Using Opto-isolator or optical coupler

Discussion in 'The Projects Forum' started by yiudavid, May 1, 2009.

  1. yiudavid

    Thread Starter New Member

    May 1, 2009
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    0
    Hi everyone..

    i would like to ask one thing:

    i have one detecting device which has output as soon as it is activated.
    The output is a buzzer and a sound will be given (0.5V).
    Now i wanna modify it to from audible to visible by replacing LEDs on it.

    i wanna using this output to light up one or more LEDs.
    Some people say i can use Opto-isolator or optical coupler to boost up the voltage.

    How can i find a suitable Opto-isolator or optical coupler?
    and
    What specific thing i need to concern?

    thank you very much!!
     
    Last edited: May 3, 2009
  2. t_n_k

    AAC Fanatic!

    Mar 6, 2009
    5,448
    782
    Opto-couplers/isolators are primarily intended for controlling a circuit condition where galvanic isolation of one part of a circuit from another is required or convenient.

    They can be used to provide a low-high power control - although you'll need more than 0.5V ??? to drive the input side isolating LED in the opto-coupler. You'll also need a power source on the higher power output side to provide the power for controlling or driving the output side device(s).

    You need to be more specific about your application and what your 0.5V source relates to.
     
  3. balisong

    Member

    Feb 26, 2008
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    0
    .5V sounds like a solar cell. Are you just controlling the LEDs, or trying to power them from .5V?
     
  4. yiudavid

    Thread Starter New Member

    May 1, 2009
    5
    0
    Thanks replying!!

    i want to claify it
    One detecting device will have output as soon as it is activated.
    The output is a buzzer and a sound will be given (0.5V).
    Now i wanna modify it to from audible to visible by replacing LEDs on it.

    please help me!
     
  5. yiudavid

    Thread Starter New Member

    May 1, 2009
    5
    0
    can anybody help me??
     
  6. bertus

    Administrator

    Apr 5, 2008
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    hello,

    Do you have a schematic of the circuit with the buzzer?
    May the buzzer be removed?

    Greetings,
    Bertus
     
  7. yiudavid

    Thread Starter New Member

    May 1, 2009
    5
    0
    i haven't removed...but i tend to do it.
    can i simply removed it and using LEDs to check whether it can light or not?
     
  8. bertus

    Administrator

    Apr 5, 2008
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    2,346
    Hello,

    Remove the buzzer and measure the voltage.
    The voltage may be higher than with the buzzer.
    Report the voltage back so we can see what actions to take.

    Greetings,
    Bertus
     
  9. yiudavid

    Thread Starter New Member

    May 1, 2009
    5
    0
    i have removed the buzzer and test again.
    it is 3V for the output.

    but i have search several opto-coupler's datasheets
    most of their operating forward voltage are 1~1.7 V
    may i need to step down the voltage first, but how ?
     
  10. rghkk1

    New Member

    May 7, 2009
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    0
  11. bertus

    Administrator

    Apr 5, 2008
    15,647
    2,346
    Hello,

    The voltage is enough to drive a led.
    You will need to put a resistor in series with the led of the optocoupler to limit the current through the led.
    The current needed is dependend on the type of optocoupler you want to use.

    Greetings,
    Bertus
     
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