This circuit was found in an English publication from 1967. The circuit is for listening on a phone. Transistors are types of germanium of the time.
The figure shows a remote-control receiver working the 27 MHz band, very popular in the 60’s. The...
This oscillator uses a crystal to set the frequency. The operating limit of the unijunction is in...
This circuit appears in several versions in publications of the time and can be modified by...