Use MC1455PIG to make automatic cycle light-emitting diode circuit

This automatic cycling light-emitting diode circuit can be used in various flashing and lighting situations.

The circuit is as shown in the figure. The moment the power is turned on, pins (2) and (6) of MCl455PIG are low level. Since capacitor C1 has just started charging, pin (3) of MCl455PIG outputs high level, and the light-emitting diode LEDI does not light up. , LED2 lights up because there is forward voltage at the positive terminal. As resistors R2 and R3 charge capacitor C1, the voltage across capacitor C1 gradually increases. When the voltage reaches the threshold voltage of about 3.7V, pin (3) of MCl455PIG outputs low level, LED1 lights up, and LED2 goes out. At this time, the capacitor C1 is discharged through the resistor R3 and the circuit inside the MCl455PIG. When the voltage across the capacitor C1 drops to 2.6V, the MCl455PIG (3) pin voltage flips again, LED1 goes out and LED2 lights up. Repeatedly, the two high-brightness light-emitting diodes, red and green, are turned on and off in turn.

Changing the values ​​of resistor R3 and capacitor C1 can change the flashing frequency of LED1 and LED2. By increasing the resistor value or capacitance, the flashing time will increase, and vice versa.

The total operating current of this circuit is 7.8mA~10.2mA (measured with a VC97 digital multimeter).