RTTY Demodulator (CB21760E)

This circuit was found in a 1977 radio amateur manual. Integrated circuits are operational amplifiers of the time.

Touch switch (CB9562E)
This sensitive touch key appears on this website from other sources. This version was taken from a...
Missing Pulse Detector MC1455 (CB14586E)
The integrated circuit used is equivalent to the 555 and the transistor can be the BC548. The...
DC power source with transistor (CIR22516E)
This circuit was published in the Radio Electronics magazine of September 1950. The transistors are from...