Proofreading Transistors

Georacer

Joined Nov 25, 2009
5,182
It's true that that part is a bit confusing. If we refer to the node where the emitter arrow ends as "the pointing end", then it is true that in the NPN transistor has P-type diffusion in the middle and the PNP transistor has P-type diffusion in the endpoints.
In that way, the e-book is wrong.
 

Wendy

Joined Mar 24, 2008
22,472
It helps to be specific...

Bipolar transistors are constructed of a three-layer semiconductor “sandwich,” either PNP or NPN. As such, transistors register as two diodes connected back-to-back when tested with a multimeter's “resistance” or “diode check” function as illustrated in Figure below. Low resistance readings on the base with the black negative (-) leads correspond to an N-type base in a PNP transistor. On the symbol, the N-type material corresponds to the “non-pointing” end of the base-emitter junction, the base. The P-type emitter corresponds to “pointing” end of the base-emitter junction the emitter.
Actually, I disagree. The verbage is not clear, but it says what it means to say.

How about this...

Bipolar transistors are constructed of a three-layer semiconductor “sandwich,” either PNP or NPN. As such, transistors register as two diodes connected back-to-back when tested with a multimeter's “resistance” or “diode check” function as illustrated in Figure below. Low resistance readings on the base with the black negative (-) leads correspond to an N-type material in the base of a PNP transistor. On the symbol, the N-type material is "pointed" to by the arrow of the base-emitter junction, which is the base for this example. The P-type emitter corresponds to the other end of the arrow of the base-emitter junction, the emitter. The collector is very similar to the emitter, and is also a P-type material of the PN junction.

The important thing to note it is the transistor shown in both illustrations is a PNP, and the description refers solely to a PNP transistor. The description is confusing, but is consistent with a PNP BJT.

If you think you can tweak the verbage to make it clearer please do.
 
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