Building A Home Automation Mesh Network

March 19, 2011 by Mike Szczys 12 Comments

[Ian Harris] designed a bunch of home automation for his parents using X10 hardware. He was a bit disappointed by the failure rate of the modules and the overall performance of the system so he set out to replace it with his own hardware. Lucky for use he’s documented the journey in a four-part series about mesh networks.

The hardware seen above is his test rig. He’s using a couple of Sparkfun breakout boards to develop for nrf2401a RF transceiver chips. These could be used as slave modules, with a central command device, but due to the home’s architecture wireless signals don’t propagate well from one end of the house to the other. The solution is to build a mesh network that will allow each module to act as a network node, receiving and passing on messages until they arrive at the target device. He’s trying to do this with cheap hardware, selecting the PIC 16F88 which boasts 7 KB or program memory and 368 bytes of ram. In the end it doesn’t take much code to get this running, it’s the concepts that take some time and research before you’ll be comfortable working with them.

[Thanks Oakkar7]

Add A Shutoff Timer To Your Bathroom Fan

March 19, 2011 by Mike Szczys 17 Comments

Adding this board (translated) to your bathroom fan will turn it into a smart device. It’s designed to automatically shut off the fan after it’s had some time to clear humidity from the room. It replaces the wall switch which normally controls these fans by converting the fan connection to always be connected to mains. The board draws constant power to keep the ATtiny13 running via a half-wave rectification circuit. A single LED that rises from the center of the PCB lights up to signal that the fan is in operation, but it is also used as a light sensor, similar to the LED communications hack from a couple of days ago. When the lights go on in the bathroom the microcontroller will turn on the exhaust fan via a Triac. It will remain on until the light level in the bathroom drops.

There’s an interesting timing algorithm that delays the fan startup, and varies the amount of time it will stay on in the dark depending on how long the bathroom lights were on. This way, a longer shower (which will build up more humidity) will cause the fan to remain on for the base of five minutes, plus one minute longer for every two minutes the bathroom was in use. Pretty smart, and quite useful if your bathroom sees high traffic from several family members.

Automatic Dog Dish Filler Never Goes Dry

March 18, 2011 by Mike Nathan 37 Comments

automatic_water_dish

[Avatar-X] has a Siberian Husky that gets a lot of exercise throughout the day, and as you would imagine, drinks a ton of water as well. We all suffer from memory lapses at one time or another, and while he is normally good about keeping the bowl filled, he occasionally forgets. He has tried a handful of various auto-filling dog dishes, but none of them seemed to work all that well, and they often rapidly built up healthy bacterial colonies.

With the help of some friends, he rigged up an automatic water dish filler, that ensures his pup always has a sufficient supply of water. He tapped into his kitchen water supply with a standard refrigerator hookup kit, and ran some tubing up into his cabinets, where he placed a garden irrigation valve. The valve is controlled using an Arduino which senses the bowl’s water level using a pair of wires.

The system looks like it works pretty well if the video embedded below is any indicator. [Avatar-X] provides code and schematics for the water control circuit on his site, free to anyone looking to build a similar system for their pets.

If you are interested in learning more about automating some of your pet’s care, be sure to check out these hacks we featured in the past.

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Free Home Phone Method Uses Parts We’re Familiar With

March 18, 2011 by Mike Szczys 19 Comments

[Headsheez] found a way to get his home phone service for free. He’s using a set of tools that we’re familiar with to route service from a typical analog phone system (which involves the extensions wired into your home) through a server to the Internet. On the hardware side of things this starts out with an Analog Telephone Adapter which translates the analog signal for use in a PBX system. He uses a copy of the open source PBX project called Asterisk which we’ve also seen used on devices like routers and the SheevaPlug. The actual telephone number comes from a Google voice account which for now is a free service but there’s no guarantee that it will remain that way in the future.

This should provide seamless service just like you’re used to with a traditional home phone line. There’s even caller ID for the number – but not the name – for incoming calls. The one big feature that is missing from this setup is the ability to call 911 for emergencies.

[via Reddit]

Beginner Project: Super Cheap Magnetic Mixer

March 16, 2011 by Jesse Congdon 23 Comments

[wesdoestuff]’s mother needed a clean way to mix together fragrance oils. Being the stand up kinda guy he is, [Wes] threw together a few spare parts to make this Magnetic Stir Plate.

The whole setup is amazingly simple. Pry the fins off of an old computer fan, glue a couple magnets to the fan’s hub. Drill a hole for a DC connector, find some sort of cover and.. Bob’s your uncle! [Wes] advises that you test the spacing of the magnets on the hub before gluing them permanently, as they can be a bit tricky to align.

The stir bar for non food items is a magnet bar from one of those crazy magnet and ball bearing toys, it is basically just a solid magnet covered in plastic. Food safe bars can be acquired, though they are not as cheap. With all that room under the hood we would love to see him throw in some kind of a PWM speed control but that could be a bit complicated. Most of us could throw this together from spare parts. Video after the jump!

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Electronic Diaper Bag Reminds You To Pack Everything But The Baby

March 15, 2011 by Mike Nathan 15 Comments

lilypad_diaperbag

[jnorby] knows what it’s like to leave the house with her baby in tow, only to realize that she has left something she needs at home. Instead of relying on a paper checklist, she decided to craft her own diaper bag that alerted her if she had forgotten to pack a particular item.

She built her bag from scratch, wiring small circuits into each of the pockets she created on the inside of the bag. Wires were run to each half of a snap fastener, so that they would complete the circuit when the snaps touch. The LEDs and snaps were then connected to a LilyPad Arduino, which checks the status of the snap circuits, lighting the appropriate LED once the proper item has been packed.

While we like the idea of a bag that uses functional indicators that remind you to pack items, we do think that the use of the Arduino, or any microprocessor for that matter, is massive overkill. We would ditch the LilyPad and snap fasteners for reed switches or perhaps normally closed micro leaf switches that turn the LEDs off once the proper item has been packed, rather than the other way around.

Automatic Ball Launcher Is For The Dogs

March 15, 2011 by Mike Nathan 24 Comments

automatic_ball_launcher

A while back, [Dino] built an automatic ball launcher for his dogs, but he wanted to revise it to make it smaller and a bit more user-friendly. While watching an episode of “Prototype This”, he came across a great idea to improve his launcher, so off to the workshop he went.

He repurposed a power window motor from a car, and mounted it to some wood-reinforced aluminum sheeting in his garage. He added a piece of aluminum tubing to serve as a spring-loaded launch arm, which is drawn back by a small lever attached to the window motor.

When a ball is dropped onto a switch at the bottom of the launcher, the window motor starts turning, which pulls the launch arm back into place. Once the arm reaches the tipping point, the spring snaps it forward, launching the ball across the yard. The lever attached to the window motor eventually makes its way back under the launch arm, and is stopped by a switch that is also attached to the motor.

After the prototype was finished, he added some more wood to protect the mechanism from his dogs and vice versa. A hopper was added to the top of the structure to allow the dogs to load the launcher themselves, after a bit of training.

Now, some of you might wonder what is wrong with [Dino’s] arm. Truth be told, it works just fine. If you are a frequent Hack-a-Day visitor, you know that he spends plenty of time in the workshop, so this is an easy way to let the dogs entertain themselves until their owner is ready to play.

Check out the video embedded below for a demonstration of the launcher, as well as a detailed walkthrough of how the mechanism works.

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