Calling out to Weezard for LED advice

[DreadedHermie]

Weezard, I don't know much about electronics, but I can solder WAY better than your average bear. I've got a Weller WESD51 digital station and Cardas Audio Quad Eutectic solder. Cardas advises a small wattage pencil @ 700 deg F. for small connections. There's not that much total heat to dissipate but it gets the connection done quickly. It's worked well for me in the past. Looks like a piece of cake to me. I didn't want to use bigger supply wire than necessary 'cos to avoid dissipating excess heat into the the device (?)
I've got a big-ass gun too, but I wouldn't put that many watts on such a small package unless necessary. What say you?

[Weezard]

The PCB is so flexible, can't I just lift up the solder pad end and slip something between the pad and the heatsink while I solder? I've only just now attached one LED and only cemented pad behind the emitters, not the entire body of the device.

Seemed easier than having the thing squirm around while I try to attach the wires, then fighting the wires while I try to glue the LEDs down(?)

Like the man said. "typed before I thought"
It's the ledengine beeg boys, ya?
Glue away .

Ignore the doddering stoner that was obviously thinking 5 Watt MCBs.

I think it was the washers trick that threw me.
I just used a fat rubberband for mine.

I'll try to pay mo' betta attention, but :stoned:...

Lolo Weeze

[Weezard]

Weezard, I don't know much about electronics, but I can solder WAY better than your average bear. I've got a Weller WESD51 digital station and Cardas Audio Quad Eutectic solder. Cardas advises a small wattage pencil @ 700 deg F. for small connections. There's not that much total heat to dissipate but it gets the connection done quickly. It's worked well for me in the past. Looks like a piece of cake to me. I didn't want to use bigger supply wire than necessary 'cos to avoid dissipating excess heat into the the device (?)
I've got a big-ass gun too, but I wouldn't put that many watts on such a small package unless necessary. What say you?

Again, disregard my soldering mis-adventures.
I glued a batch of 5 Watt MPCBs to a heatsink before soldering on my first array and am still kickin' myself over it.
:weedpoke::jointsmile: :rastasmoke: :smokin: :rasta: :stoned: :S5: :bigsmoke: :error:
The 20 guage wire between leds is jus' peachy.
It's the long run, (from supply to the lamp) that I would use 16 g. for.
Because it's cheap, readily available and overkill.

In a fog
Weezard

[DreadedHermie]

Not too happy with my first glue joint. A little thicker than I would have liked.

Gonna dash off to the hardware and get some wire, I need one more color so I can keep Blue LED + and - and Red LED + and - easily identifiable. If you have time to check back in later, I'd feel a bit more confident. It'll be a few hours but I'd like to at least test fire this baby tonight! :yippee:

[DreadedHermie]

It's the long run, (from supply to the lamp) that I would use 16 g. for.

Actually, I found some 2 conductor 14 ga with a nice flexible jacket called "low voltage wire" which I think is intended for decorative lighting. Not sure what my eventual driver situation will be but for running 6 LEDs off my bench supply I think I'll use that. It's such a short run, I can be extravagant for 6 feet!

I may run a separate 16 g. to each pair of LEDs, that'll be easy to work out once I've got parts in hand.

[DreadedHermie]

It's been an expensive night so far. :sadcrying I got everything glued onto the heatsink. The first joint which I thought was too thick was actually OK, but I somehow killed that LED anyway.

First, I set the Mastech to full volts, no amps. I just touched the probes to a red LED. It lit briefly, not super bright, but when I tried it a second time, nothing. I could see one of the 4 emitters was darkened--it was fried. It was almost like the power supply gave it a capacitive discharge.

I fired up the other reds, one a time, with no problems. Let them burn in for awhile; they were fairly consistent 10.8V giving 1.2A and 11.2-3V giving 1.5A. Then, on one of many go-rounds, that first one I glued failed to light. On examination, that one also had one cooked quadrant.

The wire I was using was so stiff it was really manhandling the LEDs. I tried to hold off on attaching the wires to the sink cause I hadn't had a chance too really think about they'd be routed: through a hole, around the side, etc. I managed to rip a solder pad each off two of them. Fortunately, I was able to scrale down to the trace and get a lead soldered to them. That's when I decided to go ahead and just use some thermal epoxy to secure the wires near the LEDs for some strain relief.

Gets worse. Still online?

[DreadedHermie]

Cause I cooked them, too. Both of 'em. :sadcrying

They were working fine, although they wern't too close electrically.
Blue#1: 15.2V gave 1.5A, 14.7V gave 1.2A
Blue #2: 15.6v gave 1.5A, 15.1V gave 1.2A

I ran them singly, and together, and let 'em burn in for awhile. Here's where I must have made a mistake, but then I'm still not sure how these CC / CV supplies are "bending" the "law." It seemed like the pair should be able to handle 3A between them. 14.8V gave 2.2A when I dialed it in. I played around near those parametersfor awhile, disconnected them (spike there somehow?) and when I tried to reignite them, they too had one "corner" out.
So the blues are history, too. :i feel stupid:

Not really sure why I've had such a destructive night. I've still got 3 working reds, but now I don't want to hook them up as a group without some advice. Should 3 of them be able to take 3.6A at 10.8V, or will this PS somehow feed 3.6A to each of them?

[Weezard]

Wow! you are having one expensive night.
The 1.5A rating is the absolute max and is not usually do-able in real life.
So, in order to push an emitter to abs max current one might have to exceed Vf max.
That will show no mercy. a millisecond is too long
Ouch, brah!

[Weezard]

Cause I cooked them, too. Both of 'em. :sadcrying

They were working fine, although they wern't too close electrically.
Blue#1: 15.2V gave 1.5A, 14.7V gave 1.2A
Blue #2: 15.6v gave 1.5A, 15.1V gave 1.2A

A .48 ohm resistor in series with Blue #1 would have balanced the two emitters in parallel at 15.1 V.

I ran them singly, and together, and let 'em burn in for awhile. Here's where I must have made a mistake, but then I'm still not sure how these CC / CV supplies are "bending" the "law." It seemed like the pair should be able to handle 3A between them. 14.8V gave 2.2A when I dialed it in. I played around near those parametersfor awhile, disconnected them (spike there somehow?) and when I tried to reignite them, they too had one "corner" out.
So the blues are history, too. :i feel stupid:

Not really sure why I've had such a destructive night. I've still got 3 working reds, but now I don't want to hook them up as a group without some advice. Should 3 of them be able to take 3.6A at 10.8V, or will this PS somehow feed 3.6A to each of them?

If they draw 1.2A at 10.8V within .1 V. each, then 3 in parallel should divide the 3.6 A. draw almost equally.
I'm wondering if you are getting zapped by static electricity.
These pups will not tolerated much reverse bias. and should be treated like cmos when handled.
That means no shoes and/or a wrist strap.
Never did ask where you are from.
Most of the mainland is cold and low humidity in February.
Perfect conditions for zapping LEDs.

[DreadedHermie]

Don't think it's static. Hot and humid here, all year long. (That's why I need the LEDs.) Dirty power's probably at least as likely, and I don't think that's it either. The problems occur when I hook up multiple LEDs. And they never seem to "blow" while they're operating.

When I got started, I deliberated toasted a whole grab bag of Radio Shack cheapies just so I'd get a feel for how it happens. This is strange. They seem to be working okay, and when I go to start 'em up again, nothing happens. On exam, they're cooked. I 4 x color-coded the wires so I'd be able to easily tell 'em apart--pretty certain I didn't reverse-bias 'em, too.

Maybe I "milliseconded" them by accident. In that case do they keep working but refuse to fire up next time?