Converting 220 volt gralab timer

walter23 · Oct 30, 2008

I got a free timer that's rated for 220V and doesn't have a proper electrical cable (looks like it was wired in to someone's darkroom at some point and the wiring cut). Any idea of the prospects of converting it to north american voltage and adding a power cable?

Bob-D659 · Oct 30, 2008

All depends on what voltage the timer motor requires. Have a look inside, it should be stamped on the timer motor somewhere.

ron110n · Oct 30, 2008

For my side of the pond, Radio Shack has a "step-down transformer" (240v to 120v), I'm sure you will find one at Canadian Tire or Sears Canada. Just replace the plug with an appropriate one. Using a 120v type of plug won't really hurt the 240v Timer if plugged to 120v outlet by accident. "It just wouldn't work".

Plugging a 120v Timer to a 240v outlet is a different story. "It will not work anymore", unless it is auto volt.

I don't have to worry about the Hertz unless it is 100v (Eastern Japan, Tokyo, Yokohama, Tohoku, Hokkaido) It will work to 120v but your time will be off and too fast since it is 50Hz. North America & Europe is 60Hz.

Hope this helps,
-Ron

pelerin · Oct 30, 2008

walter23 said:
I got a free timer that's rated for 220V and doesn't have a proper electrical cable (looks like it was wired in to someone's darkroom at some point and the wiring cut). Any idea of the prospects of converting it to north american voltage and adding a power cable?

What model of timer is it and what do you want to do with it. Do you plan to run an enlarger off the timer?
Celac

mmcclellan · Oct 30, 2008

If it's the big round timer with the clockface and rotating hands, I would not bother trying. The 50-60 cycle business will screw everything up. GraLab makes a special timer for overseas use (220V, 50 HZ) and one for US (110V, 60 HZ) and if you have the wrong HZ, you'll get screwy times. As far as I know, you cannot "step up" or "step down" the cycles, only the voltage.

On the other hand, if it's a digital timer, then the transformer alone will probably do the trick. Good luck!

Steve Smith · Oct 30, 2008

mmcclellan said:
As far as I know, you cannot "step up" or "step down" the cycles, only the voltage.

Whilst this is true, in reality it doesn't matter. So long as it is consistant, it makes no difference if your seconds are 1 second long or 0.83 seconds long (50Hz unit running on 60Hz).

If it is being used as an enlarger timer and you are using test strips to evaluate then the time is just an arbitary unit which is repeated.

If it was mine, I would try it on 110 volts, 60 Hz anyway. You won't damage it and it might just work on half voltage (probably won't though).

Steve.

Mike Wilde · Oct 30, 2008

shaded pole motor - undervoltage risk

The clasic Gralab timer, as I understand it, uses a shaded pole motor, whose speed is power frequnecy dependent. Yes, it would need a different gear set to run on 60hz, to do absolute time. Running on 60Hz would yield repeatable times though.

The suggestion that plugging it into 120V is not that good of an idea. I suspect too little EMF will be generated to turn the gears reliably - so times may not be repeatable, and the motor coil may overheat.

Steve Smith · Oct 30, 2008

Mike Wilde said:
The suggestion that plugging it into 120V is not that good of an idea.

I didn't say it was a good idea. I said it is what I would do!

steve.

walter23 · Nov 4, 2008

Okay, thanks for all the info. I'll give it away if anybody is interested (though I suspect it would hardly be worth the shipping cost overseas).

Cheers

Renato Tonelli · Nov 9, 2008

walter23 said:
Okay, thanks for all the info. I'll give it away if anybody is interested (though I suspect it would hardly be worth the shipping cost overseas).

Cheers

I need a 220volt timer for use in Europe; I would gladly barter my 120V for it.
Mine is in good running shape.

Converting 220 volt gralab timer

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