Digital running water lamp design based on NE555 and CD4017

1 Project Introduction
     Based on the design of digital running lights based on NE555 and CD4017, the NE555 timer is used to form the clock pulse generated by the multivibrator, which is counted by the decimal counter CD4017. The 10 output terminals output high level one by one, and the cycle continues, and the 10 LEDs are sequentially Take turns to light up to achieve the effect of running water lights. By adjusting the resistance of the potentiometer, the flashing speed of the running water lamp can be changed.
2 Overall Scheme
    The overall scheme system block diagram is shown in the figure. The power supply supplies power to the NE555 timer to form a multivibrator and the decimal counter CD4017 drive circuit, and the LED realizes the running light display effect.
Figure 2-1 Block diagram of the water lamp system based on NE555 and CD4017
3 Circuit principle
    The power supply part adopts a Micro USB interface sinking board design, with a 2.54mm 1×2P pin hole reserved for external power supply. Capacitor C1 plays the role of power supply filtering.
    The power supply VCC charges the capacitor C2 through the resistors R1, R2 and the potentiometer RP1. When the capacitor C2 is charged to a certain level, the voltage of pins 2 and 6 of the NE555 timer rises to 2/3VCC, and the voltage of pin 3 becomes low. level, pin 7 is in a low impedance state. Capacitor C1 discharges to ground internally through potentiometer RP1 and resistor R2 to pin 7 of the timer. When the voltage of pins 2 and 6 is discharged to less than 1/3VCC, pin 3 changes from low level to high level again, and pin 7 shows a high impedance state. Continuous cycle of capacitor charging and discharging process.
    By adjusting the resistance of the potentiometer RP1, the pulse frequency and duty cycle generated by the NE555 timer pin 3 can be changed, which is used as the working clock pulse of the decimal counter CD4017. When the CD4017 counter is working, the output terminals Q0~Q9 output high levels in sequence, and the cycle continues. The LED display circuit LED0~LED9 of the subsequent stage lights up and emits light, producing a running water horse racing effect. When the resistance of the potentiometer decreases, the running water lamp The flow speed becomes faster; when the resistance of the potentiometer increases, the flow speed of the running water lamp becomes slower.
Figure 3-1 Principle of digital flow lamp based on NE555 and CD4017
4 Bill of Materials Serial Number Tag Parameter
Package Quantity Product Number 1 R1 2.2KΩ R0805 1 C114237 2 R2 10KΩ R0805 1 C100047 3 R3~R12 1KΩ R0805 10 C140871 4 RP1 50KΩ RES -ADJ-TH_3P 1 C118910 5 C1,C2 1uF C0805 2 C16834 6 LED0~LED9 LED red light LED-TH-3mm 10 C84774 7 U1 NE555 SOIC-8 1 C7593 8 U2 CD4017BM/TR SOP-16 1 C356694 9 USB1 Micro USB MICRO-USB-SMD_5P 1 C40957 10 J1 2P pin header 2.54_1×2P 1 C160332 11 TP1~TP4 copper pillar screw M3×10+6 4 C551322 12 — PCB blank board — 1 — 5 Soldering assembly Figure 5-1 Based on NE555 and CD4017 digital running water lamp kit Figure 5-2 Digital running water lamp assembly drawing based on NE555 and CD4017 Figure 5-3 Physical picture of digital running water lamp based on NE555 and CD4017