SHARK REPELLING DEVICE INCLUDING PULSE GENERATOR PRODUCING ELECTRICAL FIELD IN WATER BETWEEN WIDELY SPACED ELECTRODES

• US 3,683,280 A
• Filed: 11/09/1971
• Issued: 08/08/1972
• Est. Priority Date: 11/09/1971
• Status: Expired due to Term

• Current Assignee: John K. Holt
• Original Assignee: John K. Holt
• Inventors: John, K. Holt
• Primary Examiner(s): Robert L. Richardson
• Application Number:
  US05/196,908
• Time in Patent Office: 273 Days
• Field of Search: 325/28,105,116,118,141,164,169 307/252 49/59 43/17.1
• US Class Current: 43/9.6
• CPC Class Codes: A01K 79/02 by electrocution
• CPC Class Codes: H05C 1/02 providing continuous feeding of dc or ac voltage

Abstract

A sealed, water-proof housing encloses an inverter which is energized from a direct current source, such as a relatively low voltage battery in the housing, and has a secondary winding connected to opposite input terminals of a full wave rectifier, also enclosed in the housing. One DC output terminal of the rectifier is connected directly to an output terminal for a first electrode, and the other DC output terminal is connected to an output terminal for a second electrode. The first and second electrodes are spaced widely apart in the water, as by being trained along opposite edges of a trawl net or '"'"''"'"''"'"''"'"'bag.'"'"''"'"''"'"''"'"' Preferably, two pairs of electrodes are used, with corresponding polarity electrodes being connected to the same output terminal. The housing is attached to the net at a midpoint, with one pair of electrodes extending forwardly and the other pair extending rearwardly. A power capacitor is connected across the DC output terminals, and a variable resistor is connected between one AC input terminal of the rectifier bridge and the gate of the SCR. The SCR, during each alternate half cycle of AC potential applied to the input terminals of the rectifier bridge, is gated conductive through the variable resistor to discharge the power capacitor through the electrodes and the body of water therebetween to establish an electric field in the body of water. The potential across the power capacitor rapidly decreases to a value at which the SCR becomes non-conductive to interrupt the electric field. The charging of the capacitor and the discharge thereof is repeated cyclically. The battery in the housing is rechargeable.

Claims

1. A shark repelling device comprising, in combination, a selfcontained source of low frequency AC potential haVing a pair of output terminals;

a full-wave rectifier bridge having a pair of AC input terminals, connected to said output terminals, and a pair of DC output terminals;

a power capacitor connected across said DC output terminals;

an SCR having one of its anode and cathode terminals connected to one terminal of said capacitor for discharging said capacitor;

a variable resistor connected between one of said AC input terminals and the gate of said SCR for supplying the firing voltage of said SCR;

at least one first electrode connected to the other terminal of said capacitor;

at least one second electrode connected to the other of the anode and cathode terminals of said SCR;

said first and second electrodes extending into the surrounding body of water and, in use of said shark repelling device, being spaced apart by a distance of the order of ten feet;

said SCR, during each alternate half cycle of AC potential applied to said AC input terminals of said rectifier bridge, being gated conductive through said variable resistor to discharge said power capacitor through said electrodes and the body of water therebetween to establish said electric field in the body of water between said first and second electrodes, with the potential across said power capacitor rapidly decreasing to a value at which said SCR becomes non-conductive to interrupt the electric field.

2. A shark repelling device, as claimed in claim 1, in which said self-contained source of low frequency AC potential comprises a single source of low voltage DC potential;

and an inverter having DC input terminals, connected to said source of DC potential, and a pair of AC output terminals connected to said AC input terminals of said full-wave rectifier.

3. A shark repelling device, as claimed in claim 2, in which said inverter is a transistorized inverter.

4. A shark repelling device, as claimed in claim 1, including a water-tight sealed housing enclosing all of said components except said electrodes;

said electrodes extending in sealed relation from said housing.

5. A shark repelling device, as claimed in claim 4, in which said sealed housing is secured to a trawl net arranged to be drawn behind a fishing vessel and connected to the fishing vessel by cables;

said first and second conductors extending along respective opposite sides of said net from said sealed housing;

said electrodes extending from respective exterial outlet terminals on said sealed housing connected to said output terminals of said source of low frequency AC potential, in sealed relation.

6. A shark repelling device, as claimed in claim 1, including plural first electrodes commonly connected, in parallel to each other, to said other terminal of said capacitor, and plural second electrodes commonly connected, in parallel to each other, to said other of the anode and cathode terminals of said SCR.