With this circuit found in an American documentation from 1969 it is possible to vary the selectivity (Q factor) of a tuned circuit. The operational is from that time.
Found in 1967 General Electric documentation this circuit appears elsewhere in this section. SCRs are...
July 2017 - The new TC6321 integrated circuit consisting of a pair of transistor MOSFET...
June 2016 - Mouser is making available a new series of operational amplifiers from Texas...