555 Help!

Discussion in 'General Electronics Chat' started by Martyn, Nov 4, 2012.

  1. Martyn

    Thread Starter New Member

    Oct 27, 2010
    20
    0
    Hi Guys

    Can anyone help me with my question?

    Im trying to make a circuit with a 555 timer that will allow me to press a momentary push to make button and then latch the output (which i have managed to do).

    However I also need to the circuit to be able to switch off an output using a relay or similar when either a external -ve or +ve is detected using the same on/off switch.

    I have attached a basic circuit below as to what i i have done so far.

    Can any of you guys help me?

    Thanks


    [​IMG]
     
  2. nepdeep

    Member

    Sep 14, 2011
    139
    0
    -ve or +ve detected where...??...do you mean the input...do you want input over voltage protection ??
     
  3. Martyn

    Thread Starter New Member

    Oct 27, 2010
    20
    0
    Basically what i want is to be able to turn somthing off with the switch using a relay or somthing like that.

    Im thinking that when a 12v signal is detected it will illuminate the LED but i can override the signal with my button thus firing the relay and removing power to the LED.
     
  4. Wendy

    Moderator

    Mar 24, 2008
    20,764
    2,534
    I am one of the experts on the 555 around here. Feel free to point me to your posts on them. I am writing several articles for the AAC book using them.

    I think this will answer your question...

    555 Bistable Multivibrator

    Bill's Index (my blog)
     
  5. Martyn

    Thread Starter New Member

    Oct 27, 2010
    20
    0
    Hi Bill

    Thanks for the responce.

    Are you saying that the circuit you posted is what i need? as i dont understand how it will let me overide when a signal is detected.

    Thanks
     
  6. nepdeep

    Member

    Sep 14, 2011
    139
    0
    follow this dude
     
  7. Wendy

    Moderator

    Mar 24, 2008
    20,764
    2,534
    The circuit I showed is a simple flip flop, but it can also be reset with the reset input on pin 4. I am not sure I understand your requirements, but I think this fills them. Reset on the 555 overrides all other inputs.
     
Loading...