[pure-silver] Re: Enlarger Lamp Life

That's strange, as I haven't had a lamp blow in my Meopta enlarger with colour head - ever. And I do just the same with a metronome and the power switch.
The transformer on mine delivers about 13V too, many colour head lamps are deliberately overvolted.
Also: The voltage supplied by the electricity companies hasn't increased over the years. But as lines are replaced, transformers upgraded et cetera, the assumed voltage delivered to the customer has increased through a reduction in transmission losses. 

Ole Tjugen
På Wed, 29 Oct 2008 13:32:35 +0100, skrev Eugene Barrington <eandpbarrington@xxxxxxxxxx>: 


You know what they say about overlooking the obvious - well, I thought
that might be the problem. I use a metronome as a timer. As a result I
switch the power on at the transformer each time I make a print. If I
had an inline switch or timer I could leave the transformer powered on
continuously. Would this make a difference -perhaps there would be
less of a jolt to the lamp itself? (I'm only guessing here.)

Eugene

On 28 Oct 2008, at 04:03, Jacques Augustowski wrote:


I think there is an AC capacitor in parallel to one of the windings,
fiddling with the value changes the regulated output voltage. It was
a long time ago that I played around with CSV transformer.
Richard might know more about them
My preference is a regulated  117 V DC. But there is catch in using
DC to feed lamps, the filament burns only in one side. The Beseler
enlarger uses a 82v lamp, it is easier to regulate 117v to 82v. In
my hook up I used a transformer that delivers at least 170v ACx 5A,
very heavy. Now someone could build a regulated switching power
supply weighing a pound and delivering 600w, that's the power
computer PS uses.

Jacques


----- Original Message -----
From: Nicholas O. Lindan
To: pure-silver@xxxxxxxxxxxxx
Sent: Monday, October 27, 2008 10:09 PM
Subject: [pure-silver] Re: Enlarger Lamp Life

"Richard Knoppow" <dickburk@xxxxxxxxxxxxx>

> One virtue of a CSV is that the output shuts down
> completely if its shorted.

They don't really shut down, they deliver a constant
current when they are shorted are quite content to
deliver this current forever.

A foible of CV transformers is they draw the same power
from the AC line no matter what: a 500W transformer will
draw 500 watts with no load, with a 500 watt load or with
a dead short across it's output.

I was filing a patent with the same attorney who represented
Sola (the largest maker of CV transformers), we got to talking
about CV's and it was his opinion that no one at Sola, or
anywhere else for that matter, really understood how they worked.

--
Nicholas O. Lindan
Cleveland Engineering Design, LLC
Cleveland, Ohio 44121

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Ole Tjugen

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