555 gas stove flameout sound & light alarm circuit

Published:2011/6/1 2:05:00 Author:TaoXi | Keyword: 555, gas stove, flameout, sound, light, alarm circuit | From:SeekIC

The electronic switch is composed of the VT1，R1 and VT2，R2. VT1 uses the phototransistor 3DU series devices, you need to put it on the horizontal plane that is about 25cm away from the stove. When the fire is normal, the VT1 is in the low resistance state, the VT2 is in the positive bias state, the pipe pressure drop is only about 0.3V, this makes the pin-4 of IC(555) in the state of forced reset -- the quiescent state. The astable multivibrator is composed of the 555 and R3，R4，C1.etc, the oscillation frequency fc=1.44/(R3+2R4)C1. The parameters are designed according to 1000Hz. VT1 uses the 3DU series devices such as the 3DU5, 3DU6, 3DU212.etc.



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