the foregoing descriptions and drawings should be considered as illustrative only of the principles of the invention . numerous applications of the present invention will readily occur to those skilled in the art . therefore , it is not desired to limit the invention to the preferred embodiments or the exact construction and operation of the preferred apparatus shown and described . rather , all suitable modifications and equivalents may be resorted to , falling within the scope of the invention . referring now to fig1 - 3 , a first embodiment of a dual speaker pest repeller according to the instant inventive concepts is designated generally by the reference numeral 20 and comprises a lower , fixed speaker 25 ( shown with the cover removed for illustrative clarity ) having a downwardly depending stem 26 , and a rotatably - supported , upper speaker 35 having a downwardly depending stem 36 . the base for this unit is not shown , but will be similar to that discussed below with respect to the second embodiment of this invention and may include a “ snap - joint ” support for the stem 26 of the lower speaker unit 25 . a wire from a power unit ( not shown in this embodiment ) may pass through the hollow stem 26 to be electrically connected to the transducer ( not shown ) of the lower speaker unit 25 and may then pass through the rotatably - supported hollow stem 36 of the upper speaker unit 35 to power the transducer therein . the electrical connections are well within the skill of the art . as seen in fig1 - 3 , the stem 36 of the upper speaker unit 35 is seated in a saddle 28 carried by the back 30 of the lower speaker unit 25 for rotation with respect thereto . a stop 38 carried on the stem 36 of the upper speaker unit 35 limits the rotation of the upper speaker unit 35 with respect to the lower speaker unit 25 to 90 ° in either direction as seen , respectively , in fig2 and 3 . even with the embodiment of fig1 - 3 wherein the lower speaker unit 25 is fixed relative to a base , a maximum potential of 210 ° coverage , when the speakers are offset 90 ° from each other as seen in fig2 and 3 , is possible , in contrast with the 150 ° coverage afforded by the side - by - side , fixed speaker units currently in the market . with reference , however , to fig4 - 11 , a preferred embodiment of the instant inventive concepts can be seen at 40 , wherein both the lower and upper speaker units , 45 , 60 , are rotationally carried on a single stem 70 , having locking ribs 72 on its lower surface as seen particularly in fig9 adapted to be engaged , as by snap - joint 74 seen particularly in fig8 in a base element 90 . with this embodiment , the stem 70 passes through saddles 46 and 61 on the lower and upper speaker units 45 , 60 , respectively , so that each unit can rotate relative to the stem 70 as seen , for example , in fig5 and 6 wherein the transducers of the speaker units can be offset from each other by as much as 180 ° ( note fig6 ). in this manner , a full 240 ° of coverage is possible . technically , the same concepts can be used to rotationally mount three speaker units relative to each to provide a full 360 ° coverage . the specific physical constructional details of each of the speaker units for either of the embodiments of this invention are not critical to the instant inventive concepts and , in many respects , are quite similar to prior art ultrasound units . for example , with reference to fig1 , each of the speaker units or “ eyeball assemblies ” 45 , 60 will include front housing elements 48 , 62 and back housing elements 50 , 64 , a metal grill 50 , 66 , a buzzer 52 , 67 and a buzzer housing 54 , 68 , respectively . the stem 70 can be formed from two elements 70 a , 70 b to facilitate assembly . as seen in fig1 , the base unit 90 may comprise a base plate 92 which may be supported on rubber feet 94 , a sheet of insulation 96 , a main pcb assembly 98 , which is conventional , with a power cord 100 and a base cover 102 . each of the speaker units commonly beam a barrage of ultrasonic waves in excess of 130 db while pulsing in a frequency range of 32 khz to 62 khz , although the sound waves may be adjusted , as necessary , to repel selected pests without annoying humans . considering the foregoing , it will now be seen that there is herein provided multiple - speaker pest repellents which meet all of the objects of the instant invention , and others , including many advantages of great commercial potential . the foregoing descriptions and drawings should be considered as illustrative only of the principles of the invention . as noted , the invention may be configured in a variety of shapes and sizes and is not limited by the dimensions of the preferred embodiment . numerous applications of the present invention will readily occur to those skilled in the art . therefore , it is not desired to limit the invention to the preferred embodiments or the exact construction and operation shown and described . rather , all suitable modifications and equivalents may be resorted to falling within the scope of the invention .
a pest repeller including at least a first ultrasound transmitter mounted on a base and a second transmitter rotatably mounted above the first transmitter . both transmitters can be rotatably mounted on a common post carried by the base . the arrangements permit a greater ultrasound coverage of an area because of the relative rotation of the superimposed speakers .