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Thread: Removed sense wires from 24-pin and tested on Chroma

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    My worry is the response; if the supply senses the voltage is down it pumps up its end, but then there is the concern about what it does if it senses zero.
    Last edited by ashiekh; 08-01-2020 at 10:50 PM.

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    Quote Originally Posted by ashiekh View Post
    My worry is the response; if the supply senses the voltage is down it pumps up its end, but then there is the concern about what it does if it senses zero.
    If it senses nothing, it does nothing. The sense wire is an ADDED sense. It's still getting voltage readings from the output side of the output filtering caps and on the modular interface (if applicable).
    Last edited by Jon Gerow; 08-02-2020 at 01:52 PM.

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    That is non trivial as its job is to compensate when sensing a low voltage. i.e. as the voltage drops it compensates, but that needs to stop at some point.


    Quote Originally Posted by Jon Gerow View Post
    How to prove sense wire isn't required in theory
    Actually the whole thing can be done WITHOUT sense wires: the supply can detect the current and compensate for the calculated drop; that would be rather neat, do any supplies do it that way?

    Proof enough?

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    Of course. The only thing the sense wires are doing are sensing the voltage at the load. Nothing more. The ICs already know what the voltage is at the PSU.

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    What's the range that the PSU can compensate the voltages to in response to the sense wire readings?

    Like if you have a stupidly long cable or just put a couple of resistors on the sense wires so that it reads 11V (on 12V rail) would the PSU be able to compensate? What's the limit that it could adjust to?
    Last edited by Spotty; 08-02-2020 at 01:05 AM.

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    Quote Originally Posted by Spotty View Post
    What's the range that the PSU can compensate the voltages to in response to the sense wire readings?

    Like if you have a stupidly long cable or just put a couple of resistors on the sense wires so that it reads 11V (on 12V rail) would the PSU be able to compensate? What's the limit that it could adjust to?
    Awesome question! Maybe that's my next test. Make a stupidly long cable, see what the voltage drop is and the compensation done.

    In all seriousness, let me research what's already implemented and see what it is.

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    Quote Originally Posted by Jon Gerow View Post
    Of course. The only thing the sense wires are doing are sensing the voltage at the load. Nothing more. The ICs already know what the voltage is at the PSU.

    I was suggesting doing the voltage correction WITHOUT sense wires.
    Last edited by ashiekh; 08-02-2020 at 09:30 AM.

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    Quote Originally Posted by Jon Gerow View Post
    LOL! My post on Reddit was removed by their mods!!!!!!
    Par for the course on some subreddits. I see you deleted your account after this, too.

    Quote Originally Posted by ashiekh View Post
    I was suggesting doing the voltage correction WITHOUT sense wires.
    Power supplies without sense wires already do voltage correction without sense wires.

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    Quote Originally Posted by Orion View Post
    Power supplies without sense wires already do voltage correction without sense wires.

    So if 0.5V is lost across the cable, the supply will deliver 12.5V?

    i.e. I mean going beyond just regulating 12V
    Last edited by ashiekh; 08-02-2020 at 11:08 AM.

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    Quote Originally Posted by Spotty View Post
    Like if you have a stupidly long cable or just put a couple of resistors on the sense wires so that it reads 11V (on 12V rail) would the PSU be able to compensate?

    The sense wires carry almost no current, so putting resistors in the sense wires should not do much; the resistors need to go in the main wires.

    Much easier would be to just control the voltage on the sense wires with a lab power supply; no 'stupidly long cable' needed.
    Last edited by ashiekh; 08-02-2020 at 12:49 PM.

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