This unique digital clock is built around a circa 1960 Burroughs decimal counting module (model DC106A, serial #554). The module incorporates a Beam-X switching tube (also known as a Trochotron), a fascinating but short-lived technology that used crossed electric and magnetic fields to produce a vacuum tube with ten stable states, capable of counting at rates in excess of one million per second. The module's display is an end-view Nixie tube with 5/8" digit height. The module has been mounted on top of a black plastic project box containing the clock's electronics and setting switches. A clear plastic cover prevents touching the portions of the module that contain high voltages.

Before reading any further, please understand that this clock is somewhat of a fake - it doesn't actually use the Beam-X tube at all, it drives the Nixie display directly. I chose to do things this way due to lack of documentation on the counter module, and the fact that some previous experimenter seems to have modified the module (so it wouldn't necessarily operate according to specifications, even if I had those specifications). There is one huge advantage to this: you'll never have to worry about replacing the Beam-X tube, which would likely prove to be impossible - they show up occasionally on eBay, but mostly later versions which did not need the huge external magnet and shielding required in this module.

Features of the clock:

JavaScript animated clock mockup
Here's a mockup of what the clock actually looks like in operation. The time initially shown here is 4:17 (it could be either AM or PM, there's no way to tell other than using a 24-hour display format).