Basics group, Thanks again for all your helpful responses last week. Also, I purchased an old copy of Forest Mims' "Getting Started in Electronics" for $5.00 and am finding it clear, concise, and fairly easy to understand. Here are my latest newbie questions.
TRANSISTORS
In experimenting with some of the simple circuits in Mims' book, I burned out several 5mm round LEDs ... they're cheap ... and I learned a lot from my mistakes. But I haven't quite figured out how to determine when I've blown out a transistor. Here are some things I've learned about transistors by using my digital multimeter.
Transistor HFE Resistance between Base/Emitter
2N2907 312 80,400 ohms 2N2222 170 81,000 ohms 2N3906 156 80,000 ohms 2N3904 170 80,200 ohmsSo I'm deducing that all (?) small transistors have a base/emitter or base/collector resistance of about 80,000 ohms. I've learned that HFE is a measure of forward gain (what unit of measurement is attached to HFE?) But this experimentation hasn't helped me to determine if I've blown out a transistor. What method can I use to determine if a transistor is bad?