Re: [photo-3d] Re: Halogen viewer bulbs

["John A. Rupkalvis" <stereoscope@xxxxxxxxxxxxx>]

> ...According to one theory, improved
> life in halogen bulbs is achieved if the bulbs are
> used at their rated voltage (not lower).  However,
> every bulb will last longer if used at less than
> the rated voltage.
>
> George Themelis

True, if burnout is used as the only criterion for determining a bulb's
life.  All filament type bulbs, including halogens will likely last longer
(keep burning) at a lower voltage.

However, the halogen cycle (which is what keeps the bulb from blackening or
changing color) is dependent upon a certain minimum heat to work.  Operating
the bulb at lower than the rated voltage, which means cooler operation, will
shut down the halogen cycle.  Then, the bulb will darken before its normal
service life has been completed.  It will also operate at a warmer (redder)
color temperature.  It will then actually put out less lumens than a
comparable conventional bulb of the same rating until actual burnout.
Lower voltage = cooler operating temperature = warmer color temperature =
premature blackening = shorter useful service life.  Operating a halogen at
its rated voltage should normally give it a longer useful service life.

JR


 

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