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Circuitbenders Forum => Circuitbending discussion => Synths & Samplers => Topic started by: carbon crab on December 07, 2008, 11:26:40 PM

Title: Adding a pitch bend to a keyboard?
Post by: carbon crab on December 07, 2008, 11:26:40 PM: Specifically a Casio CTK 800.

I'm awarethis sort of thing could be hard since it's not the typical circuit bending stuff and is a more controlled modification, but I was just wondering if there's a way I can modify this keyboard so that a knob or switch could bend the pitch up or down like on most synths.

If this is possible, can anyone point me in the right direction or just help me out on here?

Thanks head of time!
Title: Re: Adding a pitch bend to a keyboard?
Post by: kick52 on December 08, 2008, 01:56:36 PM: Normally you can find a pitch resistor by licking your fingers and touching different points. Once you find the resistor that handles pitch, you could replace this with a potentiometer (larger values for more pitch depth)

Some things may use an oscillator to produce a clock signal, these are usually little white boxes with two or three points. You could create a circuit involving a 555 timer to replace this, but this is more complex than normal bends. (You should search sailormouth's site for information)

Good luck.
Title: Re: Adding a pitch bend to a keyboard?
Post by: carbon crab on December 08, 2008, 07:37:38 PM: i'm going to look into this stuff but
1. can you or someone be a little bit clearer? i've never done something like this before and
2. i can't help but think you're pulling my leg with this "licking my fingers" business

but I appreciate your input nonetheless!
Title: Re: Adding a pitch bend to a keyboard?
Post by: kick52 on December 08, 2008, 09:36:02 PM: Quote from: carbon crab on December 08, 2008, 07:37:38 PM
i'm going to look into this stuff but
1. can you or someone be a little bit clearer? i've never done something like this before and
2. i can't help but think you're pulling my leg with this "licking my fingers" business

but I appreciate your input nonetheless!

1. Well, basically you can remove a resistor which controls pitch, and solder in a variable resistor (also called pot/potentiometer) which is controllable.
2. Nope, wet fingers can short the resistor slightly, lowering/raising the value of it. That way (by listening) you can isolate which resistor is the pitch resistor.

If the keyboard uses a crystal clock/oscillator for pitch, making a circuit might be a tad too complicated to attempt at the moment.

EDIT:
Googling the keyboard, it looks rather new (and therefore quite complicated) so it will probably use an oscillator to control pitch :(
I'm not sure how the keyboard would do with other bends, if you try shorting the chips (the pins which connect to other chips) inside you might be able to glitch it.
Title: Re: Adding a pitch bend to a keyboard?
Post by: computer at sea on December 08, 2008, 09:42:06 PM: Poking around the board with wet fingers is a totally legit method.
Title: Re: Adding a pitch bend to a keyboard?
Post by: Signal:Noise on December 21, 2008, 01:56:51 PM: As long as the keyboard is ether battery or DC wall wart adapter powered. Otherwise you might be frying tonight.