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Thread: Using resistors

  1. #1
    Constant Bitrate
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    Question Using resistors

    I 'm making a ir receiver for which i found the schematics in the web . i need a resistor of a value i cant find can i add other resistor up to that value and if yes is there a polarity i should respect ?

  2. #2
    FLAC mp3z24's Avatar
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    basic electronics:

    resistors in series (one after another):
    R(total) = R(1) + R(2)

    resistors in parallel (side by side, with their lead connected):
    1/R(total) = 1/R(1) + 1/R(2)
    or
    R(total) = {R(1)*R(2)} / {R(1)+R(2)}

    someone PLEASE correct me if im wrong.

    also, the equations can be continnued for more than 2 resistors, although the second eq for the parallel gets pretty hairy. just use the first one (for parallel) and a calculator!! the series one is always easy.

    oh, and the equations are switched for capacitors.

    ~mike
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  3. #3
    Maximum Bitrate
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    someone PLEASE correct me if im wrong.
    you are correct.

    resistors is parallel are strange things.

    On another note does any one know a site with the chart to tell you what coloured bands you need for a particular resistance??

    hornet
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  4. #4
    Rob
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    Maximum Bitrate Rob's Avatar
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    Originally posted by hornet
    On another note does any one know a site with the chart to tell you what coloured bands you need for a particular resistance?
    No but

    0 = Black
    1 = Brown
    2 = Red
    3 = Orange
    4 = Yellow
    5 = Green
    6 = Blue
    7 = Purple / Violet
    8 = Grey or White (can't rember which but nobody uses 8)
    9 = Grey or White (can't rember which but nobody uses 8)

    The first 2 or 3 (depends on the resistor) colour bands are the first 2 0r 3 numbers in the value and the last band is the number of zeros.

    I think an example might help

    red red yellow would be 220000 ohms or 220k ohms
    yellow purple black red would be 47000 ohms or 47k ohms

    The odd colour on it's own normaly gold or silver is the tolerance, just ignor it.

    I cann't rember which way round you read the colour bands, but one way makes sense and the other doesn't.

    I hope that make sense, rather than confussing things.

    Rob

    PS. Does any one know which is 8 & which is 9
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  5. #5
    Constant Bitrate jboy's Avatar
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    8 grey
    9 white

  6. #6
    FLAC mp3z24's Avatar
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    this calculator is pretty handy if you are working near a computer.

    ~mike
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  7. #7
    Newbie
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    mp3z24,
    Man, that calculator and that entire site, rocks!

    I can't get over the stuff you can do with Java.
    Wellfooled
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  8. #8
    Variable Bitrate
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    Solder a small pot, adjust it, then use a drop of superglue to permanetly fix it's value.

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