4027 as latching flip flop and resettable

Discussion in 'General Electronics Chat' started by chrischrischris, Sep 28, 2012.

  1. chrischrischris

    Thread Starter Member

    Feb 18, 2012
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    10
    Hi.
    Can someone please help me here.
    I've been searching the net to try work out how to use and existing 4027 I have on a board to achieve both a latched flip flop as well as be able to reset it to say "high" no matter the existing state.

    I was looking at this following circuit but I can't get it to work:

    http://www.circuit-innovations.co.uk/push_switch.html
     
  2. Wendy

    Moderator

    Mar 24, 2008
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    Lets chat...
     
  3. chrischrischris

    Thread Starter Member

    Feb 18, 2012
    283
    10
  4. Wendy

    Moderator

    Mar 24, 2008
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    OK, look at this...

    [​IMG]
     
    Last edited: Sep 29, 2012
  5. ScottWang

    Moderator

    Aug 23, 2012
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    767
    IF you want CD4027 have the toggle switch functions, then you can do like this to try:
    1. Disconnect CLR(Pin 4) from GND.
    2. Add Reset Switch - Add one more input circuit, as one switch, one 1N4148, two Resistors, one cap, and connecting to CLR(Pin 4).

    Also you can try to use like this:
    1. Disconnect CLK from input circuit, and connecting CLK to GND.
    2. Disconnect PR(Pin 7) from GND.
    3. Connect the input circuit to PR(Pin 7).
    4. Disconnect CLR(Pin 4) from GND.
    5. Add Reset Switch - Add one more input circuit, as one switch, one 1N4148, two Resistors, one cap, and connecting to CLR(Pin 4).
     
  6. Wendy

    Moderator

    Mar 24, 2008
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    [​IMG]

    OK, this is a revamp of the changes shown. This latch has a Set input, the output of the 555 will go high if the Set input is high. Just shown to show what/why I did what I did.

    It may not be needed, but look at R7, which is not in your schematic.
     
    Last edited: Sep 29, 2012
    chrischrischris likes this.
  7. chrischrischris

    Thread Starter Member

    Feb 18, 2012
    283
    10
    Bill, you did it. Excellent! :):):)

    I didn't need to use the 4027 after all. Your mods to the existing 555 has done the trick. Thanks again.
     
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