555 Mono Stable Question.

Discussion in 'The Projects Forum' started by NM2008, Jun 13, 2008.

  1. NM2008

    Thread Starter Senior Member

    Feb 9, 2008
    Could anybody tell me if it is possible to make a delay for the circuit in the attachment?
    I am working on a device which when turned over a relay triggers. This circuit works well for this idea, but one problem, where the mercury switch is mounted there is vibration(near an engine). I have to have this switch mounted at 45 degrees for it to operate the way I want it to, but the vibration jumps the mercury to the contacts causing the relay to latch.
    So I was wondering if there is any way to make a delay for the switch to trigger the circuit, this would stop the unwanted triggering until the device definitely overturned.

    Thanks for your help,
    Regards NM
    Tilt switch.gif
  2. mik3

    Senior Member

    Feb 4, 2008
    Yes you can make a delay with a 555 but as i can see from your schematic the circuit is not connected properly to make a delay when the tilt switch triggers. Make the ordinary 555 monostable circuit and use the tilt switch to trigger it. Take another 555 and use it as a monostable too but with a turn on time of 1 ms and connect its trigger input to the output of the first 555. With the first 555 you will define the time delay you want.

    With this circuit you will delay the signal when the tilt triggers the first 555, after the delay you want has passes then the second 555 will output a 1 ms pulse to control your device.
  3. stellarhopper

    New Member

    Sep 20, 2007
    what is the time for which the tilt switch will remain tilted?
    if it is long enough..you can add an RC circuit working as a high pass filter immediately after the switch...
  4. Digi Dave


    Apr 25, 2008