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Re: Lighting question. . .

At 15:39 -0400 4/9/97, :Edziu Iskra  wrote <edziu at cybernex_net>:

>I have some extra 12-v mini-halogen fixtures that I've been contemplating
>using on my plant tank.  I've found metal halide to look a bit stark (makes
>corals look a bit bleached, to me), and prefer fluorescents (call me weird),
>but I haven't tried halogen over a tank.  I've seen the spectral
>distribution of halogen lighting, and it very nicely simulates sunlight,
>albeit with a bit of a drop as one approaches the UV end of the spectrum, so
>I'm considering doing mini-halogen, plus an actinic fluorescent.  Also, the
>12-v halogen is relatively efficient (compared to 120-v halogen or
>incandescent).  I haven't been able to find a reference, however, for how
>many lumens I can expect from the halogen bulbs, so I'm not sure how many
>I'll need. . .  True, I can jury-rig a trial, but if I expect to need, say,
>10 bulbs, it may not be worth my bother, as I'd have to get more bulbs,
>additional transformers, etc. . .
>Any comments, advice, suggestions?  And no, I haven't figured out exactly
>how I'm going to set up reflector/s just yet.  8)

They will work fine, however Halogen effiency is poor compared to
flourescent. After all there incandescent bulbs with a halogen gas added to
prevent filament deposition inside the envelope.

Halogens generate a lot of heat, and you have to figure the ineffiency of
the transformer if you use a 12 volt unit. A 120 volt unit should be just
as efficient for a given filament temperature. A 12 volt unit may be able
to sustain a slightly higher filament temperature because the filament can
be much shorter and thicker, therefore it is mechanically stronger. A 120
volt filament is fragile, and hence the designer may elect to run the
filament a little cooler for mechanical strength reasons. Otherwise the
effiency will be the same.


Paul Nicholson               Electronic Imaging Systems, Inc.
TEL 805 532 1068             5148 Commerce Avenue, Unit F
FAX 805 532 1065             Moorpark, CA 93021 U.S.A.
paul at eisusa_com		     http://www.eisusa.com