in a first embodiment , the above mentioned problem has been solved by the present invention by providing an electrically powered animal trap , which comprises means for communicating a surveillance signal between the trap and an external surveillance unit . due to the means for communicating a surveillance signal between a trap and an external unit , the keeper of the trap may know the condition of the trap without direct inspection of the trap . the trap may thus be left unattended for a long period time , where the trap keeper can rest assure , that the trap is fully operational . the trap may comprise a bottom section with an upwardly extending sidewall , a top section , and at least one entrance . the entrance may be either in a sidewall , in the top section of the trap , in the bottom section of the trap , or anywhere else . upon entering the trap , the animal enters a chamber , where a bait or lure may be placed in the opposite side of the chamber . the set of electrodes may comprise at least two electrodes , e . g . placed between the entrance and the end section where bait can be placed . the bait may be a liquid dripping in a controlled way , which ensures a continuous supply of strong scent , it may be in the form of dry pills or tablets , it may be food , or it may be a scent means . a bait storage arrangement may be provided , this may enable automatically feeding the bait to a trough , and furthermore control the flow of the bait from a storage to ensure optimal dosing . the surface of the electrodes may be rough . e . g . by adhering metal or plastic shavings to a metal plate in any conventional way , e . g . plastic composites incorporating metal conductive wires or shavings . another possibility for making the electrode surfaces rough , is by using powder metallurgy . however , smooth surfaces of the electrodes may also be provided . in case three electrodes are used , the electrodes may be interconnected in a way such that a first of the electrodes is connected to a second of the electrodes and wherein a third of the electrodes is electrically insulated from the first and second electrodes . a small voltage up to 4 , 5 v dc may be maintained between the two first electrodes and the third . the source may be a small accumulator , such as a 12 v motorcycle battery . an electronic circuit ( a sensor circuit ) may be adapted to detect a leak current between the first and the third electrode by detecting the presence of a finite resistance . this will happen when an animal is touching electrode 1 , at the same time as it is touching electrode 3 . a high - voltage potential difference between the first and the third electrode should then be generated by an additional “ power electronics ”, which can be incorporated with the sensor circuit . the result is that the animal is electrocuted . the high - voltage potential may be in the form of a continuous voltage maintained for a predefined time , or it may be in the form of a series of pulses . the use of pulses may be advantageous , as the animal may be killed faster and less painfully . these pulses may have the form of steps , where each step comprises different voltages kept for different time periods . the pulses may also be in the form of a sinusoidal wave , or it may be a series of short pulses . the electronic circuit may be made in a versatile way where these aspects can be adjusted electronically . alternatively , only two electrodes may be used . the trap may comprise additional or different means for detecting the presence of an animal by equipping the trap with a weight sensitive detector , a motion sensitive detector , which may be achieved by using one or more infrared sensors , or a lever arm . these means may be added in order to increase the certainty that an animal is present in the trap , before the high - voltage potential is generated , or they may be used as alternative means for detecting the presence of an animal . the trap may be equipped with an exit for removing the electrocuted animal into a receptacle . this receptacle may be an open receptacle as a sewer or a small stream of water into which the dead animal may be dumped by e . g . using a trapdoor in the bottom of the trap . to accommodate a trap in such a situation , the trap may be equipped with lifting means to lift up the trap . the lifting means may be one or more legs that are adjustable in length , for example telescopic legs , i . e . legs where a single or a series of thinner legs are sliding inside a thicker leg , and where a specific length can be maintained by a fixing means . the adjustment of the length of these legs can be facilitated by using pressurized gas in a similar manner as with office chairs . the receptacle may likewise be a sealed container on top of which the trap is fastened . the containermay be equipped with a bag in which the dead animals are collected . a bag will ensure easy and hygienic emptying of the trap as no physical contact with the dead animals is needed . the receptacle may contain a chemical bath for dissolving the animal . the trap is fully automatic and controlled by the electronic circuit . the exit can be actuated either electrically , hydraulically , pneumatically , mechanically or by any combination of these . for example a trapdoor where the locking - unlocking is an electromagnetic tap which unlocks the trapdoor when the electrocution has finished . the trapdoor can be fastened to the trap by a pivotal hinge at one side such that the door opens upon the weight of the dead animal , and tips back due to a counter weight . in another design the trapdoor is also attached at one side with a pivotal hinge , but in this case the opening and closing is controlled by a motor which unrolls and rolls up a piece of string . it is also possible to place the hinges at opposite sides of the trapdoor , such that the trapdoor tips around an axis perpendicular to the axis around which , the trapdoor tip when the hinges are places in the same side of the trapdoor . as the trap may be raised above the surroundings , an entrance ramp may be needed . the ramp may be constructed in wood . but it may likewise be constructed in plastic , stainless steal , nickel or any suitable material . as the inside of an electrocution trap may be dangerous to touch , a tube or a flexible hose may be mounted in front of the trap entrance . by using a bent tube ( or a flexible hose ), e . g . an s - form , an elbow form or a zigzag form , a child will not be able to get its arm inside the trap . a trap which has such a mount placed in front of the entrance is therefore a lot safer to place in areas where children may play than other types of traps . the entrance may also be equipped with a clipping means , thereby enabling to clip on and use any suitable material as entrance . a battery can only supply a limited number of electrocutions before it needs to be recharged . the trap may therefore be equipped with a power adapter that allows connection directly to a power grid . some traps may be placed at locations where it is not possible to directly connect the trap to a power grid . in this case the trap can be equipped with a chargeable battery . the trap may be able to stand flooding or high water levels if , e . g ., it is located in a sewer . this may be achieved by embedding the electronics in a waterproof housing , and furthermore by incorporating a water detector that may transmit an electronic signal , e . g . in the case the water level rises above a predetermined level . the electronic circuit may be adapted to react in response to a signal from the water detector , by disabling the generation of the high - voltage potential . the water detector may comprise a timer detecting at predetermined time interval whether or not high voltage generation may be performed , or whether or not it may be safe to switch on the electronics . the electronic circuit could comprise means for storing an identification code for the trap , and / or information relating to the number of captured animals , the remains of the bait , and the battery condition . a display could be included in the electronic circuit , such that the above mentioned trap information may easily be read - out . the electronic circuit could furthermore comprise means for sending out a wireless electromagnetic surveillance signal that may be received and read by an external unit . the signal may comprise the above mention features and may only send out upon receiving a request signal from the external unit , thereby avoiding draining the battery . a surveillance signal may also automatically be sent out in the case of a capture , in the case of low battery power or in the case of loss of bait . the surveillance signal may be any electromagnetic signal , such as a radio - signal , or a signal around 2 , 4 ghz which is the bluetooth standard frequency , or a signal in the low frequency domain , such as few hundred khz . the trap may additionally comprise means for determining the geographical position of the trap . this may be achieved by incorporation a global positioning system devise ( gps ), a mobile positioning system device ( mps ), such technology has been demonstrated by the swedish corporation ericsson , or a nordic mobile telephone ( nmt ) device . the surveillance signal can therefore further comprise the position of the trap . the electronic circuit may also be equipped with a means for receiving a command signal send out by the external unit . this would be useful if , for example , the trap is further equipped with a size adjustable entrance opening . above , only the situation of a single trap is described . an ensemble of traps may be monitored by a software program adapted to store information on the identity code , the position , etc ., of the individual traps in the network . the software should collect information about the number of captures , the condition of the bait , and the current power on the battery . a trap keeper could then fast obtain an overview of the traps that are needed to be tended to . in the following , a preferred embodiment of the invention will be described with reference to the drawing in which : fig1 a and 1b are 3 d cut of preferred embodiments of the invention , fig3 a and 3b are preferred embodiments of a trapdoor , fig4 illustrates the invention in connection with a closed receptacle , and in fig1 a , a 3 d cut of a preferred embodiment of the present invention is presented . the trapping chamber is inside a housing which comprises sidewalls 1 , a top 2 and a bottom section 3 , 4 . the access to the trapping chamber is an opening in one end of the trap housing . the entrance is not shown , but it could be an opening in a wall adjacent to the sidewall 14 . the bottom section 3 , 4 comprises two parts , one part 3 which is fixed with respect to the housing as a whole , and another part which is movable . the movable part 4 constitutes an exit , here illustrated as a trapdoor that opens in a downward direction . a set of electrodes comprising a first electrode 5 , a second electrode 6 and a third electrode 7 , are placed sequentially between the entrance and the section where the bait 8 , 9 and 16 is placed . from the bait reservoir 9 , a scent - liquid is dripping into a small bowl 8 . the bait reservoir may be re - filled from outside the trap 16 , as the reservoir protrudes through the top section of the trap . the power source of the trap is a 12 v dc battery 10 , placed on top of the trap . an electronic circuits 11 is also placed on top of the trap . the electronic circuit includes a means for communicating a surveillance signal . the surveillance signal is transmitted through the antenna 15 . the opening and closing of the trapdoor is actuated by a small motor 12 adapted to unroll and roll up a string in order to open and close the trapdoor . 1 . an electronic - print card with a microprocessor , a sensor circuit , a “ power electronic ” to drive the motor and the high voltage generator , 2 . a motor to remove the animal from the trap chamber , 3 . a display , and 4 . a transmission system to remote read - out . the sensor circuit is set to detect a leak current between the first electrode 5 and the third electrode 7 , alternatively , between the second electrode 6 and the third electrode 7 , by detecting a finite resistance between the electrodes . it can be adjusted electronically to register a resistance between 2 kω and 500 kω . the electrodes are kept at a potential of maximal 4 . 5 v dc between captures . in case of a detection of a finite resistance between the first electrode 5 ( or the second electrode 6 ) and 7 , an electrocuting high - voltage potential is generated between the same electrodes . the duration of the high - voltage potential can be adjusted electronically from 100 ms and up to permanent , with an output voltage between 500 v and 4 kv , and a transmitted power between 100 mw and 25 w . the potential change uses that the inductivity in the transformer when the period for the high voltage transformer is short . the duration is controlled by the microprocessor . the power in the electrocuting - process is changed by changing the duty - cycle of the voltage transformer , the total power admitted is thereby controlled . also the electrocuting voltage can be varied , one example is given in fig2 . the details of the variation in the voltage difference can be further elaborated upon using experience gained in experiments . the power - electronics control the motor , both with respect to speed , and with respect to the time the exit remains open . a circuit can be added which register when the motor stalls . a display shows the number of electrocutions , the remaining amount of the bait as well as the current voltage on the accumulator . the transmission system should be of the wire - loop principle , as this does not require broadcasting approval . furthermore , this type of system works at low frequencies and can be used to transmit through earth and water . in fig1 b , the trap as described in connection with fig1 a is slightly modified . here the bait reservoir 9 and a the small bowl 8 are positioned in the central region of the trap . the presence of an animal is detected using an infrared sensor 100 , and only two electrocuting electrodes 101 , 102 are used . fig2 gives an example of the voltage difference between first electrode 5 and the third electrode 7 , or between electrode one 101 and two 102 , versus time during the electrocuting process . at t = 0 the electrocuting voltage difference is generated . at t = t 1 the voltage difference drops to a predefined level which is kept until t = t 2 where the voltage difference is raised until a new pre - defined level . at t = t end the voltage difference is set to zero . fig3 a shows a second embodiment of the trapdoor 4 , where instead of using a motor 11 and a string 13 , the actuation of the trapdoor is an electromagnetic switch 30 adapted to open upon a signal from the electronic circuit 11 . due to the weight of the electrocuted animal , the trapdoor opens by pivoting around a pivot tap 31 , and closes after release of the animal due to counter weights , here exemplified by a threaded bolt 33 and a nut 32 . in fig3 b and 3c a third embodiment of the trapdoor is shown . here a solenoid 202 is used to open and close the trapdoor . the solenoid may be fixed to the trap using fixation means 200 and 201 . by activating the solenoid , rod 203 is pulled into the solenoid , which through a mechanical coupling to the trapdoor , opens the trap door , as shown in fig3 c . using a solenoid may e . g . increase the control of the trapdoor . for example it may be possible to shake the trapdoor to make sure the animal has fallen off , or to clear the trapdoor from debris or dirt on the electrodes or the trapdoor in general . fig4 and 5 show two examples of trap set - ups . in both figs . the trap 20 is raised above the surroundings , and access to the trap chamber is ensured by a ramp 21 . in fig2 the trap is placed on top of a receptacle 22 , into which the animals are dumped after the electrocution . where fig4 present a trap set - up that can be used in many different locations , e . g . a store - house , a barn or a field , fig5 envision a special case where the trap is placed directly above a sewer stream . in this situation the sewer it - self is used as a receptacle where the animals are dumped directly into after electrocution . the trap is fastened in the sewer by using length adjustable legs 23 . in fig5 the trap is positioned along the sewer , however , the trap may also be positioned so that it bridges the water stream , i . e . positioned rotated 90 degrees with respect to the one shown .
an electrically powered rodent trap which includes a surveillance system for remote surveillance of the trap so that the trap may be operated without being attended to . a rodent which enters into the trap is killed by means of electrocution electrodes . the dead rodent is automatically dispatched from the trap , e . g . by a trapdoor , into a container or reservoir beneath the trap . the number of electrocutions and possible other data is stored by an electronic system incorporated in the trap and a signal is sent out , either by request from an external unit , or automatically to an external unit . a city rodent exterminator is capable of monitoring the status of the trap from an office location and thereby effectively tend to the trap or to a series of traps .