4017 troubleshooting

Discussion in 'The Projects Forum' started by Nickage, May 30, 2013.

  1. Nickage

    Thread Starter New Member

    Jan 3, 2013
    7
    0
    Hey all,

    using this link as a guide:

    http://www.allaboutcircuits.com/vol_6/chpt_7/6.html

    My problem is, instead of LEDs, i'm driving relays. Occassionally, the sequence goes out of sequence, for example instead of 1-2-3-4 every time, I get sporadic 2-3-4-1.

    What causes this? I don't have any diodes on the coil side for back-emf, and the relays are the micro relay type. Any ideas?
     
  2. absf

    Senior Member

    Dec 29, 2010
    1,493
    372
    I think there are interference from the relay coils or contacts. Did you put a diode across each relay coil? Did you put a few 0.1uF caps across the VCC and GND and one close to the 4017?

    Allen
     
  3. JoeJester

    AAC Fanatic!

    Apr 26, 2005
    3,373
    1,159
    Post your schematic and the relay specifications.

    If your powering the circuit by a battery, your battery voltage could be spiking too low.
     
  4. edwardholmes91

    Member

    Feb 25, 2013
    185
    19
    The OP mentions in their post that they haven't put any diodes in for back EMF. I would recommend just popping a 1N4001 for good measure across each relay coil. And as absf mentions, sprinkling a few 100nF caps over the supply pins of the ICs is always a good idea.
     
  5. tracecom

    AAC Fanatic!

    Apr 16, 2010
    3,871
    1,394
    This is the same circuit that is being discussed in this thread.

    With no resistance between pin 7 and pins 6/2, the pulse from the 555 is very short. I don't have a scope good enough to measure it, but it may be less than 5 microseconds. I strongly recommend lengthening that pulse width by putting a resistor between pin 7 and pins 6/2. A 1M resistor inserted there will give a nice 4.8 Hz clock with a 67% duty cycle.

    All the other noise suppression suggestions given here should be followed as well. Finally, I would place a .01 μF cap from pin 5 to ground.
     
    Last edited: May 30, 2013
  6. sheldons

    Active Member

    Oct 26, 2011
    616
    101
    how are you driving your relays-are you using transistors to drive them?as in the two examples ive got here-plus there is no reset for the 4017....
     
  7. edwardholmes91

    Member

    Feb 25, 2013
    185
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    There is a reset for the 4017. It is pin 15. If you connect the output pin after your total count to the reset it will only count to there before it resets. Have a look at this electronic dice to see what I'm reffering to.
     
  8. sheldons

    Active Member

    Oct 26, 2011
    616
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    i meant the reset was tied lo-if you include a capacitor to supply and a resistor to ground you get a switch on reset,include a diode as shown and you have a counter which is reset on switch on and is reset at whatever count depending on the output you use with your diode....
     
  9. edwardholmes91

    Member

    Feb 25, 2013
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    19
    I don't think you need a reset when you turn it on because it doesn't remember where is has got to anyway. The electronic dice that I linked you to always start with dice number two because the 4017 always turns on with the same output high.
     
  10. sheldons

    Active Member

    Oct 26, 2011
    616
    101
    its up to who ever builds the circuit ,just means the ic will have a random output hi on power up not a problem if it isnt required to start from Q0 everytime on power up-just my preference when using 4017`s in my led controllers to have a power on reset so all logic starts off in a pre defined state and i was referring to the schematic in this link

    http://www.allaboutcircuits.com/vol_6/chpt_7/6.html
     
  11. edwardholmes91

    Member

    Feb 25, 2013
    185
    19
    With the 4017 that I'm using for an electronic dice it always starts with Q0 on high every time for some reason. Not a problem to me... I don't mind which output starts high for this application.
     
  12. Nickage

    Thread Starter New Member

    Jan 3, 2013
    7
    0
    Just to update, I tried adding caps, and diodes on the coils of the relay to prevent back emf, and I'm still not getting consistent startup at q0 every time. I'm only using q0-q2, then resetting.
     
  13. tracecom

    AAC Fanatic!

    Apr 16, 2010
    3,871
    1,394
    As was requested back in May, post a schematic of what you have actually built. Without a schematic, anyone who tries to help is either reading your mind or guessing.
     
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