This 1968 circuit is intended to switch the polarization of a satellite TV antenna of the time. The circuit is powered by 12 V and the transistors are from that time.
The circuit in the figure is based on an LM101A; diodes can be replaced with equivalents. The...
This circuit, with magnetic sensor, uses an operational amplifier of the time. The circuit is from...
Found in a 90s Popular Electronics, this circuit checks if a remote-control transmitter is...