Category Archives: Week 8 Assignment


This week is to explore different motors. The first part of the assignment is to shortly describe the differences between DC motors, servo motors, and stepper motors. Basically, the DC motor is the one good for continuous spinning. It runs at a high RPM (revolutions per minute) and can be used for something like fan and blender. Servo motor is easy to connect and can generate high performance. The advantage of the servo is to control the rotation degree from 0-180. Otherwise, if the rotation degree exceeds 180, it will turn counterclockwise. General usage for servos can be robotic arms while its movement is rude along with the noisy sound. Stepper motor is famous for its precise controllability of rotation angles. Unlike servo motor, it can go around 360 degrees with its fractional increments. Stepper motor is good for steady, precise and quite movement such as the mechanism of 3d printing machines.

For the self-exploration about motors, I choose DC motor to make a hand blender.

The goal of the project: Using the potentiometer to control the speed of DC motor and make a mini blender.


1) Arduino

2) D.C. motor

3) NPN transistor TIP120 X1

4) Rectifier Diode X1 (I used 1N4001)

5) 1* 220 ohms resistor

6) 10K Potentiometer

7) Breadboard

8) Jumper wires

How it works: 

Using the potentiometer( the adjustable resistor ) to change the speed of DC motor, as the value of potentiometer goes up, the motor will rotate faster.  Circuit sketch: connect 1N4001 to pin3 and potentiometer to a0.


Very simple code, remember to transfer the value of potentiometer from 0-1023 to 0-255 to fit the capability of the output pin. you can use map function but I just roughly divided it by 4.

Problem: the most difficult part is not about the circuit, but the blender itself. Because the rotation speed can be really fast, my handmade blender was thrown out by the motor after 3 sec and I have to tight the blender with iron wire to the motor for several times.



Week 8 Using Knob Control Stepper Motor

1. The difference between DC motor, Stepper motor, and Servo.

DC motor have a high speed of rotation, and once it is power charged, it will spin until the power is removed. Stepper motor has much precise control which have multiple magnetics installed inside to push the torque spin at  a specific direction and speed. Servo is like a DC motor with potentiometer installed inside for a speed control. It can rotate either clockwise or anti-clockwise.

2. Make a circuit using any of the new things you learned today- H bridges/ controlling high current loads OR work with a motor you haven’t worked with before OR Try making a circuit using multiple motors. Document it on the blog per the usual format.


Using potentiometer to control speed of stepper motor


The value of potentiometer determines the speed of stepper motor.

  • How it works: the value from potentiometer serves as a analog input and determines the speed of stepper motor as a analog output.


The range of speed does not spread too much making it almost like two stages: stop and rotate. Also, the maximum speed of stepper motor was not high enough for a more conspicuous presentation.


  1. Arduino UNO R3 x 1
  2. Breadboard x 1
  3. Stepper motor x 1
  4. Stepper motor driver x 1
  5. Potentiometer x 1
  6. Wires

Connection Diagram:



week 8 motors

DC motors

DC motor is a continuous rotation motors, it only has two wires. This motor will work when you give it the power no matter what, and it will stop when you remove the power.

Servo Motors

The position of servo motors can be controlled more precisely than those of standard DC motors, and they usually have three wires (power, ground & control).Power to servo motors is constantly applied, with the servo control circuit regulating the draw to drive the motor. Servo motors are designed for more specific tasks where position needs to be defined accurately.

Stepper Motors

A stepper motor is essentially a servo motor that uses a different method of motorisation. Where a servo motor uses a continuous rotation DC motor and integrated controller circuit, stepper motors utilise multiple toothed electromagnets arranged around a central gear to define position.


design goal:

I use the potentiometer to control the servo motor rotates, when you give more power to the servo motor, the motor with move faster. I think it can use in the children electronic toy, as a parent, they can control the toy move or stop.

-Arduino + USB Cable
-Servo Motor





Week 08 Assignment


DC motor: Continuous rotation, very fast.

Servo motor: Turn 90° in either direction for a total of 180° movement. Have a position sensor inside for feedback.

Stepper motor: Precise positional control, move 1 step each time. No position sensor for feedback.




A DC Motor fan which works for a while and rest for a while. I think it can be used for cooling down the computer when it operates tasks which generate lots of heat.



A water pump made with a 6V DC Motor. I made a installation out of it. One side of the pump is up-taking water and the other is dropping the water in the same container. I used 4 AA battery as external power for the water pump and a potentiometer to adjust the speed of the water pump.

Week 8 – Stepper – Xiaoyu

Part 1

DC Motor:
Two wire (power & ground), continuous rotation motors
Using pulse width modulation (PWM) to control the speed of DC

Stepper Motor:
Use multiple electromagnets around gear to divide a full rotation into equal steps.
Requires extra controller.

Servo Motor: Generally assembled by a DC motor, a gearing set, a control circuit and a position-sensor (so position can be controller precisely).
Usually three wires (power, ground, signal)
Using pulse width modulation (PWM) to control the signals of servomotors.


Part 2

Use knob to control the speed of a stepper motor.

Core components
1* potentiometer
1* step motor
Wires & jumpwires
Arduino board

How it works
Use knob to control the speed of a stepper motor.

Can’t see the movement of stepper, though I can feel it changes.



Motors (Week 8)

Making things Move: Physical Computing Week 8

  • The three most common motors for Arduino include;
    • DC motors: Is the simplest of the motors. There are two terminals. When you apply direct current to one terminal and ground the to the other, the motor starts spinning.
      • DC motors are usually very fast, often spinning at several thousand revolutions per minute (RPM).
        • Will keep spinning until power is taken away
      • Depending on electricity the faster or slower it goes.
      • Gearhead motors: subset of DC motors that replaces speed for power.
      • Examples include computer cooling fans and toy wheels
      • Widely used in robotics because of their small size and high energy output.
    • Servo motors:Servo motors are small in size but very energy efficient and precise.
      • Consist of four components:
        • DC motor
        • A gearing set
        • A control circuit
        • A position-sensor (usually a potentiometer)
      • A servo motor can usually only turn 90° in either direction for a total of 180° movement.
      • Servo motor are controlled by sending electrical pulse width modulation (PWM).
    • Stepper motors:
      • The motor’s position can then be commanded to move and hold at one of these steps without any position sensor for feedback (an open-loop controller), as long as the motor is carefully sized to the application in respect to torque and speed.
      • Precise positional control, move 1 step each time
      • Slower than DC
      • Don’t need to get feedback during the rotation
  • To change direction change polarity.
  • How do they work: they work on the principle of electromagnetic induction. When you put an electric current through a wire- it generates magnetic field around the wire.
  • The blue and red portions are the magnet shields.

Objective: The goal of this project is to better understand how a servo motor can be controlled with a potentiometer through an Arduino. Goal of the project and/or desired interaction

-Arduino + USB Cable
-3x M-F jumper cables
-3x M-M jumper cables
-Servo Motor

Servo Motor:
-Connect power wire (red) to the 5V pin on the Arduino
-Connect ground wire (brown) ground pin on the bread board.
-Connect signal pin (orange) to pin 9 on the Arduino.
-Plug into breadboard with room for placing cables.
-Outer pins are connected to power (+5V) and ground via directly next to the (+5V) and ground on the bread board.
-Middle pin is connected to analog input 0 on the Arduino.
-Library Servo.h
-Code Servo Motor Code

Download the library, upload the code, and now you have control over the servo motor.

Thanks to this great Instructables I now better understand the motor components.

Controlling DC Motors – on/off, speed, and direction (week 8)

  • Goal of this project : I made a circuit that is controlling DC motor in 3 different ways – on/off, adjusting speed, and changing direction. In order to turn the motor on and off, I used button switch, and to change direction of the motor I used H-bridge and button. And by the “analog” value read from potentiometer, the speed is also adjustable.
  • Assembly description : To change direction of the DC motor I used H-bridge. The one I used is SN754410 and I found data sheet of that model through internet search.

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Servo Motors (Week 8)_Alyssa

What are the different motors?

DC motors rotate continuously. Their speed is controlled by PWM, which actually turns the motor on and off so rapidly it looks like a smooth movement. DC motors rotate until power is detached.

Servo motors are good for exact tasks because they can be more precisely controlled than standard DC motors. Power to the motor is constant but regulated by the servo control circuit. PWM  “unlike DC  motors it’s the duration of the positive pulse that determines the position,   rather than speed, of the servo shaft.” (source:

Stepper motors use electromagnets around a central gear to determine the position. Each electromagnet must be individually powered to make the motor shaft turn.

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