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.
The purpose of this circuit is to improve the reception of signals from the short-wave band. The...
This highly sensitive light sensor was found in a 1970 General Electric documentation. The circuit...
This circuit was found in a Popular Electronics from the 90's. The CMOS integrated circuit used is...