Found in a 1965 CQ magazine, this circuit uses period components. The unijunction transistor can be a 2N2646 and the relay has voltage according to the supply.
This device can be used as a proximity arm, touch sensor or electronic bell. When connected to a...
This circuit is from the component's own manual, but it applies to others in the same family. The...
This circuit was found in a 90s Popular Electronics. The circuit uses several relays in order to...