5 Pulses then STOP!

Discussion in 'The Projects Forum' started by NM2008, Apr 12, 2008.

  1. NM2008

    Thread Starter Senior Member

    Feb 9, 2008
    I am trying to set up a circuit where I get 5 pulses then after the fifth, the pulse stops.
    Could this be done with a 555 and a decade counter?
    For example say, with the 555 in monostable once triggered with the push-button, could 5 pulses be given then the cycle stops until the next trigger.
    How would I go about building this type of circuit?

    Thanks for your time.
    Regards NM
  2. SgtWookie


    Jul 17, 2007
    Take a look at a CMOS 4017B, which is a 5-stage Johnson counter.

    Basically, it has 10 outputs, a clock input, and a reset. Only one output at a time is high.

    Run your 555 clock output to the 4017 clock input. Use one of the outputs as a disable for your 555 timer. When you reset the 4017, you'll get another 5 clocks from the 555.

    This is simplified, of course. You'll want to ensure that the reset of the 4017 is a pulse less than the duration of one 555 clock. You could do that with an RC network.

    Ensure that all inputs to the 4017 are tied to either Vdd or Vss. "Floating" inputs will cause problems.
  3. Wendy


    Mar 24, 2008
    Another way to do it is two 555's, one controlling the other. You set the second unit as an astable unit, and the first one as a monostable, set for the length of time for 5 pulse to come out of the second. The big drawback with this method is the first pulse out of the ocsillator (astable) is a bit longer than the rest.

    What kind of timing are you looking for?
  4. NM2008

    Thread Starter Senior Member

    Feb 9, 2008
    Timing is fine, just looking for the method, I was aware of a set-up with a 555 and a counter, just wasn't 100% on it.
    The 2 555's is an interesting method, I will try it out aswell!

    Thanks Sarge and Bill!