555 safe iron frame circuit

Published:2011/5/30 18:53:00 Author:TaoXi | Keyword: 555, safe, iron, frame | From:SeekIC

As the figure 15-2 shows, the circuit is composed of the step-down voltage rectifying circuit, the timer control circuit and the audio circuit.etc. When the electric iron is on the frame, the weight of iron presses the button AN, so IC2's trigger port pin-6 gets the partial voltage of R1 and R2, and this voltage is higher than 2/3VDD trigger electrical level, 555 resets, pin-3 has the low electrical level. IC3 is set because pin-2 has the low electrical level, pin-3 has the high electrical level, the relay J closes, and also the J1-1 twin contact points, so the electric iron has power to heat. When you pick up the iron, the C3 which has be charged discharges through R2, when the voltage is lower than pin-2's trigger electrical level 1/3VDD, 555 sets, pin-3 has the high electrical level.



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