I remember one of the reasons I first got into electronics was after watching the series
"Bugs", which aired on BBC1 in the UK.
A few years later, I bought a few of the audio bug kits from Quasar Electronics -
they still sell them, but not in the UK. These were really basic transmitters, pretty small, but very low range, heavy on battery power, sensitive to the presence of humans and metal... essentially useless for actual bugging!
Back then, the thought of hobbyists soldering SMD was ridiculous, so these were about as small as you could get. We also didn't have small, low power processors that can run for weeks off a small battery.
There's also so many tiny wireless devices coming out of Hong Kong, though after taking a few of these 2.4Ghz devices apart, it's quite clear why they are so small and cheap.
So the question is, why does the internet seem devoid of interesting pages on the technology behind surveillance electronics? Has anyone found any?