Indicated for the protection of three-phase systems, this circuit was found in an American documentation of the 70's. The circuit can be implemented with modern components.
This circuit of a 1978 American publication monitors a telephone line by triggering a relay. The...
This interesting FET-tester circuit was obtained from an old American documentation. The bipolar...
This old VHF TV booster that also serves FM was found in Radio Electronics magazine from April...