Connect with us

LED flasher circuit

Discussion in 'LEDs and Optoelectronics' started by abramelin, Oct 21, 2010.

Scroll to continue with content
  1. abramelin

    abramelin

    2
    0
    Oct 20, 2010
    Hello all
    I'm in need of advice and/or a circuit diagram for the following.

    One group of 6 LEDs to flash for one second on and off for one second.
    Second group of 4 LEDs, to flash for .5 second on and off for .75 second.

    Can it be built as one circuit or will it have to be two seperate circuits, I would perfer it as one if possible. I have built a circuit that flashes 2 LEDs that uses a 555 chip from what I've found online but I have no idea how to adapt it to do any or all of the above.

    Cheers in advance for all help with this.
     
  2. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,482
    2,830
    Jan 21, 2010
    You need 2 555 oscillator circuits. One for the first flash rate, the second for the other.

    A 555 can easily drive multiple LEDs. If these are high power LEDs, then it's not too hard to use a MOSFET or bipolar transistor driven by the 555 to switch them on and off.

    I can't tell you exactly how to connect your LEDs as the best arrangement depends on your supply voltage. The simplest way is to place a resistor in series with each LED and then connect all of these between the 555's output ground.

    Look at this page which shows how to connect multiple LEDs to a 555 for varying supply voltages.

    edit: it could be 1 board with 2 555's on it, or 2 boards (each with 1 555), or a single board with a 556 (a dual 555) on it. As to whether you describe it as one circuit or 2, that's up to you.
     
    Last edited: Oct 21, 2010
  3. abramelin

    abramelin

    2
    0
    Oct 20, 2010
    Thanx for that.
    Will give it a try.
     
  4. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,482
    2,830
    Jan 21, 2010
    Perhaps a little clarification is in order.

    The link I gave you uses the discharge pin and a transistor to drive the LEDs. All I was intending to show was the way the LEDs are wired up. They can be connected to pin 3 (output).

    Note that the 555 is typically limited in the duty cycle of the output. There are various methods that can be used to get around this limitation, the link I gave being one, but this probably being easier in your case as it allows the use of the output pin to drive the LEDs.
     
Ask a Question
Want to reply to this thread or ask your own question?
You'll need to choose a username for the site, which only take a couple of moments (here). After that, you can post your question and our members will help you out.
Electronics Point Logo
Continue to site
Quote of the day

-