cd4017 keeps shorting out Help

Discussion in 'The Projects Forum' started by xile6, Jul 6, 2011.

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  1. xile6

    Thread Starter New Member

    Jun 9, 2011
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    Ok I am using a cd4017 as a latch on/off for a car. It is used to latch the ignition on with one press and off with another. It does this without any problems. I can press the button (12volt input to pin 14) and it will turn on and off a relay that turns on and off the ignition.

    I then added "555 on delay timer". So when when i push and hold the button after "x" amount of time it will apply power to another relay for the starter motor.

    Now all of this works and the ignition will lock in place and the starter will crank. The car will start and run i release the button then about 5 second later the car cut off. After that the cd4017 is shorted out and will not work. When i press the button it will not output and if it does it is only a pulse, it also will not count anymore. The 555 timer works however.

    I tried to put a capacitor on pin 16 with a resistor. That kind of worked but after about 2 starts of the car it shorted.blow out the cd4017. I also got a 12 volt regulator thinking that the 14.4volt from the alternator was to much for the dc4017. That didnt work either.

    Any help any one could give would be lovely. I really need to to work and i blow out 8 of my 10 chips. I went over my solder to see if anything was jumping and all is good. also made another board just to make sure. Both boards work just short out when used to start the car.

    I have attached a picture of my circuit. The circuit works on the program, my breadboard ,prototype board in the house hooked up to a 12volt dc.
     
  2. SgtWookie

    Expert

    Jul 17, 2007
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    I'm sorry, but your topic falls under the category of "automotive modifications", which is restricted according to the Terms of Service, Paragraph 6:

    It's restricted due to safety concerns. Your CD4017 constantly getting "zapped" is one of the reasons that it's a restricted topic. Even experienced automotive engineers make mistakes (look at the recent Toyota and Lexus recall debacles) and amateurs are far more likely to create problems that may result in property damage and injuries/deaths.

    Besides, automotive environments are amongst the most brutal on the planet. There can be electrical spikes reaching over 100v and down to -26v; either of those will kill your circuit.

    The best advice would be to have a professional restore your vehicles' electrical system to the state it was when delivered by the manufacturer.
     
  3. CDRIVE

    Senior Member

    Jul 1, 2008
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    Sorry, but automotive topics violate AACs (TOS) Terms Of Service.
     
  4. xile6

    Thread Starter New Member

    Jun 9, 2011
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    I do all my own work. So my car will never be factory in any way. I was more or less just wondering why the chip keeps shorting out during the starting process of the car. But i see that it is against your rules to talk about things like that. I am sorry for that.
     
  5. Adjuster

    Well-Known Member

    Dec 26, 2010
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    Last edited: Jul 6, 2011
  6. SgtWookie

    Expert

    Jul 17, 2007
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    You should have a read through the attached document. It may help you to understand more about what you're up against.

    Many 4000-series CMOS have 16v as their absolute maximum supply voltage, and most of them aren't rated for the automotive temperature range (-40°C to 125°C). Just forgetting something like a reverse-EMF diode across a relay coil nearby would kill your IC.
     
  7. praondevou

    AAC Fanatic!

    Jul 9, 2011
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  8. xile6

    Thread Starter New Member

    Jun 9, 2011
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    IDK about that i am using a PAC tr-7 which is a 12volt car latcher/ timer. It works great. I would still like to know what was wrong with my circuit but i will have to order some more chips before i can test it again.
     
  9. praondevou

    AAC Fanatic!

    Jul 9, 2011
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    Ok I googled PAC tr-7 and it has nothing to do with an active transient protection... At least I didn't see anything :)

    As others already said, on your 12V voltage coming from your battery there will be transients. Very short pulses with a voltage exceeding your maximum allowable IC voltage. First thing to make sure is that you have a protection against those transients. In your circuit I don't see a transient surpressor.

    What about SgtWookies hint: "Just forgetting something like a reverse-EMF diode across a relay coil nearby would kill your IC." ?

    The relays you are using are on the 12V battery voltage too, aren't they? In your circuit diagram there is no diode across the relay.
     
  10. xile6

    Thread Starter New Member

    Jun 9, 2011
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    there is a diode across the relay. just not in that diagram. It just seems like the circuit drops in voltage and maybe is shorting to ground. I added a cap and resistor on the power side and it seemed to have worked. But it some how caused the cd4017 to not reset when it went to output 2. (0 is off, 1 is on, 2 is reset).
    Im using the tr7 for now but i will try my circuit again i hate failing at things and i work till they are right.
     
  11. praondevou

    AAC Fanatic!

    Jul 9, 2011
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    so the is the circuit in your diagram complete, except from the relay diode?
    What values have the RC you added?
    There is still missing a component that would protect your device, like a Transorb for example.
     
  12. CDRIVE

    Senior Member

    Jul 1, 2008
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    I have no idea why this thread remains open but since it does....

    IMO you would have been well advised to not power the 4017 directly from the 12V rail. Instead, I would have powered it through A 5V regulator using all recommended input and output caps.
     
  13. bertus

    Administrator

    Apr 5, 2008
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    Hello,

    I overlooked the thread.

    I am closing this thread as it violates AAC policy and/or safety issues.

    Quote:
    6. Restricted topics. The following topics are regularly raised however are considered “off-topic” at all times and will results in Your thread being closed without question:

    • Any kind of over-unity devices and systems
    • Automotive modifications
    • Devices designed to electrocute or shock another person
    • LEDs to mains
    • Phone jammers
    • Rail guns and high-energy projectile devices
    • Transformer-less power supplies
    This comes from our Tos:
    Terms of Service
    There will be enough sites where automotive questions can be discussed :
    Member selected automotive forums

    Bertus
     
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