This untuned circuit uses one of the world's first commercial transistors, the CK722, having been found in a 1966 publication. Equivalent modern types can be used.
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...