project help...

Discussion in 'The Projects Forum' started by kuxz2008, Jan 16, 2010.

  1. kuxz2008

    Thread Starter Member

    Nov 16, 2009
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    i need help in my electronics project.

    for instance, the tamiya car is at station 3, the 7 segment LED will light up a '3'. when either the front or the back microswitch attached to the car is activated, relay2 will be activated (com1 go to no1 and com2 go to no2). when relay2 is activated , the tamiya car motor will stop.

    the problem is that when the relay2 is switching back to the original positon(com1 from no1 back to nc1, com2 from no2 go back to nc2), the 7 segment LED display will display a random value instead of '3'.

    what must i do in order not to allow the relay2 to affect the 7 segment LED display?

    NOTE:
    CPU and CPD is connected via the 2 pictures
    Q0 to Q3 is also connected via the 2 pictures
     
  2. retched

    AAC Fanatic!

    Dec 5, 2009
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    I dont see any protection for the uC from the relay coil. You should have a .1uf capacitor to filter across Vcc and Ground on the uC(You have them marked as pins 16 and 8). A diode to keep spikes from the relay coil from hitting the uC should help too.
     
  3. kuxz2008

    Thread Starter Member

    Nov 16, 2009
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    is it for the relay1 or relay2 ?
    what do you mean by uC?
     
  4. retched

    AAC Fanatic!

    Dec 5, 2009
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    both should have protection. Just sprinkle them around. :)

    Electromagnetic coils can send a spike, higher than rated, backwards. If it hits your microcontroller, it can cause problems. Also 'noise' from inductors can cause weird things to happen. Its best to isolate these types of things from others.

    u is micro, uC is shorthand for microcontroller
     
  5. kuxz2008

    Thread Starter Member

    Nov 16, 2009
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    u mean i need 4 0.1uf capacitor for both the vcc and ground for relay1 and relay2?
     
  6. retched

    AAC Fanatic!

    Dec 5, 2009
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    The .1uf capacitor connects the Vcc and Gnd pins. Straddling the chip, as close as you can get it.

    See the picture
     
    Last edited: Jan 17, 2010
  7. SgtWookie

    Expert

    Jul 17, 2007
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    I'd try to help, but your schematics are so dark that I have a very hard time reading them.

    Please try to get better lighting when you're taking images, or better yet, use one of many freely available software packages to draw your schematics with. LTSpice is a very good (and free!) schematic capture and simulation program. Google is your friend here.

    Take a screen print (Ctrl+PrintScreen), paste it into MS Paint, save it as a .jpg format file.

    Then upload it as an attachment.
     
  8. kuxz2008

    Thread Starter Member

    Nov 16, 2009
    84
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    i have upload a clearer pic.
    hope you can help me ....

    link of pic:
    http://5b5889bd.linkbucks.com
    http://8349b46a.linkbucks.com
     
  9. kuxz2008

    Thread Starter Member

    Nov 16, 2009
    84
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    the pic u upload seems like the .1uf capacitor is connected across the ic chip.
    so do i connect the capacitor across the ic chip or the relay1 and relay2?
     
  10. kuxz2008

    Thread Starter Member

    Nov 16, 2009
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    the pic u upload seems like the .1uf capacitor is connected across the ic chip.
    so do i connect the capacitor across the ic chip or the relay1 and relay2?

    anyone can help me /??
     
  11. retched

    AAC Fanatic!

    Dec 5, 2009
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    yes, ACROSS the chip connecting Vcc and ground
     
  12. kuxz2008

    Thread Starter Member

    Nov 16, 2009
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    which chip do i need to connect ?
    or do i need to connect all the chip ?
     
  13. retched

    AAC Fanatic!

    Dec 5, 2009
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    All of your chips with a Vcc and a ground. It isn't REQUIRED. It is good practice. It will help keep bad things from happening.
     
  14. BillB3857

    Senior Member

    Feb 28, 2009
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    Sgt, I can't believe you said "save it as a .jpg formt file." I ran out of fingers counting how many posts you made saying "PNG". :)
     
  15. kuxz2008

    Thread Starter Member

    Nov 16, 2009
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    bill can you helo me? Must i connect .1uf capacitor for all the ic chip that i have?in order not to affect the display of the led when the microswitch is activated...
     
  16. BillB3857

    Senior Member

    Feb 28, 2009
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    Good power supply bypassing (that is what the caps do) is always a good idea. especially in a system that has brush type motors, relays, and other known noisy devices. They help to reduce noise spikes on the power supply seen at each and every IC they are attached to. You can even buy IC sockets that already contain the bypass caps.
     
  17. kuxz2008

    Thread Starter Member

    Nov 16, 2009
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    does connecting the capacitor solve me problem (what must i do in order not to allow the relay2 to affect the 7 segment LED display)?
     
  18. BillB3857

    Senior Member

    Feb 28, 2009
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    It will probably help. Other things can cause your problem. Things like having wires that are attached to noisy devices being placed close to wires that feed the input to devices like counters, etc.
     
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