🚀 go-pugleaf

"Paul Bealing" <paul@pmb.co.nz> wrote in message
news:TINca.5877$8b.679066@news02.tsnz.net...
> DaveC wrote:
> > I've been asked to help light a small office building hallway. The
> > fluorescent lamps are way too harsh for the office workers, and the
tenants
> > favor the overhead QH approach.
> >
> > I've looked at the local home centers' lighting departments and see
quite a
> > selection of LV systems using overhead steel cable with 3 hanging
reflector
> > bulbs (with a choice of trim, or not) tapped in at appropriate
intervals.
> >
> > Price for the above from $70-100us.
> >
> > Being encouraged by what I saw, I decided to see what I could build from
> > scratch.
> >
> > As you probably can guess, I'm running into current supply/demand
> > limitations. Each of the 2 hallways could use about 15 lamps. Lamps are
> > available in 20 and 50w versions, which at 12v, draw approximately 1.7a
and
> > 4.2a, respectively. I now see why the cost of such a system is mostly
for the
> > supply.
> >
> > Looking for a ready-made 12v supply, I find this at Jameco for $70us
that
> > provides 12.5a:
> >
> > <http://www.jameco.com/cgi-
> >
bin/ncommerce3/ExecMacro/Jameco/searchResult.d2w/report?sort=BPA&search=1234
22
> >
> >
> > This would allow me to run 7 of the 20w lamps, or only 2 of the 50w
lamps.
> >
> > I can't see buying 2 supplies to run the 15 (well, I guess we could rev
that
> > to 14) lamps in each hall. I seem to be butting up against Ohm's Law.
> >
> > Maybe build a simple, unreg'd, analog power supply with massive
transformer
> > and rectifiers for 30A?
> >
> > Any other ideas (or links to sites) to help me reach a solution would be
> > greatly appreciated.
> >
> > Thanks,
>
> I agree with another post; there will be a considerable power waste
> using QH over Fluro.
>
> Remove a few fluro tubes and/or change the rest to a softer colour.
>
> My biggest concern would be the fire risk from all those QH lamps and
> the transformer. How close is the wooden ceiling to the lamps?
>
> I have found that most QH transformers put out 11 to 11.5 volts. If you
> run QH lamps at even slightly more than 12 volts the lamp life will be
> reduced. Most QH lamps already fail well before they should.
>
> I quite like the ease of dimming of QH lamps, but I don't like the high
> heat output, energy consumption and short lamp life when compared to
> fluorescent.
>

Buy lamps with greater power rating and reduce the voltage. This will give
you way longer lifetimes if you can live with the more "warm" spectrum of
light they emmit when driven this way.

Cheers

Klaus