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, based on a 555, was found in a Popular Electronics from the 90s. The circuit has the...
This setting is valid for other transconductance operational amplifiers. The circuit is from...
This circuit is suitable for use in radio receivers to improve the quality of weak signal...