The transistors of this circuit found in a 1965 magazine can be the BC558 and the sensitive 12 V x 50 mA relay. The other components are common.
This signal generator found in Japanese documentation of 1973 uses an unusual integrated circuit...
This circuit was obtained in the publication 101 Electronics Projects of 1979. The circuit can be...
We found this circuit in an old European publication. Integrated circuits are not common today and the...