Pulse Discharge Index


My Pulse Discharge Machine

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Previous Revisions of my Pulse Discharge Machine

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Experiments - (Amusing stuff to do with 50-100 KA)

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Shrunken quarter compared to a penny and a dime
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Shrunken Susan B. Anthony Dollar

Here are the latest quarter experiments.  
This clearly shows that 10 turns works better than 6 or 8.  The next experiment needs to be to keep the energy level constant and vary the number of turns until an optimal number is found.  The equations show that it should be an "upside down" parabola sort of thing with a definate maximum.  I was actually half-way scientific about it this time.  I always intend to be, but I wind up just blowing something up, laughing maniacally, blowing up something else, laughing, etc...

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Results of 10KV, 12T of 10ga magnet wire.  Lots of out of plane deformation (cupping) of the silver dollar.

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Notice how annealing allowed the metal to 
deform without cracking
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High energy levels caused the unannealed
pipe to split and wrinkle

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My own special recipe!  I call it "Seven Kilojoule Apple Delight!"


Bert Hickman's Telsa & Pulsed Power Page Excellent hobbyist site with lots of good photos and theory.  Be sure to read the theory of quarter crushing.  It's the best description that I have found.  Bert is the most knowledgeable pulse power hobbyist out there.  His links cover it all - go see Bert's links
Electromagnetic and Hyperplastic Forming THE premier resource for High Velocity Metalforming with Pulsed Magnetic Fields.  A MUST READ.
Robert Stephen's Quarter Picture and info on a crushed quarter
R.E. Beverly III and Associates Pulsed Power Components and Systems, Research and Development, and Scientific Software.    Commercial site that contains great technical articles on triggered spark gaps.  Nice pictures of trigatrons.
Jim Lux's Web Page Great site with lots of HV information.  Be sure to check out the HV handbook that Jim is working on.
MIT's Corridor Lab Exploding Wire Demo Nice little exploding wire demo with oscilloscope analysis
Bill the ArcStarter's "Big Capacitor" Page Bill & Fleishwulf performed and documented several excellent pulse dicharge experiments.  Be sure to crawl around in this site and visit the can crusher page, quarter shrinker page, cap autopsy, and the photomicrographs of the shrunken quarter on Fleishwulf's page

    - Jim Lux
    - Bert Hickman
    - Moderators of Telsa Coil Mailing List and High Voltage List

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Schematics and Principles

Charging and discharging a large pulse capacitor into a load is not a trivial process.  There are an infinite number of possibilities that range from simple HV switches involving banana plugs with PVC handles to complicated and expensive HV relays and triggered spark gaps.  The following schematic and text describe an optimal system arrived at after several years of iterations and refinements.  I



NOTE - the following is a bit out of date.  I'm working on the revision.

The trigatron is complete and all components are ready to go.  See description of trigatron electrical components below.  Here is a breakdown of the charging and pulse circuit.  (Note, ignore polarity of caps - I was in a bit of a hurry and didn't have time to draw them correctly)
R1 = 5K, used to limit current back into charging circuit.
S2 = actually my TC controller with deadman switch
S3 = wired a relay in parallel with my deadman.  This switch opens when I release my deadman.  Actually, I will probably wire it so that it shorts my charging circuit to ground when it opens.  This will provide some additional protection.
C4 = 178uF, 10KV Sangamo pulse cap
C2, C3 = 30KV, 500pF doorknob caps used to prevent any HVDC from getting back into trigatron trigger circuit
Work Coil = recommended coil for a quarter crusher is 10T of 10ga magnet wire.


Vacuum contactors 

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PDF datasheet for my vac contactors RF10B

Gas Filled Contactors

PDF datasheet for my SF6 contactors

High Voltage Relay
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HV contactor made by Ross Engineering.  It's rated at 30KV, 120 Amps continous. Ross P/N 23598-800559.


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Find any old meter that has a full scale (fs) reading of 50 or 100uA.  Now for a bit of Ohm's Law.  Lets say that you want your 100uA meter to read 10KV fs, lets calculate how much series resistance we need to get 100uA.  V=IR, so R = V/I = 10e3/100e-6 = 100 meg ohm.  Easy you say, those only cost about 69 cents down at Radio Shack.  Well, it's almost that simple...  A normal 1/4 watt resistor can only handle about 1kV before the voltage will simply run across the outer surface of the resistor rather than through it.  With this in mind, we quickly see that we will need at least 10 resistors in series.  This means that you should go get yourself a bunch of 10meg 1/4 watt resistors and heat up the soldering iron.  I typically solder about 9 of them together, measure the resistance with the best meter that I can get my hands on, and then fine tune the overall resistance with smaller resistors.  Have fun

photo is "clickable"

Note - this thing recently started acting crazy.  I haven't done any troubleshooting yet because I found a Fluke 6KV high voltage probe for my DMM.  It works great all the way up to 10KV with no problems.  I like seeing the trend from the analog meter better but the DMM solution is more accurate and easier to see from a distance.


Here are some pictures of the mechanical components of a home made trigatron fabricated by Brian Basura.  
All images are "clickable" for a larger view.  

See description below
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Ross is giving it one final checkout
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Trigatron housings aren't easy to build on a small lathe!
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Clear End
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Dissasembled View
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Spark Plug End

This is the prototype trigatron base and bus bar configuration.  The pulse cap hooks up via the 2ga screw down connectors on the left and the quarter goes inside the coil on the right hand side of the photo.  This is the 2nd of 2 units that Brian Basura fabricated (as usual, beautiful craftmanship!)  Turns out that the blast force was much beyond what we anticipated.  Extensive damage was done to the blast plate, wooden base, and 1" thick lexan base when the diamond plate containment box was fitted over the quarter shrinking coil and the fire button was pushed!  Regardless, with a little last minute engineering we managed to make this unit hold up for 8 or 9 quarter shots.

Notes on firing voltages:
I disassembled and cleaned my trigatron for the first time on 2/16/01. I am pleased to report that there was no significant wear and only minor corrosion of the aluminum and copper surfaces.  The plastic liner was discolored from the extreme UV produced by the main arc.  The trigatron had about 60 shots on it before the cleaning.  I had to readjust the spark gap upon reassembly.  I screwed the electrodes together until they touched and started backing them apart.  The results are as follows:  
2.25T - self triggered at 7KV  
3.25T worked great up to 10KV and would still reliably fire at 5KV.   
4T would still fire at 5KV but self triggered at 10KV after a few shots (the clean surface of the electrodes no doubt became bumpy from minute amounts of copper vaporizing and condensing back on the electrodes).  I still need to increase the distance to have safe functionality up to 10KV.

The trigatron is triggered by a high voltage arc inside of the main body.  We are using a modified spark plug as the trigger electrode.  The following circuits are various schemes to produce an arc on the modified spark plug.

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Schematic I have both a phuematic fire switch and a push button switch wired in parallel.  I only use the push button for bench testing!  

Here is a nice shot of the inside of the box.

Sizing the components:

Notes on Ignition Coils

After fooling around with several types of ignition coils, I decided that I like HEI coils best.  They are smaller and have a higher turns ratio.  I tested the turns ratio by applying a sinusoidal voltage to the input using a HP signal generator and I scoped both the input and output waveforms on a Tektronics TDS210.  I set the input for 1 volt and simply read the output voltage.  The results were the same when measuring peak-to-peak and measuring RMS voltages.  I used an aftermarket HEI coil for a 76 Cadillac with a 500 cid engine.  It cost about $12 at Kragen.  This ignition coil is nifty since it is the same one that Terry Fritz modified to turn it into a mini Tesla Coil.  Terry managed 13+ inch arcs off this baby.  (need to link to Terry's GMHEICSLR work here)

Standard Coil has a turns ratio of about 66
HEI has a turns ratio of 84V

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PULSECAP.JPG (87819 bytes) VOLTS ENERGY (Joules)
0 0
1000 89
2000 356
3000 801
4000 1424
5000 2225
6000 3204
7000  4361
8000 5696
9000 7209
10000 8900

Table valid for a 178uF capacitor
Energy (J) = 1/2*Capacitance*Voltage^2  

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These things will kill ya!
considered lethal = 50J
defibulator, max setting = 360J
my pulse capacitor = 8900J

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