555 Timer

DIY Hacks & How To’s: Laser Tripwire Alarm

DIY Hacks & How To’s: Laser Tripwire Alarm

No security system is complete without lasers. We have all seen movies where the main character has to get past a high tech security system and there is always a room full of lasers somewhere.

So in this project, I show you how to build a laser tripwire alarm. All you need is a cheap laser point, a couple of mirrors, and a few dollars of electrical parts. With this you can cover an entire house with an array of light beams. If any one of them is crossed it sets off your alarm. And unlike in the movies, these lasers are practically invisible.

Touch Sensor Workshop with Mark Frauenfelder at Engadget Expand

Touch Sensor Workshop with Mark Frauenfelder at Engadget Expand

If you make it to Engadget Expand in New York this weekend, check out Mark Frauenfelder’s workshop Sunday, Nov. 10, from 10-11am. He’ll be making a simple circuit using a 555 timer chip, an LED, and some wire and then creating touch sensor pads by painting them on a piece of paper with conductive ink. Once the paint dries, you hook it all together and watch the LED light up when you complete the circuit by touching the sensor. You will learn how to build the basic electronic circuit as well as tips and tricks for designing your own painted tough sensor.

Top 10: 555 Timers

Top 10: 555 Timers

To mark the recent passing of Hans Camenzind, we are running a 555 mini-retrospective this week. Today I’ve rounded up some of my personal favorite 555 content from our archives, arranged in arbitrary top 10 order. Many of these are “fun” or “meta” 555 type posts. We’ll be following on later in the week with more circuit-specific 555 coverage. Stay tuned!