For the final, I continued work on the video synth.  I was initially trying to get it to work entirely on solar power, but this didn't seem like the best approach – even if it were solar powered, the monitor / projector would require power, so it couldn't ever really be outdoors getting direct sunlight, and from past testing, trying this indoors wasn't successful. I didn't want to go the battery route because I wanted to use the noisy fluctuations from the solar panel.

Instead I decided to augment the power source – supplying a steady 5V, and using an additional power source that would generate 0-7v (from testing the signal generator, 5 - 12v seemed to be the safe range).

I contemplated various methods of generating that voltage, where even low voltage generating devices could be good enough since the VGA signal generator seemed to be responsive to small changes.

To figure out the circuit, I tried adding a DC motor – which was confusing at first, but thanks to help from Jeff, I figured this out, with a diode to prevent the motor from coming on

voltage from DC motor

I tried testing out piezos, hoping I could create some kind of structure/enclosure that would be conducive to drumming on – piezos seemed to be too fussy however

slapping some piezos
very short voltage spikes

motor as part of the 'interface' >>

I also rewired the circuit to use one hex-shmidtt invertor instead of 3, since 1 comes with 6 gates – this reduced the current draw to 10mA. I wanted to expand this by adding some more logic gates and switches etc – but parts arrived late, and since this part was more about circuit design than energy I decided to leave it for another day.