LEDBrick Project - DIY pendant w/ pucks
- Thread starter theatrus
- Start date
Maryland Guppy
New member
Looks great!
My board has had little progress lately.
Too much going on, selling condo, daughter school/prom, truck died etc...
Soon I will buy components and etch a board.
I am still going to use the 5 pin package though.
Been contemplating a LED array for a planted tank.
Much research on Cree diodes lately, low $ is the ticket though.
My board has had little progress lately.
Too much going on, selling condo, daughter school/prom, truck died etc...
Soon I will buy components and etch a board.
I am still going to use the 5 pin package though.
Been contemplating a LED array for a planted tank.
Much research on Cree diodes lately, low $ is the ticket though.
theatrus
100-mile-commuter
Running on a 4-channel star:
This was a ~ 50% duty cycle test - 4x full 1A channels, going from a 24V supply to a 9-16V LED Vf. This is a "not great" efficiency situation and it shows, the board gets *quite* toasty (you wouldn't want to hold it). This is the middle-range MSOP package as well, the SOT-23-5 would have entered thermal shutdown a long time ago.
This was a ~ 50% duty cycle test - 4x full 1A channels, going from a 24V supply to a 9-16V LED Vf. This is a "not great" efficiency situation and it shows, the board gets *quite* toasty (you wouldn't want to hold it). This is the middle-range MSOP package as well, the SOT-23-5 would have entered thermal shutdown a long time ago.
theatrus
100-mile-commuter
theatrus
100-mile-commuter
Observations:
I made another silk screen goof, it was supposed to be +38V max not +28V. Yes, fully compatible with 36V supplies for more LEDs in series.
Thermally, the driver is dropping about 1W per channel at full power, which gets things toasty. Putting it into a sealed box would be bad news, but in a ventilated enclosure junction temperature remains acceptable.
I made another silk screen goof, it was supposed to be +38V max not +28V. Yes, fully compatible with 36V supplies for more LEDs in series.
Thermally, the driver is dropping about 1W per channel at full power, which gets things toasty. Putting it into a sealed box would be bad news, but in a ventilated enclosure junction temperature remains acceptable.
martinm878
New member
just read thru 14 pages of awesomeness!!!! amazing builds, this is what a DIY is all about design, build, redesign, build, improve! going to message you for some info.
theatrus
100-mile-commuter
Touché
I'm looking at a thermal pad from the bottom layer to a case or heatsink.
LOL- That's what I had to do. I created a solder/ thermal pad on the boards bottom layer (measuring 12mm X 14mm) connected to the chip with a single large via. I then solder on a 12 X 14mm copper heat sink (meant for RAM cooling apps) or use a larger aluminum sink attached with paste/screws. Either one works fine, provided the heat sink receives at least a whisper of airflow or convection currents.
theatrus
100-mile-commuter
No new LED shots this time, working on some more color arrangements for the very popular 16-up boards.
But part of the original impetus of this project was DIY pendant lights, smaller and sleeker the better.
Here is my current line of thinking:
Using this round heat-sink stock (from heatsinkusa), mount a new two channel layout of the basic driver from above on top of the heatsink (which will easily fit), augmented with a 24->12V DC/DC converter to supply a small fan (convection alone will limit peak power) - there are small inexpensive fans for compact lighting out there (example: http://www.digikey.com/product-detail/en/sunon-fans/HA40101V3-E00U-A99/259-1584-ND/3466804 )
To add a finishing touch, use a thin-wall 2.5"OD (less ID) aluminum pipe section to wrap it all. Home anodize or otherwise brush the pipe/paint.
But part of the original impetus of this project was DIY pendant lights, smaller and sleeker the better.
Here is my current line of thinking:
Using this round heat-sink stock (from heatsinkusa), mount a new two channel layout of the basic driver from above on top of the heatsink (which will easily fit), augmented with a 24->12V DC/DC converter to supply a small fan (convection alone will limit peak power) - there are small inexpensive fans for compact lighting out there (example: http://www.digikey.com/product-detail/en/sunon-fans/HA40101V3-E00U-A99/259-1584-ND/3466804 )
To add a finishing touch, use a thin-wall 2.5"OD (less ID) aluminum pipe section to wrap it all. Home anodize or otherwise brush the pipe/paint.
theatrus
100-mile-commuter
theatrus
100-mile-commuter
Depends on what power levels you're pushing of course, but at anything more than about 7-10W I'd personally strongly recommend it. If you're lighting a <10g cube with the 8-up or Fredfish layout you could probably run fanless if you kept it in the open air.
If you wanted to suspend it via a cable you could probably even use the braided string in a Cat5/6 cable as it doesn't weigh all that much.
I ordered some brass (shiny!) and aluminum tubing at 2.5in OD to experiment with how to put it all together.
theatrus
100-mile-commuter
Will need to do tests - unless you want it much bigger, it will all depend on airflow, which is a lot harder to model.
theatrus
100-mile-commuter
My thermal workaround for those of you using larger heatsinks for the driver. This doesn't need any air circulation. Its a 4.5mm thick, single sided adhesive thermal pad. Spendy at about $1.70, but it fits (mostly) nicely on the bottom, if you're mounting the driver to a heatsink or T-slot setup.
Still experimenting with the driver setup - this will work nicely for one of the builds I want to do, but its not ideal yet.
Still experimenting with the driver setup - this will work nicely for one of the builds I want to do, but its not ideal yet.
