Open Source Wireless Mesh Networking Energy Meter

March 28, 2011 by Jesse Congdon 35 Comments

[Jay Kickliter] writes in to tell us about his open source energy/power meter. With his buddy [Frank Lynam] they designed a small device that crams into existing power boxes and uses and 8 core propeller (P8X32A) microcontroller to perform true RMS voltage and current measurements using a current transformer. [Frank] and [Jay] don’t stop there. The meter also features an xbee pro 900 MHZ to provide wireless (and even mesh networking) capabilities to the whole ordeal.

[Jay and Frank] estimate a total unit cost of around $80 (US) per prototype. With volume the price goes down by about half. With a larger number of units, and the magic of mesh networking, we could see cheaper xbee’s driving the cost down some. Check out the Google code page for details or the schematic (pdf) if you are interested.

So far the project is in the beta stages, and only features a single module sending data to a PC running an OS X Cocoa application. [Jay] is about to be otherwise occupied by the Merchant Marines and [Frank] the Navy, so they figured we could have a go at it for awhile.

We have seen other hardware used to monitor power consumption, but cramming this circuit into each power box is a neat idea.

[Frank] explains the whole project in the video after the jump.

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WiFi Radio Plays Your Tunes In Style

March 26, 2011 by Mike Nathan 9 Comments

wifi_radio

Instructables user [Jan] likes listening to music while hacking away in his workshop, but listening to the same CDs gets tired and boring after awhile. He contemplated listening to streaming audio over the Internet, but hated the idea of needing a computer around at all times. After a bit of reading, he found some information about building a WiFi radio, and got started on constructing his own.

Using a guide he found at the MightyOhm, he hacked an Asus router to use OpenWRT, adding a music player daemon to tune in various stations. He added a small LCD display and an ATmega32 to drive it, as well as a rotary encoder to allow him to switch between stations.

The case was built using several layers of MDF which were cut using a CNC mill, and joined together with glue and wooden dowels. The front and back panels were milled out of alucobond sheets, with the remainder of the case covered in white wood veneer. The detail that went into this build is great, we especially love the “WiFi Symbol” speaker grilles.

All of his code and schematics are available for download, should you desire to make a WiFi radio of your own. Stick around to see a video of his completed radio in action.

[via MightyOhm]

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RF Range Finder Doesn’t Need To See To Calculate Distance

March 21, 2011 by Mike Nathan 35 Comments

radio_rangefinder

Instructables user [Jones Electric] has been quite busy lately, building a radio-frequency range finder. Built as part of a German youth science competition, he and his partner built a pair of transmitter/receiver modules that can be used to measure distances of up to a mile (~1.5km). Their argument for radio-based rangefinders is that laser rangefinders are obviously limited to line of sight, whereas their range finders are not.

To determine the distance between the two stations, the base station is triggered, which starts a counter and sends a 433 MHz signal to the second station. When the second station receives the signal, it in turn broadcasts an 868 MHz signal, which is received by the base station. The total distance between the points is then calculated based upon the round trip time of the two radio signals.

[Jones Electric] claims that the range finder is relatively accurate, with a deviation of up to 5 meters per measurement, and that the accuracy could be increased by adding a higher frequency crystal to the timing circuit.

We are pretty sure using these two frequencies in the US without a license is not allowed, though we are unsure of the usage laws in Germany, where this was constructed.

RFID-based HTPC Controller Gets A Wireless Refresh

March 20, 2011 by Mike Nathan 4 Comments

RFiDJ_Refresh

[roteno] recently wrote in to let us know that he has completed work on the RFiDJ Refresh, a follow up to his 2009 project, the RFiDJ.

The concept is pretty simple – he has a set of RFID enabled tiles, which contain references to particular online streaming audio stations. He uses these tiles to tune into audio feeds on his HTPC by placing them on a block containing an RFID reader.

His previous implementation had the RFID reader tethered to his HTPC, which didn’t make it all that convenient to use. The newer version utilizes a 433 MHz transmitter/receiver pair in order to communicate with the PC, so it can be used anywhere through out his house. The reader and transmitter were placed in a shadow box picture frame, along with a rechargeable Li-poly battery that powers the whole setup. He also mentions that he has added a tactile interface that allows him to initiate mobile phone calls from the RFiDJ as well.

It’s a nice update to an already great project. We imagine it’s a bit more fun for [roteno] and his guests to tap a coaster on the transmitter box than fumble with a remote to change radio stations on the HTPC, but that’s just us.

Check out the videos below to see his new setup in action.

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Wireless Weather Station Obsessively Reports The Temperature

March 15, 2011 by Mike Nathan 11 Comments

obsessive_weather_station

[nuumio] has been hard at work building a Tweeting weather station, which he recently got up and running. The weather station is built from three major components, a Linux PC for data storage and Tweeting, a main weather sensor unit, and a remote unit.

The remote unit sits outside and includes includes both a pressure and humidity/temperature sensor. The sensors are polled every 20 seconds, reporting the data back to the main unit via a 434 MHz RF transceiver. The remote sensor also records the ambient light level and the remaining battery voltage, sending that data to the main unit for good measure.

The main unit sits inside his house and records the same temperature and humidity data as the external unit. The main unit adds its data to the packets sent by the remote unit and transmits them to the PC via USB. The PC calculates the minimum and maximum temperatures for the last 12-hour and 24 -hour periods before sending that data back to the main unit to be displayed on its LCD panel. Every 10 minutes, the computer also posts the weather data on Twitter.

If you are looking to build your own weather station, [nuumio] has provided all of the source code for his project on his web page. However, he does admit that he was too lazy to draw up a schematic, so you are on your own in that department.

USB Dongle Hack Tethers DSLR Cameras At A Fraction Of The Price

March 12, 2011 by Mike Nathan 33 Comments

wireless_usb_grip

[Neal] wanted to tether his DSLR to his computer, but he wasn’t about to fork out the $1,000 Nikon was asking for their wireless adapter. Instead, he opted to construct his own solution using two separate camera accessories which cost him less than $200 when finished.

The two components he purchased were a wireless USB transmitter/receiver pair and an external battery grip. The battery grip allows him to use a pair of batteries to power his camera, while providing just enough space to wedge in the USB transmitter. He stripped the casing off the transmitter and connected it to a mini USB plug that he wired into the battery grip. He then added a small voltage regulator to step down the Nikon battery voltage from 7.2v to the 5v required by the USB transmitter.

The battery grip and transmitter were then hooked directly into his camera using the weatherproof plug built into the grip. Once he powered on his camera, it was connected to the PC immediately.

It’s amazing how the simplest hacks can save incredible amounts of money. Nice job!

Be sure to check out the video embedded below to see the wireless adapter in action.

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Zigbee-powered Wireless Scale

March 11, 2011 by Noah Dunker 5 Comments

[joe] wanted to make it easy to record his weight every day, and added a few bits to decode the weight and send it to his computer. The end result is a ZigBee-powered wireless scale. Additionally, his scale can track more than one person’s data simply by knowing whose previous weight the new measurement is closest to. Now [joe] and his family can spend more time working out, and less time messing with spreadsheets and data entry.

[joe]’s build is not only elegant, but well-documented, too. He walks through the reasons he chose this specific floor scale, reverse engineering it to decode the weight, then provides links to his schematics, source code, and pretty much everything else you would need to play along at home.