Electronics question?

Question

I'm teaching myself some basic electronics just as a hobby. My question is does the neg. lead on both a NPN & PNP transistor always connect to the neg. side of the power supply?
I want to be able to build some basic electronics projects and know more than just where each component goes by looking at the directions. I know the proper way to learn this would be to study up on all different parts but this is purely as a as time allows hobby. Where can I find some information on circuit board design 101. Thanks

Answer 1

The formal interpretation of the NPN and PNP is the level of chemical doping each transistor region region has. N regions are doped such that excess electrons are available for conduction (and "N" carrier") and P regions are doped such that there are excess holes available for conduction.

The transistor lead designations are ordered (1)Collector, (2)Base and (3) Emmitter ..as in NPN or PNP. Transistors are commonly configured in a "common emmiter" circuit for signal amplicationn purposes. In this configuration, when the "Base" is more positive that the Emmitter in a NPN circuit, then the transistor will conduct via the "Base Emmitter diode". When the "Base" is more negative than the Emmitter in a PNP transistor, then the Base-Emmitter diode will conduct. When the Base-Emmitter diode conducts in either type, a large amount of current will be allowed thru the "Collector-Emmitter" path.

Hope this helps.

Berkeley Engineer

Answer 2

Both NPN and PNP transistors have 3 leads labeled Emitter(E), Base(B) and Collector(C). In the NPN transistor the Emitter is negative while the Base and Collector are positive. The PNP transistor is the opposite, the Emitter is positive relative to the Base and Collector.