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7 Segment Display / Counter

  1. Jun 13, 2009 #1
    Hi there

    Im building a 7 segment display that counts to 10 when a switch is activated .. this is on Multisim. Ive built it to how i think is correct .. Unfortunatly is doesn't seem to be doin anythin at all ..

    Any help is appreciated
  2. jcsd
  3. Jun 13, 2009 #2


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    Hi Dave and welcome.

    You would need to post a copy of your circuit.

    It is common in logic circuits like counters to have a number of pins that have to be grounded or brought to the 5 volt reference level. Have a look for pins like "reset" and "enable" that have to be treated like this and check which way they need to be connected.
  4. Jun 14, 2009 #3
  5. Jun 14, 2009 #4


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    Can't really see the circuit, but if that is a TTL 7490 or similar, you would need to pull the input to ground rather than to 5 volts when you provide a series of pulses to check the counter.
    TTL inputs are already at "high level" and need to be grounded for the counter to change state.

    Can you make the circuit a bit bigger?
    Last edited: Jun 14, 2009
  6. Jun 15, 2009 #5
  7. Jun 15, 2009 #6


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    You are still pulling the input high with the switch. It is already high so this will not work.

    Put a 1K resistor from input to ground and leave the switch where it is.
    Or put a 1 K resistor to 5 V from the input and a switch to ground. Simulators like you to be definite about your intentions.

    There may be other problems, but the circuit is still unreadable here.
  8. Jun 16, 2009 #7
    Thanks alot ... This seemed to fix the problem
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