This is a simple circuit based in 4 chips. L293,CD4511, CD4518 and Atmega 328(Arduino). L293 is a motor driver which can handle bigger loads of current and control the motor since arduino outputs can give us maximum 40 mA. 4518 is a counter which counts how many times the magnet passes beyond the Reed Switch, 4511 is a BCD to 7-Segment Decoder, it takes the counts from 4518 and show them in the 7 segment Display. We use the A0 Analog Input from the arduino to connect the potentiometer and select the speed of the motor. Finally we use one PWM output from arduino (pin 3,5,6,9,10,11) to control the chip.