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Guide DigiBus - Software Fan/Lights Controller Guide

Discussion in 'Modding' started by acrimonious, 1 Apr 2004.

  1. acrimonious

    acrimonious Custom User Title:

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    I'll look into that over the next few days.
     
  2. acrimonious

    acrimonious Custom User Title:

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    Part 3 is on the way within the next week or so. The software is retrieving values from MBM seamlessly now, so no problems there. The code to get those values to adjust fan speed is being worked on. :thumb:
     
  3. joelspangler

    joelspangler What's a Dremel?

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    DeadTeddy's idea has really got my attention, but looking into it, the PNP transistor wouldnt' work (seems to need a negative voltage to the base).

    Looking into it more though i'm finding the *FET (FET, mosfet, jfet, J-FET) might actually normally allow current flow, but limit flow when a base voltage is applied

    for those of you who didn't read DeadTeddy's post it baisically stated that we could use two transistors, one that only passes current when power to the base is there (NPN -- the TIP120), and another one that passes current normally, but limits it when the base is charged. We'd use a capacitor to smooth out the on/off that the PWM creates, so the *FET transistor would not pass power until the pulse stops for about a second, causing the cap to discharge, and allowing full current to the fans (so the CPU doesn't burn up)

    sort of seems like a simple/logical solution for people with concerns over a PC crash.
     
  4. c.cam108

    c.cam108 Minimodder

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    is part 3 coming soon?

    or is acrim dead :worried:
     
  5. birdie

    birdie What's a Dremel?

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    acrimonious: will you release the code? I would love to be to learn how to control the parallel port. (one project being a parallel LCD)

    Also would you consider making a "Baybus" that is less dependent on software? ie. you can control the speeds still by software but they are saved to eeprom or something so that they don't need to be constantly sent via the parallel port.
     
  6. acrimonious

    acrimonious Custom User Title:

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    I'm very much alive, part 3 will be in a few weeks but i've been spending my time that i use for this guide to come up with an even better solution that eliminates growling, stalling and freezing with a system crash, which hopefully you will see soon.
     
  7. acrimonious

    acrimonious Custom User Title:

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    I've been workign on a new version as mentioned in the previous post which should fit your discription.

    As for code, drop me an email and I'll get you some example projects and links. :thumb:
     
  8. TheAnimus

    TheAnimus Banned

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    don't forget about stuff like POST data been put on the LPT by the BIOS.
     
  9. wharrad

    wharrad Minimodder

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    Just a little note to Acrim to remind him how many people are reading and loving this - I wish I knew something to add a bit of support.
     
  10. c.cam108

    c.cam108 Minimodder

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    acrim, what language is this written in? vb?

    if vb, how did you access the parport in the first place?

    (i too would be interested in some code if your feeling generous!)

    thank you!
     
  11. joelspangler

    joelspangler What's a Dremel?

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    My Parallel port posts with voltage anyway... the only way i lose fans is if my PC crashes, or I accidently close the Digibus program. I have every fan in my case except the Power supply and my 2 cpu fans (i run a dualee) running off of this program now. but was hoping to add a single failsafe channel for my cpu fans. My p/s isn't noisy anyway, so i won't bother with that.

    So right now I've got 6 fans hooked up via 3 channels. I hope to eventually be able to use this for my CPU fans, which I currently have switched between a 5w resistor to slow them down on one side or full 12v on the other side. It would be nice to never have to remember to flip that switch again.
     
  12. darkhunter

    darkhunter What's a Dremel?

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    cool thanks this is goin on the front of my case
     
  13. joelspangler

    joelspangler What's a Dremel?

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    I've found two ways of keeping a fan running even with no pulses. The fan will run at a lower speed, but it will at least keep running. I've detailed the two solutions below.

    OPTION ONE is using a 5 watt resistor which is about 3/8 x 3/8 x 7/8 inch (pretty big ... the size of the last section of your pinkey/small finger) Energy takes the path of least resistance. When there is no pulse the transistor has almost infinite resistance, so the current pasess through the resistor.. which in my case has 27 ohms of resistance. When there is a pulse the resistance in the transistor is extremely low, probably less than .01 ohm so it ignores the resistor and goes through the transistor. hope that made sense. here's a pic
    [​IMG]
    benefit - your fan still runs if your pc chokes or you accidently close the program
    loss - you've limited your channel to 5w instad of almost 60w.
    The resistor value will have to change based on what fan you are using. The first value that my 120mm 2.4w fan would start spinning on was 27ohm. My 80mm 1.32w fan worked with a 56ohm resistor, but not with a 110ohm... i didn't have any values between 56 and 110, but i am guessing a 68 ohm would have worked. You'll really have to play with your particular fan... i baught every value my local electronics store had in stock from 18ohm up to 110ohm.. many values were missing/not in stock... when i go next time i'll probably buy some lower values as I have a 4w fan that won't start at 18 ohm.

    OPTION #2
    [​IMG]
    The gate on a transistor is baisically like a door. When there is no voltage on it, the door is shut. Put a slight amount of voltage on the gate and it opens the door a little bit. Put more voltage on it and it opens further. The further the door is open, the less resistance (ohms) the transistor has. What i am doing here is taking the voltage from the fan which normally gets stopped at the transistor and using a 1/4 watt resistor to pass some of that power over to the gate, which opens the door slightly.
    When an actual pulse comes, the door will open fully, and when it goes away it'll go back to being cracked open.

    Again, the value of the resitor will depend on your fan. My 2.4w 120mm fan spun at 39K ohm, but not at 47k ohm. Resistors of lesser value allowed the fan to spin faster. I did not test further fans.
    Benefit - you keep 60w per channel
    loss - the transistor will get UBER HOT!!!! you will probably need to add a heatsink!!!

    both options have also limited the Chatter noise coming out of the fans at low duty cycles, it's still there, but much less noticable.

    sorry about the lousy MSPAINT drawings... I know they aren't too good, but i needed a visual. I hope acrim doesn't mind that I stole his drawing of the TIP120 and used it to make my pics.
     
    Last edited: 11 Jun 2004
  14. c.cam108

    c.cam108 Minimodder

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    em.. wouldnt that last option draw loads of power from the mobo?

    i may be wrong, but i think thats right.
     
  15. joelspangler

    joelspangler What's a Dremel?

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    no, option #2 is using the power from the 12v line of whatever is powering the fan (molex connector or motherboard fan header). It might take a tiny bit more current to be able to trip the transistor, but if the power source can handle the fan, it can handle the transistor+fan unless you are dangerously close to overloading your motherboard fan header anyway. I would expect less than .1 watt to be added, and most fans are above 1.5 watts. I don't know what a header is rated for, but I'd expect it to handle 2.5-5 watts.

    edit: I am still working on a different solution that will give you full fan speed when the pulse stopped, I just have to wait until i get a few hours to properly test some theories i have.
     
  16. stoned penguin

    stoned penguin What's a Dremel?

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    ok i searched the thread but didnt find an answer so dont hate me if its there and i didnt spot it

    is there anyway i can change which pins control the channels?

    i want to know since i also want to put in an LCD
     
  17. ch424

    ch424 Design Warrior

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    On a molex connector, there are 12v, 0v, 0v, 5v connections. Does it matter if I connect the 0v ones together, or does it cause interference/kill PSU?

    Any help appreceated.

    ch424
     
  18. joelspangler

    joelspangler What's a Dremel?

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    0v (or ground) wires are OK to connect together. Actually you could even touch them to any place with bare metal in the case... it all connects to the same place - ground... earth.. whatever you call it in your country.
     
  19. joelspangler

    joelspangler What's a Dremel?

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    I hope the announcement about MBM ceasing development doesn't change your plans about incorporating it with the DigiBus software...
     
  20. joelspangler

    joelspangler What's a Dremel?

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    the lack of activity on this tread makes me sad :waah: :waah: :sigh: :sigh: :confused: :confused:
     
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