The A.F. amplifier is very standard stuff. The pre-amp is an inverting amplifier
with a gain of about 27dB. The audio output amplifier is a 2 Watt I.C. I used
the 14 pin version of the LM380. There is an 8 pin version, so make sure you don't
buy the wrong one. I built mine on a piece of stripboard (Veroboard).
