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Old 3rd July 2009, 07:46 PM   #1
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Default Help Identifying emitter lead for NPN Trans

Hi,

I have a 2N222a NPN transitor TO-18 package made by STMicro. When looking at the data sheet it I think I'm able to discern the three pins (emitter 3, base 1, collector 2) with the emitter 3 pin directly to the right of the metal tab. But on the transistor case there is an e3 circled by the pin that looks like the collector on the datasheet! Can anyone set me straight!

Datasheet
http://www.st.com/stonline/books/pdf/docs/9288.pdf


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Old 3rd July 2009, 09:19 PM   #2
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Printing on the can usually has nothing to do with the pin allocation. It's a manufacturing code.
SOME TO-92 packages are labled though.
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Old 3rd July 2009, 09:32 PM   #3
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Thanks Steerpike! That's comforting as I'm sure I understand the pinout on the datasheet. Much appreciated.
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Old 6th July 2009, 04:38 AM   #4
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EB junction is always a zener of 5-6 volts.
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Old 10th July 2009, 06:06 PM   #5
Onra is offline Onra  Germany
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Hi,
e followed by a single number describes a part of ROHS-Conformity.

e3 means tin-coated leads: http://www.st.com/stonline/leadfree/identific.htm

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Old 10th July 2009, 06:35 PM   #6
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I appreciate the recent feedback. Here, I was interpreting e3 as emitter pin 3. Ha!

And good to know that the EB junction should measure 5-6V. Great to be able to measure to figure out the pins.
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