Simple Vacuum Tube Regenerative Receiver

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Vacuum tubes are certainly antiquated technology, but that didn't prevent me from learning how to construct useful circuits with them. I'd been collecting them in a pile since I was child, and only recently did I learn how to correctly bias them. Besides that, I also finally built a suitable high voltage plate supply.

The tube I used here is a 6CG7 dual triode, which at one point must have been a part of a television set, or at least was bought for that purpose. Using care (tubes are more dangerous than transistors!) I put it together using the classic Armstrong regenerative circuit with a 'grid leak' detector and variable gain via the 'throttler' variable capacitor.

I was pleased to find that the single audio stage would drive a loudspeaker on the more powerful local stations, which are not too difficult to tune in. With some more skill and a set of headphones more distant and weaker stations can be pulled in. It's sensitive enough that I don't even need an antenna to pull in some stations!

Here's the scheme:

Me demonstrating the circuit: