Author Topic: Transistor TO92 package pinouts  (Read 236 times)

0 Members and 1 Guest are viewing this topic.

Offline cowasaki

  • Regular Contributor
  • *
  • Posts: 178
  • Country: gb
Transistor TO92 package pinouts
« on: January 22, 2018, 10:55:33 AM »
Over the past 25 years I have basically done the same as most people and just use a small subset of transistors for my projects which I know the pinouts for.  When I do repairs I check the data sheet (usually on-line now but years back in a book) to see which style the transistor is so I get the right pinout etc and to be fair most of my stuff is low voltage digital anyway, so I only use a small number of different types.  I obviously realise that there are several pinouts for the TO92 package (which always seemed silly to me but hey) so today whilst watching TV I thought I would organise my box of spares, labels them up and do a list.  So I started to put them into a list of TO92, TO92B, TO92F, H etc then thought I had made a mistake as I got the original list from a Fairchild data sheet then found them different on another data sheet!

From flat side towards you and pins down...

Fairchild shows them as

TO92A EBC
TO92B ECB
TO92F CEB

But I've seen different orders with other companies/lists on google etc.

Has anyone got the definitive answer and to stop me re-inventing the wheel a list would be nice.  My transistor data book went missing years ago.
 

Online Hero999

  • Super Contributor
  • ***
  • Posts: 9548
  • Country: gb
Re: Transistor TO92 package pinouts
« Reply #1 on: January 22, 2018, 11:06:38 AM »
I didn't know there was a standard. Is there one?

I don't bother. I keep my digital component tester handy or just Google the part number.
 

Offline cowasaki

  • Regular Contributor
  • *
  • Posts: 178
  • Country: gb
Re: Transistor TO92 package pinouts
« Reply #2 on: January 22, 2018, 11:09:58 AM »
I didn't know there was a standard. Is there one?

I don't bother. I keep my digital component tester handy or just Google the part number.

This is what I do (except that I don't have a component tester - but I've just ordered four Peak meters inc the pro component one!).  When I googled it I had the above list together with this one:

Japanese ECB
American EBC
European CBE

I was just trying to get organised now that I am building my new workshop up.
 

Offline Wimberleytech

  • Regular Contributor
  • *
  • Posts: 132
  • Country: us
Re: Transistor TO92 package pinouts
« Reply #3 on: January 22, 2018, 11:12:00 AM »
I didn't know there was a standard. Is there one?

I don't bother. I keep my digital component tester handy or just Google the part number.

Me too.  I only use two transistors anyway: 3904 and 3906 (and they are EBC).  I have about 100 of each and they are all the same.

But I really don't use transistors much so these will last me until...
 

Online floobydust

  • Super Contributor
  • ***
  • Posts: 1058
  • Country: ca
Re: Transistor TO92 package pinouts
« Reply #4 on: January 22, 2018, 11:14:32 AM »
With three leads, there are three permutations and combinations possible. EBC, ECB are the most encountered.
I don't think JEDEC actually assigns the package connections. There is also EIAJ SC-43, SOT54 etc.

I came up with this PCB footprint to handle any TO-92 transistor pinout, it might help.
 
The following users thanked this post: Cliff Matthews

Offline cowasaki

  • Regular Contributor
  • *
  • Posts: 178
  • Country: gb
Re: Transistor TO92 package pinouts
« Reply #5 on: January 22, 2018, 11:19:08 AM »
You look at BC317/BC320; BC167/BC257 and BC237/BC307.....  They are EBC, ECB & CEB. 

I'll just have to add the pinout to each label. 

So it'll be

Name
Alternatives
Complimentary
Pinout
NPN/PNP
 

Offline cowasaki

  • Regular Contributor
  • *
  • Posts: 178
  • Country: gb
Re: Transistor TO92 package pinouts
« Reply #6 on: January 22, 2018, 01:01:39 PM »
I just found a 99p app called "Transistor Handbook" (There is also a MOSFET version).  This allows you to type any transistor in and give the pinout, basic details etc and a link to the data sheet.  For 99p it is pretty useful.
 

Offline rhb

  • Frequent Contributor
  • **
  • Posts: 505
  • Country: us
Re: Transistor TO92 package pinouts
« Reply #7 on: January 22, 2018, 01:51:29 PM »
The forward voltage drop across the base-collector junction is lower than the drop across the base-emitter junction. This is because of the larger area of the collector overwhelming the higher doping level of the emitter.

Long ago I built a number of circuits that did not work using Radio Shack 2N2222s.  I eventually became convinced that the issue was incorrect pinouts, but had no way to be sure.  No one I knew could tell me.  Then a physicist turned EE professor made the comment at the start of this post.  I immediately ran home and tested the statement.  Much to my delight he was correct and all of the things I'd built had the emitter and collector swapped based on an incorrect label on the RS package.

IIRC only one person of the many people I've asked has known how to distinguish the collector and emitter using a VOM.  I have *never* seen it in print.  Everyone stops with identifying the base.
 

Offline cowasaki

  • Regular Contributor
  • *
  • Posts: 178
  • Country: gb
Re: Transistor TO92 package pinouts
« Reply #8 on: January 22, 2018, 09:49:30 PM »
The forward voltage drop across the base-collector junction is lower than the drop across the base-emitter junction. This is because of the larger area of the collector overwhelming the higher doping level of the emitter.

Long ago I built a number of circuits that did not work using Radio Shack 2N2222s.  I eventually became convinced that the issue was incorrect pinouts, but had no way to be sure.  No one I knew could tell me.  Then a physicist turned EE professor made the comment at the start of this post.  I immediately ran home and tested the statement.  Much to my delight he was correct and all of the things I'd built had the emitter and collector swapped based on an incorrect label on the RS package.

IIRC only one person of the many people I've asked has known how to distinguish the collector and emitter using a VOM.  I have *never* seen it in print.  Everyone stops with identifying the base.

Whilst looking yesterday I found that the 2N2222 is actually available with different pinouts!  Why couldn't they just stick to one!!
 

Online bd139

  • Super Contributor
  • ***
  • Posts: 3030
  • Country: gb
Re: Transistor TO92 package pinouts
« Reply #9 on: January 22, 2018, 10:05:37 PM »
I just posted another thread on this but don't assume the datasheet makes any sense either:

 

Online glarsson

  • Frequent Contributor
  • **
  • Posts: 271
  • Country: se
Re: Transistor TO92 package pinouts
« Reply #10 on: January 22, 2018, 10:20:16 PM »
Whilst looking yesterday I found that the 2N2222 is actually available with different pinouts!  Why couldn't they just stick to one!!
It's a feature! When you get the pcb pinout wrong you don't have to fix it. Just order a transistor with the other pinout.
 


Share me

Digg  Facebook  SlashDot  Delicious  Technorati  Twitter  Google  Yahoo
Smf