Neon Binary Clock

[Josiah] said ‘no’ to LEDs and instead used blue-phosphor neon lamps to build this binary clock. The ATmega328 inside uses three 8-bit shift registers to control the display. Each lamp needs a high-voltage NPN transistor in order to switch on the 150V necessary for proper illumination. A simple circuit was used to pull a 60 Hz clock signal out of the incoming 16VAC power. Unfortunately it was a bit too simple and didn’t provide a clean signal. [Josiah’s] workaround is something of a debounce subroutine in the firmware to prevent multiple interrupts on the falling edge.

The last project we saw from [Josiah] was the Coachella Lamp. That was a show piece of antiquated technology and this is another show piece with a minimalistic style. We also liked seeing the protoboard work on the inside. That’s a pretty jam-packed circuit board and keeping everything in the right place while you build up each trace with blobs of solder is no small feat.

21 thoughts on “Neon Binary Clock

  1. The neon-bulbs are actually what inspired the project! I came across them at a pretty neat electronics boutique called All Spectrum Electronics, where I was purchasing some NeonNixie HV PS kits. They still have more of the blue-lamps if you are interested in using some for your own project (more of the HV supplies too!). Tiny glass condoms… seems a strange thought to me.

    I’m glad that most people think the build quality is decent. :-) My construction skills are far better than my EE skills, which in turn are far better than my programming skills.

  2. E-gads, one face plant and you’ll lose your LSB’s!
    (Least Significant Bits)

    I think you should complete your steam-punk (that they way people spell it?) look and add some miniature metallic rack handles to the front. Some contemporary cabinet pulls might do the trick. But I think what you are really looking for are card pulls in the shape of a “U” bolts found on some electrical equipment.

  3. I suspect the neon lamps aren’t using “blue phosphor” but a different gas mixture. Using a phosphor requires (I think) requires capture of a higher energy level light source which then gets “downconverted” to a lower frequency/longer wavelength by the later emission. So that would take something like UV being emitted from the lamp gas itself, which is unlikely. (Interestingly, white LEDs generally DO use phosphor, and old CRT screens as well, though their higher-energy source is accelerated electrons.)

    If you overdrive an orange neon bulb it will glow blue but not the blue of these pictures. Also, the “All Spectrum” sales site mentioned shows a data sheet in Chinese, which probably means these bulbs are of new manufacture, and aren’t NOS from pre-1970’s. So it’s reasonable to think they are a new design.


  4. They use different gases, just like normal ‘neon’ signs do. The blue ones apparently use argon, dunno about green. There is no phosphor like LEDs or flouro lights use.

  5. If you saw these in person, you would know they are definitely phosphor lamps, the light is just obviously different than some “pure” spectral emission of single gas. They are argon-filled (these aren’t mercury doped, but some are), which produces UV emissions at the right pressure/voltage, which in turn excites the phosphor coating on the interior of the bulb. It is easy to verify this by seeing that a) there is a white, powdery coating on the interior of the bulbs and b) holding them near an intense UV source makes them glow blue.

    It turns out this is the way every color but orange is produced in neon signs. Which basically means that most of the time when referring to “neon signs,” there isn’t really any neon to be found.

    @mike- I’m over the hill in Santa Monica. They storefront for All Spectrum is actually for their avionics business, not their electronics, so there in no physical browsing. They do have local pick up though.

  6. It always help to check things rather than rely on memory.

    The green ones I have use a phosphor, but I have two types of blue, some are clear and the others have a phosphor.

    The phosphor ones are brighter.

    Interestingly, I also have a single purple one, no phosphor. I wonder where I got that.

    A bit of reading later says they all probably use argon, but the clear blue ones will have some mercury as well.

  7. I would love to see the “pure gas” blue one if you have a picture! They purple too! They sound very cool. Are they little lamps? I have a set of those gas-discharge tubes filled with a variety of gases used in spectroscopy labs. However, they are big (6″ long), require a special fixture to power (they need about 1kV to fire), and are pretty dim. I would love to get my hands on some little lamps that produced novel colors from direct emissions, not phosphors!

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