The retro alarm clock with Nixies is completely modern inside

We carry a lot of clocks here at Hackaday, but alarm clocks seem to be less popular for some reason. Maybe it's because no one likes being woken up in the morning, or just because everyone already uses their smartphones for that purpose. In any case, we are delighted to present to you the beautiful Nixie tube alarm clock by [Manuel Tosone] which cleverly combines modern and classic technologies in one package.

The clock and alarm functionality is implemented by a PIC24 microcontroller on a custom motherboard. It keeps track of time with its real-time clock with battery backup and plays a song from an SD card when it's time to wake up. A 2 x 3W Class-D audio amplifier and a pair of stereo speakers should be able to wake up even the hardest sleepers.

Of course, the real party piece is the clock display: four IN-4 Nixie tubes display the time, with neon tubes indicating the day of the week. The 180V needed by the Nixies is generated by a boost converter based on the MC34063A, which also powers the neon tubes.

Instead of using the standard current-limiting resistor for each Nixie tube, [Manuel] designed a transistor-based current source network: this allows linear control of the tubes' brightness and should maintain the constant amount of light even if the tubes age. Individual segments are switched by SN75468 Darlington arrays, without the need for those hard-to-find SN74141 drivers.

The motherboard and screen are housed in a 3D printed enclosure that mimics the style of 1980s digital alarm clocks, but with a nice 1970s twist thanks to those Nixie tubes. The GitHub page of [Manual] has all the schematics as well as extensive documentation outlining how the circuit works - a great resource if you're planning on building a Nixie project yourself. If Nixies aren't your thing, you can also make an alarm clock with a VFD tube, or even roll your own glowing analog dial.