Page 2 of 2 FirstFirst 12
Results 11 to 20 of 20

Thread: Mega Watt Power Supplies?

  1. #11
    Master Navigator
    Join Date
    Mar 2009
    Location
    Queensgate
    Posts
    1,929
    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)

    .


  2. #12
    Whacker Knot WTKX's Avatar
    Join Date
    Aug 2008
    Location
    Evergreen, CO
    Posts
    26,304
    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
    Join Date
    Aug 2007
    Location
    Lakewood, NJ
    Posts
    12,286
    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........
    "New Jersey, the most American of all states. It has everything from wilderness to the Mafia. All the great things and all the worst, like Route 22."
    Jean Shepherd K2ORS (SK) & WOR radio personality

    Engaging a troll is like playing chess with a pigeon. The bird will just knock over the pieces, shit on the board, and fly away to declare victory to his friends.

    73 de Warren KB2VXA
    Station powered by atomic energy, operator powered by natural gas.

  4. #14
    Whacker Knot WTKX's Avatar
    Join Date
    Aug 2008
    Location
    Evergreen, CO
    Posts
    26,304
    Use the clamps!

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



  5. #15
    Volcano Tamer n2ize's Avatar
    Join Date
    Dec 2007
    Location
    Crestwood, New York
    Posts
    33,876
    Quote Originally Posted by kom View Post
    "Dave-made, Dave-made, Dave-made".......


    The fact that the company's advertisements are directed at "Ham Radio" (not Amateur Radio) and list "CB Radio" on it's front page tells the whole story; a D.C. power supply that delivers 15 volts direct current at 400 amperes (6.0 Kw!); good to power a "128 pill" 12 volt bipolar transistor RF amplifier.

    How does that look on the primary side of the transformer, *if* this PSU was 100% efficient (it's not), it would pull 27 amps on a 220 volt A.C. circuit (234 vac in reality but, round numbers are easier).

    Towards the end of the page, he misspells "Reviews" and his "Reveiws" come from the WWDX free-band web site.

    Look harder, you can do better if you want to.
    As soon as I saw this I was thinking "DAVE MADE". :)
    I keep my 2 feet on the ground, and my head in the twilight zone.

  6. #16
    Volcano Tamer n2ize's Avatar
    Join Date
    Dec 2007
    Location
    Crestwood, New York
    Posts
    33,876
    Quote Originally Posted by WZ7U View Post
    Can't speak directly to them myself, but I do run old server supplies at my place for HF. Set to 13.8v, 82A max per unit as well as a 5v terminal. Bought these for $20 each about 3 years ago used. Kinda reminded me of those.

    Sorry I'm not more help.

    On edit - HP branded server supplies, cycled out for age I'm sure. First learned about them from a friend into RC stuff. Apparently that demographic uses them to charge batteries.
    If they are using them to charge up large Lithium Polymer batteries I sure as hell hope they are being careful and know what the heck they are doing. LiPO's tend to be extremely tempermental, especially during charging where they can produce one hell of an awesome and intense conflagration.
    I keep my 2 feet on the ground, and my head in the twilight zone.

  7. #17
    The Fluid of Spock KD8TUT's Avatar
    Join Date
    May 2016
    Location
    Lake Michigan Beach MI
    Posts
    2,035
    Quote Originally Posted by n2ize View Post
    If they are using them to charge up large Lithium Polymer batteries I sure as hell hope they are being careful and know what the heck they are doing. LiPO's tend to be extremely tempermental, especially during charging where they can produce one hell of an awesome and intense conflagration.
    They're all a bit temperamental. Although the Lithium Manganese can be forgiving.
    --
    So there I was, totally naked. With only a rubber hose and a stuffed animal...

  8. #18
    Master Navigator
    Join Date
    Mar 2009
    Location
    Queensgate
    Posts
    1,929
    Quote Originally Posted by kb2vxa View Post
    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.

    ...


    Just call me Professor Retro........
    I am left handed and, I used to work for this old fellow who was right handed; dude would have a conniption fit every time (almost daily - multiple times) when I would wind a Tank Coil by hand. I would grab the stock in my left hand and, form the coil in a clock-wise motion with my right hand. According to him, I was supposed to hold the stock in my right hand and form the coil in a counter-clockwise direction with my left hand - we "fought" daily.

  9. #19
    The Fluid of Spock KD8TUT's Avatar
    Join Date
    May 2016
    Location
    Lake Michigan Beach MI
    Posts
    2,035
    Thanks guys.. I was almost seduced.

    Just remembered- a friend of mine who owns the local ham radio store has one I think. I'll pop in this weekend and throw a scope on it to see.
    --
    So there I was, totally naked. With only a rubber hose and a stuffed animal...

  10. #20
    "Island Bartender" KG4CGC's Avatar
    Join Date
    Mar 2007
    Location
    EM84ru, Easley SC
    Posts
    48,012
    Quote Originally Posted by n2ize View Post
    If they are using them to charge up large Lithium Polymer batteries I sure as hell hope they are being careful and know what the heck they are doing. LiPO's tend to be extremely tempermental, especially during charging where they can produce one hell of an awesome and intense conflagration.
    Hello, John. What are you using LiPo's for?

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •