Problems solved on transistor types

The original Series of transistor numbers that started with the 2N-series left no clue as to what type of transistor it was. PNP or NPN? Silicone or Germanium?

So Along came the next Transistor Numbering starting with the 2S-series. What a welcome change that made some sense.
OK Here the real skinny:

The TO - 92 package consisted of both the 2N and 2S series, but the leads are not the same.

2N series facing the flat portion with the part number displayed is always the same, using the example of a 2n3904.
you have to look up on the spec. sheet the data to find out what the type of transistor it is. The leads are always E-B-C


2S series facing the flat portion with the part number displayed is always the same, using the example of a 2SA733

The 2SA-letter series and the 2SB-letter series Identify it as a PNP and Leads are always E-C-B and its always a Silicon Transistor




2S series facing the flat portion with the part number displayed is always the same, using the example of a 2SC945
The 2SC-letter series and the 2SD-letter series Identify it as a NPN and Leads are always E-C-B and its always a Silicon Transistor
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You might want to watch this Video on YouTube for a better explanation.