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Discussion in 'Power Electronics' started by gregfox, May 14, 2013.

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  1. May 14, 2013 #1
    gregfox

    gregfox

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    a concept...
    Readable?
     
    Last edited: May 15, 2013
  2. May 14, 2013 #2
    BobK

    BobK

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    A battery is a power supply.

    Your schematic is unreadable. How about telling us what you are trying to do?

    Bob
     
  3. May 14, 2013 #3
    gregfox

    gregfox

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    Mar 25, 2013
    Build a battery powered lab power supply.
     
  4. May 14, 2013 #4
    CDRIVE

    CDRIVE Hauling 10' pipe on a Trek Shift3

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    Why does this circuit look familiar? Maybe it's just all the white space or is it the RJ45 connector?

    Chris
     
  5. May 14, 2013 #5
    gregfox

    gregfox

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    Mar 25, 2013
    Hi CDRIVE, I got it from the EEV blog, and propose some mods... like
    Low voltage turn off/Warning, 10V output, Push Button ON/OFF etc.
     
  6. May 14, 2013 #6
    CDRIVE

    CDRIVE Hauling 10' pipe on a Trek Shift3

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    I think you're going to have to eliminate as much white space as you can. It's too difficult to analyze a schematic that has to be scrolled. ;)

    Chris
     
  7. May 15, 2013 #7
    gregfox

    gregfox

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    Mar 25, 2013
    Will try...
     
  8. May 15, 2013 #8
    (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    It looks like you've simplified Dave Jones' design to the bare bones
     
  9. May 15, 2013 #9
    KrisBlueNZ

    KrisBlueNZ Sadly passed away in 2015

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    It would also be helpful to see the original design. A link to the schematic would be enough.
    Dave Jones is a lot more knowledgeable than me, and most of the members of this forum. I trust his designs and I would only be interested in the differences between your design and his.
     
  10. May 15, 2013 #10
    gregfox

    gregfox

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    Mar 25, 2013
    Hi, The Lab power supply was presented at EEVblog #224 - Lab Power Supply Design - Part 1, Part 2 and Part 3 A link is below



    He went much further on with this power supply, adding a micro and LCD display etc. but I just need the basics, although it would be nice to have the whole design, but my c coding is poor to say the least, so the basics is just fine.

    My dream list is as follows:
    Battery powered by (4) 3.7V 2500mAH 18650 cells.
    Constant current and constant voltage
    Variable from “0” to 10-12V output.
    Variable current limit max 1AMP
    Separate meter for current and voltage
    Indicator when current limit reached
    Automatic Battery low level cutoff (So as not to damage the Li-Po batteries)

    I'm trying to reduce the Schematic, and will post when done.

    Thanks all
     
  11. May 15, 2013 #11
    gregfox

    gregfox

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    Mar 25, 2013
    Can this be read?

    Please let me know, if you can read this...
    Thanks
     

    Attached Files:

  12. May 15, 2013 #12
    gregfox

    gregfox

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    Mar 25, 2013
    Read this?

    Might be easer to read.
     

    Attached Files:

  13. May 15, 2013 #13
    gregfox

    gregfox

    149
    3
    Mar 25, 2013
    better?

    I Think this may be a better schematic.
     

    Attached Files:

  14. May 15, 2013 #14
    KrisBlueNZ

    KrisBlueNZ Sadly passed away in 2015

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    That schematic is OK. You could make it more readable by reducing the number of right-angles - instead of zig-zagging, try to keep everything direct.

    Do you have the schematic of Dave Jones's design for comparison?
    Is there a circuit description in text form?
    I looked on eevblog.com but it just has the videos.
     
  15. May 15, 2013 #15
    CDRIVE

    CDRIVE Hauling 10' pipe on a Trek Shift3

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    I guess my eyes don't make a good benchmark for schematic readability. My eyes are old and tired. Both of those prints look washed out to me. I find the contrast awful. I can barely read the text in the schematic and that's after I've magnified it. After magnifying it I'm back to scrolling it. What CAD - Spice software are you using? Whatever it is it's not eye friendly.

    Chris
     
  16. May 15, 2013 #16
    gregfox

    gregfox

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    Mar 25, 2013
    I'm using Eagle software and exporting it. I'll try some other way to export...

    Try this and please let me know how it is.
     

    Attached Files:

    • 1.png
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    • 2.png
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    Last edited: May 15, 2013
  17. May 16, 2013 #17
    gregfox

    gregfox

    149
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    Mar 25, 2013
    Org Circuit

    This is the original I got from the video...
     

    Attached Files:

  18. May 17, 2013 #18
    (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    OK, I'm going to repeat a question I asked on the eevblog forums which was never answered...

    With the low pass filter on the control input of the LT3080, surely the transient response to changes in load (when the power supply is operating in constant current mode) is going to be poor.

    edit: the time constant can;t be better than 22ms by my calculations. If you assume you need between 4 and 5 time constants, then you're looking at around 0.1 seconds. That's a long time if someone accidentally shorts your power supply.
     
    Last edited: May 17, 2013
  19. May 17, 2013 #19
    KrisBlueNZ

    KrisBlueNZ Sadly passed away in 2015

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    Yes, Steve, I was thinking that as well.
    I would prefer a design where voltage and current were both controlled by linearly varying the control voltage.
     
  20. May 17, 2013 #20
    (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    If you follow Dave's videos on this, he adds that filtering to remove noise on the output.

    This is fine for when the device is regulating voltage since you want a constant voltage and limiting the rate at which it can change is not an issue.

    I do note that he seems to have this project on the back burner for now.

    I would perhaps have an alternate arrangement which allows a smaller capacitor and a lower resistance for discharging it in the current limit path.
     
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