This circuit was found in Ferranti's 1967 documentation. The circuit drives a 40 V relay, but it can be adapted to operate with sensitive lower voltage relays.
This circuit was published in an Italian magazine Radio Elettronica in February 1976. The...
Found in a Popular Electronics from the 90's, this circuit converts a 40 V symmetrical source to a 5...
This high selectivity circuit for single tone decoding was found in 1970s documentation. The coil...