Your source for daily hacks

Published on: October 17, 2013 / Comments: None

Animatronic Rats do the spooky dance – Ratsberri Pi

Found this one while looking around for more Halloween inspired hacks.  Hari picked up a bunch of rubber rats at the dollar store and decided to make a Halloween project out of it.

A Raspberry Pi connected to a Pi Cobbler breakout board, and a 16 channel i2c PWM servo controller puppet an array of rubber rats.  Everything is powered by a pair of hobby LiPo batteries and 5v regulators.   The rats eyes were swapped out for some bright red LED’s giving a pretty authentic haunted house look.

There’s still time to put something like this together before Halloween!

Published on: October 6, 2013 / Comments: None

HardDJ Arduino based MIDI controller uses hard drives as jog wheels

Stumbled on this awesome project that uses 2 old hard drives platters as rotary encoders / jog wheels.  Obviously for the purpose of DJing!  I love it when people reuse hardware that was originally intended for another purpose.

The build uses an Arduino Mega 2560 as its main processor.  RGB LED’s for the VUmeters, some slider pots for fading, and some extra buttons and knobs for MIDI events.  On the PC software side, the author is using mixxx for the MIDI mapping.


Check out the video after the break.  More pictures in the gallery.  Source code here on GitHub. More documentation here.


Published on: October 3, 2013 / Comments: 2

Use the web to control an HDMI Switcher

Universal remote controls are a natural want.  I know I hate having 100 remotes for everything remote control.  So what do you do when you start getting used to using your phone as a remote (via web interfaces) ?  Well start converting your other stuff to be controlled via the web too!

Dalgibbard has an entertainment center using XBMC and a Raspberry Pi.  But the HDMI switcher uses an infra-red remote control.  So naturally Dalgibbard hacked the switcher to be controlled by a web interface on the Raspberry Pi.

The HDMI switcher is wired up to the Raspberry Pi via a relay and a few discrete components to the GPIO pins.  The pins are controlled by a python script that is executed by a web page using PHP and Apache.  Simple and efficient.

More pictures, schematic, source here.

Published on: September 12, 2013 / Comments: None

Modifying a DPC3010 cable modem for performance gains

Not happy with your cable modem performance?  Crack it open and fix it!  That’s what forum user Xymox did.  After cracking open his DPC3012 he noticed there were a few spots on the main PCB that were not populated with parts.  The theory is they saved on budget and didn’t populate all the parts.

Xymox stuffed a huge amount of tantalum capacitors all along the power rail.  He also added large capacitor on the power supply.  It appears that the modem also runs pretty hot so he addressed the temperature issues by adding Arctic Silver to the heat sink and a fan.  After the modifications are all done to the modem, he measured a 1000:1 reduction in power noise.

Having a spare unmodified modem to compare against, Xymox states a gain of 1db to the signal to noise ratio.  The upstream power decreased by 1.5db meaning the modem has to try less as hard to maintain a good signal.  There is also a side by side plot of ping times captured over a week.  The average ping time has improved as well.

Pretty ambitious hack.  Read more on the usbjtag forums.


Published on: September 9, 2013 / Comments: None

Pedal Powered Landspeeder X-34

I decided to make a “bumper sticker” that I think any young “Luke” would appreciate.

One way to intensify your kids workout is to weigh down their pedal car down with a few dozen pounds of wood. However, I doubt that was the inspiration blogsdo had when he turned his sons “Original KettCar” into a Pedal Powered Landspeeder X-34. This dad just may be a strong contender for the father of the year award for this awesome birthday gift.

He did not intend to document his build so there is not a whole lot to report on.  As you can see from the build photos after the break the car was basically wrapped with wood and decorated with a few custom decals. One of which probably had the little ones giggling.


Published on: September 9, 2013 / Comments: None

Use an Arduino USB host shield to add a display to a USB scale

Believe it or not there’s actually a USB Host shield for the Arduino.  The shield and accompanying libraries will let you communicate with USB client devices… like this USB digital scale.  Normally this USB digital scale is plugged into a PC which will read the weight (I assume for weighing packages for mailing).

Oleg decided to to add an LCD to the device so it could be used stand alone.  He’s using your run-of-the-mill 16×2 hd44780 compatible display, an Arduino, and the USB Host shield.  The scale reports itself as a HID device to the host but still a little reverse engineering was needed to extract the weight information from the HID report.  Once the target packets were identified, Oleg whipped up a sketch to read the USB report packets and throw the info out to the LCD display.

I probably wouldn’t have the patience for doing it this way, I would have tried to open it up and read data from one of the sensors directly, but this hack just introduces you to another vector of modification or input method.  For instance using a USB joystick or flight stick with the USB host shield might be a great addition to a flame-throwing robot or something (lol).

Source sketch and more info here.

Published on: September 6, 2013 / Comments: None

Reducing the noise on your RTL-SDR

The guys over at SDR for Mariners put together a nice writeup on reducing the electrical interference on the good ol’ cheap RTL-SDR dongle.  When the signal you’re looking for is very faint, you need to remove all of unwanted noise or else your signal gets difficult to separate.  In their case the unwanted signal is in the form of FM radio.

Even if you aren’t a big RF nerd you know some of these remedies already like ferrite beads (you know those giant blocks on the ends of the expensive cables!).  But I’m actually surprised at some of the other ones.  I would have thought that the metal connector around a USB cable would help prevent noise, but according to their tests it was acting like a collector for their intrusive FM signal.  By removing the shield and just connecting the data pins they dropped the noise by 10db.  Not using the extension cable and just plugging straight in is even better.

So the winning combo appears to be all of their methods tested.  A stick wrapped in aluminum foil, touching the metal of the USB plug, connected by a USB extension cable, inside a metal housing.

I’d love to see a picture of the final setup.  Good tips to know when chasing down a faint signal.