Simulation candle

Working principle: This circuit uses one D flip-flop in the double D flip-flop 4013 and connects it to an RS flip-flop. After the power is turned on, the differential circuit composed of R8 and C3 generates a high-level differential pulse and adds it to pin 4 of U1 (trigger RST1 end), forcing the circuit to reset, and pin 1 of U1 (trigger output end Q1) outputs low power. flat, the base of transistor Q1 is at a low level, Q1 is cut off, and the light-emitting diode D1 does not emit light. When D2 is irradiated with light, D2 presents a low resistance state, transistor Q2 is turned on, and the generated high-level pulse is added to pin 6 of U1 (trigger SET1 end), causing pin 1 of U1 to become high level, and transistor Q1 When it is turned on, the light-emitting diode D1 lights up, which is equivalent to lighting a candle with a match. At this time, even if the light leaves D2 or irradiates D2 with light again, the circuit state will not change, and D1 will still remain lit. When the electret microphone MK1 is blown with wind, the audio signal output by the electret microphone is added to the base of Q3 through C2, triggering Q3 to turn on. Because the resistance of resistor R6 is relatively large, the collector potential of Q3 drops very low, and the base potential of transistor Q4 is also very low, causing Q4 to conduct, and a high-level pulse is added to pin 4 of U1, triggering After reset, pin 1 of U1 changes from high level to low level, transistor Q1 is cut off, and light-emitting diode D1 goes out, achieving the simulation effect of "wind blowing and fire extinguishing". Working voltage 3v-5v.