This keyboard started its life as a powder-blue-edition Casio PT-1 Electronic Musical Instrument. A classic tiny keyboard that has all the great 80's sounds and rhythms, including the main rhythm part of Trio's seminal (and unfortunately overused for too-hip television ads) "Da Da Da" from the album "Trio and Error." You'll find it under the "rock1" rhythm setting.

I facilitated a bending workshop over at a friend's and the theme was keyboards. So, I dug into this one. I was quite pleased as to the ease of the bend (actually modification) and the results.

After poking around the board for awhile, I didn't seem to find anything interesting. On the bottom of the unit there is a de-tuning trim pot. I ended up just desoldering that and adding a new larger pot and an optical resistor to give me two levels of pitch control.

The biggest challenge was figuring out how to place the new added modifications. dAs suggested just leaving the keyboard part off, which I liked, and then I noticed the holes in the circuit board for the keyboard support pins. Ah-ha! With a little bit of hole-widening (very carefully—notice how close the traces are to the holes) I was able to put the shaft of the pot thru. Nice knob!
And, after a little bit of plastic removal on the bottom case, the pot fit into the case just fine! The optical resistor hole needed just a little bit of widening and it fit in perfectly. What's really neat is when you are playing it (using the little rubber nubby things as keys) your fingers are also intermittently blocking the light falling on the optical resistor. The sound is like weird space station lounge hits. And of course, you can use the big silver knob too.

I may put a strap on this and use it like a tiny keytar.

I put the eye thing there just to cover up my shitty glue-covered wiring. I always use a glue gun to seal the solder points when I am sure that the wires are in the right place. The wire I use is single core wire-wrap wire so it easily breaks. This allows me to move the board about without worrying about breaking my wires off.

I decided not to paint this one at all as I liked the blue color enough, and it would have been a pain in the ass to recreate all the written directions like rhythms, tempo, volume, tones, etc.

So, even with this very basic pitch bending modification, the sound is really excellent, especially when it is slowed waaayyyy doowwwwnnn. Even tho it's not one of my prettiest, this is one of my favorites.

Frequently played by my 2 year-old son Fineas.

Audio Bits:

BPT_Blinky.mp3 Here's an example of playing the keys with the "fantasy" tone selected, and a tiny blinky-blinky LED is placed over the optical resistor.
BPT_BlinkyPot.mp3 Same as above, but also using the big silver knob.
BPT_DaBlinkPot.mp3 This is an example of the Da Da Da rhythm, with blinky-blinky and pot control. Check out the really nice slooowww down grainyness. This happens only when the magnetic side of the blinky-blinky covers the optical resistor hole. Must be something with the magnetics adding something to the overall pitch down.
BPT_LEDGlobe.mp3 This one is me on the keys, and my 2 year-old son Fineas using this spinny LED globe thing on the optical resistor to affect the pitch. Neat!
BPT_OptKeyed.mp3 This is the one that sounds like a weird space station lounge hit. Just my fingers tapping the nubby keys, and my fingers intermittently interrupting the light falling on the optical resistor. Weird.
BPT_SloLp.mp3 This is another example of the magnetic slow down effect. Nice! Tasty grains...