1-Ttube reflex receiver (T1555E)

This one-tube circuit is equivalent to the previous one. We find it in a 1924 book by Gernsback, Power is made by batteries.

Electric eye (CB22496E)
With this name, we find a photorelay in a publication from 1966. The transistor is made of...
Commercial Radio SRF25 (CB18402E)
This 6-transistor Japanese radio from the 1960s used germanium transistors and had an output power...
Chirp Oscillator (CB24088E)
The waveform generated by this circuit produces a sound similar to that of a bird. The circuit is based...