555 home appliance dual-purpose timer circuit

Published:2011/6/13 20:25:00 Author:TaoXi | Keyword: 555, home appliance, dual-purpose, timer | From:SeekIC

As the figure 15-16 shows, the circuit is composed of the step-down rectifier circuit and the timing circuit. The monostable operating mode is composed of the 555, VT1, RP1 and C3. You can add the field-effect transistor 3DJ6F to ensure the capacitor C3 is charged with the constant-current. If you press AN, the circuit is set because the pin-2 of 555 connects with the ground potential, pin-3 has the high electrical level, the relay J and J1-1 close to supply power to the home appliances. After the 555 is set, the pin-7 is in the opening circuit state, C3 charges pin-7 through the constant current source VT1, when pin-6's voltage is higher than 2/3VDD, the 555 is from the set state to the reset state.



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