tying 595 outputs together

Discussion in 'General Electronics Chat' started by mxabeles, Jun 15, 2010.

  1. mxabeles

    Thread Starter Active Member

    Apr 25, 2009
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    is it ok ? looked around the net couldn't find anything specifically answer that...thanks!
     
  2. Wendy

    Moderator

    Mar 24, 2008
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    What is a 595?
     
  3. SgtWookie

    Expert

    Jul 17, 2007
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    Are you talking about a 74HC595?

    I fail to see why you would want to do such a thing.

    Generally, you don't want to tie two outputs together if there is a possibility that one could be high and one could be low. It's OK to do so with open-collector or open-drain outputs though.
     
  4. mxabeles

    Thread Starter Active Member

    Apr 25, 2009
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    hi guys : here is why/
    I want to use the 595 outputs as a random "chooser" for the three input pins of a 4051. I could just select three of the 12 or so bits coming out of the stream but I would rather tie 3 bits to each input of the 4051 so there isn't as much dead space if this makes sense.
    Schematic attached w/ 3 outputs from 595 tied to each a,b,c of 4051.
    Thanks
    M
     
  5. SgtWookie

    Expert

    Jul 17, 2007
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    You have multiple text overlaps, so I can't read what the values of your components are.

    Don't tie the outputs of the 595 together. Use diodes (like 1N4148,1N914) so that they can only source or sink current, and then use pull-up or pull-down resistors.
     
  6. mxabeles

    Thread Starter Active Member

    Apr 25, 2009
    182
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    cool, I think the simplest way is just to use one bit for each input and leave it at that,
    thanks!
    m
     
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