Flashing LED strip

Discussion in 'The Projects Forum' started by captainlol, Jan 13, 2014.

  1. captainlol

    Thread Starter New Member

    Jan 13, 2014
    3
    0
    Hi, I'm new to the forums and to electronics in general. I have to do a project for my final semester and what I'd like to make is a flashing LED strip for my bicycle to act as a turn signal.

    For now, I have figured that I need the LED strips and a 3-way toggle switch (for left and right). Beyond that, I'm pretty much clueless. Does anyone know how I can go about wiring this up using a controller of some sort?

    Ideally, I'd like it to be wireless but I fear that's way above my skill level, so having it hard-wired is acceptable too.
     
  2. DerStrom8

    Well-Known Member

    Feb 20, 2011
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    Having it wireless would be very complicated, and would probably require RF (remote-control) transmission circuitry. So I would recommend hardwiring it. In order to get the LEDs to flash, I would use a 555 timer. Using a couple of resistors and a capacitor you can set it to pulse the output at a frequency determined by the capacitor size and ratio of the resistor values.

    This is the basic 555 timer circuit you'd be looking at. Replace the 12v lamp with your LED strip (and any necessary current limiting resistors) and you're good to go. You'll just need the switch with the center post connected to pin 3 (output) of the 555 timer, and each of the two poles connected to one side of your bike (for the directional blinker).

    [​IMG]

    Good luck!
    Matt
     
  3. radiohead

    Active Member

    May 28, 2009
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  4. captainlol

    Thread Starter New Member

    Jan 13, 2014
    3
    0
    So would I be replacing T1 in that circuit with the 3-way switch? Also, what kind of ratio am I looking for between the resistors to make it flash on/off for 1 second, for example?
     
  5. DerStrom8

    Well-Known Member

    Feb 20, 2011
    2,428
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    You'll need to keep T1, and connect it on one pole of the switch. Then copy the circuit on the output for the second pole.

    Look up "555 timer calculator". You'll find formulas, and even online calculators to determine the capacitor and resistor values. I'm thinking a 6.8uF capacitor with R1 = 10KΩ and R2 = 100KΩ should be pretty close.

    You can always use a potentiometer (variable resistor) for R2 (as shown in the schematic) that would allow you to adjust the frequency.
     
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