Simple 555 Synth

I'm starting a new project that will hopefully get me motivated to make some tracks. It's called 'One Instrument a Week', and it's exactly what it sounds like! I'll be building one simple music instrument or effect a week for the next year, and using them in my experimental Year of the Duck project.

Here's the first entry, a simple synth I built over a weekend based on a 555 timer IC. I used this schematic as a starting point:

555 Synth

I added a single 500K pot as a course pitch adjustment, and a board of resistors I pulled out of a toy piano to simulate some keys. I also converted the speaker output to a line-level output with a couple more resistors:

Speaker to Line out

To play it, i have two probes from an old multimeter wired in line with the potentiometer. Touching the probes to opposite ends of something resistive (in this case, the resistor board contacts from the toy piano) cause changes in pitch.

Here it is in action: