| 摘要 |
<p>A horn for generating a sound comprising a diaphragm (280), vibration of which causes a sound to be generated, and switching circuitry (230, 260, 250, 270) connected to vibrate the diaphragm (280) in such a fashion that switching of the circuitry (230, 260, 250, 270) is synchronized with the oscillatory movement of the diaphragm (280). The switching circuitry (230, 260, 250, 270) comprises a main switching device (2510) through which a power electrical current passes at a power voltage to effect vibration of the diaphragm (280), and a position sensor (270) arranged to cause a switching signal to be delivered to the main switching device (2510) at a switching electrical voltage, in dependence upon the position of the diaphragm (280). <IMAGE></p> |
