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Thread: Mega Watt Power Supplies?

  1. #11
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    Quote Originally Posted by kb2vxa View Post
    Clamp on >DC< ammeter, that's a new one on me.
    Me too, I find it interesting that it can determine the polarity (direction of current flow) in the DC circuit; it has a built in "Left-Hand Rule".

    For those here that had Basis Electric Theory taught to them, where they were introduced to the "Left Hand Rule"? If so, is this the way you remember it?

    Definition of left-hand rule

    :a rule in electricity: if the thumb and first two fingers of the left hand are arranged at right angles to each other on a conductor and the hand oriented so that the first finger points in the direction of the magnetic field and the middle finger in the direction of the electric current then the thumb will point in the direction of the force on the conductor.

    So, I wonder if, holding the meter in your left hand or right hand or, the orientation on any axis makes a difference in the readings? (JK)

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  2. #12
    Whacker Knot WTKX's Avatar
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    It's a Hall effect sensor, dudes.



    "Laugh-a while you can, monkey-boy" ~ Dr. Emilio Lizardo



  3. #13
    'Grumpy old bastid' kb2vxa's Avatar
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    There is another left hand rule I learned working in a TV repair shop. Remember TV repair shops? Since most people are right handed it applies, but for a few southpaws it becomes the right hand rule. When probing live circuits put your left hand in your pocket. Look pal, I'm not putting my hand on a conductor for love or money! That is unless the conductor is that sweet young thing in uniform I met aboard a train. This monkey boy is laughing because he can't figure out how to figure out which way the magnetic field is pointing the way you have your hand configured. The way I learned it in grade school is curl your fingers and stick out your thumb. With a left hand wind on a coil the thumb is north. Do it with your right hand and your thumb points south.

    I first heard of the Hall effect when I built my first computer, the DC fans were called Hall Effect fans. Now they're called brushless motor fans or simply brushless fans. Everything is getting dumbed down including me, now I can't figure out why they want me to blow the dust out with expensive "canned air" when my 2" paint brush never runs out of air.

    Ah, the good old AC clamp on ammeter, the heart of which is a split core current transformer. As an aside, you may have seen high current KWH meters at an industrial service entrance and wondered what's in that big steel box. For each 3 phase circuit there are 3 current transformers, the voltage windings are across the phases so they can calculate volts times amps over time. Those current transformers are closed core, simple toroid cores with many fine wire windings and load resistors across them. When just measuring amps a full wave bridge rectifier and DC microammeter calibrated in amps is the readout. I dared not disassemble the company's clamp on meter, so my best guess is scales are changed by changing load resistors. These days like everything else they just had to complicate them with digital readouts and stupidize them at the same time. They used to be clamp on meters, now they're clamp meters in case you want to measure clamps.

    Just call me Professor Retro........
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  4. #14
    Whacker Knot WTKX's Avatar
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    Use the clamps!

    "Laugh-a while you can, monkey-boy" ~ Dr. Emilio Lizardo



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