Lookin for strobe effect for LEDS on a 9v

Discussion in 'The Projects Forum' started by staarklite, Mar 25, 2013.

  1. staarklite

    Thread Starter New Member

    Mar 25, 2013
    Hello all!

    So i make my own LED necklaces, and i run them off a 9v battery.

    Unfortunately, my on/off is connecting/disconnecting the battery clip.

    i'm not completely new to circuits, but i cant find much about what i need thats short of 10 dollars.

    As a next step... i would like to offer a simple on/off/strobe selection.

    i need help in selecting the cheapest way out.. (since i put more man hours into each necklace than i can charge for)

    the best would be if i could find a circuit, premade, with those 3 settings... but i couldn't find that..

    next maybe an IC chip that does strobe? i found maybe LM311DR but im not sure.

    anythign self made with a potentiometer ive looked past... since all those potentiometers are pretty large... and.. i cant find one small enough that offers the resistance range i need for a strobe... altho.. an ON/OFF with an adjustable POT from steady on to strobe would be GREAT.... if anyone could suggest a good/cheap/small POT. tho... i dont really want to have to add capacitors and more resistors. it would need to be a small simple setup.

    anyway, ill keep this simple, because i know someone must know alot more about this than me.

    i just want something i can add to my circuit that would give a strobe option. i suppose flashing would be ok..... but really i want fast like a strobe .

    Help would be MUCH APPRECIATED
    Thank you!!
  2. DickCappels


    Aug 21, 2008
    The component in the datasheet is not the right part for your application. The "strobe" pin is to effectively turn the chip on and off.

    For the level of skill you have indicated, a simple multivibrator would be the best way to start because its a reliable circuit once its wired correctly. The parts are inexpensive.


    The above image is from http://www.zen22142.zen.co.uk/Circuits/Misc/flasher.htm where the circuit is described.

    To make it flash one LED2, for example, replace LED2 with a piece of wire.
    With the component values shown, the remaining LED will be on for 50% of the time. to make the on period shorter (shorter duty cycle) reduce the value of C1.

    Problems that many people have when assembling this are:
    1) Not connecting the transistors correctly. Get the data sheet and make sure
    2) Getting the LED(s) in backwards. Same solution as #1.
    3) Getting one or more capacitor backwards.
    4) Connecting the battery backwards.
    5) Simply missing a connection or misconnecting something.

    If you get working parts and connect them properly, this circuit will work.

    Notes: The apparent brightness of the LEDs can be changed by changing R3 and R4; lower values make it brighter. Start with the values shown.

    If you can't find the exact parts in the schematic, lots of kinds of substitutions can be made. Just post your question on this forum.
    Last edited: Mar 26, 2013
  3. WBahn


    Mar 31, 2012
    I would recommend an 8-pin PIC or similar.

    I would envision the PIC with an output to your driver (the PIC may be able to drive your string, but I'm guessing not) and a simple pressure button of some type. The PIC is always on but usually in a sleep mode (ultra low power). You then press the button to wake it up and your string turns on continuously. If you press the button again and hold it the string starts to flash and the flash rate changes as long as you hold the button down. To turn it off, you press the button twice in short succession. A different choice of actions versus effects is probably better, but the basic idea is that you use a single button for all of your control options.
  4. sheldons

    Well-Known Member

    Oct 26, 2011
    heres a led strobe circuit-use hi brightness leds
  5. DickCappels


    Aug 21, 2008