LEDBrick Project - DIY pendant w/ pucks

[perkint]

Originally Posted by oreo57

BTW: A toy you need..

Isn't that sort of like putting a drink in front of an alcoholic?

Agreed tho - some very nice toys you have there!

Tim

[zachts]

Originally Posted by perkint

Isn't that sort of like putting a drink in front of an alcoholic?

Agreed tho - some very nice toys you have there!

Tim

I think alcoholics actually have more self restraint than electronics junkies now I need one of those.......

[sfsuphysics]

hmmm wonder if someone has a cheaper add on version of that to a cell phone. I mean I know you can add a spectrometer reader to a cell phone, but I'm curious if it can accurate measure the actual energy output.

[oreo57]

Think I found an O2Surplus project ...

http://publiclab.org/notes/mathew/09...s-spectrometer

http://www.tricorderproject.org/blog...-spectrometer/

The spectrograph design:

contains a ~0.2mm printed slit
400-700nm (approx) spectral range
Variable spectral resolution (~3.3nm @400nm, ~1.8nm @ 700nm), not accounting for the PSF
1000 line-per-mm diffraction grating (cut into a 4mm wide strip, and inserted into the spectrograph flush with the slit aperture)
3D printable on an inexpensive printer
Very small size — about 1cm wide x 2cm long x 3cm tall.

With a spectrometer you’re often battling for SNR, and have to worry about stray light. Although these pictures don’t show it, the spectrograph has to be spray painted with a flat matte black paint to get any kind of performance.

Example Data:
I connected the open mini spectrometer to an Arduino Uno, and wrote a quick sketch to acquire spectral data and send it serially to a Processing sketch. Let’s have a look at some data collected from the instrument from two light sources — the first a white LED, and the second a red laser diode.

[theatrus]

I've been trying to get my hands on some of these. Sadly, they appear to not be in the business of selling:

http://www.hamamatsu.com/resources/p..._kacc1216e.pdf

[Aqualund]

Looks great! I have a thread kicking around here somewhere with the same layout, but I was lazy and used the Lumias. I came to give some advice now that its been about a year since they have been running.

Corrosion.

Anything that was exposed and about 24 inches off regular flowing saltwater, nothing crazy, has produced enough corrosion to make some of the channels inoperable. Especially where the molex connecters go into the boards, and the wires where they go into the connectors.

Of course, anything under 24" was much worse.

My work around has been to cover every exposed connector with liquid electrical tape.

Obviously, if I had built an enclosure with a water tight glass panel this would have been optimal....but I underestimated the effect of the corrosion so high off the water with the molex connectors.

And of course...any leds I didnt have protected behind a lens suffered as the solder immediately went bad.

[theatrus]

Thanks for the note - corrosion is something I want to watch for of course. The upside is I am on entirely gold plate connectors, but that has limited effect. I am considering adding an acrylic shield directly under the LED cluster.

[zachts]

In my experience a splash shield is NOT an option when saltwater is in play! there are exceptions like mounting things on the ceiling with really narrow optics or potting the whole assembly in optical silicone but that's not an option for most of us .....

[oreo57]

Originally Posted by theatrus

I've been trying to get my hands on some of these. Sadly, they appear to not be in the business of selling:

http://www.hamamatsu.com/resources/p..._kacc1216e.pdf

I can see both a PAR meter and a spectrophotometer all in one.

[theatrus]

I have some exposed PCBs in the hood with no conformal coats or anything which don't seem to suffer a problem, but its totally something to watch for.

[zachts]

Corrosion is less an issue if you are forcing cool dry air into the hood/fixture. In aqualunds case it's in a shed with how many thousand gallons? and no cool, dry, totally salt free air available as would be the case with a display in the home.........still splash guards are a must IMHO.

[theatrus]

Originally Posted by oreo57

I can see both a PAR meter and a spectrophotometer all in one.

Sadly its not characterized for absolute intensity, but I imagine it would be stable and could be calibrated in.

I don't have the equipment to do that properly though

[theatrus]

Originally Posted by zachts

Corrosion is less an issue if you are forcing cool dry air into the hood/fixture. In aqualunds case it's in a shed with how many thousand gallons? and no cool, dry, totally salt free air available as would be the case with a display in the home.........still splash guards are a must IMHO.

I've been running T5s and bare (HASL, ENIG, etc) PCBs with exposed components in my open back canopy for quite some time. Splashing is an issue (especially when your giant derasa clam gets irritated), but I have not had ambient humidity be an issue for a bunch of exposed stuff. With the T5s there is forced cooling, and house humidity is generally in the 20-40% RH range.

[Aqualund]

I too was going to use acrylic shield, But I know that especially for the high energy spectrum (uv to blue) you can run into problems with diffraction and "burning" the acrylic. basically the separation between the molecules of acrylic aren't the proper distance to prevent the light waves from running into them...heating the material, and darkening it.

[zachts]

Originally Posted by Aqualund

I too was going to use acrylic shield, But I know that especially for the high energy spectrum (uv to blue) you can run into problems with diffraction and "burning" the acrylic. basically the separation between the molecules of acrylic aren't the proper distance to prevent the light waves from running into them...heating the material, and darkening it.

I've never found that to be the case. Acrylic is designed and intended for exposure to the sun in windows and such and that is much lower (down to sub 300nm UV radiation and far more intense) Reef Uv's should never go below 405nm and should never cause an issue for acrylic. Heat build up "could" melt or burn it if intense enough (i.e.with in less than an inch off a 50w emitter with no air flow, I have done that but it is more due to the trapped air being super heated not the acrylic ASFAIK and not the UV directly impacting the material). I've never seen or heard of that happening in a diy build, even those using lumia chips or even more powerful emitter arrays.

[Aqualund]

Yeah good points. I guess I saw a few bad apples and assumed it applied to all of them...and attributed probably the wrong causation to it. I only saw the issues with the 430nm and below but it was probably more due to temperature than diffraction.

[pwreef]

I have 5 of these
http://reefll.com/index.php?route=pr...&product_id=51
on a 36" makers heatskink for the past 1 year shining through the standard makers acrylic shield. There are 0 visible changes in that acrylic.

[theatrus]

Good to know pwreef!

I'm the midst of laying out the LM3414 based driver.

Would anyone be interested in the source design files for these boards? I'll be happy to put them up on GitHub or similar, however its not a freeware CAD package so I'm not sure how applicable it will be for everyone.

[aiq25]

Originally Posted by theatrus

Good to know pwreef!

I'm the midst of laying out the LM3414 based driver.

Would anyone be interested in the source design files for these boards? I'll be happy to put them up on GitHub or similar, however its not a freeware CAD package so I'm not sure how applicable it will be for everyone.

I'm interested. What software are you using to lay out the board?

[theatrus]

Originally Posted by aiq25

I'm interested. What software are you using to lay out the board?

Using an older version of Altium. But I'll happy farm out a Protel compatible set of files, and gerbers, under a CERN license.

Time ran out on the driver board last week, will be touching it up this weekend.

[theatrus]

Updates on the LM3414 driver layout:

[theatrus]

I've started populating all of the stuff in this GitHub repo under the CERN Open Hardware license.

https://github.com/theatrus/ledbrick

Gerbers, PDFs, drills and a netlist file for the emitter are included. I can provide several CAD export formats (no Eagle, sorry) - let me know what you want and I may be able to provide

[Electrobes]

I may not understand all of what it going on, but this is a fantastic thread for the visuals alone. Thanks for sharing, I love DIY and this is a fun read!

[theatrus]

Thanks Electrobes!

I pulled the trigger on a set of OSHPark boards (being Chinese new year and all its the best bet):



I'll report back when I have the actual boards in hand :-)

[theatrus]

Update: Got the driver board, but not all of the parts yet!

For future revisions, there is plenty of space to stick the microcontroller + related functionality. Going to keep with the stacked design for now.