Like so many other home appliances, it’s likely that even your air conditioner has a serial interface buried inside it. If you’re wondering why, it’s because virtually every microcontroller on the planet has a UART built in, and it’s highly useful for debugging during the development process, so it makes sense to use it. Thus, it was only a matter of time before we saw a hacked airconditioner controlled by a Raspberry Pi.
[Hadley] was growing frustrated with the IR remote for his Mitsubishi air conditioner; it can issue commands, but it’s a one way interface – there’s no feedback on current status or whether commands are received, other then the occasional beep or two. Deciding there had to be a better way, [Hadley] grabbed a Saleae Logic Analyser and started probing around, determining that the unit spoke 5 V TTL at 2400 bps with even parity. The next step was to start talking back.
Continue reading “Air Conditioner Speaks Serial, Just Like Everything Else”
Most of North America has been locked in a record-setting heat wave for the last two weeks, and cheap window AC units are flying out of the local big-box stores. Not all of these discount units undergo rigorous QC before sailing across the Pacific, though, and a few wonky thermostats are sure to get through. But with a little sweat-equity you can fix it with this Arduino thermostat and temperature display.
We’ll stipulate that an Arduino may be overkill for this application and that microcontrollers don’t belong in every project. But if it’s what you’ve got on hand, and you’re sick of waking up in a pool of sweat, then it’s a perfectly acceptable solution. It looks like [Engineering Nonsense] got lucky and had a unit with a low-current power switch, allowing him to use a small relay to control the AC. The control algorithm is simple enough – accept a setpoint from an encoder, read the temperature sensor, and turn the AC on or off accordingly. Setpoint and current temperature are displayed on an OLED screen. One improvement we’d suggest is adding a three-minute delay between power cycles like the faceplate of the AC states.
This project bears some resemblance to this Arduino-controlled AC, but it seems more hackish to us. And that’s a good thing – hackers have to keep cool somehow.
Continue reading “Arduino Replaces Bad AC Thermostat, Hacker Stays Cool”
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.
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.
Working out in the shop is usually super fun but if it’s summertime, watch out, it can get hot! We’ve all been there and we’ve all wished we could do something about it. Well, woodworker and general DIYer [April] has stepped up to the plate and built a portable low-buck AC unit to cool her shop down to an acceptable temperature.
The unit is very simple and starts off with an old thrift store cooler. A hole is cut in the back of the cooler to make room for a fan that is directed to blow air inside the cooler and across blocks of ice. The air cools down as it passes over the ice and leaves out the top of the cooler through five 90-degree PVC elbows. After all the inlets and outlets were caulked, the entire unit was given a monochromatic black paint job.
[April] says you can feel the cool air blowing from about 5 feet away from the unit. She has measured the output air temperature to be 58-62ºF. If using loose ice cubes, the unit will work for 2-3 hours. Freezing milk jugs full of water gets about 5 hours of use.
It’s practically May, and that means the sweltering heat of summer is nearly upon us. Soon you’ll be sitting outside somewhere, perhaps by a lake, or fishing from a canoe, or atop a blanket spread out on the grass at a music festival, all the while wishing you had built yourself a solar-powered personal air conditioner.
[Nords] created his from a large insulated beverage vessel. The imbibing spout offers a pre-made path to the depths of said vessel and the heart of this build, the ice water refrigerant. [Nords] fashioned a coil out of copper tubing to use as a heat exchanger and strapped it to the fan that performed best in a noise-benefit analysis.
A small USB-powered submersible pump moves the ice water up through the copper tubing. Both the pump and the fan run off of a 5V solar panel and are connected with a USB Y cable, eliminating the need for soldering. Even if you spend the summer inside, you could still find yourself uncomfortably warm. Provided you have access to ice, you could make this really cool desktop air conditioner.
[via Embedded Lab]
The people over at Gray Wolf Survival have this amazing little air conditioning project that is a perfect addition to any household that doesn’t have flowing air wafting through. It was created by [Figjam] for a trip to Burning Man, where all kinds of crazy ideas are bred in the hot dry heat of The Playa sun.
The design uses no ice, which is the cooling agent typical found in other DIY air conditioners. Those generally cut holes in the top of a cooler, put a fan on top to blow the air down across the ice. This is similar, but acts more like an evaporative cooler (not really a traditional air conditioner but it does the job).
It uses a LOT less energy than an air conditioner unit so there won’t be a need to increase the power capabilities of a simple system to work it, and it can reduce the temperature by up to 30 degrees as well as alleviate the dryness associated with living through a Burn. It runs off 12V DC so it can either use the solar panel or connect to a battery. It has a 12V power plug for this, and draws as little power as absolutely possible. Plus, it has the ability to easily connect to a larger water source so it won’t have to be continually refilled. These considerations make it very portable and perhaps backpackable as well.
[Figjam] took a 5 gallon bucket, wrapped the inside with two layers of swamp cooler matting, made a loop of hose above it connected to a submersible pump and ran a fan out the top with piping. Connecting it to a shelter is done with a vent hose.
Summer is here and with summer comes hot days. You probably know that us humans get uncomfortable if the temperature rises too much. Sure, we could turn on the loud and inefficient window AC unit and try to stay mildly comfortable while the electric company pick-pockets pennies from our change purse, but what is the fun in that? [Fran] had a better idea.
He noticed that his basement was always in the upper 50°F range regardless of how hot it was outside. He wanted the cool basement air to reside upstairs in the living area. After thinking long and hard about it he decided that a box fan and two long, skinny cardboard boxes assembled together would be enough to move the required amount of air. Both the fan and boxes were kicking around the house so was no cost and no risk to try this out. Continue reading “Zero-Dollar AC System Looks Funny But Works Well”