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

J

jc

Jan 1, 1970
0
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.
 
P

Phil Allison

Jan 1, 1970
0
jc said:
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.


** A symmetrical 2N3055 is quite a find.

Care to post a pic on ABSE ?




........ Phil
 
P

Phil Allison

Jan 1, 1970
0
jc said:
I can certainly post a pic, what's abse?



** 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
 
J

Jeremy

Jan 1, 1970
0
Ok, I've posted pics. same subject as this thread.
 
P

Phil Allison

Jan 1, 1970
0
"Jeremy"
Ok, I've posted pics. same subject as this thread.


** Please DO NOT TO POST !!!

......

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



** 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
 
J

John Larkin

Jan 1, 1970
0
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.

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
 
T

Tim Williams

Jan 1, 1970
0
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
 
J

James Thompson

Jan 1, 1970
0
jc said:
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.
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 :)
 
S

Sambo

Jan 1, 1970
0
James said:
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 :)
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
 
R

Rikard Bosnjakovic

Jan 1, 1970
0
Sambo said:
Pins at the bottom reading left to right, smallest to largest terminals
you have E B C ( base in the middle.)

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

Stan Blazejewski

Jan 1, 1970
0
Not for TO-3, which this thread was about.

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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www.cobracat.com (home of the Australian Cobra Catamaran)
http://groups.yahoo.com/group/cobra-cat/
 
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