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.
We find this circuit in a 1970 publication. Transistors can be replaced by current equivalents and LDR is...
Featuring low output impedance and high input impedance, this configuration was found in a 1980s...
Found in a 1980s American documentation, this circuit can use a SCR and a general-purpose transistor....