Automatic Wiper Control
A continuously working wiper is a big problem when it is raining slightly.The wiper control given here makes the wiper to sweep at rates from 1S to 10 S.
The circuit is build around an astable multivibrator using NE 555.Here the output at pin 3 remains high for a time period set by R2 ,and low for a time period set by R3.The low output pulse drives the transistor pair to drive the wiper motor to make one sweeping cycle and waits for next low pulse to arrive for next sweep.The high going pulse at pin 3 determines how many time should wiper should sweep in a given period of time.
Connect the circuit to 12V line from Vehicle and connect the wiper motor and wiper switch as shown in figure.
For setting the device first find out how much time it is required for the wiper to complete one sweep cycle.Now adjust R3 such that wiper makes correct one sweep cycle.Fix R2 some where on the dash board.And now the system is ready to use.
You can adjust the sweep rate of the wiper using R2 according to the intensity of rain.
Circuit Diagram with Parts List.
Modified Version of the wiper speed control circuit.
A modified version of the wiper speed control circuit is shown below. A diode is added across R3 makes the charging time and discharging time independent of each other. A freewheeling diode is added across the wiper motor. The transistors are replaced by a MOSFET for better switching characteristics. I recommend this circuit over the previous one.
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