Re:How a Gift from Schoolchildren Let the Soviets Spy on the...
by rtkwe on Sunday November 06, 2016 @10:15AM
(#12885409)
There's a lot of info out there if you search at all. It acted a lot like an RFID chip it was passively powered by the receiver transmitting on given frequency. The mic was capacitive and when powered changed the signal that was being returned by the bug.
https://en.wikipedia.org/wiki/The_Thing_(listening_device)