high-voltage, high-current electronics

updated: 1998-06-29

This is just something I threw together that I thought you might find useful. comments?

contents:

... perhaps I should categorize these into "pulsed power" (including coilguns, strobe guns) vs. "continuous power" (including Jacob's ladder).

FIXME: move this stuff to http://www.communitywiki.org/odd/MadScientist/HighVoltage /* was http://oddwiki.taoriver.net/wiki.pl/MadScientist/HighVoltage */

"Who hath divided a watercourse for the overflowing of waters, or a way for the lightning of thunder ?" -- Job 38:25

Jacob's ladder

Tesla coil

unsorted

http://home.navisoft.com/rossengineering/ Dangerously high voltage stuff.

Micro Linear Corp http://microlinear.com/ sells $2.25 (in 1 000 s) ML4877 designed to power cold-cathode fluorescent lamps for backlighting LCDs. "up to 2 KV ... up to 30 W"

there's a clever high-voltage static electricity generator at http://www.amasci.com/emotor/kelvin.html which also has other pointers to high-voltage electrostatic projects, and more construction tips: wood is surprisingly conductive at these high voltages; fishing line makes a good insulator, etc. /* was http://pw2.netcom.com/~tonyh3/ */

Geoff has also build this device, and put some nice photos online: http://www.angelfire.com/ak/egel/kelv1.html

Here's a local copy: 

                           "Kelvin's Thunderstorm"
              or Lord Kelvin's water-drop electrostatic generator
                               Bill Beaty, 1995



It is possible to build a very simple high voltage generator which has no
moving parts and is powered by the energy of falling water.  By dribbling
water through some old soup cans, several thousand volts magically
appears.  The magic lies in the fact that water (as well as everything
else!) is made of vast quantities of positive and negative electric charge
in perfect cancellation.  This device is a gravity-powered charge
un-canceller.

The basic idea is this:

                                 ||||||
                                 ||||||   Grounded
                                 ||||||   Water
                                 ||||||   Dripper
                                 ||||||
                                 ||||||
                                  \  /
                                 - || -
                                  - _ -

                                    _           + + + + + + +
                                   -o-        + -------------- +
                                    -        + |              | +
                                             + |  positively  | +
                                    _        + |  electrified | +
                                   -o-       + |  object      | +
                                    -        + |              | +
                                             + |              | +
                    Negatively               + -------------- +
                    electrified     _           + + + + + + +
                    droplets       -o-
                                    -

      Fig 1.  CHARGING OF WATER DROPLETS BY INDUCTION

Water is full of movable charges, half positive, half negative.  The
positive object causes separation of charges in the nearby water by
drawing an excess of negative ions into the tip of the water dripper,
while repelling an equal amount of positive ions back into ground.  When
the water drop detaches from the tip of the dripper, it carries away
negative charge, leaving the earth slightly positive.

This is interesting in that the positive object never needs to lose its
charge imbalance, yet the negatively electrified water drops will be
created continuously forever, as long as the water keeps flowing.  The
electrical energy is all created by the work that gravity does in pulling
the negative droplet away from the grounded dripper and away against the
attraction of the positive object.  (Note: the charge polarities can be
reversed: if the "object" is negative, the droplets would be positive.)

Suppose you build two of the drippers in Fig. 1, set them side by side,
then collect the electrified water drops from one side and use them to
electrify the "charged object" on the other.  You'll then have a
self-sustaining electrical reaction.  The negative droplets touching the
lower can of one assembly will charge the negative upper ring of the
other, and the positive droplets on the other side will touch the lower
can and charge the upper ring of the first side positively.  The grounded
drippers are connected to each other and to ground.  This all is
illustrated in Fig. 2. In fact, if you build such a device, it will
usually create voltage spontaneously without being pre-charged.

Kelvin's complete generator device looks like this:

__________________________
_   _____________________  \
  \ \                      \ \
    \ \                      \ \
      \ \                      \ \
       ||                       ||
       ||                       ||
       ||                       ||
       ||                       ||
       ||                       ||     grounded drippers (need not be metal)
       ||                       ||

     == ==                     == ==   metal disks with holes, or wire rings,
                                       or bottomless metal coffee cans, or
                                       bundt pans (supported by insulating
                                       rods)
    |    |                     |    |
    |    |                     |    |
    |    |                     |    |   metal cans on insulators (styrofoam?)
    |    |                     |    |
    |____|                     |____|
     |  |                       |  |
     |  |                       |  |
     |__|                       |__|

Fig. 2   TWO DROPLET-CHARGERS PLACED NEAR EACH OTHER (no wires shown)




Wires are used to cross-connect the cans and the wire rings.  The two
diagonal wires must not touch together:

__________________________
_   _____________________  \
  \ \                      \ \
    \ \                      \ \
      \ \                      \ \
       ||                       ||
       ||                       ||
       ||                       ||
       ||                       ||
       o  +    +         -    -  o
  +  == ==----\            /---== ==  -
       o    +   \ +    - /  -    o
                + \    /
       o            C/           o
  - |    | -       / \       + |    | +
  - |  o | -   - /   + \     + | o  | +
    |    |_____/         \_____|    |
  - |----|   -             +   |----| +
    |____|                     |____|
     |  |                       |  |
     |  |                       |  |
     |__|                       |__|

     Fig. 3   KELVIN'S THUNDERSTORM, W/WIRES SHOWN


OPERATION

Once you have the water dripping, you can expect high voltage to
immediately appear.  Touch one of the coffee cans gently and listen for
tiny "static" sparks.  Obtain a small "NE-2" neon pilot light, hold it by
one wire, then touch one of the cans with the other wire.  You should see
a dim orange flash.  Touch a can on one side, then a can on the other, and
you should receive a tiny spark each time.  Don't connect the NE-2
directly across the two wires or it will short out the generator and
prevent high voltage buildup.  Instead, you can connect the NE-2 to one of
the generator's wires and bend it so the NE-2's other lead is very close
to the other wire.  Small sparks will jump across the small gap and flash
the NE-2. The smaller the gap, the faster yet dimmer the flashing.


HINTS

If none of this works, it may be because the humidity is high and your
device is having trouble "deciding" which side should be positive and
which negative.  It takes voltage to make voltage, and if your device
starts totally at zero, it may take a minute or two to build up to
maximum. Try holding an electrified object briefly near the cans (for
example: a balloon, a 2liter pop bottle, or some styrofoam, each rubbed on
hair to electrify.)

The energy that builds up between the cans comes from the falling of the
water, and as the stored energy grows, the water has to do more and more
work to add a bit more charge imbalance to the cans.  The electrified
drops feel a repulsion force as they fall towards the like-charged cans,
and as the voltage increases, the drops will fall more and more slowly.
They may even start bending their paths, even occasionally falling
upwards!

If the device is run for very long, the lower cans fill up.  How to get
the water out of the cans without discharging them?  Here's my addition to
the classic Kelvin Waterdropper: use the "faraday ice pail" effect, where
a conductive hollow object always has no charge inside.  Connect an exit
tube inside each lower can as below, so the water DRIPS out (if it falls
in a solid stream, the cans will discharge.)


   ||                 ||
   ||                 ||
   ||                 ||
   ||                 ||
   ||/\/\/\/\/\/\/\/\/||
   ||                 ||   For best results, no sharp edges or
   ||                 ||   burrs anywhere.
   ||     WATER       ||
   ||                 ||
   ||     __   __     ||
   ||    |  | |  |    ||
   ||    |  | |  |    ||
   ||    |   U   |    ||
   ||    |   O   |    ||
    ======       ======
             O
                Uncharged drops
             O  exit from bottom


   Fig. 4  REMOVING THE WATER FROM THE LOWER CANS


Or, even simpler, install a cone-shaped piece of metal window screen
inside a bottomless can, so the water drops touch the screen and continue
through.  Make sure the screen is vertically centered, so that the point
of the cone doesn't extend past the lip of the can.

With a little catcher-tray and a fountain pump, you can make the system
recirculate.  Or, you can stack all four parts of one Kelvin device in a
single row, for an in-line waterdropper generator.

             \ \
               \ \
                 \ \
                  ||
                  ||
                  ||
                  ||
                  o
                  o
                |   |
        Neg     |   |
        can     | o |
                |   |

       Pos      |   |
       can      |...|
      w/screen  |   |
                |   |

                \    /        Connect pos to pos, neg to neg
    Grounded     \  /
    Funnel        ||
                  o
                |   |
        Pos     |   |
        can     | o |
                |   |

       Neg      |   |
       can      |...|
      w/screen  |   |
                |   |
                  o

    Fig. 5   IN-LINE VERSION (wires not shown)

The water supply need not be a "dripper", it can be a high velocity spray,
as long as the jet divides into droplets, not a contiguous stream.  And
multiple jets can be used, sort of like a shower head.

I've always wanted to build a gigantic version that works like that below,
with hollow metal toroids.  (Use halves of VandeGraff spheres, the halves
with the holes):

        \\                              \\
          \\                              \\
            \\                              \\
             ||                              ||
             ||                              ||   water
             ||                              ||   spray
             ||                              ||
     ___           ___                ___           ___
    /   \         /   \              /   \         /   \
   |     |       |     |            |     |       |     |  Four torii
    \___/         \___/              \___/         \___/   (shown cross-
                                                            sectional)


     ___           ___                ___           ___
    /   \         /   \              /   \         /   \
   |     |\     /|     |            |     |\     /|     |
    \___/   \_/   \___/              \___/   \_/   \___/

          conical screens in lower torii touch droplets and release,
          discharging them.  Entire screen assy must be deep within
          the "hole" of each donut so the torus shields it from the
          field on the outside.


  Fig. 6  GIANT KELVIN DEVICE BUILT FROM SPUN-METAL DONUTS


High-velocity waterjets and hollow-pipe cross-connecting conductors
complete the scene:  a "VandeGraaff Generator" version of Kelvin's
Thunderstorm apparatus!

The above generators can be used to run a motor, if the motor is my Pop
Bottle Electrostatic Motor at:
   http://www.eskimo.com/~billb/emotor/emotor.html
I find that the Kelvin Waterdrop Generator is a little too feeble to keep
the motor going continuously.  Instead it builds up a charge imbalance,
then the motor starts turning and rotates a few times, the imbalance is
exhausted, then it builds up again and repeats.  This happens a couple of
times per minute.  Perhaps if several generators were connected in
parallel, the motor would run continuously.


Subject:      Re: Homebuilt EDM ?
From:         wanliker@aol.com (WAnliker)
Date:         1998/06/06
Message-ID:   <1998060614102200.KAA00941@ladder03.news.aol.com>
Newsgroups:   rec.crafts.metalworking
[More Headers]
[Subscribe to rec.crafts.metalworking]

Home Shop Machinist published a construction series on the EDM.
It is available in book form from:
The Home Shop Machinist
PO Box 629
Traverse City , Mich. 49685
1-800-447-7367
Bool is titled:  BUILD AN EDM
56 page, softbound 8.5 x 11 @$17.00
This is a complete construction manual, mechanics, electronics,

railguns and coilguns

Railguns and coilguns have many characteristics in common (nearly constant acceleration down the barrel, exit speeds not limited by the speed of sound, accelerates only the payload -- not the engine/energy source, etc.).

See link_farm.html#people_that_scare_me

(DAV is interested in "rail guns" as in electromagnetic propulsion, not "rail guns" as in guns that happen to mounted on rails, although the latter are generally more ... intimidating.).

misc unsorted

Started 1998-06-17

Send comments, suggestions, bug reports to

David Cary
d.cary@ieee.org.

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