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Thread: How to reduce voltage from 12.3 volts to 11.8 volts?

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    Default How to reduce voltage from 12.3 volts to 11.8 volts?

    I have a server power supply that is running at 12.3 volts. The lowest I can adjust it down to is 12.1 volts. Is there a way to reduce the 12.3 volts to 11.8 volts. I see most buck converters need 1.5 volts more coming in than going out. I need to reduce the voltage to 11.8 volts to supply some of my older pixels. The pixels don't operate correctly with voltage any higher than 11.8. Any ideas?

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    Default Re: How to reduce voltage from 12.3 volts to 11.8 volts?

    Quote Originally Posted by kenoman742 View Post
    I have a server power supply that is running at 12.3 volts. The lowest I can adjust it down to is 12.1 volts. Is there a way to reduce the 12.3 volts to 11.8 volts. I see most buck converters need 1.5 volts more coming in than going out. I need to reduce the voltage to 11.8 volts to supply some of my older pixels. The pixels don't operate correctly with voltage any higher than 11.8. Any ideas?
    My server supply was 12.2 and got it down to 11.7.

    Sent from my SM-T710 using Tapatalk

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    Default Re: How to reduce voltage from 12.3 volts to 11.8 volts?

    How did you get it down to 12.7? The pot adjustment on the power supply board will only get me to 12.1 then it jumps back up to 12.5. It appears I can only adjust +/- 0.25 volts.

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    Default Re: How to reduce voltage from 12.3 volts to 11.8 volts?

    Quote Originally Posted by kenoman742 View Post
    How did you get it down to 12.7? The pot adjustment on the power supply board will only get me to 12.1 then it jumps back up to 12.5. It appears I can only adjust +/- 0.25 volts.
    The pot adjustment on 2 of mine got it down. The other one actually went down to 11.8. Could be the brand of power supply.

    Sent from my SM-T710 using Tapatalk

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    Default Re: How to reduce voltage from 12.3 volts to 11.8 volts?

    Hmm, a resistor in series??????

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    Default Re: How to reduce voltage from 12.3 volts to 11.8 volts?

    a silicon diode in series will drop 0,7V, Schottky diodes 0,15 to 0,4 V
    Errors for fun only.

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    Default Re: How to reduce voltage from 12.3 volts to 11.8 volts?

    A resistor voltage drop is dependent on the current going through the resistor and would be changing all the time. A diode voltage drop is inverse current dependent and the curve is VERY steep so you wont notice it in our application. A high current diode should do what you need.


    2020 Full sized show reworked for the new location. Only adding (famous last words) 13 RBLs that I finally got converted to using pixels
    2019 - Just moved into a new home (yet another change of plans). Will be dim but not dark. Too much to do at the new place to leave time for a show. Dim show (3000 pixels) had regular visits most nights.
    https://www.youtube.com/channel/UCyX...ttrsZNARkUce0Q

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    Default Re: How to reduce voltage from 12.3 volts to 11.8 volts?

    Thanks to everyone for the suggestions. I'll just have to experiment to find a solution. As a last resort I do have a generic 12v power supply I can use that is already dialed down to 11.8 volts. I am just trying to power my display with 2 - 1200 watt server power supplies. Thanks again for all suggestions.

    Ken

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    Default Re: How to reduce voltage from 12.3 volts to 11.8 volts?

    Quote Originally Posted by MartinMueller2003 View Post
    A resistor voltage drop is dependent on the current going through the resistor and would be changing all the time. A diode voltage drop is inverse current dependent and the curve is VERY steep so you wont notice it in our application. A high current diode should do what you need.
    That diode will be a nice little heater too.

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    Default Re: How to reduce voltage from 12.3 volts to 11.8 volts?

    Yes it needs to dissipate some heat. 0.7v * 60a = 42w. That is a light bulb.


    2020 Full sized show reworked for the new location. Only adding (famous last words) 13 RBLs that I finally got converted to using pixels
    2019 - Just moved into a new home (yet another change of plans). Will be dim but not dark. Too much to do at the new place to leave time for a show. Dim show (3000 pixels) had regular visits most nights.
    https://www.youtube.com/channel/UCyX...ttrsZNARkUce0Q

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