This circuit from a Radio Electronics from October 1965 shows how to obtain the action of an SCR when triggering a relay using two transistors. The relay is according to the circuit supply voltage.
This circuit activates an incandescent garden, balcony or showcase lamp when it gets dark, turning it...
This circuit is from an old publication of 1972 but can be mounted with BC548 transistors for 12 V...
This circuit is intended for the testing of junction FETs, providing several reading options...