October 10, 2013
An extremely simple yet capable compressor circuit is published by Elliott Sound Products, here: http://sound.westhost.com/project45.htm
Compressor Mk I I built the circuit exactly as-is (in an Altoids tin).
Care was taken to optically couple the bulb to the photocell (LDR), using a perspex rod, wrapped in smooth tin-foil. The perspex came from eBay: http://stores.ebay.co.uk/thewholesaleposco2009
as did the miniature “Grain of Wheat” bulbs: http://stores.ebay.co.uk/GnA-MODELPARTS?_trksid=p2047675.l2563
This was put together, and sealed in heatshrink tubing, to make it fairly lightproof from external light sources.