How do you keep people out of your change jar? If you didn’t say with a 3D printed iris mechanism and high-voltage spark gap, then clearly you aren’t [Vije Miller]. Which is probably for the best, as we’re not sure we actually want to live in a world where there are two of these things. […]
Coherers were devices used in some of the very earliest radio experiments in the 19th century. Consisting of a tube filled with metal filings with an electrode at each end, the coherer would begin to conduct when in the presence of radio frequency energy. Physically tapping the device would then loosen the filings again, and […]
When you think of an old radio it’s possible you imagine a wooden-cased tube radio receiver as clustered around by a 1940s family anxious for news from the front, or maybe even a hefty 19-inch rack casing for a “boat anchor” ham radio transmitter. But neither of those are really old radios, for that we […]