Seiler oscillator

[1] The original implementation used a vacuum tube in an Electron-coupled oscillator circuit.

It uses a voltage divider made of two capacitors, named C3 and C4 in the original schematic.

The variable capacitor C2 controls the coupling between the tube and tank (LC circuit).

The negative supply voltage V2 allows direct connection from Q1 base to ground.

The radio frequency choke L3 is needed to isolate the LC circuit from the power supply, but has a potential problem.