Old LED Light Bulbs Give Up Filaments for Spider Web Clock

We love it when something common gets put to a new and unusual use, especially when it’s one of those, “Why didn’t I think of that?” situations. This digital clock with a suspended display is just such a thing.

The common items in this case were “filaments” from LED light bulbs, those meant to mimic the look of clear-glass incandescent light bulbs. [Andypugh] had been looking at them with interest for a while, and realized they were perfect as the segments for a large digital clock. The frame of the clock was formed from bent brass U-channel and mounted to an oak base via turned stanchions. The seven-segment displays were laid out in the frame and the common anodes of the LED filaments were connected together, with the cathode for each connected to a very fine wire. Each wire was directed through a random hole in the frame and channeled down into the base, to be hooked to one of the four DS8880 VFD driver chips. The anode wires form a lacy filigree behind the segments, which catch the light and make then look a little like a spider’s web. It looks great, but nicht für der gefingerpoken – the frame is at 80 VDC to drive the LED segments. The clock is synced to the UK atomic clock with a 60-kHz radio link; see the long, painful sync process in the video below.

We like the open frame look, which we’ve seen before with an equally dangerous sculptural nixie clock. And this gives us some ideas for what to do with those filament LEDs other than turning them back into a light bulb. And if [Andy] sounds familiar, it could be because he’s appeared here before. First of all resurrecting the parts bin for an entire classic motorcycle marque, and then as the designer of SMIDSY, a robot competitor in the first incarnation of the UK Robot Wars series.

36 thoughts on “Old LED Light Bulbs Give Up Filaments for Spider Web Clock

        1. Cross-hatching is an artistic technique where you lay and layer a series of lines and criss-crossing lines to create a cross hatch. To depict shadows and shapes. In this it’d be either replacing the shadows (or their absence) with lights laid in a cross-hatch pattern.

    1. Yeah. It is mentioned in the write up though; “There is also a lazy element (it glows, but dimmer than the others) The LED itself is good. I fear a problem with the driver chip but I will try re-wiring the enamelled copper first. (in fact I will probably just run an extra wire)”

    1. These are COB (chip on board) LE modules. They’re available in a huge assortment of sized and shapes from our usual friends in Shenzen. If you search for COB LED, you’ll find the data you need.

      There’s no need to massacre decorative LEDs for a project like this. Cool as the final result is.

  1. I’ve been seeing LED bulbs like this in stores for awhile, glad to see somebody came up with a creative use for the LED filaments. It’s one of those things where you know there should be something cool you can do with them, but can’t quite put your finger on.

  2. Is it possible to bend the filaments without killing them?
    For a less dangerous version you could put the whole lot under a glass bell jar, which seem quite popular in supermarket interior decorations.

    1. The particular ones used here do not bend at all, The LEDs seem to be mounted to an especially frangible substrate.
      The article rather over-states the danger, running from a floating power supply it seems perfectly safe to touch the frame with it turned on (something I have done many times while assembling and testing it). It ought to be possible to actually ground the frame and run the cathodes at -80V with the Arduino and logic powered from -75V.

  3. They will bend (curve) a little, but I would doubt they would “kink”. They can be bought on ebay as separate ‘filaments’, usually in rows.
    Judging by how most LED bulbs fail, the LED part is just fine and it is the power supply that dies. Hence, lots of filaments should be coming ‘to market’ anytime soon!
    Only problem, they are usually 50 to 70 volts to turn on. But with a low current limit, they look quite nice. At full current, they are just too damn bright!

  4. Could you imagine something similar but instead an etched pane of glass coated with ITO and conductive glue to hold the led filaments on to the clear “traces”? It would for all purposes look like the digits are floating. Saw these led filament bulbs at the local dollar store with two bulbs with 4 filaments each for … $1. Gonna have to give them a shot. I have bought loose led filaments off ebay in the past and the likelihood of them surviving postage is terrible (I bought around 30 of them from various sellers and only about half weren’t DOA). At least buying two complete, tested bulbs for $1 and smashing them for the filaments will guarantee all of the filaments work.

      1. I’d assume since they are a series string that at full brightness they’d pull 20-30mA, but for a visual indicator application like this they’d probably be plenty visible at a more modest 5mA or so.

  5. I bought a couple of these bulbs from a local store. They were quite expensive (philips branded), but very good.
    I really liked them but not so much the price. So I bought some that looked the same off ebay, and they were junk. They were half the price for sure… but also half the brightness and twice as power hungry (yes, proper tests were done).
    In other words I was better off with the name brand.

  6. has one here earmarked for a Casio portable TV (770?) with a slight problem in the power supply.
    Incidentally they are perfect for this if you rewire the secondary on a similar coil (burned secondaries are very common in inverters on portable gadgets) and simply put two filaments back to back.
    If you want to be really sneaky backfill a glass “tube” made from an old pipette with gas to replicate the original bulb and make some LCD panel backlight replacements with them: would love to see someone try that.
    Has to be Ar or He but as long as its oxygen free it will work.

  7. > form a lacy filigree …
    > … but nicht für der gefingerpoken

    Way to use your word skills, Dan! Seriously, I enjoy your prose as much as I enjoy the actual project.

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