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EXTREAM DANGER
ELECTROCUTION HAZARD
Read This
Warning: Any device designed along the line discussed in this document has the potential of doing great bodily harm up to and including death. Proceed at your own risk. If you have no experiance with these types of devices specifically or high voltages in general I would suggest you find another pursuit. These devices can and will kill you if they are mishandled. I repeat, if you do not have the appropriate level of expertise and knowledge do not attempt to build any of these devices. I will not be held liable for any damages or injuries resulting from the use or misuse of any information provided on these pages.
General
The supply described may be divided into two subsections: the low current dc charging circuit and the high current discharge & control or sequencing circuits. This power supply is manually sequenced and the simple discharge circuit is adequate for microsecond range pulses. Provisions for automatic control could be incorporated in this basic supply.
Applications
The device described in this article can be used as is or modified to supply high voltage pulses for laser applications, experimental rail guns, explosive metal forming, experimental fusion reactions and sonar related experiments to name a few. This device also make a wonderful fishing tool for the impatient (but not from an aluminum canoe-please)
Equipment Considerations
The equipment required for this project consists of a high voltage power supply in the 2 to 3 Kv range, one or more oil or plastic dielectric capacitors capable of storing a few hundred to a thousand watt-seconds (Joules) of energy, and a well insulated switch for discharging the capacitor through the wire. Polarized electrolytic capacitors should not be used in this type of application. There is a distinct tendency towards catastrophic failure of this type of capacitor (explosions, flying shrapnel, etc.).
The energy, E, stored by the capacitor is computed per
the following expression:
E = ½ CV2 (Joules)
where C is the capacitor rated in farads and V is the charging potential in volts. A typical "home size" capacitor bank of 200 uF at 2000 volts would therefore have an energy content of 400 watt-seconds. If the discharge period of the capacitor were 10 microseconds, the power impulse in watts would be E (400 Joules) divided by the duration (10 usec) or 40 megawatts.
DC CHARGING CIRCUIT
Specific component values will vary according to the specifications of the step up transformer which you are capable of finding. The ideal charging circuit can produce 2 kV at about 50 mA but, voltages in the 1 to 3 kV range are adequate for most experiments. The output voltage of the hv transformer is continuously adjustable by means of the auto-transformer. For rectification, a full wave center tap rectifier is shown. Alternatively, a full wave bridge could be used. Current limiting is provided by Rs. Use a string of wire wound power resistors for this. Keep the maximum voltage drop per resistor to about 200 volts. Two meters are essential: a voltmeter (located after the charging resistor string so that the capacitor voltage is indicated) and a milliamp meter. Keep the meters on the ground side of the circuit as noted. The voltmeter will most likely require a multiplier resistor, Rm. Which is a string of 1%, ½ watt resistors, keep the voltage per resistor in the 200 range.
DISCHARGE & CONTROL
CIRCUITS
The discharge circuit consists of the capacitor, the high voltage drop relay, the test gap, and a charge inductor. Locate the discharge circuit away from the charging circuit with all high current wiring as short as possible to minimize the loop inductance. These cables can be made from auto battery jumper cable wire with clear flexible plastic (vinyl) tubing slipped over the wires to provide additional insulation. Terminate cables with with heavy copper lugs. Check a welding supply store for these. As a safety measure, the charge inductor will provide a relatively quick discharge path should the gap not fire. The choke should have a low resistance (about 100 ohms). Use a standard auto ignition coil as the choke or a string of wire wound (inductive) power resistors may be used for the same purpose. The high voltage end of the coil is connected to the power supply and capacitor; the primary negative terminal is connected to the ground.
The Control Circuit
The control circuit is a DPST switch that simultaneously shuts off the charging circuit and disengages the contractor when the desired voltage is reached, put a long plastic extension on the switch toggle because you don’t want your hand near this thing when it is running. Don't touch anything else during the cycle. Keep the capacitor, the drop relay and the charge inductor inside a grounded metal cabinet. Locate the test gap at least two or three feet from the capacitor. The remote ends of the cables should be connected to insulators about one foot apart from each other. To each of these insulators attach a piece of thick copper wire extending inward, between the insulators.
The discharge cycle is initiated
when the drop relay is de-energized.
REMEMBER
THIS DEVICE IS EXTREAMLY DANGEROUS
Plans For The Generic Power Supply
Plans For The Drop Relay Device
The Experimenter's Base
Recommended Reading
High Speed Pulse Technology by Frank Frungel
Two Volume Set from Academic Press, NY, 1965
Information Services
Comprehensive Legal Resources
The Alternative Local 246,
U.W.U.A. Web Page
Victims Rights
