555 timer project help

Discussion in 'The Projects Forum' started by tester101, Sep 3, 2007.

  1. tester101

    Thread Starter New Member

    Sep 3, 2007
    I want to build a circuit that will activate a solid state relay on and off constantly, meaning once the circuit is started the relay will open and close until the crcuit is turned off. I would like to be able to adjust the amount of time the relay opens and closes. I fiqured the best and simplest way would be to use a 555 timer in a constant Astable state. I have checked out a few circuits but I fiqured before I started I would try to get some advice to avoid the pitfalls. The Astable state also alows me to adjust the timing of the 555 timer output waveform. Seems like what I need but maybe someone will have a better idea. Anyways thanks for reading and any help you can give.
  2. hgmjr


    Jan 28, 2005
    What is your requried cycle rate needed for the relay?

    Can you give a few more details about the timing of the circuit?

  3. rossi

    New Member

    Sep 4, 2007
    what is the formula in finding the value of resistor instead of time
  4. beenthere

    Retired Moderator

    Apr 20, 2004
    It is not acceptable to jump in on another's thread. If you have further questions, please start a new posting to ask it in.

    You can get the datasheet for an LM555 timer and use the included formula for the resistor values.