Arduino,  Hardware

Making my air conditioner smarter – Part 3

<< Continuation of Part 2

Time to end this project and start thinking about the next one 😄.

In the previous post, we ported our code to control the air conditioner to our small ESP-01. Now we need to install everything inside the air conditioner and make it work.

First, we need the small board to power our ESP-01 and connect it to our IR LED. We do not need much: a small voltage regulator (in our case an LM317), a couple of resistors to configure it to 3.3v, a 2×4 female pin connector and a couple of resistors to put the ESP-01 into normal boot mode. The small schematic I came up with is below:

Everything looks ok, let’s assemble it. The easiest and fastest is to use a perfboard, but in the future we try etching them with acid 😊

What to do when you don’t have the exact resistor you need? You stack them in series 😊

Next step. The board needs protection, to isolate it from the cruel outside world. In our previous project, we used a common junction box. This time, the space we have to work with is tighter, and as I bought a cheap 3D printer some time ago, I thought it would be a good use here.

After making some measurements, our board measures 4.6 x 2.8 cm, with a height of around 2cm. With these measurements, I started drawing a small simple box. The program I used is FreeCAD, which is totally free. We don’t need a fancy box here, just a thing that isolates our board and has some small holes for ventilation is just fine 😜

Simple but effective

After a couple of hours, the printing process is done! The material is ABS, so the adhesion wasn’t too great, coming up a bit uneven, but it will do its job just fine. We are not going to toss it away just because it is not pretty. Next printings will be better😊

The IR LED will be connected using a couple of wires with enough length to pass it to the place it has to go.

And the last component: the power supply. As I have a pretty decent collection of old phone chargers picking up dust, we will use one of them.

Old phone chargers: the best thing you can have for DIY projects 😊

Time to plug everything in. We will need live and neutral from an uninterrupted source (which does not turn off with the air conditioner), so the board keeps listening for commands.

Neutral is easy: There is one in the side connectors that go to the outside unit, in blue.

The live wire however is not so easy we do not seem to have it in any place at sight, so we need to keep disassembling. I found one in the primary winding of the transformer of the air conditioner board. There should be a nice connector for the main power, but I just couldn’t find it, so I used what I had. I soldered a wire to the cable terminal and put back the silicone isolator.

The IR LED is routed to its permanent destination too, and secured with a bit of hotglue.

Marvelous hotglue. The cause of and solution of a lot of DIY problems 😊

And… That’s pretty much it! To control the air, we will have to add the ESP-01 to the IoT server (in my case, openHAB) and configure a component for every function (temperature, speed…).

From here on we can do tons of things… Automating the ON/OFF depending on temperature, time, only if we are home… But for now, I’ll use the manual controls 😊

You can find below the 3D model for the box, and the schematic, which you can also find on my github.

See you in the next post!

Epilogue >>

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