This simple step of low power audio is from a 1975 documentation. The transistor can be a BC548, and the transformer of the type found in small transistor radios and recorders of the time.
This circuit is more sensitive than the previous one, triggering when a laser beam that hits the...
This circuit was obtained in a 1967 Electronics World. The components are still common today, the...
The simple touch of the fingers on a sensor causes this circuit to drive a motor that goes into...