The HamBone

Gennies and Regeneration, super-regeneration too.
Regenerative receivers offer sensitive selective reception to rival a superhet, with far less components. They are cheap and easy to make, good for experimenting. While they started with tube (Brit "valve") designs, many builders like semiconductors instead now, but the early design principles can be borrowed. Ok, superhets may be easier to tune.
Super regens, strictly those gennies with quenching extend into the microwaves.
Not surprising that these receivers continue to interest, even inspire...