# Temperature and Humidity Indicator by Arduino

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This Instruction will show how to make a box which can indicate temperature and humidity with Arduino

You can put this box on table for measuring temperature and humidity in your room

By high quality of MDF box by laser cut, every thing is compacted firmly and good looking, so it is can be personal using or as a gift for your friends.

The important part of this instruction is calibration process which will guide how to make needles (control by servo motor) match with indicator ruler

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## Step 1: Summarize About Part List

This project will need:

1. Arduino UNO https://amzn.to/2P58O7s

2. Sensor temperature and humidity DHT-22 https://amzn.to/2BvBtfC

3. Servo motors SG90 https://amzn.to/2pCcJPW

4. MDF box http://bit.ly/2MxWvjH

Note: the MDF box link is desgin file (Corel Draw). You can download to cut it by laser cnc machine.

## Step 2: Circuit

Make a circuit as image, it's quiet simple for Arduino fan

## Step 3: Arduino Code

Main purpose of code is reading value from sensor, then show result into servo motor

Because servo motor angle not match with indicator ruler, so need calibration process to make reading from sensor can show exactly into indicator ruler

## Step 4: Calibration Process

For case of temperature:

1. Find servo angle for point 0 and 50 degree C

2. Input those angle into excel file to find factor a and b (in function f(x)=ax+b)

3. Input factor a and b into Arduino code to find servo angle match with sensor result.

Do the same procedure for humidity case.

## Step 5: Test Indicator

Using serial monitor screen to test if value in serial monitor screen is same with indicator or not

## Step 6: Install All Things Into the Box

Firstly, install background indicator, then arduino UNO, servo motor and sensor.

Then install needles, upload the code

Final is connect power and back cover.

Let's enjoy it!

## Step 7: Summarize All Step in Video

See the video for all process of making it.

If you have any comment, please leave here. Your comment is my next motivation for future project. Thanks

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## 3 Discussions

Hi, the needles made from MDF wood, then i cut it by laser cnc machine