Elektor electronics april 1994 has a project 'Halogen Light Dimmer'
which is an ordinary analog dimmer circuit that goes between the
mains and the transformer. Only difference is that it triggers the triac
with a burst of pulses in case the triggering would occur when the current
is zero (due to the inductive, transformer, load).

The article doesn't mention anything about lifetime reduction of the lamp.


> Glenville T. Sawyer wrote:
>
> >However, having been in the Theatre lighting / Electrics industry for a
> few
> >years I would advise AGAINST dimming Low volt' Halogens.
> > unless a halogen lamp is run at its (normal) - preferred
> >operating temperature, you WILL find that the life of the globe / lamp
> is
> > reduced by quite a dramatic amount, these lamps seem ( from Practical
> > experience ) to prefer full voltage - to achieve maximum lifetime
> operation
> > within design parameters.
>
> Are you sure the large high-voltage globes you used in theater work have
> the same charactistics as the miniature low voltage ones being talked
> about here?
>
> One reason I ask is that our local home goods/hardware store sells low
> voltage halogen kits with dimmers.  Are they selling a product that
> damages itself, or is something different about them?  I have no idea
> whether they are or not, does anyone out there know?  One thing I was
> able to see from the packaging is that the dimmer goes between the mains
> and the transformer.
>
> Don Burdette
> dlburdette@juno.com


==============================
Ruben Jvnsson
AB Liros Elektronik
Box 9124, 200 39 Malmv, Sweden
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==============================