[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [APD] LED Lighting

Message: 11
Date: Mon, 29 Dec 2003 16:17:48 -0800 (PST)
From: "S. Hieber" <shieber at yahoo_com>
Subject: Re: [APD] LED Lighting
To: aquatic plants digest <aquatic-plants at actwin_com>

--- Wright Huntley <whuntley at verizon_net> wrote:

> Message: 6
> Date: Mon, 29 Dec 2003 13:14:57 -0800 (PST)
> From: "S. Hieber" <shieber at yahoo_com>
> Subject: Re: [APD] LED Lighting
> To: aquatic plants digest <aquatic-plants at actwin_com>

. . .It certainly isn't up with the CF lamps I was immersing a
couple of years ago. Those carried some truly lethal Voltages/currents
and the current in water would have been more than non-trivial!

You were putting your bulbs in the water on purpose? I know
this is done with sleeveless UV lamps but don't recall any
other examples.  If intentional, what were you up to?

No. Not in water. I had them in a plastic tube, but sweated a lot about the hazard if one leaked or cracked open.

Illumination from below the water line is very unrestricted by such nasty optical effects as light-piping. You have never really seen them until you see a herd of Rasboras (I like the *espeis* that Amanosan prefers), illuminated from inside the tank. I love Lampeye killifish and most of them become spectacular when the light is no-longer propagating straight downward. Like windowlight, but way better.

> Wright do you really think transistors are needed in a
> power supply? Low voltage DC, a rectifier and some
> resistors ought to do the job. But with enough to light


> tank, even the resistors would be redundant, no?

The high impedance of a transistor collector is probably
cheaper than all the stuff you have suggested. Don't forget that
transistors are often way cheaper than resistors, these days, unless you
want individually packaged ones. Resistors can act as
current sources, but must waste a lot of power to do so, and I find extra
heat a problem with most lamps. A 5V wall wart with a simple transistor
array driving arrays of several LEDs in series is a pretty cheap
"ballast" as such things go. Yes it needs at least one or two resistors,
but they need not be conducting all that current and creating heat.

My ideas may be a bit overdone,

Not overdone if you supply us with some schematics. I can
solder but I can't design the circuit

Find me a cheap supply of LEDs and I'll work on it. :-)

but I would like to
roughly regulate the current to maintain constant output with age, temp, etc.

And to keep things kosher when one or more of the LEDs goes

That is pretty rare, which is why cities like them for traffic control. Ever seen a burned out one in a traffic light? :-)

Wouldn't that be kind of nice? Cheap, too, I suspect, compared to the
cost of the LEDs. Traffic lights have made red and green into cheap
commodities, but good blue is still a big problem, both in cost and maybe
lifetime. Cheap 10,000 K may still be a way off.

I see more problems working out mountings and attractive
housing. How do we keep food from fouling them, etc.? Will algae quickly
grow on the plastic lens and turn them off?

You could keep them above water, no?

I wouldn't be interested, having experienced the advantages of immersed lighting. <g>

Gotta go chop some wood. Came home from So.CA to
frozen-up water lines, last night.

Sorry to hear that. Beena there; mopped that.

Luckily no burst, just no flushing for an uncomfortable span. :-)

Finally cleared by this afternoon, but the
snow level is down about 100' above the valley floor and dropping. Come
to think of it, I'd like some lights that put out a *lot* of heat,
right now.

Think Incadescent, think heat

My reading lamp by the bed is a 100W halogen. Feels nice and toasty now, but have to move it away in August.


Wright Huntley -- 760 872-3995 -- Rt. 001 Box K36, Bishop CA 93514

_______________________________________________ Aquatic-Plants mailing list Aquatic-Plants at actwin_com http://www.actwin.com/mailman/listinfo.cgi/aquatic-plants