This 600 kHz circuit is designed to locate a lost boat anchor. The circuit has a range of up to 10 meters. The transistor admits equivalent.
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...