This is a motor speed controller circuit diagram built based MAX4295 from Maxim. By using this circuit, you will be able to control the speed of motor movement.
Resistor R1 biases the potentiometer to match the input range of U1. Full counter-clockwise rotation of the pot corresponds to maximum-speed reverse rotation of the motor. Mid-scale on the pot corresponds to motor off, and full clockwise rotation of the pot produces maximum-speed forward rotation in the motor.
The characteristics of a given motor may allow you to eliminate the amplifier’s output filter (L1, L2, C1, and C2). But, unless the control circuitry shown is located near the motor, you should include the filter to reduce EMI.
Download more explanation about the circuit diagram of motor speed control with MAX4295 in PDF version: