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 circuit is recommended by Texas Instruments in the datasheet of the TL317, equivalent to...
The circuit shown in the figure consists of a low voltage dropout (LDO) regulator for 200 mA using...
This circuit of a Popular Electronics is intended to control a wiper. The circuit consists of a...