Building LED lights from facts, no theories

[Weezard]

Weez,
So you are saying that I will most likely lose more energy in a LM317 than I would with a sense resistor?

Little bit.

I haven't had the time to really study linear regs, so I am very weak on this subject.

Not that much to know really. Take you about 15 minutes to learn all you need for practical application.

But it just seems to me if you are dropping 2.5 to 4 volts (LM317 instead of 1.5 volts (resistor) at equal currents you are going to dissipate more power.

That is correct.
Don't matter how you do it. V x A = W

Of course the trade off is you are giving up better current regulation.

Exactly!
I don't stress over a Watt or 3.
And a dropping resistor will happily pass-on a voltage spike!
The LEDs may not be quite so happy to receive it.

Knna/Weez- If I go with resistors and 24v VR driver, do I need to be concerned about start up transients damaging LEDs?

In a word? Yes.
Not to mention shut-down spikes, lightening strikes and plain old everyday "gotcha" spikes.
Of course that does depend on the VR supply used, how heavily you load it, and what you feed it.
I'd just rather Pay the piper daily when considering the cost, time and effort of LED replacement.

With voltage controlled devices, I use VR.
With current driven devices ,CC is the best way to go for full control, consistency, and longevity. IMO.

I'd really like to see your multi-source lighting scheme in operation.
It sounds like a good idea.

Aloha,
Weeze

Weezard Reviewed by Weezard on 12-07-2008. Building LED lights from facts, no theories I was going to post this at the Perfect LED Grow Light thread, but as some of what im going to post was posted 2 years ago on the stickied thread about LEDs and people still continue developing lights from wrong ideas, i think a thread about this topic is largelly needed. The main problem is related to efficacy of spectrums. When the firsts LED experiments at Overgrow, we work on the hypothesis that blue and red light are more effective. It was an appealing hypothesis that promises large Rating: 5