From: bjs@uts.amdahl.com (Barry Sherman)
Newsgroups: rec.photo
Subject: stabilizers
Date: 25 Aug 92 20:00:21 GMT
Reply-To: bjs@amdahl.uts.amdahl.com (Barry Sherman)
Followup-To: rec.photo
Organization: Amdahl Corporation, Sunnyvale CA

Please bear in mind as you read this that while I'm becoming fairly 
knowledgable about photography, I'm extremely electronically impaired.  
Down-right electronically challenged.  No, make that totally ignorant.   :-)

My enlarger is rather old.  In fact ancient.  (Durst L-1000, manufactured
during the 1960's)  It came with an after-market dichro head made by "Pavelle".
The head came with a power supply.  But the power supply is just a step-down
transformer (110v -> 24v).

I recently obtained a sensitive enlarger meter for the first time.  Actually,
it's a (used and obtained through incredible hassles) JOBO Colorstar 2000 
color analyzer.  The exposure meter portion seems to be quite sensitive.  
Sensitive enough to measure bulb brightness fluctuations due to lamphouse 
heat-up and current fluctuations.

My first experiment indicated that I need to get more cooling air flowing
through the lamphouse.  This is not a problem and I can easily add another
blower to the separately housed one that came with the lamphouse.

But my second experiment has me a little concerned.  I have a small window
air-conditioner installed in the darkroom to help maintain an ambient 
temperature that's friendly to both myself and my chemical processes.
I placed the probe of the Colorstar on the easel and, once again, turned
on the enlarger.  Then I turned the air-conditioner on and off several times,
imitating the way that its thermostat turns it on and off while I'm working.
The indicated exposure time jumped up and down by ~5-8% every time I varied
the air-conditioner on or off.  This does not make me happy!  I've had some
problems with inconsistent results in color printing and suspect that this
may account for some of them, although, interestingly, the Colorstar did
not indicate any change in the color of the light from the enlarger during
these fluctuations.  (It's sensitive to 1cc color changes.)

My first attempt at a solution will be to switch the air-conditioner to a
different circuit, although I don't expect that to make any difference, since
all my circuits are drawing from the same feed lines.  So I'd like to
get a voltage stabilizer.  Of course, there's no hope of finding one designed
specifically for my colorhead.  But I've seen generic-looking boxes labeled
"voltabe stabilizer" in electronic stores.  My questions:

* Does one just buy a "110 volt" voltage stabilizer?  

* Are they rated as to current capacity?  (My 2 bulbs draw 400 watts total.)

* Since my lamps are 24v I assume that I want a stabilizer that my step-down
  transformer will plug into.  I.e.  I assume that I want a 110 volt
  stabilizer and it will be inserted between the step-down transformer and
  the wall outlet.  Or do I want a 24v stabilizer to be inserted between the
  transformer and the bulbs?  Or does it matter?

* In other words, I, in my state of ignorance, have no idea what to ask for
  when I to into the store.  Any knowledgable suggestions?

Thanks for any help,

Barry

-- 


|----------------------------------------------------------------------------|
| Barry Sherman, Amdahl Corp.       | "Any fool can face a crisis - it's     | 
| bjs@ruts.ccc.amdahl.com           |  this day-to-day living that wears you |
|                                   |  out." - Anton Chekhov                 |
|----------------------------------------------------------------------------|
| Amdahl, being a corporation, is a legal fiction.  Therefore it is incapable|
| of holding, let alone expressing, opinions.  Unfortunately, this has been  |
| said of me as well.                                                        |
|----------------------------------------------------------------------------|