An electronic arrangement for simulating sounds emitted by animals. A clock ulse generator transmits pulses which are partially differentiated and/or integrated. The resulting pulse signals are applied to a series of astable multivibrator circuits which synthesize audiofrequency signals representing the various types of animal cries. Multivibrator circuits may be combined with each other in a particular arrangement, and these combinations may be operated in conjunction with variable integrating and differentiating circuits to produce the desired results. Loud speakers powered by amplifiers emit in audible form the signals provided and processed by the multivibrators.
An intrusion alarm having an oscillator which is turned off by the body capacitance of a would-be intruder operates in the frequency range of 17-65 MHz. At this frequency, reliable discrimination between body capacitance and stray capacitance is possible and therefore sensitivity is increased while false alarms are reduced. Battery life is increased by providing a high resistance load in the stand-by mode to reduce battery drain to 500 microamperes or less. Latching and nonlatching embodiments are disclosed.
A pest control apparatus and method for dispersing pests, e.g., rodents, from a designated area by the transmission into the area of high intensity ultrasonic sound waves having a primary frequency varying as a function of time and frequency modulating the sound waves with a secondary vibrato. The apparatus additionally provides periodic bursts of such ultrasonic power affording transducer rest periods maximizing the power handling capability of the transducer during "on" periods.
A telephone signalling system for signalling a station set in a key telephone system, said signalling system including an electronic tone-ringer which generates a tone at a first audio frequency when connected to a conventional 20Hz ringing supply. When the electronic tone-ringer is energized with an audio frequency voltage at an audio frequency greater than the first audio frequency, in lieu of the conventional 20Hz ringing supply, a different tone is generated by the electronic tone-ringer.
A complete vehicle accident prevention system utilizing electromagnetic transmissions for the purpose of: 1) alerting drivers to the presence of certain unanticipated accident threats such as pedestrians, bicyclists, joggers, emergency vehicles, disabled vehicles, etc.; 2) alerting people using the roadway that a vehicle is approaching thereby inducing them to move to the side of the road. The system also utilizes a speaker assembly mounted on the vehicle to forwardly transmit a pre-programmed array of natural sounds having a frequency audible to the typical human ear for the purpose of inducing animals and people to vacate the path of the approaching vehicle. The controller may receive data from a radio direction finder to cause the display to indicate to the driver of the vehicle the relative position of a potential road hazard.
Apparatus and method for producing ultrasonic sound waves used to disperse rodents including negative feedback damping of a tuned band-pass filter output circuit. An electrical signal is frequency modulated, amplitude modulated asynchronously with the frequency modulation, pulsed on and off and applied to a speaker to produce ultrasonic sound waves corresponding thereto. The output signal is passed through a tuned band-pass filter circuit which includes negative feedback damping to reduce the power consumption of the amplification of the output signal and in part to produce the band-pass characteristics of the band-pass filter output circuit.
