Reader [Joshua] sent in his latest project. using a sonar rangefinder, an Arduino, and some clever programming, he’s made is computer react to his distance from it. As you can see in the video after the jump, he has programmed it to change text size and background color depending on his distance from the screen. While he admits that his implementation doesn’t seem immediately useful, there’s lots of potential there. We can actually think of several uses. What would you use it for?
[Lynne] had this crazy idea to build a piece of clothing that would give you feedback about your surroundings using sonar. She started with a carefully selected thrift store jacket. She wanted something that looked good and also provided plenty of places to hide electronics. She used the LilyPad system, with a vibration pad and a sonar range finder. When the system detects an object within a certain distance directly in front of the wearer, it warns them with some vibration. Not only is it practical, it looks pretty cool too. Did we mention she designs clothing?
She notes, in the comments section, that while it can detect an obstacle, it cannot detect a void. How could she detect a drop in the floor or a step down?
[Tony Messina] had been fascinated with bat’s echolocation since he was a kid. After he retired, he decided to act on this fascination and built a simple bat detector.
The simple bat detector uses frequency division to lower the bat’s chirping to a frequency we can hear. For example, if a bat is calling at 91kHz the system will divide it by 16 and put out 5.7kHz. The system is digital, so all amplitude is lost. You’ll just hear clicks like a Geiger counter. Being digital has its advantages though. Unlike similar analog devices that have to be tuned to a small frequency range, the simple bat detector can detect a much wider window.
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