How to convert a current transformer to a digital switch


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  1. #1
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    Default Re: How to convert a current transformer to a digital switch

    http://www.bristolwatch.com/ele/vc.htm

    If speed is not an issue, you could also use a spare ADC pin of your PIC and some IF THEN.
    Steve

    It's not a bug, it's a random feature.
    There's no problem, only learning opportunities.

  2. #2
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    Default Re: How to convert a current transformer to a digital switch

    Thanks to every one for suggestions.
    My problem here is that the current transformer give me 10 mv AC, which will be 5 mv ac if i take only the positive side of it.
    The output also it is a sine wave, so first i have to converted in DC , which will result in a pulsating 5 mv wave at 60 hz.
    Then i have to convert that pulsating voltage in a dc line voltage, and in the final to use a comparator.
    I tried to use a bridged rectifier for the 10 mv output and i got nothing, almost zero. I assume because the voltage is drooped across the diodes.
    I read the page for comparators, but until i can use it, i need to get some kind a decent DC voltage to it.
    Any suggestion ?
    Best regards
    Ion

  3. #3
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    Default Re: How to convert a current transformer to a digital switch

    use an operational amplifier in non-inverted mode. give it a decent gain, and play 'round it
    Steve

    It's not a bug, it's a random feature.
    There's no problem, only learning opportunities.

  4. #4
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    Default Re: How to convert a current transformer to a digital switch

    Hi Ion,
    Put several turns thru the PRIMARY of the Current Transformer
    Full-wave-bridge rectify the secondary (don’t forget the “burden” resistor), put a capacitor on DC from FWB (=peak) use this peak to turn a bipolar transistor on (0.65V). Use the transistor’s Collector / Emitter to pull a logic pin.
    -Adam-
    Ohm it's not just a good idea... it's the LAW !

  5. #5
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    Default Re: How to convert a current transformer to a digital switch

    This is an other issue of my current transformer Adam. The CT i use, is a PCB type and gives 10 mv for an amp up to 50 mv for 5 amps.

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