Arduino Controlled Air Conditioner

Now that summer is coming, it’s time to break out the Air Conditioners! There are some old AC units out there that still work just fine, but nowadays we are used to everything being remotely controlled and automatic. [Phil] had an old window-mounted AC unit that still worked but was installed in a not-so-convenient place. To access the AC’s controls, one would have to climb over a large desk. This is a perfect opportunity to use the plethora of widely available hobby electronics to make an automatic AC controller retrofit.

First things first, there needs to be a way to turn the current control knob on the AC. [Phil] modeled up a 3D bracket to hold an RC car servo to the AC control panel. Attached to the servo horn is a slotted cylinder sized appropriately to fit the shape of the control knob. An Arduino measures the temperature of the room via a DS18B20 temperature sensor which then has the servo turn the control knob to the appropriate position, on or off. The Arduino sends temperature data back to a PC via MegunoLink Pro which graphs past data and also displays current temperature data. Using MegunoLink Pro, the min/max temperature points can also be set without uploading a new sketch to the Arduino.

Arduino Controlled AC

From the temp vs time graph, it looks like the room temperature stays a consistent 23 +/- 1 °C. [Phil] did us summer-swelterers a favor and made all his design files available. This is a great idea but wonder if leaving the air conditioner unit switch in the ‘on’ position and turning the unit on/off via a relay connected to the 120vac line would work just as well.

Monitoring Power With A 555

[Diederich] is running a Raspberry Pi loaded up with Pimatic, a great home automation server that does just about anything you can throw at it. One thing it doesn’t do is monitor electricity and gas directly from the meter – you’re going to need hardware for that. [Diederich] stepped up to the plate and built that hardware using just a 555 timer. The total cost of adding this to his Pimatic setup was less than a dollar.

The 555 can be used as a timer, a trigger, and a bunch of them can be cobbled together into a CPU. [Diederich] isn’t using some fancy logic here; he’s just using the 555 as a Schmitt trigger with a phototransistor and his electricity meter. The output of the 555 is connected to the GPIO of the Raspberry Pi, and a Python script ties into Pimatic.

It’s a neat solution that only costs a dollar, and using the 555 has a few advantages: the 555 makes it possible to use long and thin wires back to the Pi, which means [Diederich]’s Pi doesn’t have to be located right next to his meter.

Model House Models House, Vice-Versa

[Eric Tsai] is on a home-automation rampage. Not content with the usual smartphone-based GUIs, [Eric] built a cardboard model house that models his house. Open the garage door, and the model house’s garage door opens. Open the real front door, and a tiny servo motor opens the cardboard front door.

The model house also comes with a power meter that represents his current power usage, which is certainly useful for figuring out if something electronic has gone grossly wrong. You should watch the video (found after the break) all the way through, here’s the spot where he turns on an electric leaf blower. Despite a little big of lag that’s pretty cool!

But the system doesn’t stop there. Since he can control the garage door and some lights remotely via WiFi, the next logical step is to add a couple of buttons so that the model house can control the real house.

We’ve covered [Eric]’s home before. He set up simple, Arduino-based sensor packages all around his house, connected them together through the pub/sub framework MQTT and added in the open-source OpenHAB software interface. The door sensors connect to a hacked Wink hub. From whether or not his dog is barking to whether his laundry is done, [Eric]’s system knows it all.

Continue reading “Model House Models House, Vice-Versa”

RoomMote, a DIY Remote for Your Room Project

[Rohit] wrote in to tell us about a project he has created. Like most projects, his solves a problem. Sometimes while sleeping, a mosquito will infiltrate his room. He has a mosquito repellent machine but there are 2 problems, he has to get up to turn it on/off and it smells bad when in use. [Rohit] only needed a remote-controlled mosquito repelling machine but decided to make a 6 channel system he calls the RoomMote.

From the beginning, the plan was to use an old Sony TV remote to do the transmitting. The receiver unit was completely made from scratch. [Rohit] designed his own circuit around a surface mount MSP430 chip and made a really nice looking PCB to fit inside a project box he had kicking around. The MSP430 chip was programmed to turn relays on and off based on the signals received from the Sony remote.  These relays are inside an electrical box and control AC outlets. Just plug in your light, radio or mosquito repellent into the appropriate outlet for wireless control. Code for the MSP430 is made available on [Rohit’s] project page for anyone wanting to make something similar.

In addition to the relays, there is an RGB LED strip attached to the custom circuit board. By using more of the Sony remote’s buttons, the LED strip can output 6 pre-programmed colors, some mood lighting for the mosquitoes!

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Ultimate Remote is Ultimate

[Joedefa] had a Griffin Beacon Universal Remote that was collecting dust, and decided that it needed to stop collecting dust. He had a growing number of wireless devices in his house and found himself in need of a remote to control them all. The Griffin Beacon fit the bill, but most of his lights and outlets were RF controlled. So he did what hackers do best… broke out the screw driver and soldering iron and rewired it!

[Joedefa] is using an Attiny85 as the brains between an infrared LED and a RF transmit module (if anyone can identify the source of this module, please let everyone know in the comments).  A pair of red and green LEDs lets him know if the remote has received commands successfully.

It’s always nice to see a discontinued product made useful once more with a little ingenuity and an Arduino some hacking skill. Hat’s off to [Joedefa] for a righteous hack!

Ridiculously Complicated Home Automation Made Simple

[Eric T] wrote up his insanely-comprehensive home automation setup. What started out as a method to notify him when his dog barked grew into a whole-house, Arduino-powered sensor extravaganza. We’ve previously looked at two different steps from this mammoth article. One automated his dog, the other focused on the Wink hub to bridge with commercial hardware like smart lightbulbs. Now let’s look at the project as a whole.

The basic backbone of the project is actually quite straightforward. He made a radio gateway base station out of an Arduino, a RFM69 radio unit, and an Ethernet shield that connects to a Raspberry Pi to serve up a GUI interface. The open-source home automation project OpenHAB makes it all available through browser or smartphone.

Next, he made additional sensor nodes from Arduino and RMF69 radios. These sensor nodes can all be separate from each other, which has enabled [Eric] to expand his system incrementally over time.

Modules of particular interest are the Uber Sensor and the Washer-Dryer module. For the Uber Sensor, [Eric] basically threw every sensor he could at an Arduino; it sends noise levels, light levels, motion, temperature, humidity, and presence of smoke, flame, or flammable gas. Some of these conditions trigger e-mail alerts, while others are simply stored for future perusal.

On the simpler end of the spectrum, he uses a noise-level detector to detect the end of a laundry cycle and then trigger a notification. The clever bit is that the message is automatically cleared when an attached motion detector triggers, presumably because someone’s gone to the basement to empty the dryer. Very neat.

16All of this is basically made practical and affordable by the presence of simple Arduino libraries and cheap hardware modules purchasable over Ebay. If you’re at all interested in a DIY home automation project, this offering is worth a look for inspiration and a great overview.

Tracking Power Usage With A Raspi

With tiny, Internet-connected computers everywhere these days, home automation is finally hitting it big. [Jelora] was looking for a few more home automation projects and realized his electric meter had a pair of ‘digital information outputs’. With a Raspberry Pi and a few bits of wire, he figured out how to read this digital output and put a log of his electricity consumption up on the web.

The digital output on [Jelora]’s meter is a bit odd; it’s 1200 bps, 7 bits per character, parity, with one stop bit. It’s also a 50 kHz AC signal for a binary ‘0’ and nothing for a binary ‘1’. To read this signal, [Jelora] is using a diode to throw out half the signal, a 6N138 optoisolator so the Pi isn’t connected directly to the meter, and a small cap to smooth out the signal. Simple, and it works.

This cleaned up signal is then connected to serial to USB chip and a PHP script scrapes the data every minute. The data received from the meter is stored in a data base along with a few other bits of information: if the meter is being charged peak or off-peak rates, and the price per kWh. All this is saved on an IDE hard drive (more reliable than the SD card, surprisingly), and a ‘electricity cost per day’ is plotted on a nifty graph and served up by the Raspberry Pi.