2026-07-31 16:37 UTC
Before transistors, vacuum tubes were widely used as switches and amplifiers. A heater heats up the cathode, which emits electrons. They are attracted to the plate, causing current to flow. A negative voltage on the grid blocks the electrons, controlling the current flow.
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@kenshirriff@oldbytes.space 2026-07-31 16:38
The tube module uses a "dual triode" tube, two amplifiers in one glass tube. In the first photo, the two vertical dark rectangles are the two plates. The second photo shows the tube powered up, with the heaters glowing orange at the top and bottom.