This 1960s Signalite circuit uses two SCRs to achieve full wave control. The trigger elements are neon lamps.
We found this preamplifier for recording heads in a 1980s documentation. The circuit can be used...
This oscillator takes advantage of the 2000 ohms headphone inductance as the oscillator circuit coil....
The frequency of this oscillator depends on the amount of light incident on the LDR. The circuit,...