Year: 2014

Doggy DVR Alarm Sensor

January 6, 2014 by 10 Comments

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[Martin] lives in a small village about 25km from his job in a major city. Occasionally his home alarm system will trip and he will rush home to make sure everything is okay. So he decided to buy a DVR system instead… and he turned his dog’s collar into one of the main sensors.

As you may know, DVR’s also have sensor inputs in addition to loads of video cameras. These can be very handy to tell you other things that a small video clip will not, such as moisture, humidity, temperature etc. [Martin’s] DVR has 8 sensor inputs which he has configured to be the normally open type of sensors. By using a Sharp 817 optocoupler and a Funky v3 wireless module he made one of the sensor inputs wireless.

On the other end of the Funky wireless setup is a Kinder Surprise shell attached to his dog’s collar. In addition to the wireless module, it also contains a rudimentary 2-axis shock sensor consisting of a small spring that floats over a metal pin — when moved violently (when the dog is running about) it makes contact and [Martin’s] DVR alerts him by email and sends him pictures from the system.

He suspects he’ll be getting lots of pictures of the dog getting spooked by cats wandering by.

Automatic Antenna Tuner

January 6, 2014 by 48 Comments

Automatic Antenna Tuner

To get the best power transfer into an antenna, tuning is required. This process uses a load to match the transmission line to the antenna, which controls the standing wave ratio (SWR).

[k3ng] built his own automatic antenna tuner. First, it measures the SWR of the line by using a tandem match coupler. This device allows the forward and reflected signals on the line to be extracted. They are buffered and fed into an Arduino for sampling. Using this data, the device can calculate the SWR. The RF signal is also divided and sampled to measure frequency.

To automate tuning, an Arduino switches a bank of capacitors and inductors in and out of the circuit. By varying the load, it can find the ideal matching for the given antenna and frequency. Once it does, the settings are stored in EEPROM so that they can be recalled later.

After the break, check out a video of the tuner clicking its relays and matching a load.

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The Most Beautiful Floppy Disk Jukebox Ever

January 5, 2014 by 22 Comments

Playing music on floppy drives is something that has been done to death. [kiu]’s RumbleRail is something else entirely. Yes, it’s still a collection of floppy drives playing MIDI files, but the engineering and build quality that went into this build puts it in a class by itself.

Instead of the usual assemblage of wires, power cords, and circuits that accompany most musical floppy drive builds, [kiu]’s is an exercise in precision and modularity. Each of the eight floppy drives are connected to its own driver with an ATMega16 microcontroller on board. The microcontrollers in these driver boards receive orders from the command board over an I2C bus. Since everything on the RumbleRail is modular, and the fact [kiu] is using DIP switches to set the I2C address of each board, this build could theoretically be expanded to 127 voices, or 127 individual floppy drives each playing their part of a MIDI file.

The RumbleRail can also operate in a standalone mode without the need for a separate computer feeding it data. MIDI files can be loaded off an SD card by the main controller board, and decode them for the floppy drivers.

If you’d like to build your own RumbleRail, all the board files, schematics, and firmware are up on [kiu]’s git. There are, of course, a few videos below of the floppy jukebox in action.

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Wireless Thermostat

January 5, 2014 by 15 Comments

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The thermostat in [Tom’s] 100-year-old house is two floors up from where the furnace is located, so a broken wire in the wall was just the catalyst needed to design a wireless thermostat.

The system is based on a customized PCB [Tom] designed called the Magic Mote. The board contains an MSP430 microcontroller, a low power NRF24l01+ wireless transceiver, and various sensor interfaces. The wireless thermostat project uses two of these boards; one monitors the temperature on the second floor and the other controls the furnace in the basement.

The temperature sensing is done using a DHT22/AM2303 temperature and humidity sensor, which is a convenient choice, since the part is calibrated and handles the analog digital conversion; you just need one digital pin to retrieve the temp/humidity data. To control the furnace, [Tom] used the local 24VAC and a latching relay to drive the heater signal. The 24VAC also powers the board, so a door-bell transformer steps the voltage down to something more usable; about 11VAC or so, which is then rectified, filtered, and regulated down to what the control electronics like to see (3.3V/5V).

This project is actually still in the early stages of what [Tom] has planned; a network of sensors and appliances with a beagle bone base station. We can’t wait to see what’s next for this project; maybe we’ll even see some voice control, like in this epic Siri controlled home automation project.

[via Dangerous Prototypes]

Hackaday Links: January 5, 2014

January 5, 2014 by 26 Comments

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While we can’t condone the actual use of this device, [Husam]’s portable WiFi jammer is actually pretty cool. It uses a Raspberry Pi and an Aircrack-ng compatible dongle to spam the airwaves with deauth packets. The entire device is packaged in a neat box with an Arduino-controlled LCD and RGB LEDs. Check out an imgur gallery here.

You can pick up a wireless phone charger real cheap from any of the usual internet outlets, but try finding one that’s also a phone stand. [Malcolm] created his own. He used a Qi charger from DealExtreme and attached it to a 3D printed phone stand.

A while back, [John] noticed an old tube radio in an antique store. No, he didn’t replace the guts with a Raspberry Pi and an SD card full of MP3s. He just brought it back to working condition. After fixing the wiring (no ground cord on these old things), repairing the speaker cone, putting some new twine on the tuner and replacing the caps, [John] has himself a new old radio. Here’s a video of the complete refurbishment.

Here’s a Sega Master System (pretty much a Game Gear) running on an STM32 dev board. Also included are some ROMs for some classic games – Sonic the Hedgehog, Castle of Illusion, and The Lion King. If you have this STM Discovery board you can grab the emulator right here.

[Spencer] wanted a longer battery life in his iPhone, so he did what any engineering student would do: he put another battery in parallel.

Breadboarding something with an AVR or MAX232? Print out some of these stickers and make sure you get the pinouts right. Thanks, [Marius].

Mustachioed Rover Simultaneously Manly, Adorable

January 5, 2014 by 24 Comments

[Rick], an Adafruit learning system contributor, is excited by the implications of STEM’s reach into K-12 education. He was inspired to design Red Rover, a low-cost robot that can be easily replicated by anyone with access to a 3-D printer.

This adorable autonomous rover is based on the adafruit Trinket microcontroller, but will also rove under the power of an Arduino micro. It really is quite simple—the Trinket drives two continuous rotation micro servos and pretty much any flavor of rangefinder you like. [Rick] tested it with Parallax PING))), Maxbotix, and Grove sensors, and they all worked just fine.

What’s truly awesome about Red Rover are the track treads. [Rick] initially experimented with flexible filament. While he had good results, it was not a cost-effective solution. What you see in the picture and the short video after the break are actually rubber bracelets from Oriental Trading.

The plastic part count comes in at seven, all of which can be printed together at once. [Rick]’s gallery includes both small and large chassis and three different servo mounts. The Red Rover guide builds on other adafruit guides for Trinket general use, servo modification, and Trinket-specific servo control.

Update: Added [Rick]’s demo video after the break!

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Image Sensor For Filling Wine Bottles

January 5, 2014 by 22 Comments

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A wine bottling company in New Zealand got in touch with [Boz] to solve a problem. They needed a way to automatically determine if a wine bottle was filled or not. What he came up with is a very simple yet very effective fill level sensor that can scan thousands of bottles an hour.

There were a few design decisions that went into the construction of this wine bottle sensor. [Boz] could have used a VGA camera sensor, but given the speed of the bottling line (half a meter per second), pushing all those pixels to a computer and doing real-time image analysis would be difficult. [Boz] settled on a much simpler solution – a 1×128 linear CCD analog image sensor. With a PIC microcontroller, this allows the device to check multiple bottles per second, calculate if the bottle is full or not (or overfilled), and send a ‘pass’ or ‘reject’ signal to the rest of the line.

The rest of the assembly is fairly straightforward with an LED backlight providing the illumination for the CCD and a Bluetooth transmitter for checking out the machine’s settings. On the bottling line, the device has 99% accuracy for both red wines in dark bottles and whites in green bottles. You can take a gander of this device in action on a New Zealand bottling line below.

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