Due to Q1's conduction, the collector voltage drops, causing the left end of capacitor C2 to decrease, approaching 0V. Since the voltage at both ends of the capacitor cannot suddenly change, the base of Q2 is also connected to approximately 0V, Q2 cut-off, therefore the LED2 group connected to its collector is extinguished; At this point, the high voltage of Q2 increases the collector voltage of Q3 through the capacitor C3, and Q3 also quickly conduct. The LED3 group light up. The LED2 group light up, At the same time, the voltage of Q2's collector decreases through C3, and the base voltage of Q3 also decreases. Q3 changes from conduction to cutoff, and its collector voltage increases. Working principle: When connected to a 3-5 V power supply, 37 LEDs are divided into four groups. Whenever the power is turned on, the four transistors compete to conduct first. However, due to differences in components, only one transistor conduct first. Here, if Q1 conducts first, the LED1 group light up. Therefore, for a period of time, the collectors of Q1 and Q3 be at a low level. The LED1 and LED3 groups light up, and the LED2 group go out. However, as the power supply charges C2 through the resistor R2, the base voltage of Q2 gradually increase. When it exceeds 0.7V, Q2 change from a cut-off state to a conduction state, and the collector voltage decrease. The LED 3 group out. Next, the circuit cycles according to the process described above, and three sets of 18 LEDs light up in turn. At the same time, two sets of LEDs be lit up, and these LEDs are arranged in a heart shaped pattern, continuously flashing and emitting light, achieving the effect of flowing display., Manufacturer: Akfldms