Key benefits Simple clock generation and decimal counting module using widely available components (NE555 and CD4017) for LED sequencing and indicators Adjustable output frequency and LED speed through a single resistor (R4) Two main functional blocks: clock generation circuit and decimal counter circuit Direct clock drive from NE555 to the CD4017 clock input to produce reliable counting Minimal external parts (C1, R2, R3, R4) for compact integration What it is A compact clock generation and decimal counter circuit built around a selfexcited multivibrator with NE555 as the core and a CD4017 decade counter The NE555based oscillator charges capacitor C1 through R2, R3, and R4 to generate a clock The NE555 output clock is supplied to the CD4017 clock input (pin 14) to drive the decimal counting sequence How it works The circuit consists of a clock generation block and a decimal counter block C1 charges through R2, R3, and R4, forming the timing for the oscillator The NE555 produces a clock signal from its output, which is fed to the CD4017 clock input (pin 14) R4 is adjustable to control the oscillator frequency and thus the speed of the LED sequence Key specifications and parameters Timing relationship for charging: 0.695 × (R2 R3 R4) × C1 Timing relationship for discharge: 0.695 × (R4 R3) × C1 LED speed and overall clock rate are adjustable via R4 Main components: NE555, CD4017, C1, R2, R3, R4 Clock path: NE555 output drives the CD4017 clock input (pin 14) Important attributes Function: generates a clock signal and uses a decimal counter to drive sequential outputs Compatibility: designed to work with NE555 and CD4017 based systems Performance: tunable timing and LED sequencing speed through a single resistor Simplicity: minimal external components for straightforward integration Potential applications LED chaser or sequencing displays for decorative lighting or signage Indicator or status panels in electronics projects requiring simple timed counting Educational lab module to demonstrate oscillator and counter concepts using common ICs Use scenarios Build a basic LED chasing sequence by connecting CD4017 outputs to a string of LEDs to visualize the counting Integrate into a control panel to provide a simple visual indicator that advances at a useradjustable pace Use as a teaching aid to illustrate how an NE555based oscillator can drive a CD4017 counter in timing and sequencing experiments