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Low cost current indicator

Discussion in 'Electronic Design' started by TT_Man, Apr 18, 2008.

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  1. TT_Man

    TT_Man Guest

    Any suggestions.? I currently use a 4R7 in the ground line to turn on a
    BC547 and LED when the current >150 nominal and the resistor(1/4 W) gets
    quite hot... It's quite good because as the current drops, the LED dims and
    then goes out.....I now have a circuit that I need to indicate >450mA. So
    I'm thinking a 1R5 'pro' 1 watt... Trouble is , there's 6 of them in a small
    plastic box and if the resistor gets too hot, the plastic may start to
    deform.Current is limited to 600mA. Am I going to get e hex high side
    current switch for not a lot ( if at all?)
     
  2. James Arthur

    James Arthur Guest

    You could replace the BC547 with an LM339 or LM324 and a lower sense
    voltage, or you could pre-bias the BC547 a few hundred millivolts with a
    resistive divider, or a schottky, or...

    What does your circuit look like, do, run off of, etc. You haven't told
    us very much.
    Huh?

    Cheers,
    James Arthur
     
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