Which 555 timer trigger circuit is better?

Discussion in 'The Projects Forum' started by iakobos, Nov 15, 2010.

  1. iakobos

    Thread Starter New Member

    Nov 15, 2010
    I'm making a trigger circuit for a paintball gun. This will be my first IC and so the 555 timer is new to me. The timer will be used to control the firing of the gun. Since high pressure air is used to propel the ball, the solenoid valve has to be open for a precise amount of time. I already have a good feel for how to use the 555 to do this based on the info here. The gun has a micro-switch mounted to the trigger on the grip frame. When the micro-switch is depressed that's when a ball should fire. Right now I'm sorting out how to wire up the 555 and I'm wondering if I should use the micro-switch to operate terminal 2 on the 555 or do I use the micro-switch to power the entire 555 each time?
  2. Kermit2

    AAC Fanatic!

    Feb 5, 2010
  3. Tahmid

    Active Member

    Jul 2, 2008
    I would say the first, because here the 555 would be ON but not oscillating. In the 2nd, the 555 would be first turned on and then starting acting. I think the first would be the better choice.

    Hope this helps.
  4. iakobos

    Thread Starter New Member

    Nov 15, 2010
    Thanks to both. That's the way I was going with it till I discovered how much more complicated it's going to make the final design. The reason is I'm going to be able to select between monostable (semi-auto) and astable (full-auto) and switching the micro-switch between the two modes is a little tricky.
  5. shortbus

    AAC Fanatic!

    Sep 30, 2009
    You would have two 555 circuits and a double throw switch to the micro switch to change between semi and full.
  6. engrdm

    New Member

    Feb 19, 2010
    you should use the monostable mode. and select the timing resistors for your require dtime using the formulas or calculator given in the link below...

    read the article as a whole specialy the monostable operation
  7. SgtWookie


    Jul 17, 2007
    Gee, this thread had been inactive for 8 months, and the original poster hasn't been back since December of last year.

    No sense in replying to inactive threads. If the original poster hasn't been back in a few weeks, let it sleep.