Multi-Mode Running light

Running light based project is very interesting and one of the most made project. We use this type of project in many ceremony. Here is a unique project "Multi-Mode running light" in the series of LED based project because it can operate in three different modes.

Circuit description of multi mode running light

The whole circuit multi mode running light is designed and fabricated around timer IC and BCD UP-DOWN counter IC.

IC1 and IC2 is used to generate vary low and low frequency square wave respectively where output of IC1 is connected to different point (SW1) and is used when running light is working in differential modes and output of IC2 is connected to input of BCD-up-down counter IC 4510B (IC3) for producing sequential BCD output.

Outputs from IC3 is given to input pin of IC4 (BCD-to-decimal decoder 4028B) in order to decode the output from encoder IC (IC3). The ten outputs from IC4 are obtained and each output is connected to base of driver transistor in order to supply gate current to triac.

Here in circuit diagram of multi mode running light we show only one triac firing circuit because of complicated design. But similar triac firing circuit can be connected to each remaining output.

Variable resistor VR1 and VR2 is used to control period of interruption and period of running respectively where the direction of running light can be changed by mean of switch SW2.

multi mode running light


Resistors (all ¼-watt, ± 5% Carbon)

R1, R2 = 4.7 KΩ

R3 = 10 KΩ

R4 = 270 Ω

VR1, VR2 = 1 MΩ

VR3 = 100 KΩ


C1 = 10 µF/16V

C2, C4 = 0.01 µF

C3 = 4.7 µF/16V


IC1 IC2 = NE555

IC3 = CD4510B (BCD up-down counter)

IC4 = CD4028B (BCD-to-decimal decoder)

T1 = BC109

D1 = 1N4001

TR1 = 4A/400V


SW1 (a, b) = 2-pole 3-way switch

SW2 = single-pole 2-way switch

B1 = Bulb

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