This is a straightforward example of a circuit for a variable speed controller for a DC electric motor, which may be set up to regulate the pace at which windshield wipers go back and forth.

In addition to a few additional discrete components, the circuit includes a timer designated as NE555 (IC1), a motor driver transistor designated as BD239 (T1), and a switching transistor designated as BD249 (T2). The negative terminal of the power supply is linked to the ground so that it can be used in automobiles. This configuration is optimized for their use. Motor speed controller circuit As a low-frequency, free-running astable multivibrator with pulse-width modulation (PWM) dc motor speed controller output, IC1 has been set up in this configuration. The frequency of the oscillations is determined by the R-C components such as R1, VR1, R2, and C1. The potentiometer designated as VR1 serves as the motor's primary speed regulator. Decoupling the oscillator's direct current supply is accomplished via

the components R3, C3, and C4. The visual indicator that the electricity is "on" is provided by a red LED (LED1) of the blinking variety. When the wiper arm of potmeter VR1 is in the top position, a pulse train is produced at the output of IC1 that has long negative and short positive pulse lengths. This pulse train is caused by capacitor C1 charging through resistors R1, R2, and D1. Because of this, the speed of the motor is low. C1 charges through R1, R2, and VR1 when the wiper arm of VR1 is in the bottom position, and it discharges through R2 when VR1 is in the bottom position. The resulting pulse train features prolonged positive pulse widths and condensed negative pulse widths. The motor is currently rotating at a rapid rate. The output from IC1's pin 3 is routed into transistor T1, which then powers the DC motor through high power switching transistor T2 at the speed that the user specifies. The base current of transitor T2 is controlled by resistor R4, which has a limited capacity. The back e.m.f. that is created by the rotation of the DC motor is constrained by the diode D2, which is linked in antiparallel with the motor. Capacitor C5 inhibits parasitic oscillations.

The 12 V DC supply that comes directly from the battery of the vehicle can be used to power the motor control circuit. Put it away in a modest metal cabinet so you won't have to worry about it and so it will be safer. In terms of building, a veroboard of medium dimensions will do. Make sure that the DIP socket you use for IC1 is of a high grade. Finally, make sure to include a sufficient heat sink for the transistor T2 in your design. Types of DC Motors 1. Brushed Motor 2. Brushless Motor 3. Servo Motor Uses of DC Motors

Tools, toys, and a variety of household goods all make use of DC motors of a more compact size. Manufacturing machines, electric cars, and elevators all make use of large- sized DC motors.