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Isolating DC signal

Discussion in 'Electronic Design' started by Jack// ani, Nov 16, 2004.

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  1. Jack// ani

    Jack// ani Guest

    Hi, how can I isolate dc signal, over which an ac signal is riding? I
    need to glow led out of it.DC is 5volts and ac is dtmf tones.

  2. Ian Stirling

    Ian Stirling Guest

    What size of AC signal?
    If it's under 3V or so, you'll probably have no problems with just
    connecting a LED/resistor.
  3. Jack// ani

    Jack// ani Guest

    I think it is around 3.3v, I still have to confirm it.
    Oh I forget, I also have to feed this dc to microcontroller.

  4. Ian Stirling

    Ian Stirling Guest

    Is the current in the line insufficient to make the LED light?

    A simple R-C filter may do the job.
    If you don't need to sense the DC instantly, but a few milliseconds delay
    will be OK.
  5. N. Thornton

    N. Thornton Guest

    various options dpending on the app. Choke, diode & capacitor,
    resistor, one of those should suit you probably. There are other
    options too.

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