LED Filaments Make a Retro Clock Without Any Retro Parts

We love clock projects here at Hackaday, and we've seen many beautiful designs based on a wide variety of display technologies. There are various types of glass tubes like Nixies, Numitrons and classic VFD displays, all of which have that warm "retro" glow to them. Then there's LEDs, which are useful for making cool pixel-based timepieces and easy to drive with low-voltage electronics. So how about combining the best of both worlds, by using LEDs to make a Numitron-like display? That's exactly what [Jay Hamlin] did when he built a digital clock based on LED filaments.

The heart of the project consists of orange LED filaments similar to the ones used in vintage-style LED light bulbs. [Jay] bought a bunch of them online and tried various ways of combining them into seven-segment displays, eventually settling on a small PCB with a black finish to give good contrast between the LEDs and the background. To make the displays look like they're encased in glass, [Jay] bought a set of plastic test tubes and cut them to size.

The base of the clock is formed by a slick black PCB that holds an ESP32. The segments are driven through a set of 74LV595 shift registers to keep the required number of GPIOs to a minimum. There are no buttons: thanks to a WiFi connection and the Network Time Protocol the ESP32 automatically keeps the correct time.

The end result looks remarkably like a Numitron display at first glance, and remains a beautifully-made clock even if you notice that there's no glass to be found. If you're into LED filament clocks (and who isn't?), check out this analog wall clock, or this spiderweb-like digital clock.

#clockhacks #ledfilament #numitronclock #sevensegmentled

Simple But Stylish Numitron Clock Can Display Time, Date and Temperature

While it seems like Nixie tubes get all the attention when it comes to making retro-style displays, there are plenty of other display technologies that can make a good-looking retro design. Take the Numitron tube: introduced by RCA in the early 1970s, these display tubes might look superficially similar to Nixies but work in a completely different way. The Numitron uses incandescent elements that make up seven-segment displays.

The main advantage Numitrons have over Nixes is that they don't require a high-voltage supply, which makes them much easier to hook up to modern low-voltage electronics. [mircemk] used this to his advantage when he built a simple clock using four numitrons that can display the time, the date, and the ambient temperature.

The brains of the device are formed by an Arduino Nano coupled with a DS3231 battery-backed real-time clock module. For now, the time has to be synchronized by connecting the Arduino to a PC and reprogramming it, but [mircemk] has plans to update the design with pushbuttons to allow the user to set the time manually.

Four shift registers are all that's needed to interface the microcontroller to the display tubes, thanks to their low-voltage operation. They do need quite a lot of current, so [mircemk] used the high-power TPIC6C595 instead of a regular 74HC595 chip. We wonder if the tubes' high power consumption could be the reason why the temperature in his lab seems to hover around 30 °C.

A simple but stylish plastic enclosure completes the design. Since Numitron tubes are relatively low-cost and no other specialized components are needed, this could be one of the cheapest and easiest ways to make a retro display tube clock. Although we've seen a couple of Numitron clocks and even watches before, today's build is a great example of how simple such a design can actually be.

#arduinohacks #clockhacks #clockthermometer #numitron #numitronclock