This is a Colpitts Oscillator for practicing code using a tube. The circuit is 1942 and the headphone must be high impedance with at least 2 k ohms. The phone coil is used in the circuit as an inductance for frequency determination.

This is a Colpitts Oscillator for practicing code using a tube. The circuit is 1942 and the headphone must be high impedance with at least 2 k ohms. The phone coil is used in the circuit as an inductance for frequency determination.