This circuit was found in a documentation of the 80s, having didactic purpose. For R1 values between 10k to 1M can be used. Transistors are general purpose types.
This circuit for currents from 500 mA to 1.5 A was found on a Ham Radio from the 90s. R4...
November 2016 - Vishay's new proximity sensors VCNL4100 for display presence and activation,...
Found in a 1965 CQ magazine, this circuit uses period components. The unijunction transistor can...