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. Due to Q1's conduction, the collector voltage , 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. 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 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. The LED 3 group goes 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. 1. The product is made of high-quality materials. 2. This kit is very suitable for training welding skills and is also very suitable for DIY enthusiasts, which can greatly improve their hands-on abilities. 3. Composed of colorful LED lights with a flashing effect, it is a very good choice for giving away or viewing. 4. Working voltage:DC5V (mobile phone charger, dry battery, etc. can be ) 5. Adopting a design, the product has a wide range of application scenarios and can be used anytime, anywhere, making it very convenient. Name:Colorful Christmas Tree Electronic Production Kit The product is shipped as loose parts and needs to be assembled by the customer themselves. Due to different batches, there may be differences in product appearance, color, and printed text, which not affect the use. Colour:Random Color(Color is random, no specification is accepted) Material:PCB Package Contents: 1 * DIY KIT(with housing) Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.