Fight Mold and Mildew with an IoT Bathroom Fan

Delicious sheets of wallboard coated with yummy latex paints, all kept warm and moist by a daily deluge of showers and habitually forgetting to turn on the bathroom exhaust fan. You want mildew? Because that’s how you get mildew.

Fed up with the fuzzy little black spots on the ceiling, [Innovative Tom] decided to make bathroom ventilation a bit easier with this humidity-sensing IoT control for his bathroom exhaust fan. Truthfully, his build accomplishes little more than a $15 timer switch for the fan would, with one critical difference — it turns the fan on automatically when the DHT11 sensor tells the WeMos board that the relative humidity has gone over 60%. A relay shield kicks the fan on until the humidity falls below a set point. A Blynk app lets him monitor conditions in the bathroom and override the automatic fan, which is handy for when you need it for white noise generation more than exhaust. The best part of the project is the ample documentation and complete BOM in the description of the video below, making this an excellent beginner’s project.

No bathroom fan? Not a problem — this standalone humidity-sensing fan can help. Or perhaps you have other bathroom ventilation needs that this methane-sensing fan could help with?

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The Internet of Cigars

We know, we know. They are bad for you. You shouldn’t start, but some people do love a cigar. And a fine cigar is pretty particular about drying out. That’s why tobacconists and cigar aficionados store their smokes in a humidor. This is anything from a small box to a large closet that maintains a constant humidity. Of course, who could want such a thing these days without having it connected to the Internet?

This fine-looking humidor uses a Raspberry Pi. When the humidity is low, an ultrasonic humidifier adds moisture to the air. If it gets too high, a fan circulates the air until it balances out. Who knew cigar smoking could be so high-tech? The humidity sensor is an AM2302. There’s also a smart USB hub that can accept commands to turn the fan and humidifier on and off.

The wooden cabinet was an existing humidor, apparently. [Atticakes] says he spent about $100 total but that a commercial equivalent would have been at least $250. You can find his source code on GitHub.

If you are vehemently anti-cigar, we should point out that there are other uses for such a device. Because of Denver’s low humidity, for example, the Colorado Rockies baseball team store game balls in a large humidor.

For the record, a zip lock bag can do in a pinch. Without something, the experts say the cigar starts to change negatively in two or three days.

First networkable humidor we’ve seen? Hardly. If you need something to light that stogie, we suggest a laser.

Comfort Thermometer With Impressive LED Display

A frequent early project for someone learning to use a microcontroller such as an Arduino board involves hooking up a temperature sensor and an LCD display to make a digital thermometer. Not many components are involved, but it provides a handy practical introduction to interfacing peripherals. Once you’ve passed that step in your tech education, do you ever return to thermometers? Probably not, after all what can you add to a thermometer but a sensor and a display?

Perhaps if you have asked yourself that question you might be interested in [Richard Stevens]’s thermometer project, as he refers to it, a Comfort Thermometer Display. It takes the form of an Ikea Ribba frame inset with 517 LEDs arranged as a central set of seven segment displays, a ring of bar graphs, and an outer ring of RGB LEDs. Behind the scenes is a mass of cabling, and four shaped pieces of stripboard to fit the area around the LEDs. The display cycles through readings for temperature, heat index, and humidity.

Powering it all are a brace of microcontrollers: an ATMega328 for the 7-segments and a range of PICs controlling the bar graphs and RGB LEDs. Another PIC handles RF communication with the sensors, which are housed in a remote box. We’ve embedded the video of the device in operation below the break, and we’re sure you’ll agree it’s an impressive piece of work.

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Tiny House Forecasts Weather

Before the information age, it wasn’t quite as easy to glean information about the weather. Sure, there were thermometers and barometers and rhymes about the sky, but if you lived in or near Germany back then you might have also had access to something called a “weather house” which could help predict rain. [Moritz] aka [Thinksilicon] found one of these antequated devices laying around, and went about modernizing it. (Google Translate from German)

A traditional weather house is essentially a hygrometer housed in an intricate piece of artwork. Two figures, typically a man and woman, are balanced on a platform that is suspended in the middle by a small section of horsehair. When the humidity is low, the hair tightens up and turns the platform one way, and when humidity is high — suggesting rain is coming — it turns the other way. When the man comes out of the house, it predicts rainfall.

To get the weather house upgraded, [Moritz] outfitted the front with an OLED display which replaced the traditional thermometer. Instead of using horsehair to spin the figures he installed a small servo on the platform. The entire house is controlled by an ESP8266 which pulls data from the Open Weather API and spins the figures based on the information it receives.

Much like unique clocks, we enjoy interesting weather indicating/forecasting builds. This one’s right up there with using squirrels to predict the weather, or having a small weather-recreation right on your bookshelf.

Build Your Own Sensor Skin

Scientific research, especially in the area of robotics, often leverages cutting-edge technology. Labs filled with the latest measurement and fabrication gear are unleashed on the really tough problems, like how to simulate the exquisite sensing abilities of human skin. One lab doing work in this area has taken a different approach, though, by building multi-functional sensors arrays from paper.

A group from the King Abdullah University of Science and Technology in Saudi Arabia, led by [Muhammad M. Hussain], has published a fascinating paper that’s a tour de force of getting a lot done with nothing. Common household items, like Post-It notes, kitchen sponges, tissue paper, and tin foil, are used to form the basis of what they call “paper skin”. Fabrication techniques – scissors and tape – are ridiculously simple and accessible to anyone who made it through kindergarten.

They do turn to a Circuit Scribe pen for some of their sensors, but even this nod to high technology is well within their stated goal of making it possible for anyone to fabricate sensors at home. The paper goes into great detail about how the sensors are made, how they interact, and how they are interfaced. It’s worth a read to see what you can accomplish with scraps.

For another low-tech paper-based sensor, check out this capacitive touch sensor keyboard.

Thanks for the tip, [Mattias]

Fixing A Product Design Flaw In A Misting System

[Xerxes3rd] works at a place where they raise reptiles in terrariums. Such enclosures require controlled lighting, temperature and humidity. Humidity is maintained using “misting” devices. These are usually water containers with a pump whose outlet ends in a series of very fine spray nozzles which create the mist. A timer controls the pump’s on and off cycles.

[Xerxes3rd] purchased an Exo Terra Monsoon RS400 misting system – a low-cost misting device and soon discovered that it had a serious design flaw. The built-in timer malfunctions, and it mists a hundred times more than it should! A lot of folks who buy a product and discover it has an inherent design flaw will return it back for a refund. Instead,  [Xerxes3rd] decided to break in and fix it instead –  “warranty void if tampered” be damned.

To start with, he needed to figure out what the problem was. He went about it in clinical fashion, eventually creating a slick document (PDF) outlining his observations and diagnosis. The timer controller board has a PIC micro, some buttons, potentiometers, LED’s and an IR receiver. The misting cycles are set using the two potentiometers – Off time and On time for the pump. His analysis and resolution makes for interesting reading.

What he found was that the PIC micro was reading inconsistent values from the potentiometers. More specifically, the software isn’t doing any smoothing on the analog values it reads from the potentiometers. Since the PIC that controls the system wasn’t easily re-programmable, he opted to replace it with an Arduino Nano. At the same time, he got rid of the potentiometers that were used to set the misting frequency and duration, and added a 16×2 LCD. Time setting is now done using the three on board buttons. He removed the PIC micro and replaced it with two female header sockets, onto which he plugged a small board containing an Arduino Nano and a few components. He also cut the original PCB in half, removing the potentiometers and crystal oscillator in order to make room for the 16×2 character LCD.

The lizards are now probably thanking him for their perfectly timed doses of moisture. Having done this, he could probably add in more features such as a temperature-humidity sensor, a water level sensor or maybe even throw in an ESP8266 module and have the Lizards tweet when they need to be hydrated. Because that’s another thing hackers love – feature creep.

Know Your Speed on Rollerblades

[Anurag] is a computer engineering student with a knack for rollerblading. Rollerblades are not a transportation device that are often fitted with speedometers, so [Anurag] took that more as a challenge and designed this Arduino-powered computer to give him more information on his rollerblade rides.

The device uses an Arduino as the brain, and counts wheel revolutions (along with doing a little bit of math) in order to calculate the speed of the rider. The only problem with using this method is that the wheels aren’t on the ground at all times, and slow down slightly when the rider’s foot is off the ground. To make sure he gets accurate data, the Arduino uses an ultrasonic rangefinder to determine the distance to the ground and deduce when it should be taking speed measurements.

In addition to speed, the device can also calculate humidity and temperature, and could be configured to measure any number of things. It outputs its results to a small screen, but it could easily be upgraded with Bluetooth for easy data logging. If speed is truly your goal, you might want to have a look at these motorized rollerblades too.