| 摘要 |
<p>A stabilised d.c. supply feeds a light source, from which a focussed light beam passes to a photodiode. The light beam is tangential to the diaphragm of a loudspeaker so that movement of the diaphragm modulates the light and therefore the electrical output of the photodiode. After amplification and inversion this signal is added to the audio input signal to provide negative feedback. The resultant signal is impedance matched and fed into the output amplifier. The sampling method does not interfere with the functioning of the loudspeaker and is relatively simple.</p> |
