The cheapest synthesizer you can ever build

Check out Tristan Perishe's beautiful 1-bit symphony. He also builds minimal circuits by hand, and I'm always surprised at how rich and complex the music is.<p><a href="http://www.1bitsymphony.com/" rel="nofollow">http://www.1bitsymphony.com/</a>

You can actually do better than this - it's possible to build a switchable pulse, sawtooth and sine'ish wave oscillator from a single op-amp. During my childhood my father was heavily into electronics and electronic music, and one of his interests was designing and buildning his own analog synthesizers. One of his more compact feats for one of his many synthesizers was four three-wave oscillators built on a single TL074 (quad op-amp).