Unusual 7 segment display

Discussion in 'The Projects Forum' started by adriano08, Apr 26, 2010.

  1. adriano08

    Thread Starter Member

    Apr 25, 2010
    33
    1
    Hi guys. :)

    I just made a 60 seconds counter using 7 segment display. The problem is whenever I turn off the power and switch it back on, it will always start counting from 24 onwards instead of 00... and so on.

    Why is it so and how to make it count starting from 00 whenever I power up the circuit?:confused:
     
  2. SgtWookie

    Expert

    Jul 17, 2007
    22,182
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    Unless you post a schematic of your circuit, we have less of a clue than you do.
     
  3. CoolBeer

    Active Member

    Mar 29, 2010
    40
    6
    I think the answer is on page 42 in the datasheet!

    Seriously though, unless we know what you are using to drive the 7segment all our guesses will be kinda foggy, so shed some light on the situation if you please :)
     
  4. adriano08

    Thread Starter Member

    Apr 25, 2010
    33
    1
    I was using 74HC4511 and 74LS90. All connections are pretty correct. Also, 5V to power up, 270ohms to limit the current for the common cathode segment display.

    Hmmm...:rolleyes:
     
  5. adriano08

    Thread Starter Member

    Apr 25, 2010
    33
    1
    Hi there. :)

    Schematic wise I have not make one yet.:p The 60s counter works normally counting from 00 to 60. But it will always start to count up from 24 onwards whenever I power up the circuit. After that it becomes normal until I restart the whole set up again..

    :rolleyes:
     
  6. JoeJester

    AAC Fanatic!

    Apr 26, 2005
    3,373
    1,157
    Did you wire this up or is it a manufactured circuit?
     
  7. adriano08

    Thread Starter Member

    Apr 25, 2010
    33
    1
    I patched up on my own. :)

    Update from here:
    I proceeded to 4 digits counter. Everything works well. However there are some concerns again.. Whenever I supply voltage to circuit, the digits will randomly appear and then start counting from there instead of counting from 00.00 onwards.

    So how to make it goes 00 whenever I turned on the power supply 5V?:confused:

    PS: Normal typical counter wiring up using 74HC4511 and 74LS90
     
  8. beenthere

    Retired Moderator

    Apr 20, 2004
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  9. JoeJester

    AAC Fanatic!

    Apr 26, 2005
    3,373
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    True. No schematic, patch work, and problems. Who'da thunk it.
     
  10. adriano08

    Thread Starter Member

    Apr 25, 2010
    33
    1
    I see sir. How do I implement the reset function? I mean I wanted to get count from 00.00 onwards whenever I power up... but not when I power up, press reset button then it will be 00.00.

    On a side note, why mixing 74LS and 74HC can be problematic? Or any suggestion of ICs can be use with 74HC4511 because I just bought it and do not want to waste it.

    :confused::)
     
  11. adriano08

    Thread Starter Member

    Apr 25, 2010
    33
    1
    Hi. Still yet to draw out the full schematic... :D
    But the idea is roughly there.. cascading 4 common cathode segment. Will try to post a rough schematic here soon.
     
  12. adriano08

    Thread Starter Member

    Apr 25, 2010
    33
    1
    Another question, is diode necessary to be connected? Currently I did not connect any diode in the circuit. I thought of current flowing backward when the power supply is turn off. Is this logical?:confused:

    If yes, where should I normally place the diode?

    Thanks. :)
     
  13. beenthere

    Retired Moderator

    Apr 20, 2004
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    No, it's not even possible - unless there is something in the circuit we are not aware of.
     
  14. retched

    AAC Fanatic!

    Dec 5, 2009
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    Oh, the flux capacitor was wired WITHOUT a diode? geez, no wonder your going through time like that. ;)
     
  15. adriano08

    Thread Starter Member

    Apr 25, 2010
    33
    1
    I have dismantled everything and came out with a sychronous counter. The problem no longer occurs. ;)

    Ripper counter really a mess for me.

    If there's any more problem encounter, I will ask you guys.

    Thanks.:p
     
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