I had to rename the super noisy regen to the Signal Digger Regen. People are very literally minded I guess and the circuit got very low views on pinterest. Anyway the new circuit is a variation at least:
I went with the DrM prompt and changed the RF filtering to C4 as a reduced component choice. It depends on the audio amplifier that follows. For the LM386 that has power gain at 500KHz+ you may need extra filtering at least for the AM broadcast band.
I wrote a little about the circuit here:
https://sites.google.com/view/analogelectronics/home/signal-digger-regen
The circuit is more than a little like the B Kainka circuit just the AM detector is a step up.
@Sean O'Connor After looking over your noisy regen circuits and the related discussion, I stumbled upon an idea about how to implement detection more simply in the "noisy" regen. Instead of taking the audio off of the emitter, and instead of implementing a separate detector stage, how about this idea?
Implement the noisy regen as usual. One transistor's will base be tied to Vcc; the other transistor's collector will be tied to Vcc.
For the collector tied to Vcc, insert a load resistor (maybe 4.7k?) and a 10 nF bypass capacitor from collector to ground.
The 10 nF bypass capacitor serves to ground the collector at RF so that the oscillator still works.
The load resistor in the collector serves as a load for the output AF signal.
Intuitively I guess this would work and might provide louder audio -- since you're taking the AF output from the amplified collector output -- than trying to take the weak AF signal off of the emitters. I plan to try this sometime soon, but I was wondering if you had already tried this or if you have any opinions about it.
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EDIT: I started a new topic about this, titled "Improved AM detection in the "noisy regen"?". The post is awaiting approval, however, so may take some days to appear.