Hello all!

This is a quick guide on how to use an Arduino© to control whether a cooling fan and a heater is turned on depending on the detected temperature from a TC74 Arduino sensor.

This is for a final project for an Electronics class I am currently taking, though I came into this project with pragmatism in mind, because of the hot summers and cold winters (ok, 60 degrees indoors is cold for me, but that's probably because I'm Californian).

Working on this project should give good hands-on practice in working with the Arduino, soldering, and general circuitry, as well as coding for the Arduino and workin gon the logic needed for the coding.

Why adjust the fan and/or heater if the Arduino can do it for you?  (Ok, this is probably easy enough to do, but making it technologized (not a word) is just much cooler (no pun intended).

Also, there is a video at the end of this Instructables if you'd like everything described verbally.

Best of luck!

Step 1


You'll need...
* An Arduino© microcontroller, made by Arduino (with USB connector)
* A Fan (This project used the following one: http://www.amazon.com/Lasko-Personal-Inches-White-2002W/dp/B000QR6VXW/ref=sr_1_1?s=home-garden&ie=UTF8&qid=1333608671&sr=1-1)
* A Heater (This project used the following heater: http://www.amazon.com/Pelonis-Heater-fan-Heat-Settings/dp/B000PAQHLG/ref=sr_1_32?s=home-garden&ie=UTF8&qid=1333608582&sr=1-32 )
* TC74 Temperature Sensor
* Wires
* Relays,  Relays here were solid-state relays, with a smaller current (2 Amp) Crydom D2W202F for the Fan and a large current 25 Amps NTE Electronics Relay for the heater, which requires up to 1500W.
* A breadboard
* Heat-shrink tubes
* Two wall outlets for use
* Two optional (10,000 ohm) potentiometers
* A computer with Arduino software
* Code

* Soldering iron
* Wire cutter and wire stripper
* Crimper
* Screwdriver or alternative
* Heat gun (optional)

Safety warning:  Live wires may be dangerous, especially when either the fan or heater is plugged in.  Please either use the heat-shrink tubes to cover these up or better yet, box the whole contraption.

Step 1: Starting Off

Unpack the fan and heater.

We'll start with the fan, as this poses less fire hazard (the heater pulls a lot of current).

We wish to make a closed current loop through the solid-state relay, 120 V AC and the fan motor itself.  Basically, we want to be able to put in zero volts somewhere such that the fan is told to turn off and when we give in 5 V somewhere, then the fan turns on.

After this is done, we can test the fan to make sure that it's talking to the Arduino.

Use any digital output pin you want, but I chose pin 13.

For an easy pin 13 on/off program...

Go to Files -> Basics  -> Examples -> Blink when your Arduino software window is open.  (This is conveniently pointed at pin 13.)  Don't forget to plug in the fan into a 120 V AC plug or the equivalent. 

Hardware wise, follow these steps.

1.  Unpackage the fan.
2.  Make a cut across half of the wire to expose one end.
3.  Solder the two ends of this wire to the two ends on the solid-state relay's AC side.
4.  Heat-shrink tubing should cover this connection.
5.  Hook up the two other leads (+ and - 3 to 28 V DC) to the Arduino at pin 13 and ground, respectively.
6.  Upload code and watch your fan work!
<p>Can I replace the Fan by Honeywell TurboForce Fan ?</p>
<p>I see no issue with such a change!</p>
It says your video is private. Any chances of getting to review it somehow? Have you done anything more to this project since posting it on Instructables? Is there a particular reason why you chose the TC74 Temperature Sensor over the DS18B20 or TMP35/TMP36?
<p>Hello! I made the video public now. Not sure why or how it became private, as it definitely was not so earlier in this Instructables' lifetime. (Apologies for the poor quality of the video! I think I filmed it with a cellphone.)</p><p>The department machine shop suggested using the TC74 temperature sensor. However, I'm sure other alternatives (like the ones you mentioned) should fit in nicely.</p>
I assume adding a serial display to readout the &quot;setpoint&quot; temperature would not be too difficult to implement. <br> <br>Any ideas for doing that?
Adding a serial display LED to show the any of the values in the thermostat would fit nicely in with the implementation. (It wasn't done here because of time constraints, but it probably wouldn't take too much longer.)

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