Most from the least?

One of the things I like is seeing how much I can get from something not costing much. 

There are plenty of designs for regenerative receivers around, but I was pleased with this one. I am sure it may be improved.

See  https://sites.google.com/view/g3xbm4/home/hf-mf-and-lf/homebrew/80m-or-40m-regen-rx .

Lambda diode circuits

Mike Rainey AA1TJ has some good tunnel diode ideas on his pages but these devices are hard to find these days. Instead one can create a negative resistance device called a Lambda diode with a couple of FETs or an FET and a transistor. See for example the pages of Ramon Vargas Patron at http://www.zen22142.zen.co.uk/Theory/neg_resistance/negres.htm where he has examples of oscillators and regenerative receivers using Lambda diodes.