• Admin

L42, Automobile Turn Signal Circuit

This is a simple circuit that can be used as a sequential signal light in automobiles as a signal. The circuit is based on two ICs. A TS555 Timer IC and a CD4017 decade counter IC. The IC1 is configured as an Astable multi-vibrator mode. When triggered, the outputs of the IC2 goes high and low (on pins 3, 2, 4 and 7)in sequence and the speed of this sequencing will be depend on the triggering frequency. The transistors Q1 to Q4 drives the corresponding LEDs. The switch S1 can be used to select the direction of turning and the LEDs arranged at the corresponding side of the vehicle will start sequencing.


  • IC1 = 555 Time, IC2 = CD4017

  • VR1 = 500K, R2 = 47K, R3 = R4 = 470R(ohm), R5 - R8 = 10K

  • C1 = 1uf 63v, C2 = 220uf 25v

  • S1 = SPDT switch, S2 = ON/OFF switch

  • Transistor Q1 – Q4 = BC547

  • LEDs (Different colors)

  • 12volt Battery or 9volt

  1. The switch S1 can be the existing changeover switch of the vehicle itself.

  2. The circuit can be powered of the 12V available from the vehicle itself.

  3. The color of the LED depends on your choice.

  4. Assemble the circuit on a good quality PCB.

  5. Be careful with the wiring of this circuit because any wrong connection may put the electricals of your vehicle in trouble.

10 views0 comments

Recent Posts

See All