When you open the nocturnal lamp, 12V power supply access the circuit. The main point of the circuit potential is set to: Va = 8.IV, Vb = 7.4V, Vc = 6.7V, Vd = 6V, Ve = 5.3V, Vf = 4.6V, Vg = 3.gV. Connected to point B instantaneously by the resistor divider voltage by VB = 8.3V, the voltage capacitor C can not be mutated, then A point voltage Va = 0, then the op amp output level 4a is about 12V, the voltage on the capacitor through Rll C were charged, up to more than Vg Va, the op amp output from the low inversion 4b is high, but the fortunes of the output is still low discharge 3b, it is light-emitting diode LED6. Then continue charging capacitor C, when Va rose to more than Vf, the op amp 3b also reversed high, while light-emitting diode MDS M is lit, but 4b, 3b are the high output Therefore, M light-emitting diode LED6 turned off. Principle and so on.