Open Source Power Line Communication

Power Line Communication Filtering

 

Since we all have wires running throughout our houses to provide mains power, there’s a number of devices that piggyback on mains lines for communication. For his thesis project, [Haris Andrianakis] developed his own power line communication system.

The basic principle of the system is to inject a signal onto the power lines at a much higher frequency than the 50 or 60 Hz of the AC power itself. Using both active and passive filters, the signal can be separated from the AC power and decoded. This system uses frequency-shift keying to encode data. This part is done by a ST7540 modem that’s designed for power line applications. The modem is controlled over SPI by an ATmega168 microcontroller.

[Haris]‘ write up goes into detail about some of the challenges he faced, and how to protect the device from the high voltages present. The final result is a remote display for a weigh scale, which communicates over the power line. Schematics, PCB layout, and software are all available.

Peltier Mini-Fridge Preserves Chip Quik, Marriage

[Charles] uses Chip Quik to solder his SMD parts, and that stuff can keep for more than six months if it’s kept cool. His wife banned all non-food items from their refrigerator, so he had to think fast and came up with this Peltier effect Chip Quik cooler.

He first looked into that man cave essential, the mini-fridge, but they’re too expensive and use too much power. [Charles] got a nice wooden box from a hobby store and some reflective insulation from Lowe’s. He first tried using a couple of heat sinks but they weren’t going to cool things down enough. Once he got a Peltier cooling kit, he was in business. The temperature in his workshop averages 80°F, and he says the box gets down to 58°F. This is cold enough to keep his paste fresh.

[Charles] plans to use a PC power supply in the future rather than his bench supply. He estimates that his Peltier cooler uses 25-50% of the power that a mini-fridge would, and now his wife won’t overheat. Many great things can be accomplished with the Peltier effect from air conditioning to sous-vide cooking to LED rings. What have you used it for?

MC Escher Inspires a Reptilian Floor

reptile-floor

A simple room refinishing project lead [Kris] to his biggest hack yet, a floor inspired by MC Escher’s Reptiles printMaurits Cornelis Escher is well known for his reality defying artwork. His lifelong passion was tessellation, large planes covered identical interlocking shapes. Triangles, squares, hexagons all EscherExampleinterlock naturally. Escher discovered that if he cut out part of a shape and replaced it on the opposite side, the new shape will still interlock. In Reptiles, Escher created a lizard shape by modifying a hexagon. One side flipped over to become the nose, 4 others to become the feet, and so on. If the cuts are all made perfectly, the final shape would still interlock.

[Kris] was inspired by a photo of a commercial flooring project using small wooden reptiles as the tiles. He wanted to go with larger wooden tiles for his room. He knew his shapes had to be perfect, so he wrote a computer program to split the hexagon perfectly. Armed with art in DXF format, he went looking for a flooring company to help him. The silence was deafening. Even with artwork ready to go, none of the local custom flooring shops would take his job. Undaunted, [Kris] bought an older CNC machine. The machine was designed to be driven from MS-DOS via the parallel port of a Pentium II era PC. [Kris] substituted an Arduino running GRBL. After some GCode generation, he was cutting tiles.

The real fun started when it was time to glue the tiles down. With all the interlocking parts, it’s impossible to just glue one tile and have it in the perfect position for the next. In [Kris'] own words, “You have to do it all in one go”. Thanks to some family support and muscle, the flooring project was a success.  Great work, [Kris]!

Magic Screwdriver Decides If You Watch TV Or Not

OLYMPUS DIGITAL CAMERA

Video projectors are great. They can easily produce a very large image to watch. With that large image comes a large screen, and who wants to look at a large screen when not watching TV? Well, [Steve] didn’t either so he set out to make a powered retractable screen for his projector. The best part about this one is that it is done in true DIY/hacker fashion. The parts used are definitely not intended to be used as anything close to a projector screen and the overall cost is kept to an absolute minimum.

[Read more...]

Energy-Saving Fireplace Thermostat

[Andrian] has a boiler stove that heats water and sends it to a radiator. As the fireplace heats the water in a boiler a temperature sensor opens the a valve to send the warm water to the radiator. The radiator sends its cool water back to the boiler to be reheated. The valve is slow, so before the boiler can send all the water to the radiator, it’s getting cool water back causing the valve to close while the heat is built back up. To prevent the valve from working so hard and wasting energy, [Andrian] designed a better thermostat to control the valve operation.

The thermostat uses one LM85 temperature sensor to check the water in the boiler and another one for the ambient temperature. Once the boiler water reaches the desired temperature, the valve is opened via relay. The system waits for half an hour and then checks the boiler temperature again. The brains of this operation is an ATMega168 with a 32.768kHz crystal as the RTC. Code and PCB files are available in his repo.

We love to see these types of hacks that challenge the status quo and increase the efficiency of appliances. We applaud you, [Andrian], for turning your dissatisfaction into a positive plan of action and for sharing your experience with the rest of us!

If you want to up the eco-friendliness of heating water a bit, you could heat the water with a compost heap.

High Tech Convertible Desk Takes it Up a Notch

desk

Standing desks seem to be all the rage today — but do you really want to commit fully to always standing? [Jeff Minton] didn’t, and when he found out how much convertible standing desks cost… he decided to make his own.

While brainstorming ways of accomplishing this he started browsing around eBay and found 18″ linear actuators for sale. They were $45 each, ran at 24V and could lift 600lbs each. Bingo. Actually, that’s kinda overkill…

He picked up a 24V power supply, an Arduino, and a 8-channel relay board.  The actuators are attached to the desk’s original legs using U-bolts which keep the legs straight and take the load of the desk. The untreated wood supports are there to reinforce the original desk, because they weren’t that sturdy in the first place.

It takes about a minute to fully actuate the legs, so while it’s not the prettiest nor the quickest solution — it does the trick and allows you to easily switch between standing and sitting.

[Read more...]

Open Source SwitchMote Promises Easy Home Automation

moteino

[Felix Rusu] is fast becoming a big name in home automation with his clever Moteino systems. His latest is called the SwitchMote which is a super easy way to upgrade your light switches for home automation, and he’s just released the source!

The SwitchMote is a drop in wireless light switch which lets you control a standard AC load, limited to 100W at this time. It uses a solid state relay (SSR) to perform the switching, but like any project involving mains electricity… MAKE SURE YOU KNOW WHAT YOU’RE DOING!

It makes use of a Moteino (duh) which is a wireless Arduino clone that operates over RF. We’ve seen it used before to control a Keurig coffee maker, operate a garage door over the internet, and even text you when your sump pump fails and your basement is about to flood!

Excited? Take a look at his GitHub repository, and check out how it works in the following video.

[Read more...]

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