Quote Originally Posted by Ken Nadvornick View Post
I have no expertise in electrical engineering, but have wondered about this for a while. Would there be any benefit(s) to running an enlarger lamp on 12-volt DC current only? Like marine or RV vehicles do it?

I would think that an inexpensive automobile battery and a trickle charger to keep it topped could easily handle a normal darkroom session. The bulb would not be subjected to the normal AC current swings. There would be no power grid fluctuations to mess with those delicate highlight values. And heck, if you used a mechanical timer you could even print during power outages.

But would the bulb last any longer?

[Edit: Oops. I see that 'bernard_L' already mentions this in passing in post #6...]

Ken
A 12V bulb doesn't care whether it's running on DC or AC. You wouldn't get the higher turn-on peaks with DC that you get with AC so it'd be less likely (but not impossible) for it to pop at turn-on. But don't forget that a car battery is really something like 13.6V, a bit higher with a charger running. Bulb life goes inversely with the twelfth power of the voltage so the lifetime would be reduced by 80% running at 13.6V relative to 12V.

A 120V bulb running on 12V would be very dim indeed, but would probably outlast your great-grandchildren.

I've gotta build that zero-voltage-switch thing, maybe over Christmas as my employer kicks us all out for two weeks.