Motion detecting window closers keep train noise at bay

motion_detecting_window_closers

[Ed Rogers] has the unfortunate privilege of living right next to a set of train tracks, and as a man who holds his sleep in high regard, he needed to find a way to keep the noise in his bedroom to a minimum. To combat the sound of passing trains, he built himself a system that automatically closes his windows when a train passes by his apartment.

The setup relies on a web cam, which uses motion-sensing software to detect a passing train. The video is analyzed by a computer in his room which passes a message to an Arduino when a train is near. The Arduino then sends a pair of window mounted linear actuators into action, slowly (and quietly) shutting his windows.

The linear actuators move pretty slowly as you can see in the video below, but we doubt that matters. Since it looks like [Ed] lives in a slow zone, it likely takes quite a bit of time for a freight train to pass, making the 40-second closing period more than reasonable.

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DIY Segway recycles broken electric scooters

[Petter] built himself a DIY Segway out of a couple of cheap electric scooters. We’ve seen a couple of very nice Segway builds in the past like the all analog Segway, or the creepy walking version, [Petter]’s Segway build seems like it would be a useful human transport device.

The motors, chains, gears, and wheels are scavenged from a pair of electric scooters. Steering left and right is accomplished by tilting the handlebars left and right. The handlebars themselves are attached to the joint at a base that allows them to be taken on and off. We’re thinking this would be great for throwing a [Petter]’s Segway in the trunk of a car – a design feature the original Segway doesn’t have.

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Intro to DC motor control using the SN754410

So your electronic hobby skills are coming along quite nicely but you’re not very comfortable doing more than blinking a few LEDs. Now’s a good time to try something new by driving a couple of DC motors.

You probably know that you can’t just hook these up to the pins of your favorite uC and call it good. The motors draw a lot of current (especially if they’re strained in lifting a heavy load) which would burn out your logic circuitry. Add to this the excess induced current that is generated when a spinning motor is shut off and you’re going to need a control system that can handle these dangers.

Enter the h-bridge motor driver. [Chris] has guided us through the process of building and using a H-bridge in the past. This time he’s using a motor controller that has four half H-bridges built into it. He hooks up the SN754410 to two motors, giving him speed and direction control for both based on the duty cycle of a PWM signal entering the chip for less than $2.50. Check out the video after the break for an overview of his methodology, then work your way through the multi-page post that he recently published.

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Modifying a cheap robot arm for arduino control

Many a hacker has put together one of those cheap $30 robot arm kits you can get in just about any store with a section labeled, “science”.  In an ongoing search for a cheap robot arm, [Larry] decided to modify one of them to be controlled with a PC through an Arduino. The article doubles as a really basic tutorial on dc motor control. On the site he gives a brief explanation of how to use H-bridges and a good explanation of how he wired them up for this purpose. He eventually goes on to add a processing interface to the project. The next step would be figuring out how to add some kind of position feedback, such as encoders. Though, if modifying an arm is not your style, [Larry] has another cool article on rolling your own robot arm cheaply with some foam board and hobby servos.

Building a brushless motor controller

brushless_motor_controller

Brushless motors and the way in which they are controlled can be a bit of an enigma to those just starting out in hobby electronics. [Andrew] from spingarage thought it would be helpful to put together a quick tutorial showing how he built a simple brushless motor controller in about a day’s time. He constructs everything on protoboard from components he acquired at RadioShack in order to demonstrate the ease of sourcing parts and building a brushless motor driver.

While he skips most of the theory behind brushless motor control itself, he does touch on the signaling these motors require for movement as well as how motor position is determined. Specifically, he expands on how half-bridges can be used to create the sine wave signaling required by a single motor input, as well as how three of these can be combined to drive a brushless motor.

The post is the first in a series of posts about brushless motors, so we should see some code examples and some practical applications in the near future.

Reversible relay-based motor controller

[Nothinglabs] built this motor controller as an alternative to using an H-bridge. They call it the RAT controller which stands for “Relay and Transistors”. You can see above that two Darlington transistors along with their base transistors allow logic signals to switch the relay on and off, driving the motor in one direction or the other based on the open or closed state of the relay. See it working in the video after the break.

It’s a nice little workaround with few parts, but because the relay is mechanical there will be a short lifespan when compared to solid-state motor controllers. That’s okay, because the motivation here was lack of parts on hand, rather than an increase in performance. It’s also worth mentioning that all of these parts can be purchased at your local Radio Shack when you don’t want to wait for component orders by mail. We certainly appreciate that it takes far few components than [David Cook’s] H-bridges. His designs are our favorite – we’ve used them in our own projects – but for quick and dirty you can’t beat five components and the short assembly time needed when using this type of dead-bug style soldering.

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Roll away clock becomes a programmable rover

The parts laid bare in the picture above all make up a roll away alarm clock that flees when you don’t get out of bed. It’s an interesting idea, but considering most folks don’t sleep on hardwood floors we can understand why [TheRafMan] was able to pick this gem up for under $5. That’s quite a deal because there’s a very usable LCD module at the top. But for this hack, he focused on using the gearhead motors to make a programmable rover.

In order to make this programmable [TheRafMan] had to add a microcontroller. He chose an Arduino variant, called the Ardweeny. It’s a board that piggy-backs the ATmega328. But he didn’t use a stock Ardweeny; he’s altered it to play nicely with jumper wire. The uC is able to interface with the gearhead motors thanks to an L293D h-bridge motor driver chip. As you can see in the clip after the jump, the rover can now be driven around using a Wii Nunchuck or via a USB connection. If you’ve got a Bluetooth module lying around it wouldn’t be hard to make this a wireless solution that can be controlled with the accelerometers in a Wii remote.

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