My DIY LED "Expansion" Board

[IntegrityShirts]

I know this has been discussed here and there, but I would love to start a comprehensive thread about these DIY LED builds with standard formatting and an updated first post with details of each build and some kind of consensus summary.  After the new year I think I am going to try my own build and would like to further the development and discussion rather than rehash others mistakes and what not.

Can you detail the following in this format, and note after each what you might change or like to see tried for comparison:

LED Details:
-Source
-Cost (in total/per LED/shipping/etc)
-Wavelength (and any other details related to the light output itself)
-Electrical requirements/wiring diagrams, etc.

Build Details:
-Overall Size
-LED Layout (distance between bulbs,distance from glass, etc)
-Glass (thickness, type, source, etc)
-Peripheral info related to vacuum blanket, etc

Film/Emulsion/Exposure Details:
-Type of emulsion and coating technique
-Film brand and printer output
-Exposure Times and mesh used

Random thoughts, what you would improve, etc:

I agree with everything you're saying. BUT, this is still a work in progress and I don't really want to post anything as fact until we can reach a consensus on all the components. The biggest variable here is the LED type.

BUYER BEWARE - LED's are vastly mis-represented on the internet with no way of actually knowing what you're getting until you get it. There are no markings or part numbers on these led chips so you have to choose reputable seller and hope they send you the right stuff!

That being said. I have been in contact with an alibaba supplier for UV strips and his PDF catalog he attached sheds a little light on the subject, or literal lack of light...

He lists 3 categories of strip, all the same in specification:
5050 SMD UV LED 60 LED per meter, 5m rolls

The differences in the 3 categories??? Power consumption! 4.8w/m, 7.2w/m, 14.4w/m. A lot of suppliers, MOST in fact, list their LED's as 14.4w/m for a 5m roll. Now, Gilligan or North, have you measured the amperage draw of your strips? I'm willing to bet my strips don't pull 72w per 5 meters or my power supply would be overloaded immediately on start up. I'll see if I can measure one row with my cheapy multimeter and calculate actual load.

What I THINK we need either the 365-370nm range strips, or 380-385nm like Pierre suggested. There is a HUGE price jump between these two ranges and both are 3-4 times the cost of 395nm strips. The idea here is to get the times down into the starlight range, to actually make these DIY setups WORTH the effort to source and assemble. If it ends up costing $700 instead of $200 and you get starlight performance, it's worth it in my opinion.

All this being said. It would probably be easier to mimic the light setup of the vastex style led's over the strip style as there are fewer options in those larger power LED's. I'm not going down that path now though. Too much invested in this project.

[Gilligan]

I don't have a uv strip but a white strip.

I think all my meters have blown fuses, I'll have to double check.  So no way to tell DC amp draw.

According to an online calculator I found it's suggesting that based on what the psu was drawing from the wall (minus it's idle draw) I'm just under 5 amps.

[IntegrityShirts]

Just did a load test for one row (45 LED) and at 12V it draws .56 amps. Doing a little math to calculate total watts per roll vs what is advertised for this strip:

Specs: 72W per 5m roll
Actual: 44.8W per 5m roll

So TOTAL power is 201.6W when in reality they SHOULD be 324W.

I'm requesting some samples from a different alibaba seller in 365-370nm and 380-385nm. If I can get a roll of each I can make a mini exposure grid big enough to test the exposure calculator area of a screen and I can also load test each strip to verify they are high current LED's.

As an idea of cost...
Enough LED's to make a 380-385nm unit runs $650
Enough LED's to make a 365-370nm unit runs $1550

[Gilligan]

What is your math behind that conversion?

Where are you measuring your .56 amps from?

[IntegrityShirts]

Each row of my grid has 45 LED's. I disconnected one row and measured amperage draw while only powering that row. That equals .56amps @ 12V (I lowered the power supply down to 12V for this test)

Easier to google an image of how I hooked it up than explain it haha:


.56/45 = .01244amps per LED

300 x .01244 = 3.7333amps per "roll" LED (300 LEDs per roll)

amps x volts = watts:
3.7333 x 12 = 44.8watts

[Gilligan]

Ok, cool... that is of course the correct way.

Interesting.  I wonder if they are rated at "burst" power?

[TCT]

Has anyone tried buying the LED's from reputable places here in the states? Then you don't have to worry about getting the right nm. I was given these names as reputable trustworthy outlets - Arrow, Avnet, and Degikey.


I talked to my dad about this who is retired now, he was head of purchasing for a company that imported millions of LED's dating back maybe 25 years. They eventually ended up having 3 or 4 factories of their own in China and he was the main go between from US to China and vise versa. Anyway, when I asked him about a connection or lead in China he said for the most part it is a crap shoot unless you are going to be moving $100K+. What they say and advertise for nm is not necessarily what is going to ship, for a number of reasons. The places in the states may be more expensive but they have the buying power and discerning customer base that requires accuracy. Just a thought, eliminate one variable from the equation...   

Side note, it was pretty cool my first exposure unit(which we still have) is from Workhorse and when I bought it we found components in it from the company my dad worked for, pretty cool. I also think I've seen their components on damn near all the new M&R autos. Funny how it can be a small world sometimes.

[ebscreen]

I would never have thought to look, but Digikey has them in a wide range of wavelengths and packaging, etc.
Some draw up to an amp each.