On Mon, 27 Jan 2003 21:25:07 -0500, "Claude" wrote:
I thought those were kinda cool too, instructions pleeeeaassseee
Okay, here goes...
First, I use a real transformer for power - not a switching power
supply. I _think_ that for 12V Malibu lights they are selling
switching power supplies as "transformers", but the former are less
reliable and don't provide the electrical isolation from the power
line that real copper & iron transformers do. Of couse, the
transformer is powered from a GFI outlet.. That out of the way...
I run my underwater lamps from half-wave rectified 12VAC.
That is, between the 12VAC transformer and the bulb I place a diode.
This cuts the power to the bulb in half. The result is that the bulbs
run much cooler and should last just short of forever. The downside
is that it might cause the tungsten to prematurely coat the inside of
the bulb resulting in the bulb lasting a lot shorter than forever.
Time will tell. I do think it important to underpower the bulb to
keep it cooler as the quartz bulbs used normally run very hot and in
air, but I'll be running them underwater - essentially an infinite
heatsink. I'm trying to reduce the temperature difference as much
as practical. I'm using a bridge rectifier for the diode, 35A 1KV.
Two legs of the bridge are used to balance the load between two
circuits of lamps. The bridge is bolted to a small heatsink. I can
explain this more clearly later if needed.
For cord I use type SOOW, which is supposed to be rated for
underwater, or at least really really wet use.
For bulbs I use quartz bulbs from Home Depot. I tested 10W, 20W, 35W
and 50W bulbs. In my pond 35W and 50W were too bright. 10W and 17.5W
(35W with diode) were too dim. 20W and 25W (50W with diode) were just
right. So, 50W quartz bulbs run at 25W (half-wave rectified 12V) were
used. By the way - these are the 7 lights used around the perimeter
of the pond. The light inside of the center fountain is built exactly
the same way but with a 100W bulb run at 50W.
See
http://www.kissingfrogs.tv - download time is long as there are
lots of photos - sorry about that!
The lamp pins are soldered to the cord. Use solder with a good active
flux and a hot iron as the lamp pins weren't intended to be soldered,
but I had no problems. For my installation I made assemblies of lamps
with 3-foot cords. The cords drape over the liner and pass through a
groove in the bottom of the lightweight concrete 'bench-tops' that
circle the pond. (See web site.) The seven cords tap into a main
cord circling the pond.
The soldered pins and the short length of stripped cord are coated
with underwater sealant. This is built up in a few layers (it cures
slowly) before a 6-inch length of Teflon flooding heatshrink is placed
over the lamp and cord. This is shrunk with a very hot heat gun as
Teflon heatshrink takes quite a bit of heat to shrink. While
shrinking, crimp closed the half-inch of heatshrink that sticks out
past the bulb. This seals off that end of the assembly. By the way -
flooding heatshrink has an inner coating that liquifies when shrinking
to provide a watertight seal. I used p/n 7960K38 from McMaster-Carr.
It's expensive - $10 per 6-inch length, but does the job. (This ain't
no cheap hobby!) Yes - McMaster-Carr will sell to individuals. I got
the cord there too - p/n 7081K14 and the underwater sealant - p/n
7475A67.
For 'fixtures' I used 9-inch lengths of 1"x1" angle aluminum. I
cable-clamped the lamp assembly into the corner. These fixtures
fastened to thinner broad aluminum strips that were bent to hook over
the liner. The visible portions are painted black. Hardware is
stainless steel, including the cable clamps.
At night the lights look really really cool. They are fashioned and
positioned so that they don't shine in your eyes, but light up the
entire pond. Their beamwidth is 180-degrees. I think the pond looks
even better at night than it does during the day. All the fish are
clearly visible everywhere in the pond.
I'm sure I forgot something!
Steve J. Noll | Ventura California (zone 10)
| Glass Block Pond
http://www.kissingfrogs.tv