# How to choose a suitable DC motor?

Most people do not know which DC motor is suitable for their mini projects, robot projects and other automation projects. Usually, we will just use trial and error method to find out which DC motor is the most suitable for our project. Let’s figure it out how to choose the most suitable DC motor for your project.

STEP 1: Why do you need a DC motor?

• For a mobile robot?
• For a pulley?
• For a conveyor belt system?

STEP 2: Which type of DC motor do you want to use?

• DC brush motor?
• DC brushless motor?
• Servo motor?
• Stepper motor?
• Linear motor?
• Power window motor?

Comparison of the motor:

 DC MOTOR EXAMPLE OF APPLICATION ANGLE WHEEL PRICE DC geared motor Mobile robot, pulley, conveyor belt, lifting system. No Yes Rm40- Rm206 Servo motor Control position Yes(0-180) No RM 26 – Rm111 Stepper motor Rotation stage Yes (360) Yes Rm 26.50 Linear motor sliding door, No No Rm 349.80 Power window motor Lifting, pulley, mobile robot. No Yes Rm 33.92

The price shown above is the price of the DC motor sold by Cytron.

You can see more detail about our DC motor here.

STEP 3: What is the specification you need to know before you buy a DC motor?

• Maximum Torque.
• Maximum Weight.
• Maximum Voltage.
• Maximum Current.
• Maximum Speed.
• The diameter of the wheel use.

You can click here for more details  about our motor specification.

Just insert the value at input and then, you will get the specification of the motor you want at the output.

The Example of the online calculator:

A good news for you: Here, I share a quick and easy method to help all of you to know the specification of your motor by using online calculator. Please click here😆

Example:

STEP 5: Convert the torque given by the specification of DC motor to kg/cm.

Most of the DC motor specification on the market only show the torque, the current and voltage of DC motor not the weight that the motor can support. My suggestion, you need to convert the N.m to kg/cm with online converter calculator will be easier.

Question: What is the meaning of kg/cm?
Answer: We want to know the load in Kg the motor can support, for 1cm from the center of rotation.

Note: When the radius is increased, the weight can be supported will be lesser.

The picture below explaining about the meaning of the kg/cm related to motor.

Step 6: What that we need other than DC motor?

## Motor Driver

If you want to control the direction and speed of the DC motor.
Question: Why we need the DC motor driver?
Answer: Because the limited power(current and voltage) from microcontroller.

Note: The DC motor driver is different from one another. So, you need to read the user manual of the DC motor driver carefully  before you buy and use it. You can see more detail about our DC motor driver here.

## Encoder

As a sensor, user is able to identify the speed of the rotation, angle of rotation, direction of rotation or even position of the shaft. It can be applied on a robot arm’s joint, mobile robot, conveyor system or even a printing machine.

## Power Supply

Power supply is use to supply the current and voltage to the system. You need to choose your battery according to your DC motor driver.

STEP 7: Which DC motor driver suitable for your DC motor?

Most of the student only knows about L293D as a chip to control the DC motor. The problem is, you need to construct the power supply and circuit. The current is also limited if you use L293D.

The specification of the DC motor driver you need to check:

• Maximum current support for the DC motor.
• The range of voltage to supply the DC motor.

2 types of Cytron’s DC motor driver:

• DC Motor driver
Can control the direction and speed of the DC motor with high current.
• Smart Drive DC Motor Driver
Smart Drive DC Motor Driver is easier to use, just plug and play to control the robot. You just need to choose your RC controller and then control your robot without microcontroller. It has the capability to accept RC (Radio Control) signal for mix mode drive, analog voltage from potentiometer, PWM from microcontroller, and even controlled via UART command. the operation modes is configure by the DIP switch. The commonly DIP switch configurations are printed at the back of the board. MOSFETs are switching at 16KHz for quiet operation. With the on board temperature sensor, this smart driver is able to limit the output current stage by stage to prevent itself from overheat and burnt!

STEP 8: Choose the suitable encoder for your DC motor if necessary.

For your information, Cytron also sell DC motor with encoder attached to make it easier for you to buy it.

You can refer here  to see our DC motor with encoder and without encoder.

Note:
This tutorial just cover the basic element on how to choose your suitable motor. If you want to know more about the motor selection, there are so many explanations on the internet you can search and read.

If you have further inquiry about this tutorial, please post it in our technical forum here as we seldom check the comment section in tutorial site.

## 2 thoughts on “How to choose a suitable DC motor?”

1. LJ says:

Hello,

I just wanna ask, how can I test the power window motor without opening the door of the car? Can it be tested on its own?

Any reply would be much appreciated, thank you!