I got this Casio PT-80 on the Bent festival in NYC 2006. A circuit bending collective was handing out synthesizers that had been in a fire, for a small donation of whatever you could afford you could with a clean conscience grab some synths. The casio worked perfectly but smelled like smoked sausage and was covered in hard-to-remove sothe.



The modifications i've done to this unit is to add a Ken Stone Synthacon VCF + AD and an ADS for the exisiting VCA. Both EG's are based on the AD from Barry Klein's book Electronics Music Circuits. Also added is a PLL-based waveshaper that converts any incoming waveform to a Sawtooth output with selectable frequency division of 1, 2 or 8 (but it says 4 on the panel..).

Panel layout (to make it more in-your-face of what i've actually done):



I decided not to remove the built in speaker, i did this to my SK-1 which ended up with me never playing it. I did however remove the circuitboard for insertion of ROM-packs since i don't have any of those anyway. Sadly there's not enough room for the 9V batteries so far and i managed to make a powerhungry circuit enough that i don't think voltage doublers/inverters would be feasible.

Below is a picture of how the unit looked before i cleaned and modified it: