Sound control photosensitive delay switch circuit

Published:2011/7/4 6:40:00 Author:Christina | Keyword: Sound control, photosensitive, delay, switch circuit | From:SeekIC

Figure:Sound control photosensitive delay switch circuit The sound control photosensitive delay switch circuit is as shown in the figure. In the daytime, the photoconductive resistance RL is irradiated by the light, so it is in the low impedance state to conduct the semiconductor tube VT3, so the VT4 and VT5 cut off, the VT6 conducts, the thyristor VS cuts off, the bulb E is in the off state. Because the VT3 is in the conduction state, so no matter what the sound is, the bulb E will not turn on. At night ,there is no light, so the photoconductive resistance's internal resistance increases to make the VT3 in the cut-off state. If there is no sound, the circuit is the same as the circuit of the daytime; when there is the sound, the microphone B receives the sound signal and changes it into the electrical signal.



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