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How to tell base and emitter apart on a NPN 2N3055 transistor

I've got an NPN transistor 2N3055. How do I tell the base and the emitter pins apart? They both look the same and this transistor is symetrical.

Reply to
jc
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"jc"

** A symmetrical 2N3055 is quite a find.

Care to post a pic on ABSE ?

....... Phil

Reply to
Phil Allison

I can certainly post a pic, what's abse?

Reply to
jc

** A real usenet group called: " alt.binaries.schematics.electronic "

Not accessible to googlegroups users.

Do yourself a favour an get a REAL newsreader and an ISP that supplies access.

We are all just dying to see that symmetrical 2N3055 you say you have ......

......... Phil

Reply to
Phil Allison

Ok, I've posted pics. same subject as this thread.

......

Reply to
Jeremy

"Jeremy"

** Please DO NOT TO POST !!!
** Excellent work.

Shame the 2N3055 device is NOT symmetrical !!

In the top pic, the leads are clearly closer to the bottom of the package.

Same as all TO3 packages ever made.

The right hand side one is the base pin.

....... Phil

Reply to
Phil Allison

Google a datasheet.

Or use an ohmmeter; the base acts like the anode of a diode, with either the emitter or the collector behaving like its cathode.

John

Reply to
John Larkin

It's symmetrical in one plane, but none others. If you take a second look you'll notice the pins are off center between the mounting holes. Hold the transistor so the pins are facing you, the mounting holes are vertical, and the pins are above the middle. The left pin is base and right is emitter.

See also data sheet.

Tim

-- Deep Fryer: a very philosophical monk. Website:

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Reply to
Tim Williams

Any to3 transistor - if you hold it with pins facing you and pins closer to top, then left side pin is base and right hand is emiter. Usually :)

Reply to
James Thompson

THAT IS REALY WRONG!!! Never keep the pins up , if it slips out you lose your eye, hehe. Pins at the bottom reading left to right, smallest to largest terminals you have E B C ( base in the middle.)

Cheers

Reply to
Sambo

Not for TO-3, which this thread was about.

-- Sincerely, |

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Rikard Bosnjakovic | Code chef - will cook for food

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Reply to
Rikard Bosnjakovic

Pinouts for a TO-3 should be readily available but a rule of thumb for 'all transistors' is that transistors test as 2 diodes back to back with the base as common. You will find the forward voltage drop will be 'slightly' lower on the base/emitter junction (in the order of about 0.01v).

Caviet:- some power transistors, in particular scan transistors will also have a diode from collector to emitter typically cathode to collector.

--
Australia isn\'t "down under", it\'s "off to one side"!

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Reply to
Stan Blazejewski

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