Loading ...
Sorry, an error occurred while loading the content.

Re: Triggering a 555 Timer

Expand Messages
  • csakima
    As I recall, the problem lies in the fact that ... in a fight between pin 6 (threshold, I think) .. and pin 2 (trigger) .... the trigger is set to win and
    Message 1 of 4 , Dec 4, 2002
    • 0 Attachment
      As I recall, the problem lies in the fact that ... in a fight between pin 6
      (threshold, I think) .. and pin 2 (trigger) .... the trigger is set to win
      and override Pin 6.

      Thus, pin 2 goes low ... triggering the timer. The cap charges until the
      pin 6 passes its threshold. However, if at that time, pin 2 is still low
      ... the 555 goes "so what" ... ignores the pin 6 .... and the output remains
      high. Only when the trigger goes high again does the 555 "consider the
      feelings" of pin 6. At which time ... if the timer had timed out ... does
      the output go low again.

      Curtis

      Get your free newsletter at
      http://www.ezinfocenter.com/3122155/NL


      ----- Original Message -----
      From: manifold <manifold_1@...>

      I forget exactly how the trigger on a 555 is constructed but I do remember
      having the same problem many years ago. My solution was to capacitively
      couple the pulse source to the 555 trigger. You can use diodes to control
      the negative or positive overshoot.

      ---------------------------------------------
      Introducing NetZero Long Distance
      1st month Free!
      Sign up today at: www.netzerolongdistance.com
    Your message has been successfully submitted and would be delivered to recipients shortly.