This interesting circuit with a neon lamp and a transistor was found in Radio Electronics magazine from February 1968. The transistor is a special type of high voltage at the time.
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...