Found in an old Popular Electronics this circuit is still current. The SCR can be of the 106 series and the relay according to the voltage used in the supply. The voltage can be 12 V.
For a negative voltage of -48 V, this circuit from the 2005 Linear Technology manual makes use of an...
Found in a 1980s telecommunications documentation, this balanced modulator circuit uses...
This circuit is from a 2005 Linear Technology publication. It converts current into load sensing...