Found in a 90s 303 Circuits, this circuit triggers a load from a 50 mV audio signal. When the signal ceases, the charge remains active for 2 seconds.
This SCR circuit activates a buzzer when triggered. The circuit is from a Popular Electronics from...
The values of R1, R2, R3 and C1 depend on the signal to be integrated. The circuit is from Radio...
This circuit causes a small pilot lamp or a 6 V torch to light up when ambient lighting is...