MAKE author Tom Whitwell wrote this great piece on how to jump into the synth-building scene.
The hardest part of DIY electronics is starting out. My first step was building a few guitar pedal kits and learning by reading the Beavis Audio site. Other people start with noisemaker kits like the Atari Punk Console or circuit bending. They all lead in the same direction — down a very deep rabbit hole.
There’s a lot to buy – a kind of infrastructure you need before doing anything – soldering kit, a multimeter, and a stock of components. None of it costs much, but it’s hard and disconcerting to buy. Online megastores like Farnell or Mouser will stock 50 versions of every component. Get the part number wrong, and you accidentally order capacitors as small as grains of sand, or as large as golfballs.
Also be sure to check out Tom’s Lego Instruments article in MAKE Vol. 4.