Vacuum tubes used to be the building blocks of computation and the drivers of screaming guitar amplifiers, but they’re rare today — so rare that there are virtually no manufacturers producing new units. If you shop for vacuum tubes, most of what you’ll find is either used or NOS (new old stock). That has led to boutique vacuum tube manufacturing, but that is a substantial undertaking. To make the process just a little bit easier, Nick Poole created this custom vacuum controller.
As the name suggests, a vacuum tube requires a sealed chamber under vacuum. That vacuum is necessary to provide “clean” space between the anode and cathode, so electrons can flow freely. It is practically impossible to achieve a perfect vacuum, but vacuum tube manufacturers try to get as close as possible to get the best performance. Evacuating the tube before sealing is a tricky task, which is why Poole wanted a controller to streamline the process.
This requires two vacuum chambers: one for rough vacuum and one for hard vacuum. The new tube connects to the evacuation port, which connects to those vacuum chambers through specialty valves. This controller, based on an Arduino, needs to control the operation of the vacuum pumps and valves. It also needs to monitor the pressures/vacuum, drive gauges, and provide indicators. There is a lot that can go wrong in a hurry when you’re working with hard vacuum, so the Arduino ensures that each step occurs in the proper sequence so Poole can focus on forming the glass when he fabricates vacuum tubes.
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