[pure-silver] Re: Running North American 120V/60 darkroom equipment on European 220V/50?
- From: "Claudio Bonavolta" <claudio@xxxxxxxxxxxx>
- To: <pure-silver@xxxxxxxxxxxxx>
- Date: Sun, 7 Nov 2004 12:17:34 +0100
----- Original Message -----
From: "Nick Zentena" <zentena@xxxxxxxxxxxx>
To: <pure-silver@xxxxxxxxxxxxx>
Sent: Saturday, November 06, 2004 11:13 PM
Subject: [pure-silver] Re: Running North American 120V/60 darkroom equipment on
European 220V/50?
> So you mean run the enlarger with 220V power?
It's possible to run a basic (if only the bulb requires current) 120V enlarger
on the 230V just by
replacing the bulb by a 230V model of same wattage.
You may need, but it's not compulsory, to replace the fuse by a model, roughly,
half the nominal
current of the actual (see below, for the calculation).
Due to the inrush current (cold filaments have a lower resistance than hot and
let pass much more
current, up to 10 times), the fuse should be a slow model.
> I don't think that will work
> with either of my enlargers. The Beseler has a couple of small motors to
> raise/lower the head and for focus.
So, you certainly can't just put 230V on it without destroying some parts.
To avoid the transformer means you have to modify the circuits inside.
Without the schematics it's impossible to tell you precisely.
> I don't understand why it would need new bulbs?
This could have been the simplest and less costly solution if your enlarger was
a very simple one
(but it is not ...)
> Isn't a 150watt bulb the same no matter the voltage?
Nope, the following is largely off-topic:
Power=Voltage x Current
150W = 120V x 1.25A = 230V x 0.65A
Resistance of the filament = Voltage / Current
R(120V) = 120 / 1.25 = 96 Ohms
R(230V) = 230 / 0.65 = 350 Ohms
If you put the 120V bulb on 230V then you have:
Current = Voltage / Resistance = 230 / 96 = 2.4A
and Power = 230 x 2.4 = 550 Watts
There are *no* chances your 150W bulb will resist to this 550W power ...
> Worse case I can always remove the motors and just do everything manually.
I think your step-down transformer will just do the task, a 100$ is not that
much and you don't have
to worry.
> The Durst is fed from it's own power supply. The fan and timer plug into the
> power supply. I'm most worried about this one since I don't want to deal with
> replacing the colorstar.
Check the supply, some have a 120/230V switch.
If not, again, your step-down tranny will do the job.
I don't think the 50-60Hz difference will create a problem, your Durst looks
like to be sufficiently
recent for not relying on the mains frequency for timing functions.
> Thanks
> Nick
Regards,
Claudio Bonavolta
http://www.bonavolta.ch
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