Low-voltage Automatic Switching Circuit

Published:2011/5/7 3:02:00 Author:Joyce | Keyword: Low-voltage, Automatic, Switching | From:SeekIC

Low-voltage Automatic Switching Circuit is shown in the graph below.When the electric supply of 220V is depressurized by transformer T, VDw will breakdown thus making VT1 breakover and VT2 cut off.Meanwhile,the solid-state relay SSR will shutoff.At this time, after being bridge rectified by VD2 ~ VD5 andfiltered by C2.C3,it will output about 14V dc voltage. When the input ac voltage is 110V, after being depressurized by T, it is insufficient to breakdown VDw,so VT2 will breakover and VT1 will cutoff and SSR will be connected. At this moment, SSR, VD2 ~ VD3 and C2 、C3 will constitute a voltage doubling circuit ,which still output about 14V dc voltage. And the LED indicator light will be on.



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