Found in a 90s Popular Electronics, this circuit triggers a load from the audio signal applied to its input. The controlled load depends on the MOSFET.
Found in an 80's Elektor, this circuit can use any equivalent optical coupler. The buzzer is of the...
This circuit with SCR and Unijunction and which can be assembled today with modern equivalents was found in a...
This circuit was developed to find intermittent defects in an electrical control. In the event of a...