555 12V Power Off Time Delay Circuit

Discussion in 'The Projects Forum' started by PianoV, Oct 10, 2008.

  1. PianoV

    Thread Starter New Member

    Oct 10, 2008
    I know very little about designing/building circuits. I want to wire 12V strobe lights to my horn switch on my motorcycle. What I'm trying to create is a "visual horn". When I toot my horn, I want the strobes to flash for about three seconds. Typically, when I toot my horn (VERY LOUD), it is only for less than one second. I wish the strobes to operate for a duration of about three seconds after I toot the horn.

    So what I need to design and build is some sort of simple 12V circuit that is normally off, but when tripped by application of the horn button, it allows the 12V power to flow through to the strobes for about three seconds.

    I have quite a range of possible current draws for the strobes because I can either go with real strobe lights, or I can also use LEDs - just thinking that maybe LEDs would be more "simple circuit friendly" because of their low current draw.

    Can anyone point me in the right direction? Maybe something is commercially available - I've googled myself to death trying to find something with no luck. Maybe the circuit would involve a NE555 timer?

  2. Wendy


    Mar 24, 2008
    These strobes would be separate lights, right? Not your headlight. They would also be white?
  3. thingmaker3

    Retired Moderator

    May 16, 2005
    Try using the term "monostable multivibrator" in your search. Its a mouthful of a term, but it simply means "on for a defined period after I press the button." And yes, a monostable multivibrator can indeed be made from a 555.

    The 556 (two 555s in one package) would let you create both the monostable and the oscillator for flashing LEDs.

    By using the monostable to drive a switch (many types of transistor make a good switch) you can control a wide range of current.