555 home appliance automatic opening and closing timing circuit

Published:2011/6/6 8:31:00 Author:TaoXi | Keyword: 555, home appliance, automatic, opening, closing, timing | From:SeekIC

The multivibrator is composed of the 555 and R3，R4，C3. the HK1 and HK2 are the 1X11 single-blade rotary switches, the 820kX9 and RP1, RP2 are connected with them, the 820kX9 and RP1, RP2 can be used in the coarse adjustment and fine adjustment of the oscillation period and the duty ratio. When the 555 outputs the high electrical level, LED1 turns on, at the same time the SCR conducts and the load gets power to work. When the C3 is charged to 2/3VDD, the 555 everts, pin-3 has the low electrical level (lower than 0.4V), the SCR turns off and the load has no power. The length of t1, t2 depends on the number of the 820k resistances and the values of RP1 and RP2. The parameters of the figure show the shortest switch time of not less than 2 minutes.



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