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Circuit design

  1. Aug 2, 2010 #1
    hello good day, would someone kindly help me determine the part number of these 4 npn transistors here? pls help, cause my prof didn't discuss this yet.. and i dont have idea on how to calculate for the values of the transistor to determine tha part number suitable for the circuit... many thanks (um this isn't homework by the way)


    dig5a.gif


    dig6a.gif
     
  2. jcsd
  3. Aug 2, 2010 #2
    Hello, I take it you understand that the transistors are NPN>

    Pretty well any small or medium signal NPN transistor will do here, they do not even have to be of the same type.

    Common Suitable types might be

    BC547/548/549
    2N2222(A)
    2N3704
    2N3904
    MPSA42/43
    2SC1318

    Remember these have different pinouts or connection arrangements so make sure you know the one for the transistor you actually use.
     
  4. Aug 2, 2010 #3
    circuits drawn wrongly, in both 0v & +6v terminals are shorted on left side. in 1st circuit lamp terminals are shorted?
     
  5. Aug 2, 2010 #4
    Yes good catch.
     
  6. Aug 2, 2010 #5

    sophiecentaur

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    Science Advisor
    Gold Member
    2017 Award

    You should detach the 'Earthy' end of those lines and use 1k 'pull down' resistors after the switches if you want to really define the states of the input signals.
     
  7. Aug 2, 2010 #6
    o, i see, sorry i've overlooked that.. thanks.. um, btw, can i use KN2222 transistor instead of 2N2222? are they the same?
     
  8. Aug 2, 2010 #7

    berkeman

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    Staff: Mentor

    You should compare their datasheets. That's what we would do.
     
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