Vehicle Indicator Circuit

The circuit depicted in the article can be used as an indicator in vehicles. Here two identical circuits are used one for left and the other for right. This project can be installed in our vehicles when the indicators are not working. Even in Bi-cycles at the place of inbuilt indicators that works manually.

IC555 is the most versatile chip and it is (can be) used in all most every kind of application because of its multifunctionality. As we know it’s on chip multivibrator means with IC555 one can design astable, monostable, bistable multivibrators. Its main applications are to generate timings, clock waveform, generate synchronizing signals, square wave oscillator and many more.

The project here is developed using 555 timer. The timer is wired in astable mode. Now if the power supply is first connected to astable circuit then initially the timing capacitor C1 is discharged. The voltage at pin2 is 0V and the output of timer is driven HIGH. Now C1 starts charging through R1 and R2. Capacitor C1 is also connected to pin6 which is threshold input of the timer.

When the voltage through C1 goes below 1/3 of the power supply, the output of the lower comparator reaches a new value. This doesn’t change the logic state of the flip flop which means that the output remain low. The second comparator’s input get the voltage from pin6 which is threshold input and 2/3 Vcc from internal voltage divider. When the voltage through C1 goes below 2/3 of the power supply the output of the second comparator reaches a new level. The flip-flop change their state and the output becomes HIGH. So the output of 555 timer goes from HIGH to LOW.