Automobile Turn Signal

Summary of the circuit-

Easy to understand and mount circuit.
This circuit is used to give a visual effect when a vehicle is turning towards left or right.
If the vehicle is turning towards right then yellow colour of LED will blink.
If the Left turn is been taken by the automobile then the red LED will blink in this circuit.
This circuit is constructed with the help of IC CD4017 and IC NE555 timer.

Principle behind Circuit-

This is a very easy circuit which can be employed in automobiles as a sequential indicator light. This circuit is constructed with the help of two ICs- – a CMOS timer IC i.e. 555 timer and a decade counter IC i.e. CD4017.In this circuit astable mode of the 555 timer IC has been used to trigger the counter. Other discrete components are also used in the circuit.

At the time when power supply is provided in the circuit, voltage at pin 2 of IC1 goes down while the output pin of IC1 i.e. *(pin ?) switches to the high state. Now pin 3 of IC1 provides a positive clock pulse to pin 14 of IC2. This high pulse triggers the output pins of IC2 i.e. pin 3,2,4 and 7 high. At the same time output pin of IC2 is at low in sequence and the rate of this sequencing is proportional to the triggering frequency. Now the transistor T1, T2, T3, T4 collector starts conducting, as a result of its corresponding LEDs of this Transistor starts blinking.

S1 point in the circuit is used to select the left or right direction. So if S1 is connected with the right, all the LEDs connected on the right will blink. In the same way if S1 is connected to the Left then all the LED connected on the left will blink. Capacitor C2 in the circuit is used as a bypass capacitor.

Note- Although we have chosen yellow light for right turn and red for the right turn in this circuit., you can alter the colour of LED as per your choice.

(For demonstration purpose we have used only one LED for left turn and one for right turn.)

Components required building the circuit-

IC1 NE555

IC2 CD4017

Resistor

R1 47K

VR1 500K

R3 1.2K

R4 1.2K

R5 10E

Capacitor

C1 1uF