Making my own fan controller.

pseudonympseudonym Michigan Icrontian
edited January 2004 in Hardware
Hey guys. Since I now have my 92mm Tornado/Hairdryer, and realized how stupid I was for waiting to get a fan controller, I've decided to make my own (Because CompUSA only has ones based on a switch (Low/Med/High), I'd much prefer a fully variable one, and I can't wait the two days for one to get here. Obviously this involves me getting a potentiometer (sp?). I'm wondering how to choose which one I should be using, obviously no resistance is full power, but does anyone know what range one I should be getting (i.e. 0-1000 ohms)? Any experiences?

Comments

  • pseudonympseudonym Michigan Icrontian
    edited January 2004
    Ok, learned this thing draws too many amps for a pot, have to get a rheostat. Anyone know where I can get one that will handle the 1amp this beast draws?
  • croc_croc_ New
    edited January 2004
    Assuming the fan runs at 1amp and 12 volts, and watts being volts times amps, that would be 12 watts, right?

    I think THIS should work just fine.
  • Straight_ManStraight_Man Geeky, in my own way Naples, FL Icrontian
    edited January 2004
    Right-- YStech uses a 20K rheostat on the black (return) line of their rheostat controlled fans that are 92 mm in size. http://www.svcompucyle.com/ sells them with attached rheostat if anyone else wants one, and they recommend a YSTech NFD1281259B-2F which is a dual-ball bearing fan for some of the HS products they sell. It also has a sense lead, Rheostat will upper limit the sense control line feedback ability of motherboard to control the fan but let BIOS know there is a fan there so BIOS can shut down computer if CPU overheats.

    Pots are basicly low-ohm rheostats in how they work, rheostats have heavier contact plates and are wider range than pots, and adjust coarser, which is good for fans-- use very SMALL rheostat adjustments to experiment(like 4-5 degree turns), run something like MBM 5 while playing with box in Windows if you want to see changes, and change in 1 hour to 2 hour intervals. The Digital Doc, more expensive fan controller but using temp sensors to control fan within limits set by rheostats if you put those inline on fans, is probably the best overall solution to a mix of cooling and control of noise.

    John.
  • pseudonympseudonym Michigan Icrontian
    edited January 2004
    http://www.short-media.com/forum/showthread.php?t=6224

    I crippled the fan to 7volts (from that thread), till I get a Rheostat but for some reason the fan RPMs aren't picked up anymore. Did dropping the voltage like that somehow affect the output for the RPM monitor? I checked the connection and thats fine as can be.
  • croc_croc_ New
    edited January 2004
    Only thing I can think of is that the monitor runs @ 12 volts and dropping it to 7 makes it think there is no fan connected? *shrug*

    edit: I would assume you are getting about 1/2 the rpm of 12v :P~
  • pseudonympseudonym Michigan Icrontian
    edited January 2004
    Whatver its running at, its better than the 5000 it was at before :)
  • croc_croc_ New
    edited January 2004
    I am sure its still pretty loud though
  • edcentricedcentric near Milwaukee, Wisconsin Icrontian
    edited January 2004
    A pot or fixed resistor is fine for the short term. But you really want to use a voltage regulator to do this. The resistor will actually increase the current draw and will turn all of the excess into heat.
  • Straight_ManStraight_Man Geeky, in my own way Naples, FL Icrontian
    edited January 2004
    pseudonym wrote:
    http://www.short-media.com/forum/showthread.php?t=6224

    I crippled the fan to 7volts (from that thread), till I get a Rheostat but for some reason the fan RPMs aren't picked up anymore. Did dropping the voltage like that somehow affect the output for the RPM monitor? I checked the connection and thats fine as can be.

    Actually, I run a senseless fan set (including CPU fan), tell BIOS not to detect CPUFAN, and tell MBM 5 to shut down on temp alarm. IF you forced input voltage (red lead) to 7 volts, that will do what you are getting for many fans. Also, some fans just barely turn over at 7 Volts-- without a RPM meter like a car flashing light rotation sensor tool, it is hard to tell if you have enough cooling unless you use MBM and with MBM in place you do not normally need the BIOS sensing. Only an MBM 5 application-only lock would leave you needing BIOS sensing.


    By lowering on return leg, you have 12 Volts to sense determination circuit coming in, but might still have a mess if you use the 12 HOT to 5 Return trick or force to 7 volts in. Basicly with 12 hot wire hooked to fan hot, 5 volt hooked to fan return, you have an unstable anything else on fan circuitboard like a sense circuit as you end up with a potential for voltage feedback into circuit, which is what it looks like is happening here. For a non-sensed fan, this will work easily, for a sensed fan it CAN knock out or toss real low a sense reading to motherboard. Rheostat will solve this sensing problem, one reason it is used.

    John.
  • croc_croc_ New
    edited January 2004
    My 6 switch fan controller uses pots to control the fans (pot set from 7-9v). Switch goes from full to the pot setting to off. Yes it does generate heat, the actual switches are incredibly hot to the touch.
  • BudBud Chesterfield, Va
    edited January 2004
    pots get very hot mine gets soooo hot it can burn you. Its on a 80mm tornado I bought one used and it was still like 10 bucks cause it has the good windings and very reliable
  • primesuspectprimesuspect Beepin n' Boopin Detroit, MI Icrontian
    edited January 2004
    Micromaaaaan!
  • pseudonympseudonym Michigan Icrontian
    edited January 2004
    primesuspect wrote:
    Micromaaaaan!

    lol.... Here he comes to save the day??
  • jj Sterling Heights, MI Icrontian
    edited January 2004
    Wiat the 2 days......to do thiis with radio shack parts it going to take a transistor and a POT or reostat. If you want to this is the schematic
  • Geeky1Geeky1 University of the Pacific (Stockton, CA, USA)
    edited January 2004
    Why not just get a LM-317T adjustable positive voltage regulator, the caps and resistor it requires, a 5k linear pot, and use that?
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