Using a 4-layer diode, an unusual component today, this circuit was found in an American documentation from 1964. The circuit can be tested using a diac.
This circuit is from a Popular Electronics from the 90s. The integrated circuit admits equivalents...
This very interesting project was obtained in a 1980 publication. It consists of a device that is...
This circuit beeps when the sensor is triggered by the opening of the freezer door or other...