recommendations for a 1000w enlarging timer?

wildbill

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• May 30, 2007

• #1

I've got a 10x10 fotar enlarger back in michigan with a Chromega 1000watt head on it. I'm considering doing some printing this summer and i need a timer that'll handle it, preferably digital since that's what i've got on my 4x5. I've heard of devices that can be put in between a standard timer and the enlarger to handle the extra juice and i've also heard that a plain old 500 watt enlarging timer will work since it's only sending a signal to the enlarger. Any suggestions on a digital timer for a 1000 watt source?

thanks

vinny

 

RH Designs

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• May 30, 2007

• #2

wildbill said:

I've heard of devices that can be put in between a standard timer and the enlarger to handle the extra juice and i've also heard that a plain old 500 watt enlarging timer will work since it's only sending a signal to the enlarger. Any suggestions on a digital timer for a 1000 watt source?

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Vinny -

Some high power sources have a built-in relay or contactor which handle the power and require only a minimal amount of power from the timer. Does yours have this feature? If so, more or less any timer will work. Otherwise it's likely you will need a relay as I'm not aware of any timers that will handle that sort of power. Ours handle up to 750W at 230v or 500W at 115v.

 

Roger Hicks

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• May 30, 2007

• #3

Many years ago I built a relay box for a few bucks to run my 2 kilowatt 138S head. If I could find it I'd send it to you but I fear it was lost in a move. I used it with an RH timer, too.

Cheers,

Roger

 

Steve Smith

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• May 30, 2007

• #4

If I was doing this, I would think about using a solid state relay like this: http://www.mew.co.jp/ac/e_download/control/relay/solid-state/catalog/semi_eng_aqn.pdf

Either modifying an existing timer if there is space or making an external box for it a bit like Roger's relay box. The wide control voltage of 4 to 32v means that it should be able to be driven by any existing timer which uses a mechanical relay or a smaller solid state relay.

Steve.

 

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• May 30, 2007

• #5

Most timers, including ours, provide a switched mains output to the enlarger, not just a set of contacts, so you'd need a relay with a mains-voltage "coil". A solid-state relay would probably need a heatsink to cope with a 1000W load (which is nearly 9A at 115v) and there can be problems with the inductive loads presented by transformers etc. I'd recommend a mechanical relay.

 

GeorgesGiralt

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• May 30, 2007

• #6

Vinny,
Go to a washing machine repair shop and ask them. You may get one for free from the power switching of a washing machine heating element. Often the logic can't handle such loads so they help it with a relay. A plastic box, a pair of plugs, some wire et voila. You're ready to print.
Just my 2 cents.