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Thread: magnet polarity

  1. #1
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    Default magnet polarity

    Hi,

    can someone give me a hint how i can find out the correct polarity for the magnet of an ALC909? The main terminals are disassembled just the wires (with same color) come out of the magnet.

    Ronny

  2. #2
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    Default

    A compass needle (or any magnetised floating needle) points its south pole northward, so you can find which pole is which. If you bring it carefully toward the unknown magnet polarity you can find out which that is too. If you know which end should be where, you can work out how to orient it, or power it if it's an electromagnet.

  3. #3
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    Cool

    Doc, he's trying to figure out how to wire the electromagnet on an ALC 909 so that he gets the polarity correct... A compass needle isn't going to help him, because he doesn't know what the polarity is *supposed* to be. (For that matter, neither do I...)

    The funny this is that I've actually got one of these heads, and a working power supply to drive it. (My old HGM5 power supply, and the head that I got for it at SELEM...) Trouble is, I've got to wire directly into my breaker panel to power the beast, which means running the cable across the floor from the garage all the way to the living room where the laser is. That's going to be difficult right now as I have house guests. (My wife would kill me...)

    I remember that we had this same problem when we wired my laser up to the 909 head at SELEM... We guessed at the polarity, and evidently we were correct. If you get it wrong though, I don't think you'll hurt anything.

    My advice would be to try it both ways and see which one produces a more powerful beam. I would *NOT* ramp the tube current up though. Keep the tube down near idle and just see which polarity gives you better performance. (Ovbiously you'd need to shut it down each time before you swapped the leads...)

    Then too, you might want to send a PM to "Mixed Gas" here on PhotonLexicon. He's very familiar with the ALC 909 and can probably give you some better advice.

    Or, if you're willing to wait a while, I can check the polarity on mine the next time I fire it up. But that might be a week or more from now.

    Adam

  4. #4
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    Nothing wrong with my suggestion, it's logically correct. If he doesn't know the wire polarity, but does know which end should be north or south for use in the laser, then he can deduce the wiring from that method with no other information. If he does know the wiring it's irrelevant, but he said he didn't. If he knows neither the right polarity or the right wiring, then nothing can be meaningfully said except to hand the right answer on a plate.

    It seemed to me more likely that general info might be found to indicate which magnetic pole should point where, than specific wiring data for one single laser design. I stand by my advice, it will be enough to help in many cases where the magnetic poles can be defined but wiring is unknown without testing directly by applying current.

  5. #5
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    mixedgas is offline Creaky Old Award Winning Bastard Technologist
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    [QUOTE=ronny;35775]Hi,

    can someone give me a hint how i can find out the correct polarity for the magnet of an ALC909? The main terminals are disassembled just the wires (with same color) come out of the magnet.

    TUBE ANODE IS NORTH

    it doesnt matter that much.

    Steve

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