1. Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.
    Dismiss Notice

Confusing TO-92 pinout

Discussion in 'General Electronics Chat' started by BobW, Aug 21, 2017.

  1. BobW

    BobW Active Member

    Joined:
    Apr 28, 2010
    Messages:
    521
    Likes:
    54
    Location:
    Canada
    This is the pinout diagram from a Fairchild BS270 MOSFET datasheet.
    TO92.png
    I'm pretty sure that I know which pin is drain, but the jury's still out on the gate and source. What the heck were they thinking when they drew it this way?
     
  2. Mickster

    Mickster Well-Known Member

    Joined:
    Feb 24, 2008
    Messages:
    1,084
    Likes:
    57
    Location:
    BDA
    I have an iPhone app showing the left pin as drain, centre pin as the gate and the right pin as source.
    HTH.
     
    • Thanks Thanks x 1
  3. jpanhalt

    jpanhalt Well-Known Member Most Helpful Member

    Joined:
    Jun 21, 2006
    Messages:
    6,060
    Likes:
    520
    Location:
    Cleveland, OH, USA
    ONLINE
    • Thanks Thanks x 1
  4. dave

    Dave New Member

    Joined:
    Jan 12, 1997
    Messages:
    -
    Likes:
    0


     
  5. ronsimpson

    ronsimpson Well-Known Member Most Helpful Member

    Joined:
    Apr 17, 2007
    Messages:
    7,363
    Likes:
    973
    Location:
    Loveland, CO USA

    upload_2017-8-21_16-5-38.png
    It is not clear because the leads cross. (in this picture)
    I would solder a 10ok resistor G-S then with a meter test to see if you see the D-S diode.
     
    • Thanks Thanks x 1
  6. BobW

    BobW Active Member

    Joined:
    Apr 28, 2010
    Messages:
    521
    Likes:
    54
    Location:
    Canada
    I tried Ron's suggestion, and it showed that the source is at the end. Hence gate is the middle pin as Mickster and John said. Tested it in circuit, and it works correctly. So mystery solved. Thanks everyone.
     
  7. schmitt trigger

    schmitt trigger Active Member

    Joined:
    May 24, 2009
    Messages:
    912
    Likes:
    85
    Your example above, is one of the reasons I love my Peak Atlas semiconductor analyzer:
    http://www.peakelec.co.uk/acatalog/jz_dca55.html

    This has been an invaluable tool for me for close to 10 years.

    Please note: I'm not affiliated with them. I'm only a very satisfied customer.
    I'm sure you can find similar but cheaper Ebay units.
     
    • Informative Informative x 1
  8. BobW

    BobW Active Member

    Joined:
    Apr 28, 2010
    Messages:
    521
    Likes:
    54
    Location:
    Canada
    I've been thinking about getting one of those gadgets, but wasn't sure how well they worked at identifying components. I guess I'll have to look into a bit more.
     

Share This Page