Page 77 - Amphibionics : Build Your Own Biologically Inspired Robot

Amphibionics 04 3/24/03 8:23 AM Page 56
FIGURE 4.5
Oscilloscope display of
a 1.4-ms and 6.0-ms Amphibionics
pulse train.

An unmodified servo has a rotational radius limited to approxi-
mately 180 degrees. For our application, we will need a full 360
degrees of continuous rotation. This is accomplished by taking the
servo apart, removing a mechanical stop as well as removing the
potentiometer, and replacing it with a fixed resistor network. Note
that there may be differences between servos built by different
manufacturers. The concept for modifying servos is basically the
same for all servo types. Depending on the make, you may have to
improvise and stray from the procedure a little. The servo in this
example is a JR NES-527. The parts needed for this procedure are
listed in Table 4.1.

TABLE 4.1 Part Quantity Description
Parts Need for
Resistors 4 2.4-K resistors, 1/4-watt
Modifying the Servos
Heat-shrink tubing 3 inches Heat-shrink tubing

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