Nuts and Volts - March 2009

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■ FIGURES 2A, 2B, and 2C. The LEGO Spybotics remote control module sports a nice AAA battery box, IR transmitter, pushbuttons, and an LED.

HARD DRIVE HARVEST

One item that is almost always able to yield some useful parts after being opened up is the venerable computer hard drive. Some older drives (especially older 5-1/4" MFM/ST-506 type drives, and some 5-1/4" floppy drives) contain very nice stepper motors (Figure 3), gear trains (Figure 4), sensors (Figure 5), and other useful bits for the hobbyist. If you can't find this vintage of hard drive, don't despair! Similar parts can be found in most CD/DVD ROM drives.

Most all modern 3. 5" hard drives (Figure 6) contain recyclable and useful parts including very powerful neodymium magnets, .100" jumpers, precision screws, bearings, and other hardware (Figure 7), as well as the shiny data platters. Disassembly is simple, quick, and fun and the parts yielded are usually useful and worth your time to harvest.

Another item I hunt for at thrift stores is the oft-maligned wall wart (given its name due to its appearance

as an unsightly growth on the wall). It always seems I need a specific voltage, amperage, plug type/size, or gender that I don't have on hand. I've been known to walk out of a thrift store with 10 or more of these babies (Figure 8). This way, I can always dig out an acceptable, portable power supply for a small experiment.

In the Austin, TX area, wall warts at thrift stores typically go for between $0.50 and $2.00. You can also often discover orphaned "brick style" power supplies commonly used to power laptop computers. These tend to be higher voltage/amperage and can sometimes produce multiple supply voltages so they have the potential of replacing a couple of wall warts. Keep your eyes peeled (and possibly take a magnifying glass with you) as the writing on these can be very small.

KEEP IT ON THE DOWN-LOW!

In most cases, my idea of "low cost" is below $100. I know this will

probably be different for each person, but I stay with this number for two reasons. One: sub $100 purchases are less likely to be picked up on the radar by a "significant other." Two: if you are discovered, it’s easier to recover from because it’s about the same cost as a nice dinner out for two.

So, with $100 as the benchmark, can we really buy much in the way of "new" robotics parts or projects? The answer is a resounding YES!

Compared to a couple decades ago when a useful robotic training system cost thousands of dollars (think HERO-1), today's robotics offerings are immensely powerful with exceptional price/value ratios. For example, Parallax offers a complete two-wheel robot kit with their ever-popular BASIC Stamp II at its heart that retails for $99.99 (careful online shopping can nab one for $75 or less!).

The "Scribbler" (Figure 9) is a real programmable robot with the ability to move, use sensors, evaluate inputs, make sounds, and even draw pictures (hence the name). It also includes a