The original application of this 1967 Ferranti circuit can be changed so that it functions as a pass sensor shield for gears and other moving objects.
This is the circuit of a commercial radio sold in Japan in the 1960s. The IF is 455 kHz, and the...
In this radio the coil can be made with 70 + 30 turns of wire 28 to 32 in a cardboard or PVC tube...
This circuit consists of a sequential that is activated when you step on the brake pedal (brake...