AC signal across 12V (DC) halogen bulbs?

[allanlewis]

Hi,

I have a lighting controller circuit using an H-bridge, which produces
a 250Hz signal across a pair of 12V halogen bulbs. (The duty cycle is
controller by a microcontroller, but this is irrelevant to my
question.)

My question is: is a 250Hz signal with rise/fall times <100us damaging
to the bulbs? If so, what can I do to remedy this? I've tried an LC
filter (10-100uH, 100-1000uF) and this gives rise/fall times of
~500us. Is there any value in doing this, or is there something else I
should do to prolong the life of the bulbs?

Thanks,
Allan Lewis.

 

[Wiebe Cazemier]

On Monday 28 April 2008 16:23, allanlewis wrote:

Hi,

I have a lighting controller circuit using an H-bridge, which produces
a 250Hz signal across a pair of 12V halogen bulbs. (The duty cycle is
controller by a microcontroller, but this is irrelevant to my
question.)

My question is: is a 250Hz signal with rise/fall times <100us damaging
to the bulbs? If so, what can I do to remedy this? I've tried an LC
filter (10-100uH, 100-1000uF) and this gives rise/fall times of
~500us. Is there any value in doing this, or is there something else I
should do to prolong the life of the bulbs?

Thanks,
Allan Lewis.

I think if the temperature of the filament remains constant, there is no extra
wear on it. Meaning, as long as it doesn't flicker, there is no problem.