Axial LED Strobes

David_AVD

David_AVD

Grandpa Elf
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Early in the year, someone started a strobe discussion in chat. I thought about making them as a double sided PCB with 5050 white LEDs. See, I wanted my strobes to emit light from all around if possible.

I had planned to use a WS2801 (or similar) chip in each strobe and there should be plenty of cool white 5050 package LEDs to choose from. The PCB would slide into a short clear tube, with wires coming out of each end. The tube is easy enough, but the problem was how to seal the wire entries. So the idea languished while I worked on other project designs...

Then, while talking to Josh (ChillOutDocDoc) this morning in chat, I had an idea!

We could use small cable grommets with an OD the same as the tube's ID. We could add the wires to the PCB, slip the grommet over the wires and press it into the tube ends, leaving a few mm of open tube. Then, the end would be sealed with silicone (or hot melt glue?) and the grommet would stop it from bleeding too far into the tube.

Here's a diagram to explain better. Once the details were worked out, it could be done as an ACL DIY project.

davidavd Axial_Strobe.png
 
I really like the idea, seems cheap and easy to make (as I had said in chat earlier). The fun part always comes as to how it's wired, powered, and switched. Cannot wait to see the progress as I plan to add another 50 strobes next year :)
 
I emailed a plastics place today and they sell acrylic tube in various sizes. One was 25mm OD and 21mm ID, but that may be a little large for the grommet. I think they also sell a 20mm OD one with a 3.5mm wall thickness, so that's 13mm ID in theory. I'll check out commonly available grommet sizes and order a length of tube to test the general idea.

As for the wiring and controller, they'd be much the same as a standard pixel string. I was thinking 4 core alarm cable could be a suitable candidate, as it's available in black or white and thinner (7/0.2mm) or thicker (14/0.2mm) wire gauges.
 
I've designed the PCB using a WS2801 chip and 6x 3528 package white LEDs (3 per side of the PCB). It will run from 12V.

I'll get a few samples made on the next prototype PCB run. That means I should have something to show in 2-3 weeks time. :)
 
I found some 5050 LEDs that had better output and 3 dies each, so I completely redesigned this board. It still uses a WS2801, but has a single 5050 white LED on each side of the PCB.

The WS2801 will drive a separate constant current driver IC to get the maximum brightness without running the WS2801 outside it's limits.

I'm getting a dozen boards on the current prototype run, so should have them made up within 2 weeks time.
 
David, forgive my ignorance, but would the inclusion of the chip require these to be run off a DMX line? Also, would the chip provide the 'strobe' effect?
 
is this the same type of strobe idea mph had for his strobe strings?
wont you have to have a certain controller for them like mph has too?
 
[quote author=DanoNJ]David, forgive my ignorance, but would the inclusion of the chip require these to be run off a DMX line?[/quote]

These strobes will behave much like a standard pixel string, so an E1.31 or DMX controller with SPI output will be required. That is, they are not a stand alone type device that you just apply power to.

[quote author=DanoNJ]Also, would the chip provide the 'strobe' effect?[/quote]

Electrically, the LED output level will be controllable like a regular RGB pixel, but will be snapped on/off (by the software or controller) for a strobe effect.

[quote author=smartalec]is this the same type of strobe idea mph had for his strobe strings?[/quote]

I have not seen how other people have implemented their strobes, so can't really comment on that. My design ideas came about after discussion amongst several people in chat very early in the year and again recently in chat with Josh.

[quote author=smartalec]wont you have to have a certain controller for them like mph has too?[/quote]

You could drive these via any controller that supports 12V 2801 style strings. A specialised controller may be a worthwhile project as it could have the channel count reduced to intensity, flash on-time, average off-time and average fill.

Not all of the details have been worked through yet but I had a prototype PCB run going in last week, so thought I'd at least get the ball rolling with my design. :)
 
Prototype LED strobe PCB has been made up. Sorry about the crappy picture.

apc732.jpg
 
Looks like a pretty decent power trace there - how many do you reckon can be placed in-line in a string - a couple dozen at least maybe? I like this - just string them garland!
 
budude said:
Looks like a pretty decent power trace there - how many do you reckon can be placed in-line in a string - a couple dozen at least maybe? I like this - just string them garland!
Click to expand...

The power trace is good for 3 Amps. Each strobe should only draw approx 70mA max. This may change once I see how the prototype goes.
 
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