This circuit can be used as an answering password system in a store, office, or other location. The circuit is from Intersil using components of the time. The circuit is from the 80's.
This useful inductance bridge was found in a Radio Electronics from September 1963. The...
This circuit is a handset receiver that picks up the signal emitted by a coil under the rug or...
This circuit found in the October 1975 issue of Radio Electronics magazine uses an integrated...