I'm trying my hand at making a radio transmitter and receiver and I'm not sure exactly how this receiver works. I understand its a continuous wave receiver which is good for on/off transmission. I'm not exactly sure how the circuit doesn't have any continuous oscillations.
Taken from: Simple Pyro RF Receiver (27 MHz).
From what I understand it is a regenerative receiver which means the signal is amplified by passing the amplified signal back into the amplifier. I found a similar question asked here: Can someone break down how this receiver works? From what I understand in that question, L2, C2 and C1 act to filter a specific filter which gets amplified again.
My confusion comes when I was looking at an FM transmitter schematic. Taken from: How to make FM transmitter.
From what I understand about FM transmitters they are voltage controlled oscillators and essentially the mic in the circuit affects the voltage which then modulates the frequency. The circuit however is still continuously oscillating.
The only real difference I see between the regenerative receiver and the transmitter circuit is that R1 is introduced in the receiver circuit (the other question doesn't talk about it either). How does this cause the circuit to not oscillate on its own and only when a radio signal is picked up?