Voltage Stabilizer Options

[aduncanson]

I fired up my 8x10 Elwood with its 500 Watt incandescent bulb to make a print for the first time the other day and after making a test strip and deciding on an exposure time, I put an 11x14 sheet of Oriental Seagull in place on the easel and started the exposure. As I watched the image projected on the paper it was clear that my electrical supply voltage abruptly dropped and that my exposure was not going to be good.

I suppose that I could look for a Zone VI timer, but that is not my preferred approach. Is there an inexpensive (~$80) voltage stabilizer available. Does anybody make due with a computer Uninteruptable Power Supply?

Thanks for your help - Alan

[photographs42]

I have at least one or more voltage stablizers you can have for shipping cost. I'll have to dig them out to tell you what model they are. Let me know if you are interested.
Jerome

[Nathan Potter]

500 watts is a lot of power to really stabilize well. I would suggest the best way would be to run it with a DC voltage regulated supply. 120 volts at 5 amps should do it. It doesnt really need to be variable but could be to be more versatile. Tough to buy one for $80.00 though - try ebay.

Nate Potter PEI, Canada

[nolindan]

Look for a "CVS" series Sola constant voltage transformer on ebay or at a surplus industrial supply house. Do not buy a transformer rated for more power than you need - these things draw the nameplate power rating from the wall no matter what load they have on them: a 2,000 watt Sola will draw 2,000 watts even with no load. A CVS transformer will keep the voltage constant to better than 1%. .

The voltage stabilizer boxes with all the LED indicators on the front panel, sold for computer use, are useless for stabilizing an enlarger, in fact they often make the situation much worse. They consist of a transformer with 100, 125 and 150 V taps and a pair of relays that switch between the taps at low voltage and high voltage conditions. Figure voltage regulation to be 25% or worse.

[Kevin M Bourque]

I used a Sola on an enlarger and it worked well. They're heavy suckers, and they buzz while they're running. The get the job done, though. Definitely look for one on eBay.

[Peter De Smidt]

Nicholas is right. The affordable ones for computers are completely worthless. I bought at $80 tripp lite, way back when. The Sola CVS is the way to go.

[aduncanson]

Thanks all for the great advice. I have confidence in this group (particularly when they agree.) By happy coincidence a 750 Watt Sola CVS just closed on eBay, and I got it for $10 & $50 shipping, or within my $80 objective.

Interestingly, in researching this I found an engineering handbook that said that a 5 Volt change in the line voltage can make a 14% change in light output. And I expect that the case is actually significantly worse since the shorter wavelength blue and green light are probably disproportionately affected.

[Peter De Smidt]

Nicholas will correct me if I'm wrong, I'm sure, but I think you want to hook the CVS directly into the wall, and then plug your timer into the output of the CVS, with your enlarger plugged into the timer, of course. I seem to remember that these big transformers aren't happy being switched on and off a lot, which would happen if you put the CVS between the timer and the enlarger.

[PenGun]

I plug all my important stuff into voltage regulators.

http://www.apc.com/resource/include/...ase_sku=LE1200

Works well.

[Peter De Smidt]

That one might work well for computer equipment, but it's not even close for an enlarger, with an output regulation of +6% to -12%.