Electric Motors and Features

Electric motors are  devices that converting electrical energy into motion energy. Its foundations date back to the 1800s. Electric motors are generally divided into two sections as AC and DC motors according to the type of voltage they work. DC motors are mostly powered by batteries, dynamos. You can use adapters and power supplies to operate the DC motors by connecting them to the alternating current (eg city electricity). These tools convert alternating current into direct current.

Brushed Motors:

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Brush motors are a common type of electric motors. The basic structure consists of a metal wire winding wound on the motor shaft between the two positive and negative poles. The wire winding, that is, the coils, is supplied with electric current by the so-called brush, so that the commutator is charged with magnets in the opposite direction. Thus, the windings of the shaft are rotated so that the coils of the rotor interact magnetic with the stator magnets. The direction of rotation of the motor can be changed by changing the + and - directions of the current. In addition, the higher the voltage, the higher the rotational speed. The performance of brushed motors decreases over time due to corrosion of the coals.

Brush motors need to be replaced as the coal melts. So it requires maintenance. The positive aspect of brushed motors is that they are water resistant.

Brushless Motors:

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They are electric motors without brush and collector. A further difference of brushless motors from brushed motors is that the wire winding is in the rotor (moving part) in the brushed motor and in the stator (fixed part) in the brushless motors. Brushless motors are used with the abbreviation BLDC (brushless dc motor). The operating speed of the brushless motors is controlled by ESC (Electronic Speed ​​Contoller).

It has a longer life in brush motors such as coal to be eroded and collector. They are expensive if higher efficiency and torque can be achieved than brush motors. Engines are preferred. Brushless motors can be used like;

  • drones,
  • rc or wifi cars,
  • cd-dvd drives


Step Motors:

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Stepper motors can rotate at precise angles and variable speeds. Available in both AC and DC versions. You can rotate the stepper motors at different speeds, eg 5 °, 45 °, 18 °. The stepping sensitivity of stepper motors varies according to the step structure. For example, in a full rotation of a 400 stepping stepper, the step angle is 360 ° / 400 = 0.9 °.

The main difference of stepper motors from servo motors is that they do not have a control circuit and sensor. Stepper motors operate in motor drive circuit control, do not connect directly to the microcontroller such as arduino. Because the Arduino fails to provide the energy needed by the stepper motor. Motor drive circuit operates under the control of a microcontroller such as arduino, and variables such as the direction of rotation, speed, angle of the stepper motor are determined by the signals sent from the microcontroller. Depending on the type of stepper motor, the motor driver circuit to be used also varies.

Stepped motors are preferred for projects that require progressive and high motion accuracy. Step motors are used in areas requiring precise movement such as;

  • CNC machines
  • Medical machines
  • Card reader
  • Camera holders

A great video about the working principle of stepper motors is available at:

Servo Motors:

Servo motors usually consist of dc or ac motors, potentiometers and motor driver circuits and do not require extra driver board. Step motor allows angular rotation. If the operating principle of servo motors is explained simply, the potentiometer connected to the motor transmits information about the motion of the motor to the control circuit. Like the Arduino, a microcontroller transmits the angle information that the servo motor should rotate to the control circuit in the servo motor via the signal cable. The control circuit also provides the required rotation voltage to the motor, taking into account the angle at which the servo motor is located and the angle it should rotate. In this respect, we can say that servo motors are smarter than stepper motors. Servo motors have different specifications (torque, size, operating speed, operating voltage etc.) depending on the purpose of use. Servo motors are used in areas requiring fast, strong and sestrained movements such as;

  • Robotic arms
  • Humanoid robot projects
  • Air conditioners
  • Packing machines
  • Office machines

The following link is about servo motors operating system and provides good explanations and examples: