| 摘要 |
<p>The ON-OFF switching device employs a light barrier with a rectifier bridge (2) connected across the supply voltage. A controlled valve e.g. a thyristor (4) is connected in parallel with the output of the rectifier bridge. The valve is controlled via. a switching transistor (8), to which a threshold diode (10), in series with a light source, e.g. a light-emitting diode (12) is connected, so that the conductivity of the controlled valve (4) is dependant on the intensity of light received by a photodetector (17). The light source may be a gallium arsenide diode (12) with the photodetector comprising a photodiode (17), the diodes controlled in synchronism.</p> |
