Operating at a frequency of around 180 kHz, this transmitter was found in a Science & Electronics of 1970. The coil has 34 turns of 22 wire. The transistor can be the 2N2222.
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...