Tricycle Robot Using Omni-wheels

March 21, 2011 by Mike Szczys 10 Comments

[Markus Gritsch] built this six-wheeled robot using omni-wheels. Two wheels are used on each axis in order to ensure perpendicular rotation is possible no matter where the axis rotation stops. The wheels have also been improved by dipping the elliptical components to give them a rubbery coating.

The robot gets its commands wirelessly from a separate controller unit. That controller, as well as the bot seen above, uses a Teensy microcontroller board. Two analog sticks take input from the operator and transmit commands using an inexpensive RF pair. The wheel movement is facilitated by three servo motors which may seem like an odd choice. But we think that it simplifies the electronic side of the build because you do not need an H-bridge to control a servo motors. It’s a bit loud, as you can hear in the video after the break, but it certainly works quite well.

One of the commenters on the thread above asks why [Markus] didn’t use mechanum wheels. These would have allowed him to use just one wheel on each axis but the omni-wheels were so inexpensive that he went this route instead.

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All-band Receiver Hides In Plain Sight

February 27, 2011 by Mike Szczys 17 Comments

This handheld radio has a little secret. You’re not going to be able to listen to Limbaugh since the original FM tuning circuit has been removed and replaced by a diode detector. Now [Miguel A. Vallejo] a discreet way to look for interesting radio signals in public.

The first step that he took was to remove the circuit board from the case and depopulate the tuning circuit while leaving the audio amplifier hardware. Next he referenced a proven design and built the diode detector circuit on a piece of protoboard. Finally he patched the new circuit into the original audio amplifier (seen in the image above) and put everything back in the case. Now he can listen in on data burst from a keypress on a computer keyboard, RF data communications, and slew of other noise sources.

This would be really handy for tracking down the electrical noise that’s screwing up your project.

[Thanks Superlopez]

RF Control From Just About Any Device

February 20, 2011 by Mike Szczys 10 Comments

[Mirko] is working on a library that will allow you to add RF control to just about any device. The only requirement is that the device be capable of running a Linux kernel, and that it have a few GPIO pins available. One example is fairly straight forward, a Netgear router. Many, if not most routers run a Linux kernel natively and most have solder points on the board for unused IO pins so patching into the hardware is very straight forward. Less obvious and much more impressive is the hack seen in the image above. [Mirko] built an SD card adapter cable and uses the contacts in the card reader to bit bang four-wire SPI to communicate with that RF module.

Valentine’s Gift Counts The Days Spent Together

February 18, 2011 by Mike Szczys 20 Comments

[Vegard Paulsen] dug deep down to the romantic geek at his core and built this box that counts the days he’s spent together with his Valentine. As you can see, it uses a four-digit seven segment display installed in the lid of a wooden box. An Arduino mini is responsible for driving the display, but as you might already know, to keep accurate time you’re going to need a reliable clock source. Instead of using a temperature compensated crystal oscillator like the ChronoDot he decided to pull time data from the Internet via a pair of RF modules.

His closing comments mention that this display will only work for around 27 years but he figures he can always build a bigger display. We’d keep this around, physically unaltered for sentimental value, but switch to a hexadecimal readout to track just over 179 years. Maybe that’s a bit too geeky.

Sniffing RF Hardware Communication Packets

February 7, 2011 by Mike Szczys 7 Comments

[Travis Goodspeed] put together a proof of concept hack that sniffs wireless keyboard data packets. He’s using the Next HOPE badge that he designed as the hardware platform for these tests. It has an nRF24L01+ radio on-board which can easily communicate with 2.4 GHz devices.

The real trick comes in getting that radio to listen for all traffic, then to narrow that traffic down to just the device from which you want data. He covers the protocol that is used, and his method of getting around MAC address verification on the hardware. In the end he can listen to all keyboard data without the target’s knowledge, and believes that it is possible to inject data using just the hardware on the badge.

Reverse Engineering Radio Controlled Outlets

January 26, 2011 by Mike Szczys 31 Comments

[Chr] picked up a pack of remote control outlets in order to reverse engineer them and build control into his own projects. These can be plugged into outlets around your house and a relay inside each module will switch whatever device is plugged into it after receiving a command from the remote. Once he cracked open the control housing it was easy to find the data line for the RF module which was on its own board. He used a logic analyzer to capture data from various button presses and then spent some time deciphering the communication protocol. He used what he learned to roll the module and code into an interface box where an ATmega8 connects via USB and passes commands from a computer to the RF board. Now he’s added home automation via a computer quite inexpensively. After the break you can watch a clip of the outlets switched using a smartphone.

So why not just patch into the buttons on the remote? Well, this same project was attempted at our local hackerspace earlier this month and the buttons don’t just pull a pin to ground. They use tri-state logic and are arranged into a matrix that is a lot harder to mimic (if not impossible) with a microcontroller. Analyzing the communications going into the RF module is definitely the less labor-intensive of the two approaches.

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Creating Art From An Old Christmas Tree

January 7, 2011 by Mike Szczys 12 Comments

So you manged to get a great deal on a fake tree during the after Christmas sales, but what should you do with your old one? If it was lighted with fiber optics you can reuse the strands to create your own star map. [Mr Trick] shows how to disassemble one of these trees, grouping the fibers by length. He built a wood frame, then covered it with a layer of cardboard and another of black fabric. From there the painstaking process of routing the fibers in a way to looks convincing starts.[Mr Trick’s] final product uses multiple LED light sources and even includes RF control.

Think this project is large and time-consuming? Check out the same idea built into a bedroom ceiling.