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Re: [APD] LED Lighting

--- 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?

> > 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
> a
> > 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  ;-)

> 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

> 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?
> 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.

> 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 ;-)
Scott H.

S. Hieber

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