Regenerative Circuit - How IT Works

How It Works

Any radio frequency feedback oscillator topology can be operated as a regenerative receiver if modified to provide a controllable reduction in feedback loop coupling, a method of coupling the loop to an incoming signal source, and a method of coupling audio frequencies out of the loop to a subsequent audio amplification stage (or high efficiency headphones). It functions as a combination of an oscillator and mixer which converts the modulation directly to the audio baseband.

Because of the large amplification possible with regeneration, regenerative receivers often use only a single amplifying element (tube or transistor). In a regenerative receiver the output of the tube or transistor is connected to its input through a feedback loop with a tuned circuit (LC circuit) as a filter in it. The tuned circuit allows positive feedback only at its resonant frequency. The tuned circuit is also connected to the antenna and serves to select the radio frequency to be received, and is adjustable to tune in different stations. The feedback loop also has a means of adjusting the amount of feedback (the loop gain). For AM signals the tube also functions as a detector, rectifying the RF signal to recover the audio modulation; for this reason the circuit is also called a regenerative detector.