| 摘要 |
<p>The ultrasonic transmitter system is used to drive out rodents e.g. rats, by combining ultrasonic emissions which act on the auditory and olfactory systems of rats respectively. The first transmitter may use an arrangement of a primary oscillator with a single junction transistor (1) the frequency of which is determined by a capacitor (2) and a potentiometer (3). The second transmitter is similar (4,5) with a very low frequency oscillator and a resistance (6) in place of the potentiometer. The transmitted compound signal has the module and frequency of the prim. oscillator. The modulated signal transmitted in the composite power phase may be diffused by a piezoelectric transducer which delivers at 125 db modulated to between 20 and 40 kHZ.</p> |
