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.
This amplifier uses a 1975 integrated circuit, which is uncommon today. The circuit has a gain of 30...
Using junction FETs, a configurable configuration is achieved for very low frequencies. FETs can...
This 2-terminal regulator was obtained from a 1990s National Semiconductor manual. The components admit...