Stumbled across K7NS's website. There are all sorts of cool things there, some include really simple DIY zinc rectifiers and zinc negative resistance oscillators and shows a simple transmitter that uses no tubes or transistors. Shows curve traces too. There is page on a flame triode and an audio oscillator using two triodes in the same lamp flame (basically a working tube at atm without the glass) and other stuff that looks like a lot of fun to try. The memristor is pretty cool, just some brass oxidized with sulfur and it's state can be programmed! Who thinks to put spent rifle casings touching aluminum on a curve tracer??? That's some serious curiosity there!
Caution, fumes from heating galvanized sheet metal are toxic if you try the diode or negative resistance stuff.
Caution, fumes from heating galvanized sheet metal are toxic if you try the diode or negative resistance stuff.