(Need soldering kit)Simple flash circuit to make LED lamp bead flashing kit board | Электронные компоненты и

(Need soldering kit)Simple flash circuit to make LED lamp bead flashing kit board | Электронные компоненты и

Function introduction: After the power is turned on, the left and right blue LEDs (you can replace the LEDs of other colors) flash alternately, and the cycle is repeated. The higher the power supply voltage, the brighter the LEDs. Changing the capacitance of the electrolytic capacitor can change the flashing alternately The larger the capacitance value, the slower the flashing speed, and the smaller the capacitance value, the faster the flashing speed. The circuit is simple and easy to understand, and the soldering pads have been treated with tin spraying process, which makes soldering easier and the solder joints more beautiful! Especially suitable for friends and students who are new to electronics.

Working voltage: 3-14V DC


Circuit principle: When the power is turned on, the two triodes will compete to be turned on first, but due to differences in components, only one tube is turned on first. If Q1 is turned on first, then the collector voltage of Q1 drops, D1 is lit, and the left end of the capacitor C1 is close to zero voltage. Since the voltage across the capacitor cannot change suddenly, the base of Q2 is also pulled to almost zero voltage, making Q2 cut off. D2 does not light up. As the power supply charges C1 through the resistor R2, the base voltage of the transistor Q2 gradually rises. When it exceeds 0.6 volts, Q2 changes from an off state to an on state, the collector voltage drops, and D2 is lit. At the same time, the decrease of the collector voltage of the transistor Q2 causes the base voltage of the transistor Q1 to jump down through the action of the capacitor C2, Q1 changes from on to off, and D1 goes out. In this cycle, the two triodes in the circuit are turned on and off in turn, and the two light-emitting diodes continuously emit light. Changing the capacity of the capacitor can change the speed of the LED cycle.


Component list:



common problem:
1. The LED positive and negative poles are soldered wrongly, and the long legs are positive.
2. The resistance value of the resistance welding is wrong, the green color ring is 510 ohms, and the orange color ring is 33K or 30K.
3. The positive and negative electrodes of the electrolytic capacitor are welded wrongly, and the long leg is the positive electrode.
4. The triode is welded in the wrong direction, and plug it in according to the shape on the board.
5. The power supply is connected reversely, pay attention to distinguish the positive and negative poles of the power supply, and the DC voltage of the power supply is 3-12V.
6. Welding short-circuit and virtual welding, pay attention to inspection.