On today’s HacDC Blabber list, Trammell Hudson posted a link to this awesome account of British soldiers building a radio in a Japanese POW camp. Trammel writes:
Since they didn’t have a local Digikey or Radioshack, everything had to be sourced from what was available. The caps were made from aluminum foil lining of tea-chests, the resistors were rusty barbed wire with burned tree bark, the rectifiers out of oxidised foil and salt water, they smuggled a tube (“valve”) in the camps and bribed the local Chinese power station operator to slowly step the output voltage up to 130 from 110 volts.
Amazingly they were able to receive the BBC broadcasts! The initial RX design was pretty basic, so they then built a super-het regenerative transmitter, too, but never made use of it.
[FYI: The image I used above is not from this story, just a diagram of your basic DIY foxhole radio.]