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

"jc"

Care to post a pic on ABSE ?

....... Phil

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

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

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

......

"Jeremy"

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

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

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:

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

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.