Eric M. Jones
Joined: 10 Jan 2006 Posts: 565 Location: Massachusetts
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Posted: Thu Dec 24, 2009 1:32 pm Post subject: A Christmas Current Regulator for All..... |
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Happy Holidays.
This is a noise-free current regulator that will power up to three LEDs in series such as the Cree 350-700 lumens stars. ~2100 (maybe) lumens!
I have made a few of these to replace noisey Buck_Pucks. I don't have any plans to sell as a product, but you can make your own or get together with friends and make a bunch (Okay, nerds have odd choices of how to have fun get-togethers).
This uses the isolated form of the 317 Regulator. If you use the standard (non-isolated) part it is more trouble.
Design notes: This is a modified surface-mount assembly used to keep everything flat against the heat sink. Make sure the 317 gets a dab of heat sink compound.
Keep the resistor up in the air. It gets very hot. I recommend flowing epoxy over the pcb and 317 leads. You can use RTV, but don't use J-B Weld (I never thought I'd have to say that...) because it is slightly electrically conductive.
Standard issues apply--keep the leads from chaffing. I used rubber grommets super-glued in the fingers of the heat sink. This heat sink is good for 1-3 LEDs at 14.5VDC, or 6 or so at 28VDC.
I'll send the ExpressPCB file as an attachment if you email me, but this is easy to carve out of plated circuit board. Only a single-sided board is required, but you'll get a double sided-board from ExpressPCB. Forty-eight circuits for $1.25 each delivered in a few days. Cool....
Aficionados will note that different versions of voltage regulators will work for improved performance in some areas or even higher power. Yes...go for it.
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Description: |
PDF file of current regulator |
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currentregulators.pdf |
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79.81 KB |
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_________________ Eric M. Jones
www.PerihelionDesign.com
113 Brentwood Drive
Southbridge, MA 01550
(508) 764-2072
emjones(at)charter.net |
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