Page 399 - Robot Builder's Bonanza

368 BUILDING ROBOT ELECTRONICS— THE BASICS

Figure 30- 3 Reading the value of a
resistor. Be sure not to touch the test probes,
or the resistance of your skin will influence
the result. When using a meter without
autoranging, adjust the range dial just
above the expected value.

• None of the projects in this book involve working directly with AC household current—
everything is battery- powered. Should you wish to use your multimeter with an AC circuit,
be sure to consult the instruction manual that came with the meter for important safety
precautions.
• Be very careful when selecting the operating mode of the meter. Never accidentally set the
meter to read resistance and then test a voltage source. Your meter could be damaged
otherwise or, at the least, burn out a fuse if it is so equipped.
• Turn off the meter when you’re done with it. This preserves battery life.

ON THE WEB: USING A LOGIC PROBE
Another handy tool for testing electronic circuits is the logic probe, so called because it verifies
signals used in logic circuits (anything that deals with digital 0s and 1s, LOWs and HIGHs).
These kinds of circuits include microcontrollers. I’ve prepared a free “Logic Probe 101” article
on the RBB Online Support site (see Appendix A) that provides more information.

SOLDERING PENCIL
You can build robots without owning a soldering pencil, but it’s darned difficult to do anything
more advanced than just put together basic kits. Even if you never plan to make your own
circuit boards for your robots, you still need a soldering pencil for basic electronic chores, such
as attaching wires to motors. My trusty soldering pencil is shown in Figure 30- 4. I’ve had it
for years, and I have built many robots with it.
Note that I’ve called it a soldering pencil, not the more old- fashioned “soldering iron.” For
most electronics work these days, you want a slim- line modular soldering pencil. It’s smaller
than the soldering iron your dad (or granddad) used to build the family’s Heathkit color TV kit
way back when, and it’s designed specifically for the more delicate components common in
modern electronics.
Not only do you want a soldering pencil, you really want the kind that lets you change the
tip and heating element. Why? These are the parts that, over time, wear out. Rather than buy
a whole new soldering pencil, you only have to buy replacement parts.

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