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Thread: Deciphering schematics - Help!!!

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    Default Deciphering schematics - Help!!!

    While perusing a set of schematics for ideas (yes, I'm that sad) I came across a recurring (use of) a symbol I couldn't make head of tail of:

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    The symbol I'm referring to is the circle with a diagonal cross through it. I initially presumed the designer of said schematic liked to put a bunch of lamps on their boards for some reason given that was my understanding of the meaning of said symbol. That doesn't make sense in the above context so how am I to interpret this..?
    Left to right:
    -R9 is a three pin network resistor pulling lines 10 and 9 up to 5v?
    -R13 is a nine pin network resistor pulling eight lines up to 5v?
    ...and so on...
    ...the final image just being a standard resistor, or part of a larger R9 network also pulled up to 5v..?

    My assumption being the symbol I thought of as a 'lamp' is used here to denote a connection... How close / far am I from making sense of this?

    Many thanks.

    PS
    In case any are wondering it's a schematic for an Apple II Z80 board whose workings I'm trying to figure out - yep, that sad!
    Last edited by Charlie; 8th March 2018 at 00:24.
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    They are star resistor networks with the common connected to the 5V rail. Each "lamp" is where the other end of the resistor is connected.

    Bryce.

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    yep,pullup resistors

    EDIT:,yeah it is a odd way of doing it,it is a resistor network,but the package is individual resistors in the package.maybe they thought it would be harder to draw the part in,i dont know
    Last edited by roy_bates; 8th March 2018 at 08:52.
    i have got too much hardware,it would only hurt your eyes to look at it here

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    It just depends on what library the person was using. It looks like it's done in Eagle and there are some very unusual non-standard "homemade" symbols flying about for that. Resistor networks are always a difficult symbol for schematics, because they usually connect to multiple lines around the board.

    Bryce.

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    well,yeah,thats true
    i have got too much hardware,it would only hurt your eyes to look at it here

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    I wasn't too far off, good. Thanks very much, I appreciate your advice.
    Last edited by Charlie; 8th March 2018 at 16:41.
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    I believe I've seen this symbol used to indicate test-points.
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    Yes, it's a very generic symbol, I've seen it used for Test points, vias, mounting holes, bulbs and fiducials (you'll have to look that one up if you're not involved in PCB manufacturing ).

    Bryce.

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    Bryce is bang on the money Charlie
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