pls help me .......want detailed working....???

pls help me to find detailed working of the circuit below..........

it is a circuit used to control the speed of the motor that drive wiper.....?

pls help me ...how the circuit is achieved the speed control//////////

The 555 on the left is simply a monostable to debounce the switch and give a single clean clock pulse to the 4017.

The 4017 is a decade Johnson counter having a single output high at a time; the output is advanced each time you push the switch. At the 10 outputs of the 4017 are 10 variable resistors; when an output of the 4017 is high, current flows through it's associated variable resistor to charge the cap on the second 555 timer. This timer provides a constant on time (off time varies based on the value of the variable resistor) to the output motor through the current buffer transistors.

Varying the ratio of on time to off time changes the power to the motor and therefore its speed; see PWM for more info.

The very old circuit from that awful website in India does not control the speed of the wiper motor.
Instead it controls how long the wiper motor runs from nearly no time to about 10 seconds depending on the setting of the trimpot that the counter stops on.
The off-time of the motor for each cycle of its output 555 oscillator is about 5 seconds.

the circuit is for controlling motor speed with rain intensity,,,

electroguy said:

the circuit is for controlling motor speed with rain intensity,,,

Click to expand...

So where do you locatate the rain sensor?

Why do I think that recently (past 6 months) we had this very same circuit show up with the same questions? This is like Deja-Vue all over again.

Ron

Sometimes the forums feel like Groundhog Day.

Same teacher, different class.

Boncuk said:

So where do you locatate the rain sensor?

Click to expand...

in place of switch we will put rainsensor

The car (?) will be submerged in a lake for the wiper to turn on. A lot of good it does then. E

electroguy said:

the circuit is for controlling motor speed with rain intensity,,,

Click to expand...

No it is not. That terrible website has many circuits that do not work.
Look at the datasheet of a 555. With the parts values on that horrible schematic the motor simply turns on and off at almost full speed with various durations. The speed of the motor is not controlled.