Dimming a 6V bulb by half.

[Watson A.Name - "Watt Sun]

In article <965893c3b7116e42b340314e85596346@news.bubbanews.com>,
Toush@hi.com mentioned...

My spot light is too bright (500,000CD). I like to dim it down when-
ever I toggle a switch. It uses a 6 volt lead-battery with a 25W bulb.
I'm trying to dim this in the most simplest way. How could I build one
that could dim the light by half? I have resistors, mosfet, etc.
TIA, Tibur

Duct tape works well. ;-) Just cover up half the lens.

It's likely that the bulb is halogen, and if you reduce the voltage to
it, the bulb's life will be shortened, and the light will turn yellow
or amber.


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[Don Klipstein]

In article <MPG.1a758177b1420383989b54@news.dslextreme.com>, Watson
A.Name - "Watt Sun, Dark Remover" wrote:

In article <965893c3b7116e42b340314e85596346@news.bubbanews.com>,
Toush@hi.com mentioned...
My spot light is too bright (500,000CD). I like to dim it down when-
ever I toggle a switch. It uses a 6 volt lead-battery with a 25W bulb.
I'm trying to dim this in the most simplest way. How could I build one
that could dim the light by half? I have resistors, mosfet, etc.
TIA, Tibur

Duct tape works well. ;-) Just cover up half the lens.

It's likely that the bulb is halogen, and if you reduce the voltage to
it, the bulb's life will be shortened, and the light will turn yellow
or amber.

Theoretically, halogen bulbs work when underpowered. Filament
evaporation slows down more than the halogen cycle does. The main thing
that goes wrong is that the halogen attacks the ends of the filament and
moves material from the ends to the main region of the filament, so
life expectancy may not increase much from dimming.

One thing that sometimes goes wrong in practice is contaminants doing a
"reverse halogen cycle", and this requires close to full operating
temperature for the normal halogen cycle to outrun the contaminants.
Halogen lamps made by the established major manufacturers of them can
usually be dimmed significantly without blackening.

- Don Klipstein (don@misty.com)