problem 0f 7490 in counting

Discussion in 'The Projects Forum' started by Afeesh a n, Jun 12, 2009.

  1. Afeesh a n

    Thread Starter New Member

    Jun 12, 2009
    1
    0
    hi,
    i have configured a 7490 as a decade counter. but as the pulse come the counter is counting with 2 ie. 1 3 5 ......what may be the problem the pulses are coming from a monostable multivibrator with time period of .6s.so plz do suggest some idea to eliminate this.

    thank u
     
  2. bertus

    Administrator

    Apr 5, 2008
    15,649
    2,348
    Hello,

    Can you post a schematic of how you have connected the 7490?

    Greetings,
    Bertus
     
  3. RiJoRI

    Well-Known Member

    Aug 15, 2007
    536
    26
    And while you're posting the schematic, make sure the LSB is not tied high.

    --Rich
     
  4. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    Are you using bypass capacitors on both your astable multivibrator's Vcc/GND supply AND the 7490 supply pins? If not, there's a very likely cause.

    Are your interconnecting traces/wires/jumpers long? Try to keep them as short as possible; long wires have a good deal of inductance, and will cause circuits to oscillate unexpectedly.
     
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