​How to drive a DC motor without a motor driver module (2024)

Any DC motor can be driven with PWM simple signals that can be generated by the Arduino Uno and virtually any other microcontroller. Just like you can control the intensity of an LED, you can use PWM to control the rotational speed of a DC motor.

Whether it is a miniature 3V motor for toys, or a large 12V or 24V motor for your lawnmower, the principle of operation is the same.

A 3V to 5V DC motor used in hobby applications.

For example, a tiny 3V DC motor with a 15Ω total resistance in its coil (like the one in the photo above) will draw 0.2A of current.

This is just within the Arduino's I/O pin current limit. However, but if your motor's resistance is slightly smaller, the current can easily increase more than the 0.4A which exceeds the Arduino's safe operating limits. If this happens, your Arduino will be damaged.

If you are looking for the simplest possible way to control a DC motor, then you will need a single transistor. You can choose a transistor that is appropriate for the current requirements of the motor that you want to control.

A DarlingtonTIP122transistor is a common device used in DC motor control applications.

A Dalrington transistor used to control a DC motor.

The Darlington TIP122 can provide 5A of continuous current through its collector and 15A of peak current, which can be drawn when a large motor starts. You can see it marked as "T1" in the schematic above.

Your Arduino can easily control the transistor, since it only needs 2.5V in its base to switch on (notice the label "Control signal" on the left of the current limiting resistor in the schematic above).

You can add a resistor (~3.3kΩ) to protect the Arduino across the base of the transistor, and a diode (like the 1N4004) to block back-currents from the motor, and you have your motor driver, capable of regulating the rotational speed using PWM. If your motor is brushed, also add a small capacitor (~1uF) across the terminals of the motor to help with the electrical noise.

int motor = 9; int speed = 0; int speedAmount = 5; void setup() { pinMode(motor, OUTPUT); } void loop() { analogWrite(motor, speed); speed = speed + speedAmount; if (speed <= 0 || speed >= 255) { speedAmount = -speedAmount; } delay(30); }

An excellent discussion of the use of discreet transistors to control a DC motor with schematics is here.

If you would like to learn how to use DC motors with the Arduino, consider enrolling to Arduino Step by Step Getting Serious.

We cover stepper motors in a dedicated section (Section 16) that contains 10 lectures.