One Shot LED Fade In/Out w/ 555?

Discussion in 'The Projects Forum' started by Rent2Pwn, Oct 1, 2016.

  1. Rent2Pwn

    Thread Starter New Member

    Oct 1, 2016
    Hello everyone!

    Little about me, all my electronic knowledge has been self taught and so it has a few holes in it. Mainly I can look at a schematic and make a guess of what it does but designing something to do what I want from scratch I have a hard time with.

    A coworker has asked me to build her a circuit for a costume that when you press a button on the nose of the head, it has an LED in each cheek that will fade in then fade out to look like blushing. This circuit here: ( I have built and works fine, the only problem is you have to hold the button the whole time for it to complete the fade in/out and if it's held it will continue fading in and out. What I'm looking for (preferably) is a small modification to this circuit to make it so the button is quickly pressed once and it does one fade cycle and stops, but if someone can recommend a completely different schematic that's still fairly simple I would appreciate that too.

    Sorry if this has been asked before, I searched but couldn't find any exact info for my situation.
  2. upand_at_them

    Active Member

    May 15, 2010
    How about another 555 to trigger it?
  3. Rent2Pwn

    Thread Starter New Member

    Oct 1, 2016
    Can you give an example? I keep seeing 555s setup to be constant, not one shot like I need. Sorry if I sound noobish lol.
  4. Bernard

    AAC Fanatic!

    Aug 7, 2008
    The change is simple, disconnect pin 2 from R & C & reconnect it to a resistor of 1k to 100k, other
    end to + supply. Connect NO switch from pin 2 & pin 1, - supply. 555 is now connected as a one shot, a short press on switch will cause a single rise & fall. If more control is needed could try something like in You Tube, Jack Bernard, lighthouse.