Help Transistor MOSFET replacement

Discussion in 'The Projects Forum' started by ChrisChemist116, Jan 13, 2011.

  1. ChrisChemist116

    Thread Starter Active Member

    Mar 13, 2009
    78
    1
    Howdy,:)

    I came across this schematic (http://pfranc.com/pclink/myidea.htm) to build a CASIO DATA cable for calculator CFX9850.

    Everything seems to be in the right order. Except the MOSFET transistor.
    One site (http://www.casiocorner.com/data/html/modules.php?name=News&file=article&sid=13) suggests to use ZVP 3306 or VP0106 (altough it tells the model as SiVP 01069602). (I think it is Mosfet P channel).

    I can't find any of these in my location. Is there any equivalent easier to find?.:confused:

    Bellow you can see the schematic. Middle, Bottom and Tip, are Ring, Base and Tip in 2.5 mm audio plug.

    Best regards~

    [​IMG]
     
  2. CDRIVE

    Senior Member

    Jul 1, 2008
    2,223
    99
    If it's a real serial port and not a USB/Serial converter, you will have ~ +- 12V at all the serial port pins. This circuit will not demand much current, so you don't need a power FET. Honestly, probably many small PMOS FETs will work here. That said, it's late and I haven't really taken a good look at this circuit..tomorrow.

    Before you dive into this though, remember that unless you're very experienced you can fry your serial port if you make a wiring mistake. If your UART is on the mother board (not a card), the damage could be catastrophic. The Max232 is a RS232 interface chip and is what's widely used for RS232 to 5V logic levels.
     
  3. ChrisChemist116

    Thread Starter Active Member

    Mar 13, 2009
    78
    1
    Alright i understand what you say. But i would appreciate if you could suggest me a replacement as there are many FETs out there. As what you can see from the schematic, is there any particular model do you suggest? :rolleyes:

    And regarding to the serial port. I see no problems at all, and i think i can give it a try.
     
  4. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    What distributors do you use? RS Components? Farnell UK?
    Without knowing what distributors you have access to, we could play "Guess the MOSFET" quite a bit before finding one that's suitable.

    Basically, you're looking for a P-ch enhanced MOSFET in a small package, preferably TO-92, that's rated for a Vdss of -30v to -60v, low gate charge (<3nC) and Id in the range of -10mA to -500mA; it doesn't have to be much.
     
  5. CDRIVE

    Senior Member

    Jul 1, 2008
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    Can you get a 2N7000 by you?

    EDIT: This is a N-Chan MOSFET. The OP is needing a P-Chan.
     
    Last edited: Feb 6, 2011
  6. thatoneguy

    AAC Fanatic!

    Feb 19, 2009
    6,357
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    That's an N-Channel, Useful small purpose MOSFET though.

    I've used the ZVP2106 as a "compliment" to the 2N7000 with semi-OK results. The Rds ON is a bit on the horrible side, but it is logic level P MOSFET in TO-92 case.
     
  7. CDRIVE

    Senior Member

    Jul 1, 2008
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    Oops, my error!
     
  8. ChrisChemist116

    Thread Starter Active Member

    Mar 13, 2009
    78
    1
    Okay Sarge. I was thinking about that. The closest distributor to my location is Futurlec. And judging from what i can see, it carries transistors among other components within JEDEC standards.

    It would be helpful if the replacement it is in such category.

    Sidenote: I have to say the first time i read your answer "guess the Mosfet" let me :D But i know what you mean.

    With that said, is there any Mosfet you suggest i can use within the range you specified and in TO-92 package on JEDEC?:rolleyes:

    Yes i can get 2N7000, but as said above it would be useless as i require a P-Chan Mosfet.

    I would be happy to give a try to ZVP2106 but i can't find it. Is there any equivalent on JEDEC or any other choice i can try?.:(

    Dont be worry, such things happens.:)
     
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