Audion receiver

An audion receiver makes use of a single vacuum tube or transistor to detect and amplify signals.

It is so called because it originally used the audion tube as the active element.

C2 is the gridleak capacitor and helps to demodulate the received signal.

L2 and L3 have inductive coupling and implement the regenerative connection from grid to anode.

C2 is a radio frequency bypass capacitor parallel to the speaker.

Regenerative control is by changing the heater current via the rheostat next to B1.

10, the variable capacitor C1 in the LC circuit L1, C1 selects the frequency.

C2, R1, D1 and the bipolar junction transistor Q1 internal base to emitter diode are the grid-leak detector.

Fig. 3 Armstrong Audion receiver
Fig. 8 Armstrong regenerative Audion receiver
Fig. 9 Another regenerative Audion receiver
Fig. 10 AM band NPN audion receiver