APPENDIX A ■ APPENDIX A
In writing a book, a lot of time is spent researching and validating facts. Since it’s going to be on paper
for a long time, with my name associated with it, I want the information to be reliable.
For the transistor chapter, I measured transistor gain in a multimeter transistor test socket. I wanted to
verify that the multimeter was displaying an accurate value and that the amount of gain multiplied by the
amount of base current determined the maximum amount of current allowed from the collector to the emitter.
With the transistors in a test circuit, I dialed the multimeter to amp mode. With this higher-rated mode,
I tested the amount of current coming from the battery to ensure it was below the 500 mA limit of the meter
in milliamp mode. The current was well below that limit.
I switched the multimeter to milliamp mode and disconnected one end of the resistor from the base
lead of the transistor. I connected the red multimeter test probe to the base lead of the transistor and the
black test probe to the negative bus. Poof!
I must have been thinking about measuring voltage. Instead, I should have connected the black test
probe to the disconnected end of the resistor. The resistor is there to limit the amount of current provided to
the transistor. By hooking the black test probe to the negative bus, I provided a short path from the positive
terminal of the battery, through the transistor’s collector lead, through the transistor’s base lead, through the
multimeter, to the negative battery terminal. There weren’t any resistors in that path to limit current.
The current through the multimeter exceeded 500 mA, blowing the fuse inside the meter. The
multimeter continued to display information (“0.0 mA”) and operate in modes other than milliamps. I can’t
tell you how long I spent trying to figure out why the milliamp mode wasn’t working.
Fortunately, the multimeter contained a spare fuse, and I was able to continue testing. This time,
I connected the multimeter correctly and obtained the validation of the experiment.
Fool Me, Twice
After finishing a chapter, I let it sit for a few days. Then, I proofread it and redo the experiments according to
my written directions before handing the chapter to the publisher.
Guess what happened? During proofreading, I blew the fuse again making the same mistake with the
test leads (see Figure A-6, again!)
Voltage’s Real Name
Throughout this book, I chose to use the term “negative voltage.” It’s not inappropriate, and the battery is
labeled that way. It’s just a bit primary school or old fashioned. Okay? It’s un-cool.
Figure A-6. Two, count ‘em, two blown fuses!