Testing J-K Flip Flop - HCF4027BE

Discussion in 'General Electronics Chat' started by PsySc0rpi0n, May 8, 2016.

  1. PsySc0rpi0n

    Thread Starter Well-Known Member

    Mar 4, 2014
    1,184
    3
    Hi...

    I wanted to check if a couple of flip flops I have here are working properly. To accomplish that I was trying to verify the truth table but I'm having some issues in understanding how this works.

    What I already did was to check the datasheet which is here.

    In terms of connections I have the following:

    Pin 16 (VDD) --> 12V DC
    Pin 8 (VSS) --> GND
    Pin 13 (CLK1) --> 100Hz Arduino square signal with 5V of amplitude

    Now, the truth table works with J1 and K1 pins and will set Q1 and not Q1 to 0 or 1, accordingly, no??? Is that it?
     
  2. bertus

    Administrator

    Apr 5, 2008
    15,647
    2,346
    Hello,

    The amplitude of the clock signal needs to be almost as high as the powersupply.
    In your case the powersupply is 12 Volts, but the clocksignal is only 5 Volts.
    Either amplify the clocksignal to about 12 Volts or use a supply voltage of 5 Volts.

    Bertus
     
  3. PsySc0rpi0n

    Thread Starter Well-Known Member

    Mar 4, 2014
    1,184
    3
    Ok, I already changed it to around 5V.

    So, the first state:
    J1 -- GND
    K1 -- GND

    I have
    Q1 -- ~5V
    not Q1 -- "moving" square wave and after some time it changes to ~5V DC. Can't figure out why it changes to a "moving" square wave.

    --------------------------------------
    J1 -- GND
    K1 -- 5V DC

    Q1 -- ~5V
    not Q1 -- "moving" square wave and after some time it changes to ~5V DC. Can't figure out why it changes to a "moving" square wave.
    --------------------------------------

    J1 -- 5V DC
    K1 -- GND

    Q1 -- ~5V
    not Q1 -- "moving" square wave and after some time it changes to ~5V DC. Can't figure out why it changes to a "moving" square wave.
    --------------------------------------

    J1 -- 5V DC
    K1 -- 5V DC

    Q1 -- ~5V
    not Q1 -- "moving" square wave and after some time it changes to ~5V DC. Can't figure out why it changes to a "moving" square wave.
    --------------------------------------

    I have no idea why this is happening... I can post a video or some pics to show it!
     
  4. bertus

    Administrator

    Apr 5, 2008
    15,647
    2,346
    Hello,

    At what levels are the S and R inputs?

    CD4027_function_table.png

    Bertus
     
  5. PsySc0rpi0n

    Thread Starter Well-Known Member

    Mar 4, 2014
    1,184
    3
    J1 -- 5V
    K1 - floating/not connected
    S1 - 0V
    R1 - 0V

    Q1 - square wave form
    not Q1 - square wave form (when Q1 is high, not Q1 is low and vice-versa)

    DS1Z_QuickPrint11.png
     
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