Push switch circuit need the led to stay lit for a few second after switch is let go

Discussion in 'The Projects Forum' started by paddyhughes086, Mar 9, 2011.

  1. paddyhughes086

    Thread Starter Active Member

    Jan 30, 2011
    48
    0
    Hi I need a circuit that when you press the switch the led will stay light. Say 30 sec and then turn off till sthe switch is pressed agen
     
  2. jpanhalt

    AAC Fanatic!

    Jan 18, 2008
    5,681
    900
    Something like this might work:

    [​IMG]

    You can adjust the resistor and capacitor to control how long it stays on after release.

    John
     
    Last edited: Mar 9, 2011
  3. paddyhughes086

    Thread Starter Active Member

    Jan 30, 2011
    48
    0
    Thanks John I can't see the image on my iPhone but il check
    It out on my computer soon thanks
     
  4. jpanhalt

    AAC Fanatic!

    Jan 18, 2008
    5,681
    900
  5. paddyhughes086

    Thread Starter Active Member

    Jan 30, 2011
    48
    0
    i see you are also saying you can di it with a 555 timer would you have anything on that scamatics
     
  6. jpanhalt

    AAC Fanatic!

    Jan 18, 2008
    5,681
    900
    How complicated do you want it to be? Do you want a "snap" action or is a gradual fading off ok? What current will the LEDs draw? Almost any analog circuit will be a variation on the RC circuit I showed.

    John
     
  7. paddyhughes086

    Thread Starter Active Member

    Jan 30, 2011
    48
    0
    Hello a gradual fade of is fine i just need to run 5 led using forward voltage of 2.8min 3.0 typ
    i also will need to run a 3v buzzer on the same circuit picture this circuit as a door bell you press the button and it light up and makes sound. but unlike a door bell it stayes on for a few seconds longer than the button is pressesd.
     
  8. jpanhalt

    AAC Fanatic!

    Jan 18, 2008
    5,681
    900
    Q1 is a generic N-channel, logic-level mosfet transistor.

    You will need to consider your supply voltage. Will it be 5V (nominally) or 3V?
    Can post a flow chart or block diagram of what you want to do. "I also want to..." can be confusing.

    John
     
  9. paddyhughes086

    Thread Starter Active Member

    Jan 30, 2011
    48
    0
    I can put as much as 12v into this circuit as it will be running off a variable powersupply so i can change it down to 3v or up to 12v what ever makes it easier for you to do thanks

    edited**** sorry was mentt to say the picture is of what the circuit looks like now with no timing at all
     
    Last edited: Mar 11, 2011
  10. paddyhughes086

    Thread Starter Active Member

    Jan 30, 2011
    48
    0
    what about this i i use this layout but were pin 3 comes out of the 555 timer i split so one cable goes to the led and the other goes to the buzzer this way i can put diffrent resisters values on for the busser and the leds that will be in series
     
Loading...