Pop wrote:

"Jeff Wisnia" wrote in message
...
: Ike wrote:
:
: We have Malibu landscape lighting and the bulbs burn out
after only
: about two months of service. They are very bright compared to
my
: neighbor's Malibu lights and he only replaces bulbs about
once a year.
: When the landscapers installed our lights they did not use
the wiring
: that came with the set. Instead, they used their own wiring
which is a
: much larger gauge resulting in less voltage drop by the time
the
: current reaches the lights. I am sure they thought they were
doing me
: a favor, but their generosity appears to have worked against
the life
: of the bulbs. Is there a simple solution to drop the voltage
enough so
: these bulbs don't burn so hot? Would a standard light dimmer
for 120
: VAC work to adjust the 12 VDC voltage?
:
: If you happen to have another transformer with a 120 volt
primary and a
: 12 or 24 volt secondary lying around you could wire it up as an
: autotransformer to subtract 12 or 24 volts from the 120 volt
line and
: use that reduced voltage as the supply voltage to the
transformer
: feeding the lights.
:
: The added transformer's secondary current rating has to be at
least as
: large as the primary current the exixting transformer draws of
course.
:
: Jeff

Where the hell did you go to school? There was no course on
common sense or safety, was there? Or, umm, more likely you're
"self" taught? Keep learning!


:
: --
: Jeffry Wisnia
:
: (W1BSV + Brass Rat '57 EE)
:
: "Truth exists; only falsehood has to be invented."



If you knew anything about college education Pop, you'd recognize that
my sig line indicates I'm an MIT electrical engineering grad without my
screaming it out. (And FWIW I hold a masters in the same field from an
Ivy League school to boot.)

You not even know what an autotransformer is Pop, but I can tell you
that back in the '50s I installed at least ten of them ahead of TV sets
and expensive home audio equipment to reduce the overly high line
voltage present on the lower floors of a high rise apartment building in
Cambridge, Taxachusetts. They were wired eggsackly the way I described
in my post.

There was a lot of line drop in that building's wiring, and the owners
had played with the supply transformer taps so the upper floor's line
voltage wouldn't sag too low. That caused the voltage to be up around
135 volts on the lower floors ... The building's manager had a nice
little side business going. He was stocking and selling high voltage
light bulbs to the tenants on those floors. G

That high line voltage raised hell with the filaments in the vacuum tube
electronics of that era, just like it appears it might be doing with the
OP's light bulbs.

If you think you're right about decrying my advice Pop, let's hear you
tell us why you think it's unsafe if done in a workmanlike manner using
a transformer with adequate winding insulation ratings.

Otherwise, kindly STFU.


Happy Holidays,

Jeff

--
Jeffry Wisnia

(W1BSV + Brass Rat '57 EE)

"Truth exists; only falsehood has to be invented."