This circuit was obtained in an American documentation of 1964. The transistors are of the time. The circuit includes a counter circuit.
This circuit was obtained in the publication 101 Electronics Projects of 1979. The circuit can be...
This simple optical alarm circuit was found in the 1991 Electronics Experimenter Handbook. The...
This simple 5.6 V regulator circuit was found in a 1966’s Philips. The zener can be changed to...