The Spectramin is a just-for-fun project to make a theremin that drives the AY chip in a 128K Spectrum. The interface card is a ZX Breakout board, using an XC95144 CPLD. The interface provides three channels (all of them essentially 12 bit counters, to read the frequency of the theremin oscillators). As such it'll be really a theremin synthesiser, using the AY chip to make sounds other than the sine wave most theremins make. It might offend purists, since it'll have a foot pedal as a 3rd channel (so that volume, effects and pitch can all be controlled simultaneously).
It's planned that it'll be ready for the next VCF-GB which will be held within the Silicon Dreams festival, near Ashby-de-la-Zouch in the summer of 2013.
Browse SVN: Spectramin SVN