Acceptable current for logic probe.

Discussion in 'The Projects Forum' started by grant1842, Feb 29, 2012.

  1. grant1842

    Thread Starter New Member

    Aug 21, 2010
    5
    0
    Hi all I am learning circuit design.

    I have a logic probe circuit that I have breadboard and testing.

    I used my multi meter to check the amps/milliamps and the max reading while checking a test PCB is(.024) .

    I work on lcd tv / monitors / laptops / etc.

    Question:= Is this an acceptable amount of amps/milliamps to draw while voltage testing a PCB that will not damage the PCB under test ?


    sch below.
    [​IMG]

    Thanks for your comments.
     
  2. robbage

    New Member

    Feb 13, 2012
    2
    0
    I believe your input impedance will be too low for many logic circuits. Also your transistors are the wrong way around; C and E are reversed Also your buzzer is connected directly to the input. I think there are two or three other problems as well.
     
  3. grant1842

    Thread Starter New Member

    Aug 21, 2010
    5
    0
    I would like to have the buzzer sound if it is on a PWM pin or sine wave, as a basic test if the IC is puting out a signal.
    Thanks for all the comments / help.
     
  4. grant1842

    Thread Starter New Member

    Aug 21, 2010
    5
    0
    Does anyone know if this is an acceptable amount to use as a logic probe ?
    Thanks
     
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