RE: Any instructions on how to build a radio control system from scratch?
The model mags, back in the dark ages, used to run all sorts of circuits and explanations, RCM&E ran a full series on a 5 chan digital propo tx and rx with servo amps, using 'off the shelf' parts and available (Orbit?) mechanics. I'll bet you can't get those bits any more, but the circuits will be similar to those in use. I'll bet RFJ will know which months/years it was...
Evan, WB #12.