Help, please... if you can..

I have a number of 20 watt small "spotlights" ....(halogen ... low voltage
wiring) in my backyard. They shine on some trees and bushes. The bulbs go
out all of the time.

Yesterday, I was in Lowes and I saw some LED lights that were shaped
similarly to what I presently own. They were about $15.00 each. A comparable
halogen light costs about ten bucks each. The present light-bulbs cost
about $4.00 each and they go out annually. ...I am thinking about converting
over to the LEDS. The extra cost isn't that much, and I've heard that LEDs
last much longer than incandescent or halogen bulbs. LEDs supposedly also
use far less electricity. Less worry about which bulb is going to go out
next... and the time to replace the blown bulbs...would more than make up
any cost differential, anyhow.

However the box contained NO useful information on wattage/ equivalent light
output/ appropriate input voltage, etc. Of course, there wasn't anyone
anywhere near in the store who might have been able to answer my question.

Has anyone on this group used them? Can you provide any help on whether or
not I can just substitute them for my present system? Any help
appreciated. thanks RichG TX

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In article , "RichG"
wrote:


Yesterday, I was in Lowes and I saw some LED lights that were shaped
similarly to what I presently own. They were about $15.00 each. A comparable
halogen light costs about ten bucks each. The present light-bulbs cost
about $4.00 each and they go out annually. ...I am thinking about converting
over to the LEDS. The extra cost isn't that much, and I've heard that LEDs

However the box contained NO useful information on wattage/ equivalent light
output/ appropriate input voltage, etc. Of course, there wasn't anyone
anywhere near in the store who might have been able to answer my question.

I have not used them, however, I did extensive (web based) research on LED
lighting last August as I plan refurbishing my aquarium lighting systems.

What I found is that it depends. :-)

The very latest white LEDs are very efficient and long lasting. However,
in order to know that you're getting the latest LED technology, you'd have
to do things like identify the LED part numbers in the electrical
engineering literature and datasheets and then determine which LED is
actually used in the light that you're buying. The latter may be
impossible depending on how the manufacturer treats things. Older
technology LEDs are still on teh market and being manufactured.

Until very recently, LEDs were not as efficient at converting electricity
into light as a good fluorescent light. They were about half as
efficient. The very latest bulbs probably approach about the same
efficiency, but you can do just as well on power consumption vs. light
output by using the newer compact fluorescents. In a linear (straight
fluorescent) these are known as T5 bulbs wtih electronic ballasts.

Old style fluorescent ballasts are magnetic (big (relatively big) heavy
coils of wire) ballasts which switch the current on and off relatively
slowly. Electronic components use, well, electronics, to switch the
current on and off at a much higher rate and in fluorescent lights this
leads to higher efficiency than slower switching systems.

Additionally, white LEDs are actually very similar to fluorescents in how
they generate light. A "white" LED is actually a semiconductor (the
electronic chip portion) which emits ultra-violet light. It is surrounded
by a dome or cone or lens coated with chemical phosphors which emit red
green (or yellow) and blue light when excited by UV light. So "white"
LEDs don't actually produce white light directly. They produce UV
directly and convert it to a mix of light frequencies which approximate
white using these chemical phosphors. Over time the phosphors wear
out. First they lose efficiency.

Early white LEDs wore out very quickly--less than a year to a significant
(20% or more, sometimes 50%) reduction in light emissions. The latest
ones have mostly solved the phosphor durability issues.

Sooo, if the packaged lights you buy are based on the latest LED
technology, then there's a pretty good chance that it will be about as
efficient and long lasting as a compact fluorescent light bulb. If the
wattage is listed on the bulbs/fixtures, you can assume it's about as
efficient as an equivalent wattage CF bulb, which is about 4 - 7 times as
efficient as a same wattage incandescent bulb.

I don't know how that converts to halogen bulb wattages because I never
considered halogens for aquarium lighting.

Finally, they sell compact fluorescent style spot lights. It's a CF light
spiral, like a normal bulb, in front of a cone shaped reflector. You
could just get those, they're widely available and much simpler, though
not low voltage. The main disadvantage of CF spotlights is that the
reflector and lens is made out of ridiculously thin glass/plastic (it's
not holding a vacuum like an incandescent spotlight, so the glass doesn't
need strength) and they are very fragile. The light emitting portion is
strong (and holding a vacuum), but the surrounding reflector is stupidly
delicate. I went back to incandescents after breaking two of the CF spot
lights--tap against the bricks below the spotlight fixture and
shatter. An incandescent light doesn't do that.

Jeff Walther

--
A friend will help you move. A real friend will help you move a body.