Relay to protect timer from 120v converted chromega D

Discussion in 'Darkroom Equipment' started by 3e8, Nov 24, 2013.

  1. 3e8

    3e8 Member

    Messages:
    71
    Joined:
    Oct 28, 2008
    Location:
    Maryland, US
    Shooter:
    4x5 Format
    I recently converted the halogen lamp in my chromega to 120V with a 300W 120V halogen bulb. It works fine when plugged directly into a wall outlet, but when I attempt to use it with a timer, it blows the fuse of the timer. I'm guessing the inrush current is just too much, so I'm looking to wire in a SSR and just have the timer provide the switching current and the power current from a wall outlet. I'm just not up enough on electronics to calculate which SSR I would need. Could someone help me figure out what specs I would need for the SSR?

    Thanks,
    Bryan
     
  2. Erik L

    Erik L Subscriber

    Messages:
    641
    Joined:
    May 9, 2007
    Location:
    Grand Juncti
    Shooter:
    4x5 Format
    I used one of these http://www.mcmaster.com/#general-purpose-relays/=pis43f
    To protect my timer. They also sell a handy enclosure to make a neat installation at
    The bottom of the page. Medium amp relay is what I selected on the McMaster car link, for some reason the
    Link goes to all the relays available.
    Regards
    Erik
     
  3. Chan Tran

    Chan Tran Member

    Messages:
    2,386
    Joined:
    May 10, 2006
    Location:
    Aurora, IL
    Shooter:
    35mm
    Use an SSR rated for at least 120VAC but not more than 240VAC and at least 5A but preferably not more than 25A. I would want to pick one with 125-145VAC or so and 10 to 15A rating.
     
  4. Dr Croubie

    Dr Croubie Member

    Messages:
    2,014
    Joined:
    Mar 21, 2013
    Location:
    rAdelaide
    Shooter:
    Multi Format
    Any particular reason to use a Solid State Relay instead of a regular electromechanical?
    SSRs switch faster than regular e/m relays, but in general the pickup and dropout time of electromechanical is the same, so it won't affect your timings. (ie if it takes 20ms to switch on, it'll take 20ms to switch off, so the light stays on the same length of time)
     
  5. ic-racer

    ic-racer Member

    Messages:
    7,485
    Joined:
    Feb 25, 2007
    Location:
    Midwest USA
    Shooter:
    Multi Format
    What timer do you have that won't handle 300w? For the price of a relay, maybe consider a timer upgrade.
     
  6. 3e8

    3e8 Member

    Messages:
    71
    Joined:
    Oct 28, 2008
    Location:
    Maryland, US
    Shooter:
    4x5 Format
    I'm using a RH Designs Stopclock timer, which is rated to 500W, but with the new bulb, as soon as the timer switches on, it fries the fuse. The same thing happens with a Gralab 300 as well.
     
  7. fotch

    fotch Member

    Messages:
    4,820
    Joined:
    Mar 16, 2005
    Location:
    SE WI- USA
    Shooter:
    Multi Format
    Contact RH Designs Stopclock timer and ask them for help. They should be able to advise. Something is wrong here since the Gralab is rated at 600watts.
     
  8. mr rusty

    mr rusty Member

    Messages:
    758
    Joined:
    Sep 7, 2009
    Location:
    lancashire,
    Shooter:
    Medium Format
    My Analyser (230V) has a T4A fuse - it says so on the casing. This is a "time delay" fuse rather than a "fast acting". You are replacing with a T fuse? because a similarly rated fast-acting fuse may blow when a T fuse won't.
     
  9. Steve Smith

    Steve Smith Member

    Messages:
    9,092
    Joined:
    May 3, 2006
    Location:
    Ryde, Isle o
    Shooter:
    Medium Format
    I was wondering that too. Most SS relays I have seen need a low dc voltage on the input which would mean wiring it internally to the internal relay driver. A normal relay would be much easier to connect and wouldn't entail any modifications to the timer.

    The obvious answer which I couldn't possibly condone or suggest includes the words 'fit', 'fuse' and 'bigger'.

    But check this first!


    Steve.
     
  10. Cruzingoose

    Cruzingoose Member

    Messages:
    211
    Joined:
    May 27, 2006
    Location:
    South Dakota
    Shooter:
    Medium Format
    Here is a simple way to fix your problem. Radio Shack or other electronic supply store will have the relay. The rest is easy junk box parts.
     

    Attached Files:

  11. Neal

    Neal Subscriber

    Messages:
    1,625
    Joined:
    Dec 3, 2004
    Location:
    Chicago, Wes
    Shooter:
    Multi Format
    A relay is ridiculously cheap insurance. You even get multiple contacts so that if one dies (it won't) you can just wire to another.

    Neal Wydra