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# 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. So let’s figure it out how to properly 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 motors sold by Cytron.

You can see more detail about our DC motors 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.

If you want to know how to calculate your motor specification by using mathematical formulas, please click here for more details.

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😆

STEP 4:  Where do you want to put your load?

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 is to convert the N.m to kg/cm with an online calculator first to make everything easier.

Question: What is the meaning of kg/cm?
Answer: We want to know the load that the motor can support (in kg), if we use a turning axis of 1cm radius.

Note: As the turning axis’ radius is increased, the weight can be supported decreases.

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

Step 6: What else do we need other than DC motor?

## Motor Driver

If you want to control the direction and speed of the DC motor.
Question: Why do we need a DC motor driver?
Answer: Because the current and voltage from a microcontroller is tiny.

Note: Every DC motor driver is different. So, you will 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 drivers here.

## Encoder

Encoders are sensors that identify the speed of rotation, angle of rotation, direction of rotation and even position of the shaft. They can be applied on a robot arm’s joint, mobile robot, conveyor system or even a printing machine.

## Power Supply

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

Note: You can click here for more details about our power supply.

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

Most students only know how to control DC motors with the L293D. But the problem is you will still 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 supported by 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
The Smart Drive DC Motor Driver is much easier to use, just plug and play! You only need to choose your RC controller and then you can control your robot even without a microcontroller. It has the capability to accept RC (Radio Control) signal for mix mode drive, analog voltage from potentiometer, PWM from microcontroller, and can even be controlled via UART commands. These operation modes can be configured via the onboard DIP switch (commonly configurations are printed at the back of the board). The MOSFETs switch at 16KHz for quiet operation. With the on board temperature sensor, this smart driver is also able to limit the output current stage by stage to prevent itself from overheating and burning!

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

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

You can refer here  to see our DC motors with encoders and without.

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.

Thank You, I hope this tutorial will help you to choose your DC motor.  🙂

## Comments (5)

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!

NURUL SYUHADA

You can directly connect the power window to 12V battery or power supply to test the power window motor.

what is the kind of motor that can used as GENERATOR for mini prototypes wind turbine ??

QWERTY

Hello there , can someone tell me what kind of motor that i can use for my door lock on the deadbolt?????

Hi I need a motor to act as a generator to convert mechanical power to electrical power. this will be used in a car braking regenerative system (theoretical project) so the shaft will be at 1500 Rpm and 161N*m. what motor would you recommend?
The power generated will be used to power auxiliary functions such as the AC as well as stored in a battery.