Keep The Burglars Away With Some Pi

May 9, 2017 by Jamie Navarro 32 Comments

Ten years ago, we never imagined we would be able to ward off burglars with Pi. However, that is exactly what [Nick] is doing with his Raspberry Pi home security system.

We like how, instead of using a standard siren, [Nick] utilized his existing stereo system to play a custom audio file that he created. (Oh the possibilities!) How many off the shelf alarm systems can you do that with?

The Pi is the brains of the operation, running an open source software program called Home Assistant. If any of the Z-Wave sensors in his house are triggered while the alarm system is armed, the system begins taking several actions. The stereo system is turned on via IR so that the digital alarm audio file can be played. Lights flash on and off. An IP camera takes several snapshots and emails them to [Nick].

Home Assistant didn’t actually have the ability to send images in an email inline at the time that [Nick] was putting together his system. What did [Nick] do about that? He wrote some code to give it that ability, and submitted it through GitHub. That new code was put into a later version of the program. Ah, the beauty of open source software.

Perhaps the most important part of this project is that there were steps taken to help keep the wife-approval factor of the system on the positive side. For example, he configured one of the scripts so that even if the alarm is tripped multiple times in succession, the alarm won’t play over itself repeatedly.

This isn’t [Nick’s] first time being featured here. Check out another project of his which involves a couple of Pi’s communicating with each other via lasers.

Conflict Escalates Between Brilliant Rat And 555 Timer

May 8, 2017 by Sean Boyce 64 Comments

After [Casey Connor] captured and relocated a number of unwanted rodents in his home using commercially available live traps, he was presented with a problem: a rat had learned to avoid them.

In an epic, and adorable, conflict caught on video (and embedded below), he documents the designs used and how the rat escaped them by either recognizing the trap, or sheer agility. We can only tip our hat to the determination of both parties.

All the trap mechanisms are based on a 555 monostable solenoid triggering circuit that ensures that a pulse of sufficient duration is sent to the solenoid to trigger the trap correctly. This way even intermittent contacts will trigger the trap rather than just causing the solenoid to twitch without fully actuating. This is the same technique used to debounce a switch using a 555 timer.

A Raspberry Pi Zero detects motion using an IR camera to film the interesting parts. This is also a good indicator for when you’ve trapped your quarry – if you’re trying be humane then leaving it in a trap for days is counterproductive.

With the time and effort we spend building better and more complex rodent traps, we sometimes wonder who has cleverly trapped whom.

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The Internet Connected Dog Treat Machine

May 7, 2017 by Jenny List 5 Comments

[Eric] and [Shirin] have a dog called [Pickles], who is the kind of animal that if you are a dog lover you will secretly covet. They evidently dote upon [Pickles], but face the problem that they can’t always be at home to express their appreciation of him. But rather than abandon him entirely, they’ve applied technology to the problem. [Eric] has built an Internet-connected dog treat dispenser, through which they can dispense treats, and watch the lucky mutt wolfing them down.

The body of the machine has been made with lasercut acrylic, and the dispenser mechanism is a rotating hopper driven by a stepper motor. The whole thing — in all its transparent glory — is controlled through a Raspberry Pi, which plays a sound clip of [Shirin] calling [Pickles] for his treat, records his dining enjoyment with its camera, and emails the result to his owners. Behind the scenes it hosts an MQTT server, which can be triggered via an iPhone app, Alexa, or the adafruit.io site. Imagine for a moment: “Alexa, feed my dog!”. It has a ring to it.

He makes the point that this machine is not simply limited to dispensing treats, it could be used to engage [Pickles] in more activities. He hints at a future project involving a ball throwing device (have you ever seen such joy from a dog). There’s no substitute for being there with your dog, but maybe with this device they can make their dog’s life a little less of, well, a dog’s life.

You can see the machine in action in the video we’ve posted below the break.

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Honey, When Did We Get An Indoor Pool?

May 1, 2017 by Jamie Navarro 47 Comments

Is it too much to ask for a home to have a little ‘smart’ built-in? If you’ve ever woken up (or come home) to your dwelling being flooded, you’ll know how terrible it feels, how long it can take to recover from, and how stressful it can be. Yeah, it’s happened to us before, so we really feel for [David Schneider]. He woke up one Sunday morning to a whole lot of water in his house. The inlet valve for his washing machine somehow got stuck in the open position after putting a load of laundry in the previous night.

[David] took progressively complex measures to prevent a broken water feed flood from happening in the future. First, he lined the entire floor of his laundry closet with a steel tray. OK, that’s a good start but won’t prevent another disaster unless it is caught very quickly. How about a simple audible water alarm? That’s good and all if you’re home, but what if you’re not?

Next, he installed a valve with a mechanical timer on the water line for the washing machine which closes automatically after 2 hours of being opened. Much better, but what about all the other thirsty appliances around the house? After searching online a little, he found plenty of whole house systems that would work for him, but there were 2 problems with these. First, most were network-based and he didn’t want to IoT-ify his house’s water system. Second, they were overpriced.

Of course the solution was to put together his own system! First, he purchased a few mostly inexpensive things — a wireless alarm, some water sensors, and a motorized ball valve. Then he collected the last few things he needed from what he had on hand around the house, and got to work connecting the 4 LEDs on the alarm to 4 analog input pins on his Arduino. Next, he added a relay between the Arduino and the motorized ball valve.

If a sensor detects water, it tells the alarm about it (wirelessly), which triggers the Arduino to energize a relay that is connected to the motorized ball valve, causing it to shut off the main water line for the entire house. Disaster averted! Sure, it’s a fairly simple hack, but it works, meets his requirements, and now he sleeps better at night knowing he won’t wake up (or come home) to an indoor swimming pool.

It’s surprising that we haven’t seen more hacks like this given it’s such a common problem. The closest thing we can remember is an overflow sensor for an aquarium. If homes came standard with a water main shutoff system, it would remove a stressful event from our lives and maybe even lower our insurance premium.

Logs For A Toilet

April 29, 2017 by Brian Benchoff 47 Comments

The Internet of Things, as originally envisioned in papers dating to the early to mid-90s, is a magical concept. Wearable devices would report your location, health stats, and physiological information to a private server. Cameras in your shower would tell your doctor if that mole is getting bigger. Your car would monitor the life of your cabin air filter and buy a new one when the time arrived. Nanobots would become programmable matter, morphing into chairs, houses, and kitchen utensils. A ubiquity of computing would serve humans as an unseen hive mind. It was paradise, delivered by ever smaller computers, sensors, and advanced robotics.

The future didn’t turn out like we planned. While the scientists and engineers responsible for asking how they could make an Internet-connected toaster oven, no one was around to ask why anyone would want that. At least we got a 3Com Audrey out of this deal.

Fast forward to today and we learn [Christopher Hiller] just put his toilet on the Internet. Why is he doing this? Even he doesn’t know, but it does make for a great ‘logs from a toilet’ pun.

The hardware for this device is a Digistump Oak, a neat little Arduino-compatible WiFi-enabled development board. The Digistump Oak is able to publish to the Particle Cloud, and with just five lines of code, [Chris] is able to publish a flush to the Internet. The sensor for this build is a cheap plastic float switch. There are only three components in this build, and one of them is a 4k7 resistor.

Right now, there are a few issues with the build. It’s battery-powered, but that’s only because [Chris]’ toilet isn’t close enough to a wall outlet. There’s a bit of moisture in a bathroom, and clingfilm solves the problem for now, but some silly cone carne would solve that problem the right way. [Chris] also has two toilets, so he’ll need to build another one.

Replicating A Victorian Era Console

April 26, 2017 by Adam Fabio 27 Comments

[Dt99jay] lives in a historic Victorian-era district in the UK. Most homes in the area have ornate exterior window dressings with stone consoles holding up heavy stone hood molding.

The window hood molding turned out to be wood — most likely the result of damage repaired after the blitzkrieg bombings of WWII. The 1940’s era work is now rotting away, so it was time for a repair. When the hood was pulled away from the window, disaster struck. One console completely crumbled, while the other lost large chunks of material. The They weren’t solid stone after all, but replacements most likely molded with Coade stone.

There are no ready replacements for consoles like this. [dt99jay] couldn’t just swap them out for modern looking replacements, so he set about replicating the consoles. The remaining console was much too delicate to remove from the building, so [dt99jay] glued the missing pieces back on. He then filled any missing parts and carefully scraped way all the loose paint. Then came the difficult part — making a mold while the console was still mounted on the house.

Room Temperature Vulcanizing (RTV) silicone rubber was carefully applied to the console. The RTV is thick enough to stay on while it dries. After several thick layers of RTV, the console was covered. [Dt99jay] then covered the mold with plaster of Paris bandages to support it. The finished mold was carefully removed from the house, and [dt99jay] filled all the low spots and air bubbles with RTV.

New castings were made using a mixture of cement and playground sand. Once painted, the results matched perfectly. The historic conservation committee was pleased, and the window was once again structurally sound.

A Cool Mist That Dries Your Clothes

April 23, 2017 by Mike Szczys 77 Comments

This one is both wild enough to be confused as a conspiracy theory and common sense enough to be the big solution staring us in the face which nobody realized. Until now. Oak Ridge National Laboratory and General Electric (GE), working on a grant from the US Department of Energy (DOE), have been playing around with new clothes dryer technology since 2014 and have come with something new and exciting. Clothes dryers that use ultrasonic traducers to remove moisture from garments instead of using heat.

If you’ve ever seen a cool mist humidifier you’ll know how this works. A piezo element generates ultrasonic waves that atomize water and humidify the air. This is exactly the same except the water is stored in clothing, rather than a reservoir. Once it’s atomized it can be removed with traditional air movement.

This is a totally obvious application of the simple and inexpensive technology — when the garment is laying flat on a bed of transducers. This can be implemented in a press drying system where a garment is laid flat on a bed or transducers and another bed hinges down from above. Poof, your shirt is dry in a few seconds.

But individual households don’t have these kinds of dryers. They have what are called drum dryers that spin the clothes. Reading closely, this piece of the puzzle is still to come:

They play [sic] to scale-up the technoloogy to press drying and eventually a clothes dryer drum in the next five months.

We look at this as having a similar technological hurdle as wireless electricity. There must be an inverse-square law on the effect of the ultrasonic waves to atomize water as the water moves further away from the transducers. It that’s the case, tranducers on the circumference of a drum would be inefficient at drying the clothing toward the center. This slide deck hints that that problem is being addressed. It talks about only running the transducers when the fabric is physically coupled with the elements. It’s an interesting application and we hope that it could work in conjunction with traditional drying methods to boost energy savings, even if this doesn’t pan out as a total replacement.

With a vast population, cost adds up fast. There are roughly 125 M households in the United States and the overwhelming majority of them use clothes dryers (while many other parts of the world have a higher percentage who hang-dry their clothing). The DOE estimates $9 billion a year is spent on drying clothes in the US. Reducing that number by even 1/10th of 1% will pay off more than tenfold the $880,000 research budget that went into this. Of course, you have to outfit those households with new equipment which will take at least 8-12 years through natural attrition, even if ultrasonics hit the market as soon as possible.

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