I built this when I was a kid. The tube is a 6U5 with 1M resistors mounted in the rear. We assembled a power supply from parts harvested out of a very old PA system including a 6V4 full wave rectifier tube, transformer, and 16uf cap to provide B+. Remarkably, some many years later, the Magic Eye still works fine. The case partially open to permit access to wires and internal connections.
