GB699346A - Improvements in or relating to an apparatus for fishing by means of electricity - Google Patents

Abstract

699,346. Fishing. KREUTZER, C., and PEGLOW, H. July 7, 1950 [July 9, 1949], No. 17099/50. Class 48. An apparatus for catching fish comprises either (a) fish catching means such as a net and a ship-borne electrical D.C. pulse generator connected to electrodes spaced in the water in front of the net or (b) a ship-borne D.C. pulse generator of frequency about 100 per sec. connected to electrodes spaced in the water, the pulses having steep fronts and gradually sloping backs and the duration of each pulse being short relative to the pulse spacing so that the ratio of peak value to total effective value is in the order of a few hundred, or (c) a ship-borne D.C. source connected to a condenser which discharges in D.C. pulses through the water between electrodes immersed therein and intermittently conductive control means for controlling the discharge of the condenser, or (d) electrodes in front of a net and connected to a plant generating electric D.C., pulses with frontal peaks and rearward slopes such pulses being of short duration and long spacing, the pulses in the water in all cases (a), (b), (c), (d) being of fish directing magnitude. A condenser C1, Fig. 1, charged through a rectifier V1 and a choke D discharges through electrodes connected to terminals 1, 2 and through a valve Th the grid of which is connected to a timing circuit Z charged through a condenser C2.. In another arrangement a condenser charged by mercury vapour rectifier discharges through an ignitron ignited by a valve the grid of which is connected to a timing circuit including a condenser which is recharged when the valve conducts. In the circuit shown in Fig. 3 an A.C. generator G is connected to the electrodes through two ignitrons J1, J2 arranged in a full wave circuit and ignited by two grid controlled valves Th2, Th3. The fishing vessel S serves as an electrode and two counter electrodes E1, E2 are arranged in front of the mouth of the trawl net N and connected to the generator by a cable K which may also serve as a tow cable for the net. Alternatively a pair of electrodes may be arranged on each side of the mouth of the net, the two positive electrodes being nearer to the mouth. The two negative electrodes may consist of or be attached to the otterboards.