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.

Love this. I just dont know what else to use those leds for than segments?

Would take a more patient and capable person than me, but how about a cross-hatching display?

What is a cross-hatching display?

Cross-hatch display is not a thing … according to my first instinct and the internet.

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.

Oh, now I see what you mean, thanks for taking the time to explain.

For a moment I thought you were thinking about something like this:

Imitation vacuum tubes (valves) if the right glow could be achieved.

Nice, but it looks like there’s a dead segment in the top right of the 2nd-last digit.

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)”

anyone have a pointer to data sheets for LEDs like these?

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.

I’ve ordered these LEDs by themselves and they just ship them loose in a bag. They were all broken by the time they arrived.

You mean LED filament…..COB is quite a bit different….

In what way is COB different?

LED filament is a long skinny COB.

https://en.wikipedia.org/wiki/LED_filament

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.

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.

Here’s my experiment with them, where they are bent https://github.com/svofski/ledfilament To answer your question, you can bend them but not too much. They are just tiny led chips on a flexible strip, embedded in a phosphor-filled tube.

I think, most are coated with a phosphor-paint.

I was wondering that as well, for use as flashing colon separating the hours and minutes.

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.

Some a re on metal substrate and some on glass substrates.

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!

IIRC they are LEDs on a glass substrate. So no bending possible. But aren’t there new ones that are flexible? Would make for a fun faux nixie display

Yes. Some bend, some shatter. BigClive did a video about it.

I picked up 20 of these bulbs with candelabra base for 25 cents each on clearance at Walmart. Should’ve bought all they had. Unfortunately they had less than 20 that were dimmable. But they did have lower power, non-dimmable ones. My mom’s house has two 10 arm brass chandeliers so with 10 15 watt bulbs they were 150 watts each. I installed the non-dimmable bulbs in the chandelier in the kitchen dinette and the dimmable ones in the chandelier in the living room, along with replacing the switch with a dimmer.

They work great, provide more light than the incandescents did while using much less power, even with the dimmer all the way up.

https://www.designboom.com/design/lambert-kamps-tube-lamp-clock-at-london-design-festival-09-23-2016/

Absolutely beautiful! With a “special” enclosure (or behind a metal-sheet grid like Nixies) one wouldn’t see the thin wires. This could look hella nice as well!

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.

Well, yes, I could imagine. But I imagine these leds to take up at least 20ma (at the 75v). Can you pull 20ma through a thin layer of ITO?

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.

5mA is too bright. The video is running at 1.2mA. Rather conveniently the driver chips are adjustable between 0.1 and 1.5mA.

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.

“old bulb gives up filaments”? No, the creator had them, because he bought them. Did you even read the original Instructable?

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.

another previous instance: https://hackaday.com/2015/04/18/mike-illuminates-us-on-led-filaments/

Beautiful project and great execution. Mike Harrison has an informative video on the subject that is worth a watch to anyone interested in experimenting with these elements: https://youtu.be/H_XiunR-cAQ

> 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.

Nice. But not cat compatible. :-(

Hi Andy, great to meet you at emf (spider silk talk). I’d love to display your clock – tweet me @mellchie for a postal address. ~M

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