Abstract:
An irrigation apparatus is provided, comprising: a pressure vessel configured to hold water under pressure, and configured to expand and contract based on the pressure of the held water; a selectable throttle configured to receive water at a first pressure, configured to provide the water to the pressure vessel at the first pressure when the selectable throttle is at a first setting, and configured to provide the water to the pressure vessel at a second pressure that is smaller than the first pressure when the selectable throttle is at a second setting; a control circuit configured to control whether the selectable throttle is at the first setting or at the second setting; and a piezoelectric element attached to the pressure vessel and configured to generate electricity when the pressure vessel expands or contracts.

Description:
FIELD OF THE INVENTION 
     The present disclosure is related in general to irrigation units configured to provide water to a specific plot of land. More specifically, the present disclosure is related to irrigation units that include a piezoelectric element that uses the deformation of one or more elements in the irrigation unit to generate electricity to power the irrigation unit. 
     BACKGROUND OF THE INVENTION 
     Irrigation units are used in a variety of situations, including personal yards, commercial properties, golf courses, farms, etc. Anywhere in which a plot of land needs to be irrigated can benefit from the use of an irrigation unit. 
     A typical irrigation unit will only irrigate a limited area, e.g., several hundred square feet. As a result, areas to be irrigated that are larger than this will require multiple irrigation units, the operation of which should be coordinated. Furthermore, in addition to control signals, each of these units must be provided with both water and power. Thus, when a large area must be irrigated, water pipes and power lines must be run to a large number of individual irrigation units. This can be an expensive undertaking. 
     Generally, it is unavoidable to have to run water lines to the irrigation units, since the entire purpose of having irrigation units is to distribute water. However, it is possible for power to be locally generated at the irrigation units. Having sufficient power generated at each individual irrigation unit could potentially eliminate the need for running power lines to be irrigation units, thus both simplifying the irrigation system, and making it cheaper to install and maintain. 
     Therefore, it would be desirable to provide an irrigation system in which individual irrigation units generated sufficient power at their locations for the running of each irrigation unit. 
     SUMMARY OF THE INVENTION 
     An irrigation apparatus is provided, comprising: a pressure vessel configured to hold water under pressure, and configured to expand and contract based on the pressure of the held water; a selectable throttle configured to receive water at a first pressure, configured to provide the water to the pressure vessel at the first pressure when the selectable throttle is at a first setting, and configured to provide the water to the pressure vessel at a second pressure that is smaller than the first pressure when the selectable throttle is at a second setting; a control circuit configured to control whether the selectable throttle is at the first setting or at the second setting; and a piezoelectric element attached to the pressure vessel and configured to generate electricity when the pressure vessel expands or contracts. 
     The pressure vessel may be one of a sprinkler body, a rotor body, or a supply pipe. 
     The irrigation apparatus may further comprise: a rechargeable battery, wherein the piezoelectric element is further configured to recharge the battery. 
     The piezoelectric element may be further configured to provide power to the control circuit. 
     The irrigation apparatus may further comprise: a radio transceiver, wherein the piezoelectric element is further configured to provide power to the radio transceiver. 
     The irrigation apparatus may further comprise: a solenoid, wherein the piezoelectric element is further configured to provide power to the solenoid. 
     The irrigation apparatus may further comprise: a swing joint located between the selectable throttle and the pressure vessel and configured to carry water from the selectable throttle to the pressure vessel. 
     The irrigation apparatus may further comprise: a swing joint located between the selectable throttle and a water supply pipe, wherein the swing joint is configured to carry water from the water supply pipe to the selectable throttle, and the selectable throttle is configured to carry water from the swing joint to the pressure vessel. 
     The piezoelectric element may comprise a piezoelectric strip. The piezoelectric strip may be attached to the pressure vessel. 
     A method for operating an irrigation apparatus is provided, comprising: supplying water to a pressure vessel with a first water pressure as a supply water pressure; engaging a throttle on the supplied water to reduce the supply water pressure to a second water pressure that is less than the first water pressure; providing water to the pressure vessel at the second water pressure; generating electricity from a deflection of the pressure vessel using a piezoelectric element; disengaging the throttle on the supplied water to increase the supply water pressure to the first water pressure; providing water to the pressure vessel at the first water pressure; and generating electricity from an expansion of the pressure vessel using the piezoelectric element, wherein the first water pressure and the second water pressure are sufficiently different that the pressure vessel will expand to a first size when provided water at the first water pressure, and the pressure vessel will contract to a second size that is smaller than the first size when provided water at the second water pressure. 
     The pressure vessel may be one of a sprinkler body, a rotor body, or a supply pipe. 
     The operations of engaging a throttle, providing water to the pressure vessel at the second water pressure, generating electricity from a retraction of the pressure vessel, disengaging the throttle, providing water to the pressure vessel at the first water pressure, and generating electricity from an expansion of the pressure vessel may be repeated multiple times. 
     The method may further comprise: recharging a battery with the electricity generated from the contraction of the pressure vessel; and recharging the battery with the electricity generated from the expansion of the pressure vessel. 
     An irrigation apparatus is provided, comprising: a means for containing water; a means for supplying water to the means for containing water with a first water pressure as a supply water pressure; a means for increasing a throttling of the supplied water to reduce the supply water pressure to a second water pressure that is less than the first water pressure; a means for decreasing the throttling of the supplied water to increase the supply water pressure to the first water pressure; a means for providing water to the means for containing water; a means for generating electricity from an expansion or a contraction of the means for containing water using a piezoelectric element, wherein the first water pressure and the second water pressure are sufficiently different that the means for containing water will expand to a first size when provided water at the first water pressure, and the means for containing water will contract to a second size that is smaller than the first size when provided water at the second water pressure. 
     The means for generating electricity may comprise a piezoelectric strip. The piezoelectric strip may be attached to the means for containing water. The means for generating electricity from a retraction of the means for containing water using a piezoelectric element, and the means for generating electricity from an expansion of the means for containing water using the piezoelectric element may comprise a piezoelectric strip. 
     The irrigation apparatus may further comprise: a means for storing energy, wherein the piezoelectric element is further configured to recharge the means for storing energy. 
     The piezoelectric element may be further configured provide power to the means for increasing the throttling of the supplied water and the means for decreasing the throttling of the supplied water. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying figures, where like reference numerals refer to identical or functionally similar elements and which together with the detailed description below are incorporated in and form part of the specification, serve to further illustrate an exemplary embodiment and to explain various principles and advantages in accordance with the present invention. 
         FIG. 1  is a block diagram of an irrigation system according to disclosed embodiments; 
         FIG. 2  is a block diagram of an irrigation unit according to disclosed embodiments; 
         FIG. 3  is a block diagram of an irrigation unit according to other disclosed embodiments; 
         FIG. 4  is a block diagram of an irrigation unit and associated elements according to yet other disclosed embodiments; 
         FIG. 5  is a block diagram of an irrigation unit according to still other disclosed embodiments; 
         FIG. 6  is a perspective view of a portion of an irrigation unit according to disclosed embodiments; and 
         FIG. 7  is a flow chart showing the operation of an irrigation unit according to disclosed embodiments. 
     
    
    
     DETAILED DESCRIPTION 
     The instant disclosure is provided to further explain in an enabling fashion the best modes of performing one or more embodiments of the present invention. The disclosure is further offered to enhance an understanding and appreciation for the inventive principles and advantages thereof, rather than to limit in any manner the invention. The invention is defined solely by the appended claims including any amendments made during the pendency of this application and all equivalents of those claims as issued. 
     It is further understood that the use of relational terms such as first and second, and the like, if any, are used solely to distinguish one from another entity, item, or action without necessarily requiring or implying any actual such relationship or order between such entities, items or actions. It is noted that some embodiments may include a plurality of processes or steps, which can be performed in any order, unless expressly and necessarily limited to a particular order; i.e., processes or steps that are not so limited may be performed in any order. 
       FIG. 1  is a block diagram of an irrigation system  100  according to disclosed embodiments. As shown in  FIG. 1 , the irrigation system  100  includes a central controller  110 , and a plurality of satellite controllers  120  connected to the central controller  110  by a control bus  130 . The central controller  110  controls the operation of the satellite controller  120 . Each satellite controller  120 , in turn, controls the operation of a plurality of irrigation units  140 . 
     The central controller  110  operates to control the entire irrigation system  100  from a centralized location. In various embodiments, the central controller  110  can be a centralized computer connected to the plurality of satellite controllers  120  by the control bus  130 . 
     The plurality of satellite controllers  120  are distributed throughout the irrigation system  100  at disparate locations in order to control the various irrigation units  140 . Typically, a single satellite controller  120  will control the operation of a plurality of localized irrigation units  140 . In various embodiments the satellite controllers  120  can be microprocessors programmed to control the operation of the irrigation units  140 . Each of the satellite controllers  120  is connected to the central controller  110  by the control bus  130 . 
     The control bus  130  carries signals between the central controller  110  and the plurality of satellite controllers  120 . In various embodiments it can be a wired bus or a wireless bus. If the control bus  130  is a wired bus, physical wires connect the central controller  110  and the plurality of satellite controllers  120 . If the control bus  130  is a wireless bus, there is no physical connection between the central controller  110  and the plurality of satellite controllers  120 . However, in such a case, each of the central controller  110  and the plurality of satellite controllers  120  must contain a transceiver of some sort to pass signals wirelessly. 
     The plurality of irrigation units  140  operate to irrigate adjacent plot of land using water obtained from a water source (not shown). In various embodiments these irrigation units can include sprinklers, water jets, or any other suitable water delivery system. 
     System Using a Piezoelectric Generator and a Rechargeable Battery 
       FIG. 2  is a block diagram of an irrigation unit  140  according to disclosed embodiments. In particular, the embodiments of  FIG. 2  show an irrigation unit  140  that employs a piezoelectric generator  250  and a rechargeable battery  260  in order to provide power to the irrigation unit  140 . 
     As shown in  FIG. 2 , the irrigation unit  140  includes a remote unit controller  210 , a swing joint  220 , a throttle  225 , a pressure vessel  230 , a nozzle/rotor apparatus  240 , a piezoelectric generator  250 , a rechargeable battery  260 , and an electrical device  270 . 
     The remote unit controller  210  controls the operation of the irrigation unit  140  based on control signals received from the satellite controller  120 , which, in turn, is controlled by the central controller  110 . These signals can be sent over wires, or wirelessly, in various embodiments. 
     The swing joint  220  connects the water supply to the pressure vessel  230 , and serves as a conduit for water provided by the water supply to the pressure vessel  230 . In this embodiment, the water supply can be a water supply pipe, e.g., a PVC pipe, that carries the water from a central source. In various embodiments, the water supply can be above-ground or underground. A swing joint  220  is used in this embodiment to connect the water supply to the pressure vessel  230  in order to provide flexibility for the positioning of the pressure vessel  230  with respect to the water supply. 
     The throttle  225  is placed in between the water supply and the swing joint  220 . It is used to regulate the flow of water from the water supply to the pressure vessel  230 , via the swing joint  220 . The throttle  225  is controlled by control signals from either the satellite controller  120  associated with the irrigation unit  140 , or the remote unit controller  210  that controls the operation of the irrigation unit  140 . 
     In operation, the throttle  225  is configured to provide the water to the pressure vessel  230  at two or more different water pressures in a repeating pattern. For example, the throttle  225  may be configured to provide water to the pressure vessel  230  at a first (high) pressure for a first duration, and then to provide water to the pressure vessel  230  at a second (low) pressure for a second duration. In the alternative, a succession of multiple changing water pressures can also be used. 
     The pressure vessel  230  serves as a reservoir for water received from the water supply, and sprayed by the nozzle/rotor apparatus  240  onto an adjacent plot of land. When the water provided to the pressure vessel  230  is varied in pressure over time, the pressure vessel  230  will expand and contract, expanding when water of a relatively higher pressure is provided to it, and contracting when water of a relatively lower pressure is provided to it. In one particular embodiment in which the water pressure is varied between 25 PSI and 150 PSI, The pressure vessel  230  can deform on the order of approximately 600 microstrain (i.e., 600 ppm deformation with respect to the size of the pressure vessel  230 ). 
     The nozzle/rotor apparatus  240  operates to spray water received from the pressure vessel  230  onto an adjacent plot of land. In various embodiments, the nozzle/rotor apparatus  240  can spray in a single direction, or can be configured to rotate such that it sprays in multiple directions over time. 
     The piezoelectric generator  250  is attached to the pressure vessel  230  in such a way that microstrain deformation of the pressure vessel  230  will cause the piezoelectric generator  250  to generate a voltage. In one set of embodiments, a piezoelectric generator  250  that is properly attached to the pressure vessel  230  can generate approximately 5-15 μV per microstrain. In an embodiment in which the pressure vessel  230  expands and contracts by approximately 600 microstrain, this means that the piezoelectric generator  250  can generate a voltage of approximately 3-9 mV. 
     In one embodiment, the piezoelectric generator  250  can be a piezoelectric gauge wrapped around the pressure vessel  230 . In alternate embodiments, other types of piezoelectric generator can be used. 
     The rechargeable battery  260  is connected to and charged by the piezoelectric generator  250 . It provides power to the nozzle/rotor apparatus  240 , the remote unit controller  210 , and the electrical device  270 . 
     The electrical device  270  can be any type of electrical device associated with the irrigation unit  140 . For example, the electrical device  270  can be a radio transceiver used to send and receive control signals from a satellite controller  120 . Alternatively, the electrical device  270  could be a solenoid that detects magnetic signals used to control the irrigation unit  140 . Other types of electrical device  270  are also possible. 
     In this way, an irrigation unit  140  that is relatively self-sufficient can be provided. The rechargeable battery  260  can be used to power all of the parts of the irrigation unit  140  that require power. As a result, this can eliminate the need for power lines to be run to each of the irrigation units  140 , thereby simplifying the entire irrigation system  100 , while making it cheaper to install and maintain. 
     System Using a Piezoelectric Generator Alone 
       FIG. 3  is a block diagram of an irrigation unit  140  according to other disclosed embodiments. In particular, the embodiments of  FIG. 2  show an irrigation unit  140  that employs only a piezoelectric generator  250  in order to provide power to the irrigation unit  140 . 
     As shown in  FIG. 3 , the irrigation unit  140  includes a remote unit controller  310 , a swing joint  220 , a throttle  225 , a pressure vessel  230 , a nozzle/rotor apparatus  240 , a piezoelectric generator  350 , an electrical device  270 , and a nozzle/rotor starting circuit  380 . 
     The swing joint  220 , the throttle  225 , the pressure vessel  230 , the nozzle/rotor apparatus  240 , and the electrical device  270  all operate as described above with respect to  FIG. 2 . 
     The remote unit controller  310  controls the operation of the irrigation unit  140  based on control signals received from the satellite controller  120 , which, in turn, is controlled by the central controller  110 . These signals can be sent over wires, or wirelessly, in various embodiments. 
     The nozzle/rotor starting circuit  380  operates to provide startup power to the nozzle rotor apparatus when the irrigation unit  140  is initially turned on. It need only store enough power to start the nozzle/rotor apparatus until the piezoelectric generator  350  provides sufficient power for the operation of the nozzle/rotor apparatus  240 . The piece electric generator  350  can then replace the charge used from the nozzle/rotor starting circuit  380 , in preparation for the next time the irrigation unit  140  is turned on. The irrigation unit  140  may be installed with the nozzle/rotor starting circuit  380  fully charged. In various embodiments, the nozzle/rotor starting circuit  380  can be a capacitor (e.g., a super capacitor circuit), a battery, or any suitable element for temporarily providing power to the nozzle/rotor apparatus  240 . 
     As in the embodiments of  FIG. 2 , the piezoelectric generator  350  in the embodiments of  FIG. 3  is attached to the pressure vessel  230  in such a way that microstrain deformation of the pressure vessel  230  will cause the piezoelectric generator  250  to generate a voltage. As noted above, in one set of embodiments, a piezoelectric generator  250  that is properly attached to the pressure vessel  230  can generate approximately 5-15 microvolts per microstrain, which can translate into 3-9 mV when the pressure vessel  230  expands and contracts by approximately 600 microstrain. 
     Unlike the embodiments of  FIG. 2 , the irrigation unit  140  of the embodiments of  FIG. 3  does not use a rechargeable battery as an intermediary between the piece electric generator  250  and the devices that require power (the remote unit controller  210 , the nozzle/rotor apparatus  240 , and the electrical device  270 ), but connects the piezoelectric generator  350  directly to the nozzle/rotor apparatus  240 , the remote unit controller  210 , and the electrical device  270 . Thus, the voltage provided by the piezoelectric generator  350  will directly power the remote unit controller  210 , the nozzle/rotor apparatus  240 , and the electrical device  270 . 
     As noted above, the nozzle/rotor charging circuit  380  will provide the initial power required to get the nozzle/rotor apparatus  240  operating, after which time it is recharged and the nozzle/rotor apparatus  240  continues operation using power from the piezoelectric generator  350 . 
     System Using a Throttle Separate from the Irrigation Unit 
       FIG. 4  is a block diagram of an irrigation unit  140  and associated elements according to yet other disclosed embodiments. In particular,  FIG. 4  shows the use of a throttle that is separate from the irrigation unit, e.g., connected to a water supply  490  associated with the irrigation unit  140 . 
     As shown in as shown in  FIG. 4 , an irrigation unit  140  is connected to a satellite controller  120  and to a throttle  485  through water supply pipes  480 . The throttle, in turn, is connected to a water supply  490 . The irrigation unit  140  includes a remote unit controller  210 , a swing joint  220 , a pressure vessel  230 , a piezoelectric generator  250 , a rechargeable battery  260 , and an electrical device  270 . 
     The remote unit controller  210 , swing joint  220 , the pressure vessel  230 , the nozzle/rotor apparatus  240 , the piezoelectric generator  250 , the rechargeable battery  260 , and the electrical device  270  all operate as described above with respect to  FIG. 2 . Likewise, the satellite controller  120  operates as described above with respect to  FIG. 1 . 
     The water supply pipes  480  receive water from the throttle  485 , and provide water to the swing joint  220 . 
     The throttle  485  receives water from the water supply  490 , and supplies it to the water supply pipes  480 . The throttle  485  operates in response to control signals from the satellite controller  12   o  to regulate the flow of water from the water supply  490  to the water supply pipes  480 . In particular, the throttle operates to regulate the pressure of the water supplied to the water supply pipes  480  between two or more different water pressures. 
     The water supply  490  can be a water supply pipe, e.g., a PVC pipe that carries the water from a central source. In various embodiments, the water supply  490  can be above-ground or underground. 
     Unlike the embodiment of  FIG. 2 , the embodiment of  FIG. 4  places the throttle  485  outside of the irrigation unit  140 , and separated from the irrigation unit  140  by the water supply pipes  480 . However, the throttle  485  operates in a manner similar to the throttle  225  from the embodiment of  FIG. 2 . 
     In particular, the throttle  485  is configured to provide the water to the water supply pipes  480  at two or more different water pressures in a repeating pattern. For example, the throttle  485  may be configured to provide water to the water supply pipes  480  at a first (high) pressure for a first duration, and then to provide water to the water supply pipes  480  at a second (low) pressure for a second duration. In alternate embodiments, a succession of multiple, different water pressures can also be used. 
     System Using a Throttle Between a Swing Joint and a Pressure Vessel 
       FIG. 5  is a block diagram of an irrigation unit  140  according to still other disclosed embodiments. In particular, the embodiments of  FIG. 5  shown irrigation unit in which a throttle  520  is located between a swing joint  525  and a pressure vessel  230 . 
     As shown in  FIG. 5 , the irrigation unit  140  includes a remote unit controller  310 , a swing joint  520 , a throttle  525 , a pressure vessel  230 , a nozzle/rotor apparatus  240 , a piezoelectric generator  250 , and an electrical device  270 . 
     The remote unit controller  310 , the pressure vessel  230 , the nozzle/rotor apparatus  240 , the piezoelectric generator  350 , and the electrical device  270  all operate as described above with respect to  FIGS. 2 and 3 . 
     The swing joint  520  operates as the swing joint  220  described above with respect to  FIG. 2 . Likewise, the throttle  525  operates as the throttle  225  described above with respect to  FIG. 2 . However, in the embodiment of  FIG. 5 , the throttle  525  is located between the swing joint  520  and the pressure vessel  230 , rather than the swing joint  220  being located between the throttle  225  and the pressure vessel  230 . 
     Nevertheless, the throttle  525  is still configured to provide the water to the pressure vessel  230  at two or more different water pressures in a repeating pattern. For example, the throttle  525  may be configured to provide water to the pressure vessel  230  at a first (high) pressure for a first duration, and then to provide water to the pressure vessel  230  at a second (low) pressure for a second duration. As in the previous embodiments, a succession of multiple, different water pressures can also be used. 
     Exemplary Pressure Vessel and Piezoelectric Generator 
       FIG. 6  is a perspective view of a portion of an irrigation unit  140  according to disclosed embodiments. As shown in  FIG. 6 , the portion of the irrigation unit  140  includes a pressure vessel  610 , a piezoelectric gage  620 , a resistor  630 , connection element  640 , and a power supply line  650 . 
     The pressure vessel  610  is an element of the irrigation unit  140  that receives a quantity of water from a water supply, and provides the water to a nozzle, sprinkler, or other water distribution element, where the water is provided to irrigate an adjacent plot of land. 
     The piezoelectric gage  620  is wrapped around the pressure vessel  610 , where it will be moved by the expansion and the contraction of the pressure vessel  610 . As the piezoelectric gage  620  is moved, it will generate electricity. 
     The resistor  630  is connected to the piezoelectric gage  620  by the connection element  640  and serves to generate a current that can be provided into the power supply line  650 . The connection elements  640  in this embodiment can be solder tabs or any appropriate connection element. 
     Using this design, power can be generated that can be provided directly to elements in the irrigation unit  140 , or can be provided to a rechargeable battery for future use by irrigation unit  140 . 
     Method of Operating an Irrigation Unit 
       FIG. 7  is a flow chart showing the operation of an irrigation unit according to disclosed embodiments. As shown in  FIG. 7 , operation begins when water is provided to a pressure vessel  230  at a first water pressure ( 710 ). 
     A water throttle  225 ,  485 ,  525  is then engaged to reduce the supply water pressure to a second water pressure that is less than the first water pressure ( 720 ). Water is then provided to the pressure vessel  230  at the second water pressure ( 730 ). 
     Electricity is then generated from the retraction of the pressure vessel  230  using a piezoelectric element  250 ,  350  ( 740 ). The electricity generated at the piezoelectric element  250 ,  350  can be used directly by elements in the irrigation unit  140 , or can be stored in a rechargeable battery  260  for future use by the irrigation unit  140 . 
     The water throttle  225 ,  485 ,  525  is then disengaged to increase the supply water pressure to the first water pressure ( 750 ). Water is then provided to the pressure vessel  230  at the first water pressure ( 760 ). 
     Electricity is then generated from the expansion of the pressure vessel  230  using the piezoelectric element  250 ,  350  ( 770 ). 
     In the engaging and the disengaging of the water throttle  225 ,  485 ,  525  (i.e., operations  720 - 770 ) can then be repeated multiple times to continually generate electricity at the piezoelectric element  250 ,  350  based on the expansion and retraction of the pressure vessel  230 . 
     Although this embodiment shoes the use of two different water pressures, alternate embodiments could use a multiple succession of water pressures to generate electricity. In such embodiments, the water throttle  225 ,  485 ,  525  could vary between three or more different water pressures, each of which would cause expansion or contraction of the pressure vessel  230 , which in turn would cause the piezoelectric generator  250 ,  350  to generate electricity. 
     In addition, although in the various disclosed embodiments, the piezoelectric generator  250 ,  350  is shown as being attached to the pressure vessel, in alternate embodiments it can be attached to the swing joint, the throttle, or an associated hydraulic pipe. In particular, any deformable part of the water flow system that receives water of two different pressures can be used to operate a piezoelectric generator. 
     Alternate Placement of the Piezoelectric Generator 
     Although the above disclosed embodiments show the piezoelectric generator  250 ,  350  as being connected to the pressure vessel, in alternate embodiments the piezoelectric generator  250 ,  350  could be connected to the swing joint  220 , to a pipe connecting any of the swing joint  220 , throttle  225 , or pressure vessel  230 , or to any other suitable element in the irrigation unit  140 . In particular, any element of the irrigation unit  140  downstream from the throttle  225  that will expand and contract as the water pressure changes can be used by a piezoelectric generator to generate power for the irrigation unit  140 . 
     For example, in one alternate embodiment a piezoelectric generator can be attached to a swing joint located between the throttle and the pressure vessel. In another alternate embodiment, a piezoelectric generator can be attached to a pipe located between a swing joint and the pressure vessel. Numerous other suitable locations may also be selected, depending upon the configuration of the irrigation unit. 
     Conclusion 
     This disclosure is intended to explain how to fashion and use various embodiments in accordance with the invention rather than to limit the true, intended, and fair scope and spirit thereof. The foregoing description is not intended to be exhaustive or to limit the invention to the precise form disclosed. Modifications or variations are possible in light of the above teachings. The embodiment(s) was chosen and described to provide the best illustration of the principles of the invention and its practical application, and to enable one of ordinary skill in the art to utilize the invention in various embodiments and with various modifications as are suited to the particular use contemplated. All such modifications and variations are within the scope of the invention as determined by the appended claims, as may be amended during the pendency of this application for patent, and all equivalents thereof, when interpreted in accordance with the breadth to which they are fairly, legally, and equitably entitled. The various circuits described above can be implemented in discrete circuits or integrated circuits, as desired by implementation.