| 摘要 |
<p>A photo detector with a fast response is provided by a luminscent diode and a photo-transistor. The diode (1) is coupled through resistor (2) to the supply. In parallel is a series circuit consisting of a photo-transistor (3), transistor (4) and reference voltage resistance (5). The luminscent diode is optically coupled to the photo-transistor. When the light from the diode falls on the photo-transistor, the collector-emitter path resistance is low and the signal is high. When the light is interrupted the output drops.</p> |
