with reference to fig1 through 3 , the basic elements of the inventive pet confinement system are shown . fig1 a , 2a , 2 b and 3 generally show a receiver 10 that is secured to a collar 12 that is worn by a dog d around its neck . the receiver contains two probes 14 and 16 that make contact with the skin of the dog so that when the dog gets too close to an electrified boundary , a shock is created within the receiver 10 and passed through the probes 14 and 16 into the dog as way to alert the dog that behavior such as approaching the fence should not be done . the receiver 10 also contains a charger receptacle 18 that mates with a complementary connection provided in the transmitter 20 , which is the subject of this invention . the receiver 10 contains a light emitting diode ( led ) 22 which indicates when the receiver is functioning and an on / off switch 24 for placing the receiver in an on position and in a desired mode of operation . one such receiver that is contemplated to be used in the present invention is that provided in the woodstream 5140 fence free system . the receiver is discussed in greater detail at the havaheart website having url : www . havahart . com , the discussion of which is incorporated by reference herein . fig1 shows a diagram for the installation of a pet confinement system according to the subject invention . most often the pet confinement system is used in the context of creating a boundary 100 for providing an area 102 within which a dog d is free to roam . most often the boundary is set up about a structure such as a house 104 . frequently , a boundary area 102 contains additional areas such as 106 which are areas where the animal should not roam . in its simplest form with reference to fig1 and 3 , the pet confinement system comprises a wire 110 that is buried in the ground in a loop with the ends of the wire 112 and 114 being connected to a wire pair 116 and 118 that is twisted in the manner shown in fig3 and identified as 120 and terminating in ends 116 and 118 secured to input terminals provided on the transmitter 20 . the twisted wires are used to cancel the magnetic field that normally flows through the wire when it is being used as a single strand to define the boundary 100 . the same concept of the twisted wire can be used such as shown by the use of twisted pair 122 to cancel the field which then makes conductive contact with the wire 124 that surrounds a pool 126 in area 106 . in this way , the boundary 100 is defined about the entire property and the dog is free to roam anywhere within that boundary . at the same time an inner boundary 124 is defined within the boundary 100 to provide an area 106 that the dog is not permitted to enter . the transmitter 20 also contains six push - button switches s 1 through s 6 that are used to control the amount of the current passing through the boundary wire 110 . switch s 6 turns the system on and off and causes an led 130 to light when the system is on . switches s 1 through s 5 place the transmitter into a mode where a signal is passed through the wire 110 to generate a magnetic field having a predetermined width . in the present invention , pushing switch s 1 causes the transmitter 20 to emanate a signal that creates a field width with a radius of 1 . 5 ft . in turn , pushing switch s 2 yields a field width of 2 . 5 ft . whereas pushing switch s 3 yields a field width of 3 . 25 ft . finally , pushing switch s 4 yields a field width of 4 . 0 ft . and pushing switch s 5 yields a field width of 5 . 0 ft . fig4 shows a general block diagram of the elements that constitute the inventive transmitter 20 . the transmitter contains an input jack 210 which accommodates a connection plug from a portable transformer ( not shown ) in order to provide an input voltage for the system . through the use of a full wave bridge rectifier 212 , the input voltage can be ac or dc , but is preferably dc . the rectifier yields a dc voltage , vcc , that passes through a voltage regulator 214 which has an output port 216 that provides operating voltage to circuit elements within the system . the voltage regulator also has an output 218 connected to a charge jack 220 for mating with the charger receptacle 18 in the receiver 10 in order to charge a rechargeable battery ( not shown ) housed in the receiver 10 . the heart of the inventive transmitter 20 is a microcontroller 300 that provides various control signals on lines 310 to a voltage adjuster 312 . eeprom 314 is used to program a desired identification code which matches a comparable identification code set in the receiver 10 that is worn by the dog d . when the eeprom is operating , the identification code ( id ) is transmitted to the microcontroller 300 through data lines 316 . this identification code is constantly transmitted to boundary antenna 320 under the direction of controller 300 as will be explained hereinafter so that the receiver is able to detect and pick up the information that is also contained within the signal that carries the id . also forming part of the invention is the boundary antenna 320 which is made up of a wire that is buried in the ground in the manner shown in fig1 with reference to the wire 110 . this boundary antenna 320 transmits information from the microcontroller 300 that includes the id along with other information to cause the receiver 10 to respond in different ways . one end of the boundary antenna is connected to a switch 322 that passes through an arrangement of resistors 324 to signal ground 326 . the other end of the boundary antenna is connected to the output of an adjustable voltage regulator 330 . this regulator has an input for receiving an input voltage vcc of predetermined value from the output of the full wave bridge 212 . the regulator 330 also contains an adjustment port for receiving a signal from the voltage adjuster 312 in order to change the magnitude of the output voltage appearing at the output of the regulator 330 . the inventive circuit also includes an operational amplifier ( op amp ) 340 that is used to amplify a voltage signal appearing on line 342 which represents the voltage passing through resistor arrangement 324 when the switch 322 is on . the voltage signal appearing on line 342 is amplified by op amp 342 to a usable value and then placed into the microcontroller and passed through an a - to - d converter housed in the microcontroller . the transmitter also contains a switch array 350 made up of a series of six push button switches that are used to cause the microcontroller 300 to ultimately adjust the current passing through the boundary antenna 320 to yield a magnetic field of desired width appearing around and about wire 110 . switch s 6 is used to turn the circuit on and off . switches s 1 through s 5 are used to cause the microcontroller 300 to control the transmitter circuit in order to create a desired boundary field width around wire 110 that defines the boundary antenna 320 . basically , when switch 322 is on , the boundary antenna 320 receives a current that passes through the antenna through the switch and then through the resistor arrangement 324 to signal ground . the flow through the boundary antenna creates a magnetic field around the wire that constitutes the boundary antenna . the op amp 340 amplifies the voltage across the resistor arrangement 324 to increase the voltage amplitude to a usable value for conversion by the a - to - d converter in the microcontroller 300 . for each field width requested by switches s 1 through s 5 , there is a unique current flowing through the wire that is the boundary antenna 320 . in order to constructively measure the current flowing through the wire , set points are used . a set point is simply an a - to - d converter count which represents the desired loop current for a field width setting . each of the five field width settings has its own set point . the set points were calculated using a spreadsheet and are based on an amplifier gain of 40 . the set points are 54 for a field width of 1 . 5 ft ., 95 for a field width of 2 . 5 ft ., 124 for a field width of 3 . 25 ft ., 149 for a field width of 4 . 0 ft ., and 190 for a field width of 5 . 0 ft . as will be explained in greater detail hereinafter , when a push - button switch is selected , evidencing a desired field width across the wire making up the boundary antenna , the microcontroller 300 puts out a signal on lines 310 into a voltage adjuster 312 made up of resistors and transistor switches . the adjuster , in turn , causes the voltage regulator 330 to put out an output voltage that passes through the boundary antenna 320 . the actual loop current is monitored in the microcontroller and the microcontroller looks to see if the count represents a desired field width . if the count is too low , then the microcontroller causes the voltage adjuster 312 to increase the output voltage from the voltage regulator 330 . this interaction takes place until the microcontroller a - to - d converter reading equals or exceeds the predetermined set point value for a desired field width . at that point , the microcontroller no longer yields signals for changing the voltage output of the voltage regulator and the field width passing through the wire of the boundary antenna is at the predetermined desired value . having covered the general operation of the transmitter , the detailed operation of the circuitry that constitutes the fig4 embodiment of the present invention will now be described with reference to fig5 with like reference numerals denoting like elements to those described in the other figures . fig5 is a schematic diagram of a preferred embodiment of the present invention . at the heart of the system is microcontroller 300 . six push - button switches s 1 - s 6 are connected to the microcontroller 330 . switches s 2 , s 3 and s 4 share a common connection with pin 15 of controller 300 , whereas , switches s 1 , s 5 and s 6 share a common connection with pin 9 of controller 300 . in turn , the other connections of the switches are as follows : switches s 4 and s 5 are connected to pin 8 ; switches s 3 and s 6 are connected to pin 7 ; and switches s 1 and s 2 are connected to pin 12 . eeprom 314 has pins 1 - 4 connected to ground . the eeprom also has pin 7 connected to ground . pin 8 is connected to the output 216 of voltage regulator 214 . pins 5 and 6 of eeprom 314 through resistors r 18 and r 19 , respectively , are connected to output 216 which in turn are connected to ground through capacitor c 11 . pins 5 and 6 are connected to pins 1 and 2 , respectively , of controller 300 . with regard to the power supply aspects of the present invention , fig5 shows diodes d 1 - d 4 arranged as a full wave bridge rectifier . dc jack 210 has one conductor 60 connected to node n 1 formed between the cathode of diode d 1 and the anode of diode d 2 and the other conductor 62 connected to node n 2 formed between the cathode of diode d 3 and the anode of diode d 4 . the anodes of diodes d 1 and d 3 are connected to ground . the cathodes of diodes d 2 and d 4 are connected to the input pin 1 of rectifier 214 . pin 1 of rectifier 214 is also connected to ground through capacitor c 1 . output pin 3 of rectifier 214 is connected to ground through two parallel capacitors c 2 and c 3 . pin 3 also provide a 5 v dc power source . pin 2 of rectifier 214 is connected to ground . pin 3 of rectifier 214 is connected in series with resistor r 16 and led d 8 to pin 11 of controller 300 . finally , pin 3 is connected to conductor 70 of charge jack 220 through resistor r 31 . the other conductor 218 of jack 220 is connected to ground . turning now to transistors q 2 - q 6 , these transistors have their bases connected to controller 300 in the following way : transistor q 2 has a base connection to pin 20 of controller 300 in series with resistor r 26 ; transistor q 3 has a base connection to pin 13 of controller 300 in series with resistor r 25 ; transistor q 4 has a base connection to pin 4 of controller 300 in series with resistor r 23 ; transistor q 5 has a base connection to pin 10 of controller 300 in series with resistor r 30 ; and transistor q 6 has a base connection to pin 6 of controller 300 in series with resistor r 14 . the emitters of transistors q 2 - q 6 are connected to ground . the bases of transistors q 2 - q 6 are connected to pin 1 of the regulator 330 via series resistors r 5 , r 21 , r 22 , r 28 , and r 1 , respectively . resistor r 4 is connected to ground and pin 1 of regulator 330 . pin 2 of regulator 330 is connected to pin 1 of regulator 330 via resistor r 2 . pin 2 is also connected to ground via capacitor c 5 and to the anode of diode d 6 . the cathode of diode d 6 is connected to terminal 321 of boundary antenna 320 via series resistor r 3 . terminal 321 is also connected to ground via transzorb d 5 . in like manner , terminal 323 of boundary antenna 320 is connected to ground via transzorb d 7 . terminal 323 is connected to ground via resistor r 24 and to the collector of transistor 322 . in turn , transistor has its base connected to pin 14 of controller 300 via resistor r 15 , and its emitter connected to ground via the parallel arrangement of resistors r 6 - r 8 . transzorbs d 5 and d 7 are transient voltage suppressors such as those bearing product number smbj 12 a made by fairchild semiconductor corporation , www . fairchildsemi . com . the transzorbs provide protection for the transmitter circuitry from transients caused by lightning strikes . pins 17 and 18 connect to crystal xt 1 and to ground via capacitors c 9 and c 10 , respectively . pin 16 is connected to voltage source 216 and to ground via capacitor c 8 . also pin 19 is connected to the cathode of led d 9 whose anode is connected to voltage source 216 via resistor r 20 . finally , pin 12 of controller 300 is connected to ground via resistor r 17 . the emitter of transistor 322 is connected to pin 3 of op amp 340 via resistor r 9 . pin 2 of op amp 340 is connected to ground via resistor r 10 and to pin 1 via resistor r 11 . pin 5 of op amp 340 is connected to ground via capacitor c 7 and to 5 v source 216 . pin 1 of op amp 340 is connected to pin 3 of controller 300 and to ground via resistor r 12 . as explained before , the heart of the inventive circuit is the microcontroller 300 . the microcontroller is an eight bit microcontroller developed with low power and high speed cmos technology . one such controller is that made by elan micro electronics corp ., hsinchu city , taiwan and bearing product designation number em78p458 . as stated before , six push buttons s 1 through s 6 are connected to the microcontroller 300 to provide controlling inputs . switch s 6 turns the system on and off . switches s 1 through s 5 provide an input to cause the microcontroller to adjust the field width around the boundary antenna 320 . the microcontroller 300 executes a program to carry out specific actions based upon which of the buttons is pressed . when a button is pressed , the microcontroller runs a program and outputs analog control signals to the five transistors q 2 through q 6 , which are in the voltage adjuster . in a preferred embodiment the transistors are npn type switching transistors . a preferred embodiment of eeprom 314 bears model number at24c04 made by atmel corp ., san jose , calif ., www . atmel . com . the eeprom is an electrically erasable and programmable read only memory organized as 512 words of eight bit each . light emitting diodes d 8 ( 132 ) and d 9 ( 130 ) are contained on the exterior shell of the transmitter 20 and are used to indicate certain conditions of the transmitter . in particular , led d 8 lights to indicate that the boundary antenna is connected to the transmitter and operative . led d 9 indicates whether the transmitter is on or off both of the leds are activated by signals emanating from the microcontroller 300 . the voltage regulator 214 in a preferred embodiment bears product designation number lm7805ct and is manufactured by national semiconductor corp ., www . national . com . voltage regulator 214 regulates the power to power up the remaining devices in the circuit such as op amp 340 , the microcontroller 300 , the eeprom 314 , and other items in the circuit . looking now at the programmable voltage regulator 330 , this device in a preferred embodiment bears product designation number lm 317 and is made by motorola , inc ., www . motorola . com -. the output voltage of the regulator designated as v out can be solved by the formula : the variable resistance is determined in the voltage adjuster by which of the transistors q 2 through q 6 are conducting in order to selectively place one or more of resistors r 4 , r 5 , r 21 , r 22 , r 1 and r 28 in parallel . as can be seen from fig5 , the formula in its basic form , when all transistors are not conducting , is : 1 . 25v ( 1 +( r 4 / resistor r 1 )). this represents the highest voltage output of the voltage regulator 330 . by way of example , let &# 39 ; s assume that the microcontroller 300 wishes to provide a certain voltage out from the programmable voltage regulator 330 . further , assume that the desired voltage relies on the parallel arrangement of resistors r 4 , r 22 , and r 28 in voltage adjuster 312 . to accomplish this , the microcontroller puts out activation signals to cause resistors q 4 and q 5 to conduct ; thus , placing the resistors r 4 , r 22 and r 28 in parallel arrangement and creating an output ratio in order to arrive at the calculation of v out . through the use of the five transistors q 2 through q 6 and the permanent resistor r 4 , thirty - two different values are possible for v out . in this way , for an initial value , all of the transistors are conducting so that all of the resistors are arranged in parallel to produce the lowest v out . through the output of the opt amp 340 , the adc rating is read in the microcontroller and compared with a desired reading for a given field width in the manner described above concerning the use of set points . as explained before , transistor q 1 performs two primary functions . first , it is used to complete a path for the boundary antenna and second , to transmit data from the transmitter to the collar worn receiver by making and breaking the loop voltage . this arrangement provides one way communication . this is accomplished by opening and closing the circuit at a specific frequency . in essence , a binary signal is sent to the receiver 10 by the on / off operation of transistor 322 . the output port pwm 2 of controller 300 turns transistor 322 on and off at a specific rate to create the digital signal passing through the loop antenna 320 . transistor 322 can also be used in the second mode for calibration to adjust the current passing through the boundary antenna 320 to produce a magnetic field of a predetermined width . in this way , a desired field width can be created . the field width can be known precisely each time a calibration is accomplished . whether or not the boundary antenna is connected or is in an open circuit condition can also be detected and in this way , control the lighting of the loop led d 9 . calibration is carried out under several circumstances . the first is when any button is pressed . the second is when the unit is powered up . the third is at regular preset intervals . in a preferred embodiment , the intervals are every five seconds . when entering the calibration phase the desired field width must be known . the user can manually select it by pressing any of the field width buttons ( 1 - 5 ) or by using the default setting when the transmitter is powered up . the microcontroller then goes through the following routine : 1 . set the programmable voltage source to the lowest output voltage ( q 2 - 6 on ). turn the loop led off . 2 . turn q 1 on . this completes the loop circuit that forms the boundary antenna 320 . 3 . take 16 adc readings and average them . this significantly increases the accuracy of the reading by reducing induced noise picked up by the loop wire from nearby sources . 4 . compare the averaged adc reading to the set - point : a . if greater than or equal to the set - point the calibration is successful and complete . go to step 5 . b . increase the programmable voltage source output voltage to the next higher voltage . i . go to step 3 if all 32 levels have not been tried . ii . error — all 32 levels have been tried and the set - point has not been reached . the loop is either broken or not connected . turn the loop led off . loop detection is simplified by implementing it in firmware . the loop is either present or not present , based on the existence of loop current . on a periodic basis , perhaps once every five seconds , when data is not being transmitted , the loop can be powered on for a brief instant to determine if loop current is present or not . the loop power would then be turned off by setting q 1 to the off state , and then normal operation can continue . a calibration phase shall begin if the loop present state changes from not present to present . it is to be understood that the present invention is not limited to the illustrated user interfaces or to the order of the user interfaces described herein . various types and styles of user interfaces may be used in accordance with the present invention without limitation . modifications and variations of the above - described embodiments of the present invention are possible , as appreciated by those skilled in the art in light of the above teachings . it is therefore to be understood that , within the scope of the appended claims and their equivalents , the invention may be practiced otherwise than as specifically described .
an electronic animal containment or confinement system that contains a transmitter which generates a regulated signal through a boundary antenna made from a buried wire . the regulated signal creates a field signal of a predetermined width regardless of the length of the wire used to define the boundary antenna . the field signal is received by a receiver worn by a dog . if the dog gets too close to the field signal , the receiver generates a current that passes across a pair of probes that contact the skin of the dog in order to give the dog a shock . this represents a form of training to teach the dog to respect an electrified boundary formed by the buried wire . there is also provided a system for protecting a transmitter in a pet confinement system against lightning strikes .