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After destroying the switch on my kiddie casio yesterday, and replacing it, the darn thing still had trouble functioning, so I cut lots of wires and re-did a lot of them. I'm not sure precisely what happened after that, but I've got a nice little burn on my finger now. I think that I managed to set up a short-circuit that channeled most of the battery power right back into the batteries. Oi.

I still can't get the darn thing to work, but I'm starting to really dislike that particular toy, and it may be too screwed up to work with anyhow at this point. *chews on plastic casing thoughtfully*

The next keyboard has pretty much the same circuitry, but it's much tighter (the first keyboard was chunky and oversized, about 11X17. This one's a narrow little strip, maybe 10X5 or so, if not smaller.

I guess I just overreached. I tried to include EVERYTHING that could possibly work. This time, I'm just going to limit myself to 1) a few small connections that 2) don't reach outside the actual keyboard. I'm thinking if I confined myself to two 1mg pots (dials) and two push-button connectors, and a handful of body contacts (points where skin contact is sufficient to change the musical tune) that'll be sufficient.

It's such a small keyboard, it'd be sexier if it didn't need a "breakout box" to house its controls. But the batteries sit right against the circuitboard, and there's v-e-r-y little front panel that doesn't have text all over it.


( 4 comments — Leave a comment )
Feb. 6th, 2007 07:12 pm (UTC)
Circuit bending can be a lot of fun, though the results are inconsistent. Short circuiting places on the board usually causes more havoc than needed to alter sounds. You may want to consider soldering resistors in series with potentiometers and buttons to limit the amount of current flowing through them. Same with body contacts. 1K, 10K, 100K, 1M (or thereabouts) are good starting points. 10K is safer in terms of the electronic chips on the boards than 1K. A 10K resistor will limit current to about 1mA in a 9 volt circuit.
Feb. 6th, 2007 07:19 pm (UTC)
Unfortunately, understanding most of this message is going to take me really understanding components more than I do. Give me some time on that.
Feb. 6th, 2007 08:06 pm (UTC)
Electronics is a complicated topic, but the gist of it is that you probably want to use a resistor everywhere you have been using a wire.

Batteries are like electron pumps. They pull electrons away from the (+) terminal and push them over the (-). Normally, electrons can't travel through air so they don't spill off the battery while it's sitting on the table. When electrons travel through the air, that's when you see and hear an arc. Batteries normally won't arc over like that.

A battery is kind of like an air pump with both ends capped. They are self-contained electron pumps that can only pump so many electrons before they stop working, which is why batteries die and you have to replace them. Continuing with the air pump analogy, a wire is like a vinyl tube for air (like the ones used in aquariums) but for electrons. If you connect a wire across the battery, electrons will zoom through the wire quickly and the battery will be dead soon. Also, the rush of electrons might be fast enough to create enough heat to ruin integrated circuits, which might be the case if you are connecting random points on the board rather than connecting the ends of a battery together. To prevent that sort of damage, you can use a resistor. A resistor is like a vinyl tube with a sponge crammed into it. The "sponge" slows down the electron movement to a safe speed that keeps the battery from running down quickly and reduces the likelihood that a transistor in the circuit will have too many electrons flowing through it at any one particular time.
Feb. 6th, 2007 08:21 pm (UTC)
I understand the very very basics (what a diode is, etc, though capacitors are a bit strange). Mostly it's a matter of getting my mind to understand how it all works together. Thanks for the advice, though! I know I can fry a circuit really easily, typically I'm working a little bit away from the battery, so the current's diluted a bit. I just missed this one entirely...
( 4 comments — Leave a comment )

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