I'm planning to build an "Ironside" Dalek as seen in the recent Doctor Who episode "Victory Of The Daleks". This is going to be on a very tight budget and after searching through different Dalek voice generators, including the Mooger Frooger system, I thought I'd build my own.
There's various schematics around the web including some very complicated systems, but I thought I'd try the simple "2 transformers 4 diodes" systems which is probably what the BBC Radiophonics workshop used originally anyway:
Here's a video I've done explaining the set-up and doing a quick test:
YouTube - Dalek voice ring modulator
After a bit of tweaking and a bit more research, I found the frequencies for the various Dalek stories on the Project Dalek Forum. So here's me trying out the various frequencies:
YouTube - Dalek voice modulator frequency test
Have to say, my favorite setting so far is the 14.5 Hz from Destiny of the Daleks.