CMOS 4013 Toggling Issue

Discussion in 'General Electronics Chat' started by Robin Mitchell, Feb 1, 2016.

  1. Robin Mitchell

    Thread Starter Well-Known Member

    Oct 25, 2009
    732
    199
    Hi all,

    So I am making that Z80 Computer (ZBM), and I am having issues with these 4013 chips. Firstly, they are from china and I have tried two different chips but the same problem is still happening.

    Simply put:

    I have a toggle made from the flops (connecting /Q to ), so when the clock line is pulsed the flop toggles. Now this works if I use a wire directly from the clock line and connect it to the power but if I use a tactile switch it will happily turn on but not toggle back.

    Now get this... If I use a supply of less than 3V (currently using 5V), the tactile switch works perfectly every time! That makes no sense at all to me:S! Why would it work only at a lower voltage when these devices are rated up to 15V!

    I measured the voltages on the pin and nothing unusual is showing up :(

    I do have de-bouncing circuitry
    All unused inputs are pulled to ground

    For now I am digging around for an "official" 4013 as a reference incase these chips are rubbish.
     
  2. crutschow

    Expert

    Mar 14, 2008
    13,000
    3,229
    As usual, post your circuit including the debounce.
     
    kubeek and Robin Mitchell like this.
  3. Robin Mitchell

    Thread Starter Well-Known Member

    Oct 25, 2009
    732
    199
    I have just found an official 4013 TI chip, and it now works.

    Damn Chinese Parts!
     
  4. Robin Mitchell

    Thread Starter Well-Known Member

    Oct 25, 2009
    732
    199
    @crutschow

    I would have posted the schematic if this new chip did not work. I have a feeling that it is either some kind of minor voltage breakdown where the higher voltage is interfering with the silicon and causing mayhem.

    Lesson Learned :(
     
  5. dl324

    Distinguished Member

    Mar 30, 2015
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    Where did you buy them and what manufacturer did they supposedly come from?
     
  6. Robin Mitchell

    Thread Starter Well-Known Member

    Oct 25, 2009
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    199
    Got them on Ebay and they are "supposedly" TI. I know that they are not but I am irritated that they work on low voltages but not at 5V which my whole system runs on!
    Any who just bought some more from a UK supplier so that fixes that!

    I am requesting a refund from the seller and claiming they are faulty and forgeries.
     
  7. Robin Mitchell

    Thread Starter Well-Known Member

    Oct 25, 2009
    732
    199
    What I cant understand is that it works when you take a wire and connect the clock to power but if you connect it through a switch then it suddenly does not work. And both attempts use the de-bouncer which is just a capacitor and resistor in parallel. It works flawlessly with a REAL 4013 but these chips, im going to have to throw 100 of these things away :(
     
  8. dl324

    Distinguished Member

    Mar 30, 2015
    3,242
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    As a public service announcement, what is the eBay seller and feedback rating?
     
  9. Robin Mitchell

    Thread Starter Well-Known Member

    Oct 25, 2009
    732
    199
    Sinus23 and hp1729 like this.
  10. Robin Mitchell

    Thread Starter Well-Known Member

    Oct 25, 2009
    732
    199
    Here are two photos I took with my microscope.
    The 4017 Chip is an official TI part where the 4013 is the fake chinese part.
    FakePart.png RealPart.png
    • Font is bigger
    • Logo is wrong
    • Pins are too wide
    • E4 is in the wrong place
    • The notch is too big (not shown in the picture)
    • The epoxy colour is wrong
     
  11. hp1729

    Well-Known Member

    Nov 23, 2015
    1,948
    219
    Super! Thanks.
     
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