The 451 is a general purpose industrial timer and isn't made for darkroom use.
A lot of its features are of no use, and make no sense, in a darkroom setting.
If you want to control a bread oven or a chemical mixer, that's different.
The contactor accessory is needed if your enlarger's lamp(s) draw more than
~600 watts. You will notice a GraLab 451 has only one power outlet and that's
used by the enlarger so a contactor/relay is also needed if you want the
safelights to turn off when the enlarger turns on. I think you have to do some
jiggery-pokery with the GraLab's contactor to wire up a safelight socket.
Contactors are available from McMaster-Carr and Grainger for ~$30 - this isn't
anything exotic. For safelight control you only need a bog-standard relay for a
few dollars, figure some more money for a metal box and some outlets &
wiring. If you aren't comfortable with wiring you will have to get an
electrician or bribe a relative or friend to hook it up for you.
The inrush current and such ratings are not relevant to your purpose. The
contactor is not a 'power supply.'
I am constantly amazed, and dismayed, that people buy these timers for their
darkrooms, and spend excessive amounts of money doing so. There are still two
firms supplying proper timers for darkroom use, one in the US and one in the UK.
I am the owner of Darkroom Automation
http://www.darkroomautomation.com/da-main.htm - a manufacturer of f-Stop ;
darkroom timers in the US. If you are in the UK or EU then the place to go is
RH Designs.
Nicholas Lindan
I was shopping around online for used Gralab 450 and 451 enlarger timers (I
currently have a 450), and came across this:
https://www.ebay.com/itm/113926291993
I notice that it comes with a contactor - I had no idea what this is - until I
did some googling and discovered it is actually a power supply.
More googling (on my Saunders/LPL 4550XLG), only to find that a replacement
unit is about $900, and a refurbished unit from KHB is $500+. The 120V/60Hz
ratings on the aforementioned Gralab are the same as on my LPL:
https://www.bhphotovideo.com/c/product/90222-REG/Omega_200400_LPL_Power_Supply_for.html/overview.
Is there something else I need to look at? The Gralab's12 Amp continuous and 50
Amp inrush designations are Greek to me, and I have no idea whether this
contactor would be adequate if my current power supply gives up the ghost.
I would appreciate some (simplified) explanation as to how to evaluate a
replacement unit, and how important are these continuous and inrush numbers.
Thanks in advance!
-Adrienne
Adrienne Moumin
Handmade B&W photographs and photo collages: picturexhibit.com
(http://picturexhibit.com/)
Architextures series: http://picturexhibit.com/html/architextures.html
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212-602-1809
