Graflarger Back - Aristo Light Source Advice

Discussion in 'Darkroom Equipment' started by Steve Smith, Jul 25, 2008.

  1. Steve Smith

    Steve Smith Member

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    I have just received a Graflarger back with Aristo light source from Ebay for the sum of £0.99 ($2).

    I was expecting it not to work and intended to convert it to LED however, it does work so I may keep it as it is for now although I may replace the transformer for one with a 230v primary.

    I have measured the AC output of the transformer and when powered up it starts at 580, rises to 650 then drops and stabilises at 630. I have some valve amplifier HT transformers which would give me around 500 - 600 volts so I will probably try one of those.

    Can anyone tell me if it will produce light connected directly to 230 volts or does it need a higher voltage to start?

    It does not have the negative carrier which isn't a great problem as I have use of a CNC router so I can easily make another one (and options for smaller formats).

    If anyone has one of these, I would appreciate it if you could tell me the distance the negative sits from the diffuser and the overall thickness of the holder. I measure the slot at 5.5mm (7/32").

    Thanks.



    Steve.
     
    Last edited by a moderator: Jul 25, 2008
  2. Nicholas Lindan

    Nicholas Lindan Advertiser Advertiser

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    The 'transformer' is also the ballast, and has two functions: raise the voltage; and regulate the current. You can't replace it with a regular HT transformer without getting into a lot of trouble with the lamp - though you could arrange your own ballast. If it is a 115 V Graflarger the easiest solution is to use it with a 230->115V step down transformer. Performance will be a bit different because of the 50 Hz frequency (lamp current will be 17% higher than it should be) but it shouldn't make that much difference.
     
  3. Steve Smith

    Steve Smith Member

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    Thanks for the information. I didn't really want to use it with a step down transformer but since my LPL enlarger is also 110 volt and I already have a transformer, it's not too much of a problem. I didn't realise there was more to it than just a transformer though.


    Steve.
     
  4. David A. Goldfarb

    David A. Goldfarb Moderator Staff Member Moderator

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    The negative carrier consists of two aluminum frames that together are just shy of 3/16".

    Aristo will still update the bulb, if you want.

    Like other old-style cold light heads that don't have a heating circuit, the output of the bulb varies noticably, particularly if you are trying to make lots of prints with a short exposure time, like a batch of postcards. If you don't have a compensating timer like a Metrolux, you might want to use an enlarging lens that can be put in a shutter to control exposure time, or use a black card over the lens, so you can leave the lamp on.