle) changes in pitch or length of the sound.

Tips:
Its good to have some croc clips + some different pots of varying values handy. Once you've nailed something as effecting the sound - try identifying the resistor and replacing it with a variable pot of the same value using a cut and some croc leads - does it work? Yes? Then try a higher value pot - hopefully u'll get some superb dirty deep tones and stupidly high bleeps :) this works really well on toy drum machines... A 3euro toy can become a monster industrial drum machine for a few cents :)

Drain to hell:
Another really simple bend that works on a lot of devices is the battery drain:

1) Get a low value pot; 0.5k to 1k work well 
2) Open up your toy/keyboard
3) Locate the battery+ line (usually red)
4) Snip the wire and attach the wire leading to the board to the 'Wipe' (middle leg) of the pot (the middle leg) and the wire coming from the battery compartment to the outer leg 
5) Turn the machine on and play some notes, experiment with moving the pot up and down as u play - it might affect the pitch or it might send the machine into a random frenzy creating odd space jazz and white noise glitches :) Also try draining the battery and hitting some of the presets... This can yeild some great loops as it glitches out :) 

Kb's that respond well to this are:

* Casio SA / CA / CS / MA keyboards
* Yamaha PSS sample based keyboards
* My music center/kawasaki kids kb's
 
Well that's it for my article preview - you'll have to check out Zine to read more about Circuit Bending including some tips on hacking a casio sa-2 keyboard within an inch of its life :)