Voice Scrambler (CB22462E)

We found this circuit in a Popular Electronics from 1992. It consists of a voice scrambler used in telephone transmissions.

ELF Monitor (CB21055E)
This circuit monitors extra-low frequency (ELF) fields. We found it in an American documentation from the...
Controlled Oscillator (CB12682E)
We can use any type of resistive transducer with central resistance in the range of 10 k ohms to 1...
Triac Double Dimmer (CB16915E)
This circuit controls two lamps so that when one increases in brightness the other decreases. The...