| 摘要 |
<p>A typical application is to the detection and amplification of the output of crankshaft position transducer on a motor vehicle engine. Due to the wide speed range the output voltage of the position transducer varies over a corresponding range, and must be controlled to give satisfactory results. In the proposed circuit the transducer output (Ue) is applied to the input of an operational amplifier (2). The feedback resistors (R2,R4) are connected to a potential divider and are optically sensitive. A proportion (R6,R7) of the amplifier output (Ua) is applied to a second amplifier circuit (4,5,7) connected as a peak voltage detector. Its output controls a transistor (6) regulating the voltage applied to a light source (3) linked with the feedback resistors. At low signal voltages (Ue) the feedback resistance is high giving high gain for the first amplifier (2). As the input voltage increases so the current through the light emitter also rises causing the feedback resistance, and hence the amplifier (2) gain, to fall in order to keep the output voltage constant.</p> |
