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An old WWII veteran who built the on-board CCTV system on a ship in the Pacific once walked me through making an AM radio that worked with no battery — just the
by reaperducer 4y ago
An old WWII veteran who built the on-board CCTV system on a ship in the Pacific once walked me through making an AM radio that worked with no battery — just the power of the radio waves, themselves. Like what today powers RFID chips.
It took him maybe ten minutes of soldering probably six or eight components he pulled out of a box of junk parts.
He grounded the thing by sticking a nail into a wall socket.
It helped that this was in a small town with only a couple of AM signals, so fine-tuning wasn't all that necessary.
- 9wzYQbTYsAIc 4y agoYou might get a kick out of this: “I bought 1000 meters of wire to settle a physics debate” https://m.youtube.com/watch?v=2Vrhk5OjBP8 https://m.youtube.com/watch?v=2Vrhk5OjBP8
- password4321 4y agoAM: https://en.wikipedia.org/wiki/Foxhole_radio https://en.wikipedia.org/wiki/Foxhole_radio
- myself248 4y agoA crystal-set radio was a LOT of people's introduction to electronics, I remember building one with my dad at age 6 or so. We were a fair distance from the station so the signal was faint, but the earphone reproduced enough to hear the news and most importantly, the station call letters. They really are extremely simple things, and you can use the base-emitter structure in any BJT if you don't have a discrete diode around. The trick is knowing how many turns of wire to put on the inductor, but if you're stuck in a foxhole for who-knows-how-long, you have time for a lot of trial and error.