Amazing LED Chaser Circuit – Beautiful Decoration Idea

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An LED chaser is an electronic circuit that lights LEDs one after another in a sequence. It creates a running or chasing light effect commonly seen in decorations and indicators.

The sequence can move left-to-right, right-to-left, or in patterns. It’s usually built using ICs like 555 timer + 4017 decade counter.

Components Required:

  • 555 Timer IC
  • CD4017 IC
  • 10k Ohm Resistor
  • 10uf Capacitor
  • 10k Ohm Potentiometer
  • Led – 27 Pcs
  • 9-12v power supply

Circuit Diagram:

LED Chaser circuit

Gerber File:

Download Gerber File

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555 Timer IC:

The 555 Timer IC is a legendary integrated circuit that has powered electronics projects for more than five decades. Introduced in 1972 by Signetics, this compact and versatile chip quickly became one of the most widely used ICs in the world. Its popularity comes from its simplicity, reliability, and flexibility, making it ideal for beginners as well as seasoned engineers.

The 555 timer is a monolithic timing circuit, designed to generate accurate time delays and oscillations. Inside the IC are key blocks such as a voltage-controlled oscillator (VCO) and a flip-flop. The VCO produces a square wave, while the flip-flop—acting as a Schmitt trigger—ensures clean and stable switching with hysteresis.

Pinout and Configuration of the 555 Timer

The 555 Timer IC comes in an 8-pin package, with each pin serving a specific purpose:

  • Pin 1 – Ground (GND)
  • Pin 2 – Trigger (starts the timing when voltage falls below 1/3 Vcc)
  • Pin 3 – Output
  • Pin 4 – Reset (active LOW, usually tied to Vcc)
  • Pin 5 – Control Voltage (optional timing control)
  • Pin 6 – Threshold (ends timing when voltage reaches 2/3 Vcc)
  • Pin 7 – Discharge (discharges timing capacitor)
  • Pin 8 – Vcc (power supply, typically 5–15V)

Operating Modes of the 555 Timer

The 555 can be configured in three main modes:

  • Monostable Mode (One-Shot)
    Produces a single timed pulse when triggered.
  • Astable Mode (Free-Running)
    Continuously generates square waves, used for oscillators and blinkers.
  • Bistable Mode (Flip-Flop / Schmitt Trigger)
    Has two stable states, used in switches and memory circuits.

Applications of the 555 Timer IC

Thanks to its versatility, the 555 Timer IC has been used in countless projects, including:

  • Timer circuits (egg timers, alarms)
  • LED flashers and blinkers
  • Oscillators for audio and signal generation
  • Pulse generators (IR transmitters, ultrasonic circuits)
  • Alarm circuits (motion detectors, smoke detectors)
  • Audio tone generators and sound effects

CD4017 IC:

The CD4017 IC is another highly popular digital IC widely used in automation, sequencing, and counting applications. It is a decade counter that counts from 0 to 9, making it perfect for LED chasers, digital clocks, and timing circuits.

The IC outputs a HIGH signal one-by-one on its 10 output pins (Q0–Q9) for each clock pulse it receives. It also includes a carry-out pin, allowing multiple CD4017 ICs to be cascaded for larger counting sequences.

Pinout of the CD4017 IC

The CD4017 comes in a 16-pin package that includes:

  • 10 Output Pins: Q0–Q9
  • 1 Carry-Out Pin
  • 1 Reset Pin (resets count to Q0)
  • 1 Clock Pin (input for each step)
  • 1 Clock Enable Pin
  • Vcc and GND Power Pins

How the CD4017 Works

Each time a clock pulse arrives at the CLOCK pin, the IC increments its count and activates the next output pin.
The RESET pin forces the count back to zero.
The CARRY pin enables connection of multiple counters to create larger sequences.

Applications of the CD4017 IC

This IC is widely used in:

  • Digital clocks
  • Counters
  • LED chasers and sequencers
  • Traffic light controllers
  • Display drivers
  • Scoreboard circuits

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