Optocoupler circuit design

Discussion in 'General Electronics Chat' started by Honeybee, Nov 22, 2005.

  1. Honeybee

    Thread Starter Member

    Nov 1, 2004
    12
    0
    HI

    I have to design an optocoupler circuit using the IL300 to isolate a DSP from the circuit from which it is monitoiring hign voltage signals that are stepped down before connection to the optocoupler.

    Most of the spec sheets and application notes make use of opamps as amplifiers.

    Can anyone please explain to me what the purpose of using an amplifier is? because as far as I can tell, I don't think that I need to amplify any signals.


    www.vishay.com/docs/83622/83622.pdf
    That was the spec sheet I was referring to.

    Any help would be appreciated.
     
  2. beenthere

    Retired Moderator

    Apr 20, 2004
    15,815
    282
    Hi,

    If you need an optocoupler to isolate from high voltage, then the amp will be needed to buffer the signal out of the opto. They are generally pretty weenie in the output.

    Without some idea of the circuit, it's hard to be very specific about a solution.

    Some years ago, I had to make it possible to control a power supply floating at 10 KV. It had an analog 0 - 10 VDC control input. I used a voltage to frequency converter to make a proportional pulse train, and sent it to the floating circuit with an optocoupler. After a buffer amp. a frequency to voltage converter restored the DC control voltage, now floating on the 10 KV. DC is easy to isolate.
     
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