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
    2
    0
    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: (http://www.instructables.com/id/ThrobbingFading-LED-with-555-Timer/) 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
    246
    29
    How about another 555 to trigger it?
     
  3. Rent2Pwn

    Thread Starter New Member

    Oct 1, 2016
    2
    0
    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
    4,173
    397
    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.
     
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