[Ladyada] takes some time out of her day to explain the common options available for connecting projects through USB. You may be thinking that you already do this with an Arduino. Well, yes and no. The Arduino uses one of these options, an FTDI chip that handles the USB on one side and spits out microcontroller-friendly voltage signals on the other. This chip can be used with your projects, a topic that [Phil Burgess] covered in great detail.

In the video after the break you’ll also hear about USB to serial converters which connect to the Universal Serial Bus and output the traditional 12-20V serial signals (with the exception of cheap knockoff cables like the one from last week). These need to be stepped down to 5 volts or less using a MAX232 chip to work with your project.

Finally there’s the option of using a microcontroller running the V-USB firmware package. This is how the USBtinyISP works and I’ve used it in my own projects to build a LIRC compatible IR receiver.

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The line between serious research and well-executed hacks has been getting pretty blurry lately. The device above could have been designed in your basement but it actually comes from researchers at the University of Washington. They are working on low-power home automation sensors for monitoring things like humidity, temperature, air quality, and light. The key point in their research has been the use of a home’s electrical system for wireless communication. Operating at 27 MHz has proven quite efficient to the point that one of these modules placed within 10-15 feet of an electrical run can communicate with the rest of the home, powered only by a watch battery projected to last ten years.

That’s kind of exciting, it’s a heck of a lot easier to produce and distribute a set of small boards like this than to run communication wiring throughout the house. Now we just need to pair this with the Air Force’s parasitic power work and there’ll be no need for a battery at all.

[Thanks Sidhant]

[Doug] needed to update his watering system to comply with his city’s new water saving ordinance. The old system wasn’t capable of being programmed to water only on even or odd calendar days. Rather than purchase a replacement he decided to build his own sprinkler controller. It needed to switch 12V solenoids, a job that’s not too hard to design for. Rather than re-invent the wheel, he modified a previous controller design. It is basically an Arduino and Ethernet shield on a his own etched board. In addition to the ATmega328 and an ENC28J60 (for ethernet connectivity) there is a bank of transistors to drive the watering solenoids. Now he has a web interface that controls the watering schedule and is fully in compliance with the new city code.

If you need another way to save when watering your grass you should take a look at the sidewalk-avoiding sprinkler.

Having experienced quite a bit of trouble getting the Nintendo Wii remotes to work reliably with his home theater projector, [Sprite_TM] designed his own sensor bar replacement. If you’re not familiar, the Wii remotes have an infrared camera in the tip that sense two IR LEDs in the sensor bar that resides above or below your television. The problem is that if you’re too far away, the points of light are not where the remote expects them to be and the cursor will not perform as expected. Since this is a huge projected display it’s no surprise that the player is further away from the screen than the system was designed for.

[Sprite_TM's] solution was to build a projection system for the two IR points. The unit in the picture above is a driver circuit with two IR emitters mounted on a heat sink, each with its own reflector. The reflected beams are shined through a Fresnel lens and projected on the same wall as the TV image. The viewer will not be able to see this light as it’s in a longer wavelength than the visible spectrum. But the Wii remote performs beautifully now and the replacement sensor bar is happily mounted out of sight above the projector.

While hobby brush motors are pretty cheap now adays, there’s always that feeling of why replace when you can rebuild and reuse. As such [John Carr] presents how to change the brush position in motors to revive a dead motor. So long as the motor dies from natural causes commutator wear, the idea is the brushes can be moved along the axes and fixed to a new portion of commutator that’s not worn at all. [John] also goes through the details of some tricky reassembly, but we think to make this complete a guide on brush replacement and commutator replacement might be in order hint hint.

[Shay] and his friend built some battling robots for a school project. Instead of destroying each other’s robots with saws or torches, they are playing laser tag. Each robot sports an eeePC, a laser pointer on a movable arm, and some photoresistors. The goal is to get your laser to hit the other robot’s photoresistor to lower its health towards a kill. A server keeps track of the bout, monitoring shot fired because you won’t find unlimited ammo in this game. As for piloting the rig, the netbook webcam is streamed to a control station with an Xbox 360 controller for motion, aiming, and firing. Check it out after the break.

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This laser message scroller is built with inexpensive parts. The heart of [Raul's] system is a spinning pill-box with eight mirrors on it. Each redirects the laser to a different vertical portion of the projection surface. There are eight small arms on the apparatus that each break the beam of an optical sensors as it spins, facilitating the precise synchronization needed to generate the projected image correctly. In the video after the break we can make out what looks like an Arduino controlling the system. This makes sense as it’s easy to connect the laser pointer and sensor, and the USB connection allows for the streaming of messages to the system.

Want to see a more complicated setup? Check out the POV laser projector from a few years back. Read the rest of this entry »

Behold [Retromaster's] field programmable gate array implementation of an Atari 2600. The processor and video chip have both been built in the 100,000 gate Spartan-3E FPGA, with connectors for audio, video, and a Sega controller. The output signals are generated using two DACs made from R-2R resistor ladders, much like the project we saw in August. [Retromaster] included functionality for the system switches (difficulty and select) in the controller itself. There is VHDL code and board details available if you want to make one of your own. To help in making that decision we’ve embedded video of it after the break. Read the rest of this entry »