power transistor check

Discussion in 'General Electronics Chat' started by jody, Jun 1, 2013.

  1. jody

    Thread Starter Member

    Nov 12, 2012
    39
    0
    hi
    i have a bux 127 power transistor. when i check between c an e with multimeter on diode check should it be open reading either way round. if i check a smaller low power transistor that is what i get. the transistor is new from a lucky bag so i assume its ok.
     
  2. MrChips

    Moderator

    Oct 2, 2009
    12,442
    3,361
    c to e should appear open in both directions

    bux127 is a darlington and hence don't expect the same readings as with a regular NPN BJT when reading b to c and b to e.
     
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  3. jody

    Thread Starter Member

    Nov 12, 2012
    39
    0
    thanks
    in one direction on c and e im getting .700 on the meter and the other open circuit, could this be because its a darlington type.
     
  4. Dodgydave

    Distinguished Member

    Jun 22, 2012
    4,986
    745
    Thats because there is a diode across the C/E terminals
     
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  5. jody

    Thread Starter Member

    Nov 12, 2012
    39
    0
    thankyou
    i just found a data sheet for it and see the diode.
     
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