frequency

On any given day you can find a miniature multimeter in my pocket. These devices are the equivalent of a Leatherman for electronic enthusiasts. (The Leatherman would be in my other pocket.) Most of the time, I want to check the voltage of a deep-cycle battery in my electric-vehicle or troubleshoot a problem with a solar photovoltaic system. But multimeters do things like current measuring, resistance and continuity, which make them handy for solving problems ranging from home wiring to electronics repair. (For more on what do do with one, check out Ladyada's multimeter tutorial on adafruit.com). I've used a number of "portable" units over the years, and while many are anything but, one jumps out as my solid favorite. Here's my take on a few popular units.

If it were up to us, everything would be faster by at least one order of magnitude, but the laws of physics often get in the way of unlimited speed and efficiency. Take fiber optic data transfer: the pulses of light carrying data through the worldwide network of fiber optics move really fast, but alas, cannot go any faster than they do. However, scientists at Cornell University have figured out a way to pack more data into those pulses of light, using a system they're calling a "time telescope," which has the potential to increase fiber optic data speeds by 27 times.

When you´re tearing downhill on your snowboard, it´s a little distracting to take off your glove and dig out your iPod just to, say, hit pause. Instead, build this simple radio-frequency ID system and control your iPod by waving your hand in front of your coat.
A tag sewn into your glove sends instructions to a reader stashed in your pocket.
Unwire Your iPodCost: $161Time: 6
HoursEasy | | | | |
Hard