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7404 Hex inverter stuck on 2.5v

Discussion in 'Electronics Homework Help' started by evilmorty, Apr 14, 2016.

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  1. evilmorty

    evilmorty

    3
    0
    Apr 14, 2016
    Hi,

    I got a problem with the hex inverter. The idea is to clearly define the pulses coming in from a few optical encoders working on phototransistors, but I'm having a problem where 7404 output suddenly settles to around 2.5v.
    Would anyone have any guidance on how i can fix this issue?

    Many thanks
    Morty
     
  2. Anon_LG

    Anon_LG

    453
    117
    Jun 24, 2014
    Could you provide us with a circuit diagram please?
     
    Arouse1973 likes this.
  3. evilmorty

    evilmorty

    3
    0
    Apr 14, 2016
    It's basic I don't have any external components such as pull up/down resistors
    image.jpg

    The inverter outputs will go into the MCU or a LS7084 clock converter that will take the A and B channels and make one pulse. I've yet to get to that stage to decide what will work best
     
    Last edited: Apr 14, 2016
  4. Alec_t

    Alec_t

    2,928
    798
    Jul 7, 2015
    Have you checked that with a 'scope? If the output were oscillating and you checked with a DMM, 2.5V would be a reasonable measurement.
     
    (*steve*) likes this.
  5. evilmorty

    evilmorty

    3
    0
    Apr 14, 2016
    Yes I'm using a scope to measure the voltages
     
  6. Alec_t

    Alec_t

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    Jul 7, 2015
    Have you left any of the unused inverter inputs floating? That might produce weird results.
     
  7. duke37

    duke37

    5,364
    769
    Jan 9, 2011
    Is it a 7404 or a 7414 as in your diagram?
     
  8. Colin Mitchell

    Colin Mitchell

    1,417
    313
    Aug 31, 2014
    Take everything off the chip and put 1k between input and 5v rail. What is the output ?
    Put 1k between input and 0v rail. What is the output ?
     
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