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Electro Pounce Machine

Discussion in 'General Electronics Discussion' started by David Shaughnessy, Jun 28, 2017.

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  1. David Shaughnessy

    David Shaughnessy

    3
    0
    Jun 28, 2017
    So I work for a pretty large scale sign painting company, and in preproduction we use a machine called and Electro Pounce Machine. Its basically a machine that is plugged into the wall and has a 10 foot cord with a wand at the end of it. There a mesh metal screen stapled to the wall, a large sheet of paper is rolled over the mesh screen and an image it projected onto the paper. We then use the wand from the machine to trace the image, when the tip of the wand comes close enough the screen an arc is formed burning tiny holes in the paper creating a stencil of the image. I was recently given the task of replacing the wand on one of these machines and opened it up, it seems like a pretty straight forward machine if I knew more of what i was looking at. I took some pictures, i was wondering if someone could help me identify some of the parts. I can see there seems to be a custom transformer inside. I don't know much about electrical engineering and this is my first time going on a forum like this so any help would be greatly appreciated.
     

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  2. AnalogKid

    AnalogKid

    2,424
    690
    Jun 10, 2015
    Looks like a high voltage transformer with a capacitor in series to limit the current once the arc has been struck. Transformer construction and capacitor type are very similar to the innards of my old electrostatic air cleaner. That one produced around 7 kV.

    ak
     
  3. 73's de Edd

    73's de Edd

    2,987
    1,261
    Aug 21, 2015
    Sir David Shaughnessy . . . . . .

    I heartily second the motion, with a strong Mega- ditto to Sir AK for his astute observations..

    Whatt I am seeing is AC line input thru a fuse and power switch that then feeds through a lamp dimmer, which then feeds its outputted variable AC to the primary of a high voltage transformer.

    That transformers secondary, is outputting its 2500VAC as specified at a . . . . shudder . . . . .shudder . . . . .SHUDDER . . . . a 50 milliampere current capability.


    ( You do also realize that this unit could additionally be used in neon sign work / analysis / testing . . . . don’t you ? )

    I do see some attempt at diminishing that current level by its passing through a 33K resistor, but a BODACIOUS (<--- That's being in 475 FONT ) amount of current is STILL being passed thru it.

    You can see that the low side of the HV winding of the transformer is being a bare wire to transformer frame and the whole units BLUE case housing.

    Your transformers RED high voltage AC lead is going to . . . my guestimate . . . a RED 470-thru-/500 pf hi voltage ceramic doorknob capacitor . . .with It probably being rated at 10KV.

    You are dealing with AC here, but this capacitors in circuitry presence should give the produced arcing / corona effect, a better action than without having it.

    Then there is the shielded wire to the probe, with the probe getting direct connection to the transformers RED HV AC and the doorknob cap, but the shielded line gets that 33K resistor in series before it connects to transformer frame and case.

    Your RED probe has a needle chuck on it's end, that is geared towards holding a 1930-1950’s steel phono needle.

    That very-very fine pointed end will give you a more optimal arc or corona spray with more and finer holes in your pattern plotting operation.

    NOW . . . . If I were using that “contraption” I would have on my THICK rubber soled shoes. The probe would be held with a certified high voltage lineman’s insulated glove on that hand.

    My left hand would always be in my left pants pocket.

    Then, fully shut power down, if having to adjust or move the paper pattern, until its repositioned.

    If the RED probe had to be used by bare hand, it would be rebuilt as being centered within a 1 inch internal diameter, 1/4 inch wall thickness, clear acrylic tube, with just the probe chuck sticking out.

    Pee Ess . . . . . ever been "pounced upon" with that suckah ?


    Thasssssit . . . .

    73’s de Edd


    .
     
    Last edited: Jun 28, 2017
  4. David Shaughnessy

    David Shaughnessy

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    Jun 28, 2017
    You response is more than I could have hoped for, thank you so much. The red cylindrical piece, is that the capacitor? And I do use this thing bare handed, we usually snap a portion of the tip off and instead of using a pin we stick a piece of graphite in the end, so we actually get a mark on the paper. I have shocked my self plenty of times. Though it was more toward when I first started. It's really uncomfortable, but not incopassitating.
     
  5. David Shaughnessy

    David Shaughnessy

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    0
    Jun 28, 2017
    Cool thanks, I'll look into the air cleaner for pieces.
     
  6. Axis59

    Axis59

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    Dec 18, 2020
    Not seeing any capacitor being used here I'm assuming the red cylinder is a isolation terminal not a capacitor
     
  7. AnalogKid

    AnalogKid

    2,424
    690
    Jun 10, 2015
    1. Nope. It has printing on it that says "Warning - Discharge before touching terminals". Sounds like a cap to me.

    2. This thread died over three years ago.

    ak
     
    Axis59 likes this.
  8. Axis59

    Axis59

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    Dec 18, 2020
     
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