Key benefits Clear, reliable visual effect: Ten LEDs light in sequence to produce a continuous WaterLight (running-water) animation for decoration, indicators, or learning displays. Adjustable speed and control: R4 provides easy, analog control of the LED flow speed so you can match the effect to your application. Simple, well-known ICs: Uses the NE555 as a stable clock oscillator and the CD4017 decade counter for straightforward, dependable operation. Features and specifications Oscillator timing: Charge time = 0.695 × (R2 + R3 + R4) × C1 Discharge time = 0.695 × (R4 + R3) × C1 Clock interface: Continuous oscillation output from the NE555 is fed to pin 14 of the CD4017 to drive the counter. LED outputs: Ten LEDs are connected to the 10 outputs of the CD4017 (D1–D10). As the CD4017 outputs cycle high in sequence under the clock signal, D1–D10 illuminate one after another to create the WaterLight effect. Speed adjustment: Rotating or changing R4 alters the oscillator frequency and thus the flow speed of the LED sequence. Components referenced: NE555 timer IC, CD4017 decade counter, resistors R2/R3/R4, capacitor C1, and ten LEDs. How it works (brief) The NE555 generates a clock pulse whose high/low timing is determined by the resistor and capacitor network (R2, R3, R4, C1) according to the timing formulas above. The clock output continuously drives the CD4017's clock input (pin 14), advancing which of the ten outputs is high. Each CD4017 output in turn lights its connected LED; the result is a continuous, adjustable-running sequence of ten LEDs. Practical use scenarios Decorative lighting: Create eye-catching running-light accents for displays, signage, or home décor where a continuous water-flow effect is desired. Educational electronics projects: Demonstrate timer and counter principles (NE555 oscillator timing and CD4017 decade counting) in classroom or hobbyist build sessions. Status/indicator sequencing: Use the sequential LEDs as a simple visual sequencer or status indicator in prototypes, test rigs, or DIY control panels. Compatibility and performance notes Designed to work with the standard NE555 timer and CD4017 decade counter ICs; timing behavior depends on the chosen values for R2, R3, R4, and C1. R4 is the user-adjustable element for controlling oscillator frequency and LED flow speed; changing R4 or C1 will change pulse rate according to the provided formulas. Ten outputs of the CD4017 are used directly to drive the LEDs in sequence (D1–D10). What makes it stand out Combines widely used, easy-to-source ICs (NE555 and CD4017) with a simple resistor/capacitor timing network for predictable, tunable behavior. Direct, sequential LED drive provides a classic WaterLight visual effect with straightforward adjustment and integration into larger projects.