Led Strip light strobe with variable speed control

Discussion in 'The Projects Forum' started by Vincent Dickerson, Feb 13, 2019.

  1. Vincent Dickerson

    Thread Starter New Member

    Feb 13, 2019
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    Hi Guys,
    I'm a recent Matric graduate and I am busy with a home project but my lack of true understanding of circuitry is letting me down a bit.
    I took electrics at school and have always built electronic projects for fun but always from a schematic.
    I am trying to build a 12V LED white strobe light.
    I understand the working of multivibrators an I'm quite sure that a 555 would be a solution but I'm not sure how much power I could pull from it to run a few metres of LED strip or what modifications I would need to make to do so. This has left me at a loss for a suitable schem. I have searched the internet but there is either no such schematic or I just don't know what I'm looking for. Does anyone know of a circuit that would suit my purposes?
    Any help would be greatly appreciated!
     
  2. crutschow

    Expert

    Mar 14, 2008
    22,010
    6,367
    The first step in any design is the specifications, which are lacking here.
    Yes, a 555 circuit would likely do what you want.
    How much current does the LED light take?
    Does it already have a 12V supply?
     
  3. dl324

    AAC Fanatic!

    Mar 30, 2015
    8,259
    1,989
    Welcome to AAC!

    A bipolar 555 can sink/source about 200mA. Adding a MOSFET or BJT to the output can increase current capability to anything you want.

    Here's an example I drew for someone using an N channel MOSFET:
    upload_2019-2-13_9-18-8.png
     
  4. Alec_t

    AAC Fanatic!

    Sep 17, 2013
    9,607
    2,325
    Be aware that certain strobe frequencies can induce epileptic seizures in some people. Avoid frequencies in the 5-12Hz range.
     
  5. Vincent Dickerson

    Thread Starter New Member

    Feb 13, 2019
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    I haven't bought the led strips as of yet. I was intending on calculating the output of the circuit and choosing my LED strip accordingly.
    I have a 12V 4A transformer at home from a previous project that I was intending on using for the project but I can easily get another one if it is not sufficient.
    I calculated a rough estimate of a short piece of LED strip I had lying around and it worked out to about 1.2A/Metre
     
  6. Vincent Dickerson

    Thread Starter New Member

    Feb 13, 2019
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    Thank You, I will definitely
    Am I right that you could add a Potentiometer to C2 to control the rate of phase change?
    take that into consideration during operation!
     
  7. dl324

    AAC Fanatic!

    Mar 30, 2015
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    Not sure what you mean by phase change.

    C2 is to bypass noise on the control voltage. You could modulate the frequency by varying the voltage on that pin, but I'd just make R1 or R2 a pot.
     
  8. Vincent Dickerson

    Thread Starter New Member

    Feb 13, 2019
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    Thank you that's what I was going for.
    So can I use that circuit exactly and just add a mosfet over the 36V LED output and just add three 12V led strips together in Parallel.
     
  9. dl324

    AAC Fanatic!

    Mar 30, 2015
    8,259
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    Delete the 36V supply, R3, D1, and connect your 12V LEDs.
     
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