Why BJT is used here?

Discussion in 'General Electronics Chat' started by skybox, Jun 7, 2010.

  1. skybox

    Thread Starter Active Member

    Mar 2, 2009
    68
    1
    Hi guys,

    Was look at a schematic earlier was confused on why the BJT was used in the following situation? The REC_OK is a signal sent from the DB-25 connector to the uP, which tells the uP that the DVR is recording fine.
     
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  2. Bychon

    Member

    Mar 12, 2010
    469
    41
    The bjt amplifies and inverts the signal. The inversion might be important, and the amplification might not be important.
     
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  3. skybox

    Thread Starter Active Member

    Mar 2, 2009
    68
    1
    Thank you. Just read more about the common emitter amplifier. The spec sheet on the DVR doesn't give much information on it.
     
  4. kingdano

    Member

    Apr 14, 2010
    377
    19
    simple inverter - likely translates to the proper logic level as well - as was already suggested.
     
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