Check the listing for details. NE555+CD4017 Chaser Water Flowing Light LED Module DIY Soldering Practice Module. Color: Red, Condition: New. Listed at 1.79 USD. Board size. 53mm*19mm Supply Voltage :2.5 - 14 .5 V This package is mainly decimal counter circuit and circuit generated by the clock , from the core of the self-excited NE555 multivibrator power through R2, R3, R4 charge the capacitor C1, C1 started when charging , NE555 2 feet still in low, so the output pin 3 goes high when power through R2, R3, R4 to charge C1 to 2/3 of the supply voltage , the output pin 3 level from high to low , NE555 conducting internal discharge , capacitor C1 through R4, R3, NE555 7 feet discharge until the voltage across C1 is less than 1 /3 of the supply voltage , NE555 and 3 feet level from low to high . C1 and charge again this cycle oscillations formed . Charging time : 0.695 (R2 + R3 + R4) C1, discharge time : 0.695 (R4 + R3) C1, R4 can be adjusted to control the output frequency of the oscillator , the oscillation clock signal is applied continuously NE555 CD4017 14 feet , the output terminal 10 is connected with the CD4017 10 LED, when the output terminal 10 turns CD4017 generated clock signal at a high level , the D1 - D10 are sequentially lit to form a water - light effect. You can adjust the flow rate adjustment R4 LED lights Package Included: 1 x DIY Light Water Flowing Sensor LED NE555 CD4017 Not soldered module smd kit Instructions/schematic are NOT included. We don't provide technical assistance please make sure that you are familiar with the product before purchasing.