Laser trip wire – the bare essentials

[Gordon] sent us a tip about this simple laser trip wire system after reading yesterday’s post on a more complicated laser security unit. That build did a lot to provide functionality, such as a system to disarm the trip wire, and a robust light detection circuit. This time around there’s more happening with smoke and mirrors than with electronics.

[The Timmy] built this simpler version based on a laser trip system from Afrotechmods (video of that one is embedded after the break). He had a bag full of small square mirrors which he attached to a wall with some poster putty. A laser module shines a beam of light onto a cadmium sulfide sensor after it bounces around the optical network for a while. That CdS sensor controls an N-channel MOSFET, switching it off when light is detected and on when the intensity of the laser is absent. This example just turns an LED on and off, but since it uses logic-level voltages you can choose to add a microcontroller to the mix if you have other plans in mind.

[Read more...]

Bathroom mirror HUD displays time and weather

mirror_hud

By and large, the standard household mirror is one item that has not made much real progress over the years. They hang on the wall reflecting light, and that’s about it.

A few years back, some students studying in the Department of Interaction Design at Chalmers University sought to enhance their morning routine with an interactive mirror. Their project was constructed using a two-way mirror with several Arduino-driven LED displays embedded behind the glass. Once a hand is swiped past the pair of embedded light dependent resistors, the display is activated. Subsequent hand swipes trigger the mirror to toggle between the different modes, providing the user with the current time, weather information as well as a toothbrush timer.

The project writeup is quite thorough, including plenty of source code and information on some of the components they used. You can take a look at their work here (PDF).

Check out the interactive mirror we featured that served as inspiration for their project.

[Thanks Emil]

[Read more...]

8×8 LED infinity mirror

[chromationsystems] put out a couple instructibles on building infinity mirrors. One with an 8×8 array of LEDs and one with a 32 LED ring. These are very well  documented covering the construction of the mirror enclosure as well as the circuit and code. The effect is quite nice. The 8×8 array is interesting, we haven’t seen that before. These would make a fine addition to any geek cave/electronics lab. While it looks like these were basically advertisements for a product he sells, you can definitely make your own from his instructions. We like this kind of advertising.

Disco Death Ray

Wielding the power to melt glass or instantly ignite most day to day materials can be intoxicating pretty fun. With a little math, a lot of patience, and 5,800  1cm pieces of mirror, this build requires welding glasses just to look at the 1-2cm focal point. With an idea rumored to date back to Archimedes, this more portable parabolic project is perfect for your home burning needs. Unfortunately, this setup seems to have burnt itself to death at some point, though that makes room for version two, which will reportedly bump the mirror count to 32,000 or so.

There are plenty of other ways to make a death ray out there as well, including using lasers or lenses. Think you have a better tool of destruction? Be sure to tell us about it.

Laser marquee projector

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 more...]

Holy robin trap Batman!

[Matt Meerian] introduced us to his kludge of cardboard, tape, mirrors, and electronics in the form of a clever non lethal robin trap. Whenever a pesky robin would enter the box, a sensor is triggered, the solenoid drops a lid, and the bird is contained (and we assume taken far away after that).

Of course the plan backfired; we wont spoil what happened, but you can click the link above to find out.

Related: Arduino Mouse Trap

Bonfire – interactivity using pico projectors and cameras

This video shows a demonstration of Bonfire, an additional interface for computers. It consists of a pico projector and camera hang on the back of either side of a laptop. The projector displays information on the table top and the camera monitors the area for interaction. It can recognize your hand or objects such as a smartphone or headphones and react accordingly. An accelerometer in the laptop picks up tapping (we’d guess you have to tap pretty hard) and there is also support for gestures. This was presented at 2009 UIST and unfortunately the published article is not available for free [Thanks for the link Ciflet].

We hope to see this kind of thing, as well as skin based input, come to the market some day. Until then, you’ll have to build your own.

[via Procrastineering]