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How to change LED flashing?

Discussion in 'LEDs and Optoelectronics' started by sid2286, Dec 28, 2016.

  1. sid2286

    sid2286

    102
    1
    Aug 24, 2011
    Hello,

    I have circuit ( Not designed by me) which has a LED flashing(Blinking) of 250msec, i want to change that flashing to slow on and slow off. something similary to ramp output.

    please advice how do i do it?

    Thanks,
    SId
     
  2. AnalogKid

    AnalogKid

    2,307
    649
    Jun 10, 2015
    Change those two parts over there.

    If that wasn't helpful, please consider asking a question that has useful information in it.

    schematic
    voltage
    Schematic
    current
    Schematic
    Power source
    Schematic
    LED part number

    While you're at it, please post your schematic.

    ak
     
    GhostLoveScore likes this.
  3. sid2286

    sid2286

    102
    1
    Aug 24, 2011
    hello,

    this is a device with multiple functionalities , for eg: press switch - > LED ON
    Long press -> LED Blink
    press switch - > LED OFF

    Now, except LED and its terminal (Soldering pins) everything is enclosed and sealed, the supply is 5v from batteries.

    I want to twig the circuit from blinking to slow ON and Slow OFF.
    is there anyway as in i can do that using a cap, ics etc.

    want to do that at a very low cost.

    Thanks,
    Sid
     
  4. AnalogKid

    AnalogKid

    2,307
    649
    Jun 10, 2015
    The blinking is almost certainly controlled by a microprocessor. The only way to change its frequency is to reprogram it.

    ak
     
    (*steve*) likes this.
  5. Alec_t

    Alec_t

    2,699
    715
    Jul 7, 2015
    .... and while you are re-programming it it woud be straightforward (to a programmer) to incorporate the fade-in fade-out feature.
     
  6. BobK

    BobK

    7,645
    1,662
    Jan 5, 2010
    The way to change it is to throw away what you have and build a new circuit.

    Bob
     
    GhostLoveScore likes this.
  7. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,206
    2,695
    Jan 21, 2010
    The last one of those LED flashlight modules I took apart (and it was a long time ago) used a small 8 pin PIC which was flash programmable (I.e. not a OTP device).

    A more recent board that I've seen (but not examined in great detail) used a chip with a similar pin count but could not be immediately identified by me. It could have been anything and may not be reprogrammable.

    You would have to determine what your board uses to create the functionality and determine if it is viable to change it. Remember that you will likely need to start any software from scratch as you most likely won't be able to read it from a microcontroller, and even if you could you won't be reading the source from it.
     
  8. AnalogKid

    AnalogKid

    2,307
    649
    Jun 10, 2015
    Many LED flashlights now use custom chips designed specifically for the application. All random logic design, no microcode, often with a small power MOSFET onboard.

    ak
     
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