This interesting circuit from Radio Elecronics from October 1965 shows a flip-flop or bistable with SCRs simulated by bipolar transistors.
This oscillator takes advantage of the 2000 ohms headphone inductance as the oscillator circuit coil....
This circuit, in addition to providing an output that corresponds to the absolute value of the...
This circuit works with the previous two by demodulating the signals received modulated in FM. The...