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.
This circuit was found in a 1992 publication, using an operational amplifier not very common...
This is a amplifier for XTAL high impedance earphones or piezoelectric types. Current drain is...
This circuit is from the LM111 manual of the 1980s. The component no longer exists, but...