Homemade photoelectric coupler

Published:2011/9/2 23:24:00 Author:chopper | Keyword: Homemade, photoelectric coupler | From:SeekIC

Combine the Φ55mm red LED andphotosensitive resistorby transparent tape and put them into a color pen-holder (black is good),then seal the two ends with glue, and it becomes an photoelectric coupler, which is applied for low-frequency switching circuit,just as shown in Figure (a) . Figure (b) is a outage alarm circuit made by photoelectric coupler, which can send an alarm when the power fails.When the power is available,the red LED of the photoelectric coupler is bright and the resistance of thephotosensitive resistor will decrease after coupling,then VT1 stops,and the oscillator formed by VT1,VT2 does not run.



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