APPENDIX A ■ APPENDIX AAfter wiring and soldering up a couple of micro switches (see Figure A-4), they were installed in the
line-following robot brothers. One robot spun in circles, and the other robot followed dark lines but not light
lines. The switches made nasty, horrible crunching sounds when toggled.
Figure A-4. Disfigured micro switches
Figure A-5. Melted (left) and cracked (right)
Upon closer inspection, I realized the switches had melted and cracked during soldering (see Figure A-5).
I don’t know whether the switches were of poor quality or if I held the soldering iron against their leads for too long.
Larger pieces of metal do take longer to solder, so I believe the manufacturer should use material that
can withstand being heated for a reasonable period of time. A soldering gun is capable of quickly delivering
large amounts of heat to a joint before the heat has time to conduct away and cause damage. In comparison,
most hobbyists use a soldering iron, which is more precise and is designed to avoid damaging tiny chips. In
the case of this particular switch, a soldering gun or more powerful soldering iron would have worked better.
Regardless, due to this failure, I didn’t end up recommending this particular model of switch in the book.
Popping Multimeter Fuses
In the years I’ve practiced electronics, I’ve never blown a fuse in a multimeter (see Figure A-6).