Fridge close door reminding circuit

Published:2011/4/25 20:25:00 Author:TaoXi | Keyword: Refrigerator, close door reminding circuit | From:SeekIC

This circuit can send out the warning voice of close the door please if you open the fridge door for several seconds to remind the owner close the door in time. The circuit is as shown. The left of dotted line is fridge lighting control circuit, S1 is the fridge light door-control switch; right of dotted line is fridge's close-door warning circuit. When the fridge door opens, Sl automatically closes and the light H turns on. The DC power supplier charges the C3 by R3. Because the voltage across the capacitor can not change suddenly, so the positive electrode of C3 is still low-level current, VD6, VTl and VT2 cut-off. Value of R5, C5 determines the level of voice tones, in the figure there will be a girl's voice close the door please . If the value of C5 increased to 560pF, there will be a boy's voice close the door please .



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