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21 Arduino Modules You Can Buy For Less Than $2


The Arduino community has created a wide variety of modules and shields that can enhance your projects. Here’s the ultimate collection of 21 Arduino Modules that you can get for less than $2 on eBay. Let’s start!

1. HC-SR04 Ultrasonic Module

The HC-SR04 ultrasonic sensor uses sonar to determine distance to an object like bats do. It offers excellent non-contact range detection with high accuracy and stable readings in an easy-to-use package. Here’s a complete guide on how to use this module. View this module on eBay ->1

2. IR Infrared Obstacle Avoidance Sensor Module

This module is very easy to use. When the module detects an obstacle in front of the signal , the green indicator light on the board level , while low-level continuous output signal OUT port , the module detects the distance 2 ~ 30cm, detection angle 35 °. View this module on eBay ->2

3. Soil Hygrometer Detection Module Soil Moisture Sensor

This is a simple water sensor can be used to detect soil moisture when the soil moisture deficit module outputsa high level, and vice versa output low. Use this sensor produced an automatic plant waterer device, so that the plants in your garden without people to manage. View this module on eBay ->3

4. Microphone Sensor

For sound detection Module has two outputs. AO, analog output, real-time output voltage signal of the microphone. DO, when the sound intensity reaches a certain threshold, the output high and low signal. The threshold-sensitivity can be adjusted via potentiometer on the sensor. View this module on eBay ->4

5. Digital Barometric Pressure Sensor Board

You can use this module to measure the absolute pressure of the environment. By converting the pressure measures into altitude, you have a reliable sensor for determining the height of your robot or projectile for example. View this module on eBay ->5

6. Photoresistor Sensor Module Light Detection Light

You can use this module for light detection with an Arduino. View this module on eBay ->6

7. Digital Thermal Sensor Module Temperature Sensor Module

The thermal sensor module is very sensitive to the ambient temperature, generally used to detect the ambient temperature. Through the adjustment of the potentiometer, you can change the temperature detection threshold. View this module on eBay ->7

8. Rotary Encoder Module Brick Sensor Development Board

When you rotate the rotary encoder it counts in the positive direction and the reverse direction. Rotation counts are not limited. With the buttons on the rotary encoder, you can reset to its initial state and start counting from 0. View this module on eBay ->8

9. MQ-2 MQ2 Gas Sensor Module Smoke Methane Butane Detection

This sensor module utilizes an MQ-2 as the sensitive component and has a protection resistor and an adjustable resistor on board. The MQ-2 gas sensor is sensitive to LPG, i-butane, propane, methane, alcohol, Hydrogen and smoke. It could be used in gas leakage detecting equipments in family and industry. The resistance of the sensitive component changes as the concentration of the target gas changes. View this module on eBay ->9

10. SW-420 Motion Sensor Module Vibration Switch Alarm

This module can be used to trigger the effect of various vibration, theft alarm, intelligent car, earthquake alarm, motorcycle alarm, etc. View this module on eBay ->10

11. Humidity and Rain Detection Sensor Module

This is a rain sensor. It’s used for all kinds of weather monitoring. View this module on eBay ->11

12. Passive Buzzer Module

A simple sound making module. You set high or low to drive this module by changing the frequency you’ll hear a different sound. View this module on eBay ->12

13. Speed Sensor Module

Tachometer is a simple module that allow you to test the speed of the motor. Widely used for motor speed detection, Pulse count, position limit, and so on. View this module on eBay ->14

14. IR Infrared Flame Detection Sensor Module

Flame Detection Sensor Module is sensitive to the flame, but also can detect ordinary light. Usually used as a flame alarm. Detects a flame or a light source of a wavelength in the range of 760nm-1100 nm. Detection point of about 60 degrees, particularly sensitive to the flame spectrum. View this module on eBay ->13

15. 5V 2-Channel Relay Module

This is a 2 Channel 5V Relay Module, it allows you to control various appliances, and other equipment with large current. It can be controlled directly by any microcontroller. View this module on eBay ->15

16. Breadboard Power Supply Module 3.3V 5V

A simple module to power your breadboard. It supplies both 3.3V and 5V. View this module on eBay ->16

17. HC-SR501 Pyroelectric Infrared Sensor Module

A PIR sensor is a little module that allows you to detect movement from humans or pets, it’s easy to integrate with your microcontroller. You can learn here how to use this module with an Arduino. View this module on eBay ->17

18. Accelerometer Module

This module measures the acceleration. It’s commonly used in portable devices and video game controllers to detect movement and actions from the player. View this module on eBay ->18

19. DHT11 Temperature and Humidity Sensor

It’s a great little sensor to measure temperature and humidity from your room or outside. It integrates seamlessly with the Arduino. You can learn here how to use this module in your project. View this module on eBay ->dht-11

20 or 21. RF 433MHz Transmitter/Receiver

If you need data sent from one microcontroller to another the 433MHz link modules are a cheap way to do that (all data is sent via Radio Frequency). View this module on eBay ->

433 - Copy

[Extra] ESP8266 WiFi Module ($4)

This module costs a little bit more than $2, but it’s totally worth it. You can get one ESP8266 WiFi Module for about $4 on eBay. This module can send emails, host a web server, control LEDs, etc. If you are curious about this module check out my eBook Home Automation Using ESP8266.

Click the image above, to see on ebay.

Wrapping Up

Do you have all these modules? Are you thinking about ordering one of theses modules listed above?

Leave a comment down below!

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Thanks for reading,


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