This LED chaser display is build around readily available, low cost components.This circuit is easy for build for a beginner in the electronics. The power supply for the chaser circuit is from a 9v battery.The circuit diagram of the chaser is below.
Click the circuit for enlarging.
The NE 555 timer ic and decade counter 4017 is the heart of the circuit. The astable multivibrator built around IC2 produces a clock frequency at its output pin 3. This output is connected to clock pin (pin 14) of the decade counter Cd 4017.The decade counter can count up to 10. But in circuit we only use 4 O\P so the Q4 (pin 10) is connected to the reset (pin 15) of the CD 4017. The output of IC3 advances by one count every second (depending on the time period of astable multivibrator IC2). The VR1 connected between the Pins of IC2 determine the speed of the glowing of the bulb.
When Q0 (pin 3) output of IC1 goes high, transistor Q1 conducts and the current flows through D1 via resistor R6 .The LED D1 glow. Next, when Q1 (pin 2) output of IC3 goes high, transistor Q2 conducts and the current flows through D2 via resistor R6 . The LED D2 glow.Again, when Q2 (pin 4) output of IC1 goes high, transistor Q3 conducts and the current flows through D3 via resistor R6 .The LED D3 glow.Similarly, when (Q3 pin 7) output goes high, transistor Q4 conducts and the current flows through transistor Q4 conducts and the current flows through D4 via resistor R6 .The LED D4 glow.
When the Q4 (pin 10) output of the IC1 goes high, it resets the IC1 to the initial counting. Then the cycle repeats.
Connect the pin 16 to the +ve and the pins 8,13 to the -ve supply. The real world picture of the PCB is below (after the manufacture of the components on the pcb).
Actual-size, single-side PCB of LED CHASER
Component Layout for PCB
Prototype Board
Components List:
- R1 - 10K
- R2 to R6 - 1K
- VR1 - 10k
- C1 - .01pf
- C2 - 10uF / 25 v
- Q1 to Q4 - BC 548
- IC1 - 4017B Decoded Decade(Divide by 10) Counter
- IC2 - NE555 Timer IC
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