Quote Originally Posted by DreadedHermie
Here's the last one that got eaten...
"Going back a ways to ask:

Ever get the lenses you were waiting on?

Yes,
and no.
Got the lenses, but they were not what I wanted.

Boneheads set them in a black plastic collar that gets very hot very fast.
(This bonehead, read all about that and ordered them anyway)
I'm looking for those little parabolic reflectors that are used in mini-mag flashlights. They can be shimmed for different spread angles and run much cooler than refractive lenses, when clean.

You gonna add small heatsinks to the triacs in your dimmers?

Um, I mis-spoke when I called 'em triacs.
(I'm used to dimming AC)
This being DC, they are prolly SCRs or SCSs
Full-on the voltage drop across them is about .7 V.
At 6 Amps that's only 4.2 Watts.
Now that they are in the airstream, they run quite cool without any added 'sinks..


It's surprising they'll operate like that.

Not too. They are, after all, "little Off n onnies"
Very low Vf when on, and 0.0 current when off


I belive I'll glue additional sinkage to my meanwells once I get the hang of crippling my epoxy bond. Then I can bust 'em back off to reassemble the case if desired.

How about a "show us yer UFO's guts" comparison thread? Better still, with the actual power consumption included, and price paid. That's prolly the only way we'll get any "truth in advertising" out of these hucksters. I'll bet there's a dozen varieties being sold under double that many brand names.

That's a very good idea!

Looks like you tacked down your leds with an extra spot of glue close to the solder pads. Probably really helps keep the bastids from squirming around as you try to work with them. My question: is that thermal epoxy, or the "other" stuff you're using (which I assume is Devcon 5 minute epoxy or something similar) to secure your leads to the heatsink.

That's just plain old, cut it off with a razor, stickum

Another question: (sorry, been saving these up for awhile ) Do you have a plan / technique for accessing the leds individually after you connected them in the 2 parallel strings? (Like to retest after a month of burn-in) Or are they staying permanently wired up once you connect the strings?

Yes, the wiring is semi-permanent as it stands.:rastasmoke:
I used removable stickum just in case my "even-ing" scheme was a wild pipe dream.

The scheme;
I tested and labeled each emitter then arranged them with the "Hottest" ones, (those with the lowest Vf. at 1.25A), at the end of the buss. Then fed them only from the cool end.
Each emitter added it's current load which increased the voltage drop in the supply wire. Putting the "hotter" ones at the end allows me to keep a good match in output of the emitters that _should_ hold as the unit ages
Had all the emitters matched, I'd have tied both ends of the + and - bus to the power supply and used heavier gauge buss wires.

I ran a "+ and -" lead to each led and tacked it down in one place with epoxy. I ran each pair of wires around to the fin / topside of the light and connected them there so I could group them according to Vf. With more than 6+2 wire pairs this may get a little sloppy looking (especially with the free-air-architecture wiring technique). "

Yep, using the wire resistance to "even out the bumps" allowed the shroud some free air flow.
And that solved my heat problem.
Kinda.
2 days of cookin' with the bloomery sealed and temps stayin' around 80 had me happy.
Then I looked in around noon and the room was 94 F. and the color was wrong!
Only the 2 blues were lit.

Unlikely that both dimmers would fail and the blues have their own power module.
So, gotta be the 12V. 21 Amp supply. 'cause the fan was down too.
Though I had placed the supply right under a ceiling vent,
It still got hot enough at 14 Amps draw, to trigger a thermal shutdown! Dang!
That supply now has it's own 120 mm. muffin fan and runs cool to the touch.

This will free up one of my earlier arrays for use in a clonery

Just lit this message up and hit control-C for luck.
Weeze takes a deep breath and...
Yay! The preview worked.
l8r
Weezard
Weezard Reviewed by Weezard on . Calling out to Weezard for LED advice My friend, I've read your stuff here and at Steve F.'s site. I want to build a dedicated flowering lamp using Ledengin 15 watters. (4 reds, 1 blue, and possibly 1 warm white; LM 317's so I can tweak the ratios.) Essentially, a copy of your 4+1 cake pan lamp but built on a 4 x 18" finned heatsink so I can see what's going on under it.) If I were to post my picks for power supply, resistor ratings / values, etc., would you critique and perhaps offer some guidance? I have already purchased Rating: 5