This circuit maintains on a flashing LED at a frequency determined by the capacitor. The unijunction transistor can be 2N2646.
We found this sensitive high input impedance voltage amplifier in the November 1970 Radio...
This capacitive approach alarm circuit was found in a 2002 documentation. The wire to the sensor...
This circuit for crystals from 100 to 500 kHz was found in an American documentation from 1954. The...