What would cause the Low state to go to -2 volts vdc? or to +2 volt vdc?

Discussion in 'General Electronics Chat' started by Danwalker, Oct 2, 2014.

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  1. Danwalker

    Thread Starter New Member

    Oct 2, 2014
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    What would cause the Low state to go to -2 volts vdc? or to +2 volt vdc?

    Most Low logic states are close to zero volts, but what faults would cause the logic low state for either TTL or CMOS to go to another voltage other then zero volts?

    What are the Common failures that would cause the logic low state to be other then zero volts?
     
  2. alfacliff

    Well-Known Member

    Dec 13, 2013
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    power supply fault. negative side of supply open to ground.
     
  3. Danwalker

    Thread Starter New Member

    Oct 2, 2014
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    The Logic low would be at what voltage?
     
  4. MrChips

    Moderator

    Oct 2, 2009
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    What are you using to measure the voltage?
    If you are using an oscilloscope make sure your probe and scope input are both set to DC.
     
  5. alfacliff

    Well-Known Member

    Dec 13, 2013
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    if the ground reference of the supply opens, what voltage do you measure to ground? I have had it happen with a + and - 15 volt supply, very strange readings.
     
  6. Danwalker

    Thread Starter New Member

    Oct 2, 2014
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    if a pull down resistor is shorted or open, what would happen to the Low logic state?

    When a logic IC chip gets damaged, the High logic state goes to 1.7 volts , why is that?
     
  7. shortbus

    AAC Fanatic!

    Sep 30, 2009
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    Hi again Billymayo, still using multiple personalities? :(
     
  8. tom_s

    Member

    Jun 27, 2014
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    in order - (1) low (2) high (assumption - you have an inkling of how logic circuitry is intended to operate)

    apparently your not familiar with the rhetorical theorem?
     
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