While the Robotic Arm that comes with the NXT looks pretty neat, I must confess I've never built it.  It just didn't look all that intresting, and only had a tiny reach.  Apparntly Patrick Miles shared my dissapointment with the Lego arm, and therefore built his own.  Its got a much better reach and is better weighted and counter balanced.  And the best part is he put up some building instructions over on Imageshack.

» Read more: A Better Robotic Arm

After lots of fiddling and a few blown chips I managed to get the solenoid valves working my NXT.  When I first got my NXT two of my biggest problems were the lack of actuators, and the lack of linear acutators.  I've since learned through design tricks to overcome most of these issues, but I kept trying to think of a better way.  Then a few months ago I came across a manifold of pneumatic valves.  They had fittings on them that was the proper size for Lego tubing, and I thought they would be an excellant fit.  Only problem was, how do i get the NXT brick to control the valves.  Turns out after lots of research and a few Digikey orders, it was actualy quite easy.  Read on for the whole story.

» Read more: Pneumatic Valves

You may have noticed the lack of postings lately, thats due mostly to two things.  One I just bought a house and thats kept me away from Lego.  The other has been a general lack of intresting NXT news lately, looks like things have been picking back up this week though.

I recently picked up a PCF8574 Sensor building kit from Mindsensors.com.  I was looking at their site with the intent to just get a few cables that I could cut up and maybe a socket or two to use with my breadboard.  However I saw the kit and decided that with its included NXT cable socket, as well as a little PCB and everything needed to use a PCF8574 all for only $14 it seemed like a good idea, and I must say I'm quite happy with it.   This was one of the first things I tried with the kit, as it has eight outputs and the LED digit has eight inputs it seemed like a perfect fit.  I wired up one output to each LED in the display and then using some software I can have the NXT display any number I want (as long as its less than ten that is).

» Read more: LED Digit

Domino laying has always been a fun challenge.  Dave Astolfo built the first NXT one as part of the MDP program.  However this bot was far from perfect, and one of its biggest flaws was the need to back up after placing each bot to get a good line going.  This not only made it look a bit silly, but also made it rather slow.  Dave solved this problem by using a Mindsensors.com Motor Mutiplexor to add a fourth motor.  Pawel Piskunowicz however has managed to build a domino laying bot that only uses three motors, and lays domino quite speedily. Check out the pictures of his bot over on his Brickshelf Gallery.  He's also got a video of it in action on YouTube.

» Read more: The Dominator

After digging through the Lego NXT Hardware Developers Kit (HDK) Philo realized that Port A on the NXT brick was not the same as Port B and Port C.  On Port A when in either Brake or Driving mode, one of the two motor driving lines has a voltage (Ports B & C are grounded).  This means that you can pull this power from Port A and use it to power other devices.  You can even switch A into Coast to turn this power off.  This opens up a whole realm of possibilities, and Philo has shown a few of them.  First, you can use it to power any old Lego motors.  Which would be very useful for constant motion things, like powering a treadmill or such.  Secondly he used it to power a wireless camera, as well as a few "headlights" for the camera.  This would be a great benefit, as I've always hated having the 9-Volt battery for the camera flopping around.  Check out the full write-up as well as a few schematics and videos over on Philo's site. (The picture is of Philo's setup controlling a few other old motors off of Port A)

» Read more: Constant Power from NXT Port A

Philo has created a unique remote control for his NXT bots.  Using a Mindsensors acceleration sensor he has created a remote that responds to tilting in various directions (similar to Nintendo's Wiimote, hence the name).  In addition to the 3-axis of control provided by the sensor, he also added on a wheel and a button (based on a NXT motor and a touch sensor), allowing for secondary funtions to be controled.  Philo is kind enough to not only provide pictures of the remote, but also sample programs and building instructions.  So if you'd like to build your own, or just want to have a look see, head over to his site.

» Read more: Philo’s NXTiiMote

Making a bot that can climb over tall objects has always been a fun challenge to undertake.  One design that is quickly becoming a favorite is the two tracked bot with two 'flippers' that can lift the bot up to climb over objects.  This design which was inspired by a few real life bots, including iRobot's Packbot, is quite versitile and allows for climbing over objects almost as large as the flippers themselves.  David Astolfo has created a similar design.  Using the big tracks from the Snowmobile kit he's created quite an impressive design.  Sadly it is perhaps too impressive as it is apparntly too heavy to work very well.  Another problem he has is the lack of traction on the plastic tracks.  This is a very common complaint both with the new tracks and the old ones, they just don't provide very much traction.  Perhaps someday Lego will make rubber inserts for the tracks.  Check out all the pictures and videos over at Plastibots.com

» Read more: David Astolfo’s UNV

Michael Gasperi, Philippe E. Hurbain, and Isabelle L. Hurbain have put together a new book on the NXT called ExtremeNXT.  In the book they show you how to build a Simon clone using the NXT, as well as a few LED's and switches.  The book teaches you to program it using NBC, and now Michael has posted over on his site instructions on how to program it using NXT-G.  Sadly you still need to buy the book to learn how to build it, but the instructions are an excellent example of some advanced techniques for the NXT-G.  Check it ou over at ExtremeNXT.com

» Read more: NXT Simon

User Kevinsquest has devised this rather unique Lego Heart Rate monitor.  It uses a custom made sensor to read the pulse in your finger, as well as a sound sensor to start the program.  The NXT then measures the beats per minute and displays them on the rolling wheels. There's a ncie little video over on Brickshelf that shows the device in action.  Unfortunatley no further information on the custom sensor is given.

» Read more: NXT Heartrate Monitor

Just in time for Easter, David Schilling has put together an egg decorating bot.  Quite an ingenious design, it uses a handful of markers to draw patterns on the eggs.  It uses a few very slick inovations, my favorite being the turntable that the egg is mounted on.  The turntable is constructed of a pair of hailfire droid wheels with Lego balls in between.  He also uses the sliding worm gear trick to let one motor both switch pens, and engage them.  Check out the post on Lugnet, which has a link to the Brickshelf Gallery, as well as a few Videos.

» Read more: EggArt, An NXT Easter Egg maker