Zonemaster II power supply

Discussion in 'Darkroom Equipment' started by foraker, Nov 5, 2004.

  1. foraker

    foraker Member

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    For the AC-to-DC power supply for the ZM 2, when they say it should be capable of supplying 100mA at 9V or 7.5V does that mean the 'minimum' current it should be able to provide or the maximum. I'm guessing minimum. Just asking since I don't want to fry mine and the least amount of current I see for AC-to-DC adapters is 300mA @ 9V.
    Matthew
     
  2. rbarker

    rbarker Member

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    I, too, think they mean a minimum of 100ma (so the 300ma supply should be OK), but you might send an e-mail to RHdesigns, just to be sure.
     
  3. foraker

    foraker Member

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    Yeah, I just did that. I'm just impatient when it comes to setting this stuff up. Thought I might find someone here who had one. :smile:
     
  4. rbarker

    rbarker Member

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    I actually do have one. It's just that I run on battery. They last a long time. :cool:
     
  5. Jon King

    Jon King Member

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    Get the definitive answer from RHDesigns, but an adapter capable of supplying 300mA at 9V will also supply less than 300mA. It should be fine.

    The thing to look out for, though, is the type of connector, and then the plug 'polarity'. There is a center conductor and an outside conductor on the plugs. Sometimes the +9 is on the outside, sometimes on the inside. It needs to be what ZM 2 is looking for.

    BTW, I'm jealous :wink: - Gralab 300's only go so far...


     
  6. RH Designs

    RH Designs Advertiser

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    100mA is the maximum current the ZoneMaster is ever likely to need so anything capable of supplying 100mA or more is fine. Just make sure it's _regulated_ and between 7.5v and 9v. Any more than 10v (which you'll often get from an unregulated 9v supply) is likely to fry the regulator chip.
    TBH, a Duracell battery lasts for ages and means one less bit of wire to get in the way on the bench :smile:
    Regards
    Richard Ross
    RH Designs
     
  7. Loose Gravel

    Loose Gravel Member

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    The current and voltage rating of a power supply is a rating of the maximum power, that is, if you multiply the two numbers together. 100 mA and 9V is a 900 mW supply or 0.9 Watts or sometimes 0.9 VI. It should be pretty much 9V at all currents below 100 mA, but above 100 mA, the voltage will come down proportionately, sorta. Not a good idea to operate above rated current. It will overheat and if your lucky, blow a fuse.
     
  8. JHannon

    JHannon Member

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    If you are using a substitute power supply, make sure the polarity of the connector is correct. Some units are positive tip and others are negative tip. You will blow a fuse or protection diode if it is reversed.

    Just FYI,
    Regards,
    John