The Christmas tree kit comprises three circuit boards, assembled through DIY welding, allowing 37 colorful LED lights to flash alternately, visually presenting the three-dimensional outline of the Christmas tree (the effect is stunning when viewed at night). Product parameters: Circuit board size: 6cm*6cm*10cm Shell size: 6.7cm*6.7CM*12.8CM Weight: 169G for a complete set of parts with shell; 60G for a complete set of parts Working voltage: DC 5V DC Working principle: It can be seen from the schematic diagram that when connected to a 3-5V power supply, 37 LEDs are divided into 4 groups. Whenever the power is turned on, the 4 triodes will compete to turn on first. However, due to differences in components, only one triode will be the best. Turn on first; assume that Q1 turns on first, and then the group of LED1 lights up. Because Q1 turns on, its collector voltage drops, causing the left end of capacitor C2 to drop close to 0V. Since the voltage at both ends of the capacitor cannot change suddenly, the base of Q2 is also connected to approximately 0V, and Q2 is cut off, so the group of LED2 connected to its collector goes out; at this time, the high voltage of Q2 increases the collector voltage of Q3 through capacitor C3, Q3 will also turn on quickly, and the group of LED3 The group lights up, so for a period of time, the collectors of Q1 and Q3 are both at low level, the two groups LED1 and LED3 light up, and the group LED2 goes out, but as the power supplies charges C2 through resistor R2, Q2 The base voltage gradually increases. When it exceeds 0.7V, Q2 changes from the off state to the on state, the collector voltage drops and the LED2 group lights up. At the same time, the voltage dropped by the collector of Q2 passes through C3. The base voltage of Q3 also decreases, Q3 changes from on to off, its collector voltage increases, and the group of LED3 goes out. Next, the circuit cycles according to the process described above, and the three groups of 18 LEDs will light up in turn. On, two groups of LEDs are lit at the same time. These LEDs are arranged crosswise into a heart-shaped pattern and continuously flash and glow in a cycle to achieve a flowing display effect.
