Fun with rather a lot of LEDs.... - Page 1
Forum section: electronics / projects

author: LEECH666
author_rank: Frequent Contributor
timestamp: April 26, 2012, 11:00:31 pm
content: Looks awesome!I wonder what size the PCBs are. Maybe smaller ones clipped together somehow with some sort of interconnect?I also recon these are the PCBs you tested your Proxxon table saw on?Cheers,Florian

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: April 26, 2012, 11:07:05 pm
content: 400x600mm PCBs, 6 per layer, linked with a ridiculous number of plastic rivets - many sore fingers!

author: Unknown
author_rank: Unknown
timestamp: April 26, 2012, 11:17:49 pm
content: the biggest one yet ?15625 leds if not mistaken

author: EEVblog
author_rank: Unknown
timestamp: April 26, 2012, 11:29:35 pm
content: Did you guys design and build this one, or is it a commercial one?I know few chinese companies are making big ones like these now.Dave.

author: EEVblog
author_rank: Unknown
timestamp: April 26, 2012, 11:31:56 pm
content: Those LED are on the top of aluminium bars, so seems like you can only see the image from above the cube?Dave.

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: April 26, 2012, 11:41:53 pm
content: Quote from: EEVblog on April 26, 2012, 11:29:35 pmDesigned and built by us in the UK as a 1-off project (although may be another in the works!) - even the bare PCBs were UK made - we got so pissed off with PCBcart not being able to give us a fixed shipping quote, and not understanding that a PCB with most of the area routed out would weigh rather less than a full panel, that we asked a UK place if they could match what we thought PCBcart might end up charging.QuoteAluminium bars...?The LEDs are on horizontal PCBs, so you get something like 140 deg view angle - a 6ft person will see all layers, but short-arses will miss the top few layers.BTW total power at full blast is 4V at 180 amps!

author: McMonster
author_rank: Frequent Contributor
timestamp: April 27, 2012, 07:59:19 am
content: Looks like a Borg cube... Shields up, red alert!

author: Ed.Kloonk
author_rank: Super Contributor
timestamp: April 27, 2012, 08:41:46 am
content: Quote from: McMonster on April 27, 2012, 07:59:19 amResistancediode volt dropis futile!

author: Chet T16
author_rank: Frequent Contributor
timestamp: April 27, 2012, 08:49:15 am
content: Quote from: HAL-42b on April 26, 2012, 11:17:49 pmLooks like 24*24*24 to me

author: firewalker
author_rank: Super Contributor
timestamp: April 27, 2012, 09:06:09 am
content: Mike, is there any info for this project? Drivers, software, build video e.t.c.Alexander.

author: EEVblog
author_rank: Unknown
timestamp: April 27, 2012, 09:20:33 am
content: Quote from: mikeselectricstuff on April 26, 2012, 11:07:05 pmWhat was the interconnect system between boards?Dave.

author: EEVblog
author_rank: Unknown
timestamp: April 27, 2012, 09:22:22 am
content: Quote from: mikeselectricstuff on April 26, 2012, 11:41:53 pmSo about 10mA per LED?Dave.

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: April 27, 2012, 09:29:21 am
content: Quote from: firewalker on April 27, 2012, 09:06:09 amProbably will be at some point

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: April 27, 2012, 09:35:49 am
content: Quote from: EEVblog on April 27, 2012, 09:20:33 amAs little as possible - I spent a lot of time designing to minimise interconnect. Each plane is 3x2 boards, and the two halves are completely independent electrically. Along the '3' edge there are just a few lines for driver data linked between PCBs via some pin connectors on the underside of the edge where the drivers are. At one end of each half there's a small board underneath coverting data from one of four RS485 buses to the LED drivers on that half of the plane.Power comes via the metal support spacers. Data between planes is on ffc cables cunningly concealed inside a column of fake spacers

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: April 27, 2012, 09:36:17 am
content: Quote from: Ed.Kloonk on April 27, 2012, 08:41:46 amYou will be illuminated!

author: EEVblog
author_rank: Unknown
timestamp: April 27, 2012, 09:59:36 am
content: Quote from: mikeselectricstuff on April 27, 2012, 09:35:49 amAh, got it. I should have paid closer attention, I thought it was strip PCB's. But it's one big board with cutouts. That really simplifies the interconnect issue.1.6mm PCB?Any temptation to use really thick PCB to make it super rigid?Dave.

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: April 27, 2012, 10:12:50 am
content: Quote from: EEVblog on April 27, 2012, 09:59:36 amWe started off thinking about strips, as it makes better use of PCB, but once we added up all the interconnects we quickly realised that was a bad idea. The other issue with strips is how to keep them straight - we did think of hanging them vrtically but that didn;t give the view angle we neededQuoteYes 1.6 - the PCBs are quite floppy but the spacers keep it rigid - we were concerned with warping in reflow but they came out fine.

author: Ed.Kloonk
author_rank: Super Contributor
timestamp: April 27, 2012, 10:14:10 am
content: Quote from: mikeselectricstuff on April 27, 2012, 09:36:17 amWell played Sir!

author: Psi
author_rank: Super Contributor
timestamp: April 27, 2012, 01:09:07 pm
content: "This video is private"In the mean time, while the video is fixed, here's a video i made ages ago of fun with a large number of leds.Two metal rods with 40V @ 20mA across them. Randomly you get chains of leds that just so happen to be touching each other in series.

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: April 27, 2012, 01:15:52 pm
content: Quote from: Psi on April 27, 2012, 01:09:07 pmSorry had to hide it temporarily for 'political' reasons

author: muvideo
author_rank: Frequent Contributor
timestamp: April 27, 2012, 04:34:04 pm
content: Quote from: Psi on April 27, 2012, 01:09:07 pmAnd some in reverse breakdownI've seen many times the warning about the reverse breakdown of leds,some manufacturers include also a protection device (philips rebels),but what's the real danger of this? Is the semiconductor prone tofailure because of this?After all the reverse voltage isn't much higher than the forward one.

author: codeboy2k
author_rank: Super Contributor
timestamp: April 27, 2012, 10:57:54 pm
content: Quote from: mikeselectricstuff on April 27, 2012, 01:15:52 pmDid you get a "cease and desist" from the Borg

author: T4P
author_rank: Super Contributor
timestamp: July 09, 2012, 04:33:11 pm
content: Quote from: mikeselectricstuff on April 27, 2012, 01:15:52 pmSorry for reviving this thread though.Hey mike, how about uploading somewhere else?

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: July 09, 2012, 04:41:52 pm
content: It's being installed soon so we should be able to publish details in the next couple of weeks.

author: Zero999
author_rank: Super Contributor
timestamp: July 11, 2012, 01:45:13 pm
content: Quote from: muvideo on April 27, 2012, 04:34:04 pmIn my experience, red LEDs don't seem to be harmed by reverse breakdown as long as the current is kept low. Other colours seem to be more sensitive, especially blue, green and white but some are internally protected, as you say.