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Thread: CDRH shutter

  1. #1
    Join Date
    May 2006
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    Pasadena (Home)/UCLA (work)
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    30

    Default CDRH shutter

    Hey guys, I am still confused when it comes to making my projector CDRH compliant.

    Specifically, the shutter. Is this what I need to buy???

    http://cgi.ebay.com/LOT-NEW-LASERSCO...QQcmdZViewItem

    if not, is there anyone on the board that sells shutters?

    -MO-

  2. #2
    Join Date
    May 2006
    Location
    Native Floridian
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    3,083

    Default

    -MO-

    I looked at that auction, not sure if that will work, may be more than you need, though the price is nice. I have used two different kinds of shutters, the first kind is simple rotary solenoid manufactured by Ledex. Simple to install and implement, though, pulls a good bit of current, makes a loud noise when engaging and disengaging, and, you really need to read over the specs well because if you use a "12V" solenoid and run it open at 12V for long periods of time, you may burn up the coil. In the data sheet it will have the duty cycle spelled out, some can run indefinately but at a reduced voltage. The other kind of shutter I have used is a GM-20, which works very well and makes no noise! I'm sure someone on this board may have a spare they could part with, or you may want to check NML or Nightlite Laser. They may have stock.

    Good Luck,
    David

  3. #3
    Join Date
    May 2006
    Location
    Pasadena (Home)/UCLA (work)
    Posts
    30

    Default

    Thanks for the reply David,

    I also found this one:

    http://www.lasershs.com/laser_optical_actuator.htm

    Is this what I am looking for?

    thanks for the help.

    -MO-

  4. #4
    Join Date
    Nov 2005
    Location
    Melbourne, Australia
    Posts
    3,694

    Default

    Hi Mo,

    The medialas stp-8 cannot be used as a safety shutter as it is not spring loaded.

    We use GM-20's as well, they are pretty damm good

    Dave
    KVANT Australian projector sales
    https://www.facebook.com/kvantaus/

    Lasershowparts- Laser Parts at great prices
    https://www.facebook.com/lasershowparts/

  5. #5
    Join Date
    May 2006
    Location
    Native Floridian
    Posts
    3,083

    Default

    Dave is right. Unless your shutter is spring loaded in some way, or can be proven to stop a beam in the event of power failure, then it is not adaquate. The STP-8 is nice for a beam table as it is quiet and the throw is a good bit less violent than that of a solenoid. However, since it is just a stepper motor, wherever it is located in a power loss is where it will stay. GM-20 will be your best bet. If you descide to use a solenoid, one thing to remember is to place a diode (1n4007) reverse polarity on the leads of the solenoid. If you don't you will eventually damage or destroy your power supply, and possibly other things. As the magnetic field around the coil of the solenoid begins to collapse when power is removed, it produces an effect known as back EMF. In theory, the solenoid will produce an infinite voltage back to your power supply while the magnetic field is collapsing. Often causing the release of smoke! The diode will limit this voltage to .7V through the entire time the field is collapsing, thus making your power supply very happy!

    David

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