Echo box shakes itself to make sound

The echo box performs exactly as its name implies. If you tap out a rhythm on the lid, it will tap the same thing back to you. Except it isn’t tapping to make the sound, but vibrating.

The concept is similar to the Knock Block. In that hack, a piezo element detected a rapping on the wooden enclosure and repeated the rhythm by striking the lid with a solenoid. This iteration also uses a piezo element as the sensor. In the image above you can see a segment of PVC pipe in the upper corner. That houses the element, sandwiched between two pieces of wine bottle cork. That cork just touches the lid of the box, transferring the vibrations to the element.

The sound is created by a motor with an offset weight on its spindle. When the motor spins, it causes vibrations. The enclosure is one wood box inside of another, so the vibrating motor cause the inner box to shake against the outer one to make noise. Hear it for yourself in the clip after the break.

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Flash trigger with programmable delay

Here’s a flash trigger with a programmable delay. These triggers are often used to capture quick events like a balloon popping. The technique takes place in a dark room with the shutter open. When the event is triggered the flash illuminates the scene and an image is captured. Because these require precise timing it has typically been a chore to synchronize the event, hence solutions like using a pressure plate.

This build, which centers around a PICAXE 08M, allows the photographer to use any trigger they desire, but adds a delay. The box above shows the apparatus set up for a 42 millisecond delay. So if you’re using the sound of the balloon pop as a trigger, you can hold the flash off until the event really gets going.

[Thanks Two Part Epoxy]

SD activity indicator for Wii

[DeadlyFoez] wanted to know when the SD card in his Nintendo Wii was in use. He built and indicator LED using a PICAXE 08M and added it next to the SD slot. He uses one pin of the microcontroller to monitor the voltage on one pin of the SD card slot. That pin has a specific value when the card is idle, which rises when it’s in use. He didn’t share the details of which pin he’s sampling, or what the magic number from his source code actually represents. But the concept should be enough of a start if you want to do this one yourself. Watch it go blink-ity-blink in the clip after the break.

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Adding pan and tilt to a webcam

[Brent] and his wife wanted a way to provide more family time for Grandparents that lived far away. They tried a webcam, but their daughter just didn’t oblige by staying in the frame. Instead of chasing her around the room with with the camera¬†he added pan and tilt features to the device. He settled on IR control using a common television remote, similar to our USB remote control receiver tutorial except that it drives servo motors instead of forwarding signals over the serial connection. [Brent] used a Picaxe 08M, connecting two servos together as a base on top of the project box. If you try this yourself there’s a lot of room to grow. Once you’ve assembled the hardware it wouldn’t be too hard to make this web enabled so that Grandpa can click on a web interface to look around the room.

PicAxe LEGO tank

[TomTheGeek] built a LEGO tank with a PicAxe controller. Locomotion is supplied by a Lego Power Function motor controller. He cut an LPF extension wire in half so that he could patch into the PWM signals without altering the motors themselves. You can make out the control circuitry and a small breadboard in the tank’s turret. [Tom] added a laser pointer to the tip of the barrel but we’d like to see an IR LED. The tank is controlled by a infrared remote control and adding TV-b-gone functionality to the toy would create something of a Rube Goldberg feature for turning off the tube. But alas, there’s no programming space left for that as the PicAxe 08M is limited to 256 bytes.

There’s a video after the break of this little demon tracking its way around the room. This is a nice addition to the other LEGO tank we saw a while back.

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Harry Potter Marauders map realized


After reading about cheap wireless for microcontrollers, [Leigh] left a comment about his Marauders map. Much like the Harry Potter version, whoever holds the ‘map’ is able to see the location of the ‘marauders’ within certain bounds. Unlike the magical version however, each person being tracked needs to hold a PICAXE 08M, GPS, and 433.92MHz transmitter: while the map needs a computer running his Python script and a receiver of the same frequency. It has the potential for locating people, but we feel it might be better off in a swarm robotics setup.