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28 November 2003

A Seasonal Source for Cheap Robot Parts

by Laszlo Morocz

We're at the time of year when every Radio Shack in the US is full of radio-controlled cars. The week after Christmas their prices will begin to drop like rocks. As the New Year wears on, they'll be getting more and more desperate to dump inventory. Last January I was able to get a radio-controlled 4WD truck for 2/3 off the pre-Christmas price.

It's quite possible to build a Sojourner type robot on one of these chassis.Alternatively, the thing could be disassembled for a parts bonanza that would cost many times more than the purchase price if bought individually.

There is, of course, the radio control system. (Note that by substituting a correctly tuned, directional receiving antenna you can significantly extend the system's range without violating any FCC regulations). Then, there is the mechanical assembly. My bargain had a fully-sprung chassis with rubber tires that could easily cope with grass and mud.

Once the ugly body was removed and discarded, there was room to mount an instrument table (a piece of plywood). This table has held, among other things, a 2-meter FM transceiver and packet station, a 2.4 GHz camera and antenna, a GPS receiver, a bigger battery and so on. One day the remote control function will be taken over by a computer. Further in the future it'll be incorporated onto the instrument table.

Whether parted out or converted to a Sojourner, these cars are a bargain (at least in January). And since they come in several sizes, it's possible to find one for every pocketbook.