Great your beginners to learn arduino and for hot room that have an old manual a/c. This is a project to try!
Step 1: Prototyping the Test Circuit
This circuit is to test if the thermostat is working or not. The lcd should display a hello,world! sketch, the the current temperature of the room, and below is the ideal temperature or settemp. If the current temperature is off by a little you may need to adjust the code which calculates the 10 bit number read from A0 into a temperature reading in degrees Fahrenheit. If you need Celsius will will also need to change the line of code the calculates the temperature. If you wan to control an a/c, you can remove the led and replace it with an N-Channel MOSFET ( Metal Oxide Semi-conductor Field Effect Transistor). Then TO USE A PROTECTION DIODE! I will go over this as well. In the next step.
12 volt power supply
7805 5 volt voltage regulator
arduino uno or other arduino dev board
3x 10k ohm resistors
10k potentiometer ( or a 1k ohm and a 220 ohm resistor) (or the 3rd pin can go to ground)
16x2 Hitachi driven hdd44780 LCD
10k thermistor a.k.a. (10k ohm NTC, (Negative Thermal Coefficient)
2x tactile button switches ( or any other button switch)
usb b type connector to program arduino
For use with an a/c:
120VAC 20-40A relay
1N4007 - 1N4004 rectifier diode
perfboard / PCB
And tool that everyone should have
Let's get started!