Building a mechanical counter out of scrap wood

Watching [Matthias Wandel] fabricate this mechanical counter from scrap wood is just fascinating. He likens the mechanism to the counters you would find on decades-old cassette tape players.

You may recognize the quality of [Matthias’] work. We’ve seen several pieces, but his binary adder is still one of our favorites. This project gives us a very clear view of the development and fabrication process. He even posted a detailed guide if you want to build your own.

He started by prototyping a mechanism to increment and decrement the counter. With that proven design he started laying out the rest of the gears. These were cut from plywood scraps he had from other projects. Notice the small gears seen above which are missing parts of some teeth. Those sections were removed using a drill press with a Forstner bit. The missing teeth cause the next digit over to increment more slowly, resulting in a 1/10 ratio. This part of the design is demonstrated about three minutes into the video after the break.

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Birthday badges teach kids how to solder

[Ian Lee, Sr] wanted to have an educational activity at his younger son’s birthday party. These were uncharted waters for him as he doesn’t remember education taking place at his own early birthday parties. But he came up with a great idea, with was to teach soldering using interactive badges which each guest could assemble themselves. He needed about twenty, so he tried to keep the BOM as small as possible. But that didn’t mean skimping on features.

You can see the black LED-type package on the left of the assembled badge above. This is an IR receiver whose counterpart transmitter is on the right side of the board. When two of these get within 6-8″ of each other the start talking back and forth. There is no microcontroller involved, instead the system relies on a multivibrator design. One of the red LEDs at the corner of the ‘smile’ is always blinking. When it is off, the IR transmitter is powered. This is picked up by another badge’s receiver, which lights the second ‘smile’ LED. You can see this happen in the short clip after the break.

Although there are relatively few components that went into this, it would take the kids a long time to put them together as they’re just learning. [Ian] and his eldest son soldered on all of the components except for the resistors beforehand.

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Robot stroller lets baby steer without mowing down other toddlers

We’ve seen strollers and car seats that have a steering wheel for the baby to play with (like in the opening of¬†The Simpsons). But what we hadn’t seen is a stroller that allows baby to actually steer. You might think that a putting a motorized vehicle in the hands of someone so young is an accident waiting to happen. But [Xandon Frogget] thought of that and used familiar hardware to add some safety features.

The stroller seen above is a tricycle setup, making it quite easy to add motors to the two rear wheels. These are controlled by a tablet which you can see nestled on the canopy of the stroller (look for the light reflected on the glass). This interfaces with two Kinect sensors, one pointing forward and the other pointing back. They continually scan the environment, looking for obstacles in the stroller’s path. You can see [Xandon’s] little girl holding a Wii Wheel, which connects with the tablet to facilitate steering. A test run at the playground is embedded after the break.

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Developing a thermostat for a heat pump that only has a timer

The heat pump which cools [Chris LeBlanc’s] home lacks the sort of control he was looking for. It’s just got a timer, which switches it off automatically. He wanted to the ability to schedule the cooling cycle like you would with a thermostat-driven arrangement. He ended up build his own controller to automate the cooling process.

The heat pump came with an IR remote control which provides the access point for the project. [Chris] set out to emulate the remote protocol which saved him the trouble of having to crack open the unit and wire in a controller. He went with the IR Toy from Dangerous Prototypes as this device is able to record and transmit IR signals — it’s basically a universal remote for your USB port. His Raspberry Pi, seen to the left, controls the system. It’s connected to the red IR Toy board via a USB hub which is used to interface a WiFi dongle as well. The system works alongside Google Calendar to allow [Chris] to schedule his home’s cooling just by adding an appointment. A Python script queries the calendar, then selects and sends the appropriate IR command. He shows off the build in the clip after the break.

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Building a thermal imaging sensor from scratch

[Rob] lives in a 100-year-old house, and with these antique lath and plaster walls and old window frames comes a terrible amount of drafts. The usual way to combat this energy inefficiency is with a thermal imaging camera, a device that overlays the temperature of an object with a video image. These cameras are hideously expensive so [Rob] did what any of us would do and built his own.

The build centers around a Melexis MLX90620 far infrared thermopile that can be had for about $80. Basically, this sensor is a very, very low resolution camera (16×4 pixels) that senses heat instead of light. By sticking this sensor on a breadboard with an Arduino Mini and WiFly network adapter, [Rob] is able to pull the data down from the IR sensor to his iPhone and overlay it on the feed from the camera.

The result, as seen in the video above, is a low-resolution but still very useful thermal imaging camera, perfect for looking for cold drafts in an old house or tracking down [Arnie] just like a Predator.

Tip ‘o the hat to [Ronald] for sending this one in.

Giving an apartment keyless entry

The key for [rybitski]’s apartment is a copy of a copy of a copy, and the landlord lost the original key years ago. The lock itself still works, but opening it with [rybiski]’s key is a chore. He wanted to make it easier to get into his apartment, and with Arduinos and such he figured he could make a keyless entry device for his front door.

After figuring out how to open his deadbolt with an Arduino and a rather powerful servo, [rybiski] looked into wireless control options. He found a keyless entry remote, complete with receiver, that integrated perfectly to just about any microcontroller project.

After mounting the Arduino, receiver, and servo on a piece of plastic, he attached his contraption to the deadbolt. In the video after the break, you can see his key fob remote locking and unlocking the deadbolt, all without jamming an ill-fitting key into the lock.

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Turning the Hexbug spider into a line-following robot

You may be familiar with the Hexbug Spider, a small electronic robot toy sold at Target and Walmart for $20. While they’re able to be commanded to move forward, backward, and spin around on a dime, there aren’t any external sensors to make it really exciting. [Eric] sought to remedy this and came up with a line-following board replacement for the Hexbug Spider.

The stock Spider has a small circuit board that allows for the control of two motors with a remote. [Eric] removed this control board and replaced it with his own, powered by a TI MSP430 microcontroller. On this board, [Eric] included a pair of IR LEDs, able to detect the path of a white line drawn on the ground. With just a little bit of code, [Eric] made his $20 Hexbug Spider into a very cool looking robot.

[Eric] figured out how to improve his robot toy, but the power of the MSP430 microcontroller he used doesn’t limit him to only following lines. By using an MSP430 Launchpad, anyone can upload new code to the improved Spider, and even add new sensors to this creepy walking robotic toy.