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DIY Fan Testing . . . Find The Fan That Works Best on Your Rad

post #1 of 3
Thread Starter 
We all know that for definitive numbers we go to Martin's for information.

We may not find every fan ever made tested, but we can look at something similar and hope to come away with some idea.


What we don't see, and really can't reliably determine just from the numbers, is how a given fan is going to work on the rad we plan to put it on, and how it will compare to other fan choices for that rad.


With just a single resistor, a few connectors and pins, and a multi-meter with a Hz scale, you can create an adapter cable to use a spare fan in passive mode as a sensor to measure the airflow from different fans you may be considering for use on a rad.


What makes this feasible is that the tach portion of a fan works even it the fan is not powered up, and it works regardless of the fan's rotational direction.


By placing a powered fan against the passive fan so that the airflow goes into the "out" side of the passive fan, the fan will spin in reverse direction reasonable proportionally to the amount of airflow thru it.


If you mount a passive fan on one side of a rad you want to use, you can try several active fans and see which one gives the most rpm from the passive fan, and also know quite accurately what it's going to sound like.

You can also add a second active fan after the passive fan to see how much increase in airflow thru the rad to expect if you go with a P-P setup.


What's even nicer, is if you have a fan controller with a display available.

You can use it to power the adapter cable, control and display the active fan or fans rpm, and read the passive fan rpm.



In the pics below, I'll show how to make the adapter cable, and how it works with a few fans I have handy.




Here's the passive fan's adapter cable (lower one) . . .

The red/blk wired connector is for the power. Anywhere from a volt or so to 12V is fine.

You can use a 4 pin molex to 3 pin adapter from a PSU, or power it from a controller channel if you're using a controller for your tests.

The yel/blk wired connector is the "tach out".

You can connect it to a controller if you're using one, or with a secondary adapter, (upper one) you can connect a multi meter that reads Hz or frequency.





Here's the passive fan end of the adapter cable:

Notice that it's a 4 pin shielded connector that's slotted so that it only works with 3 pin fan connectors.

The 4th pin is used as a connection point for the red (+ power) wire in to connect to a 10K resistor which then connects to the 3rd pin with the yellow "tach out" wire.

There is no connection to pin 2.

Both black (gnd) wires are connected to pin 1.




And an expanded view:





Here's the other ends of the adapter cable:

The red/black wire pair connects to the usual Gnd and +V pins of a 3 pin fan connector

The yellow/black wire pair connects to the usual Gnd and tach pins of a 3 pin fan connector




The upper adapter cable is just to make it easier to connect a multi meter to the yellow/black wire pair's 3 pin female connector.


Here's the adapter cable all setup with a generic 140 fan to use in passive mode. I doubt it makes a lot of difference what fan you use, as long as it's always the same one each time you test.




Here it is in operation with several fans I have handy:

Multiply the Hz reading by 30 to get RPM.


BGears Blaster:




Aerocool Shark:




Prolimatech Aluminum Vortex:




I'll be adding some more pics and info about using a controller with a display instead of a multi meter in the next post.


Hope you decide to try this for yourself,

Darlene
Edited by IT Diva - 11/23/13 at 2:50pm
post #2 of 3
Thread Starter 
Here's a few pics using a fan controller with display in place of the multi meter.

The convenient aspect is that it allows you to see the active fan's RPM, the passive, or sensor fan's RPM, an additional pull fan's RPM, as well as being able to power the adapter cable from one channel's output.

The biggest plus is that you can see what the airflow and sound level is like at various speeds and look to see if there's a "sweet spot" for your rad/fan combination.

One of the interesting things you can evaluate is how adding a pull fan increases the loading on the push fan and the RPM drops a little, while the pull fan's RPM is above the rated RPM.

While the pics below are just with the fans without a rad, it's just a matter of adding the rad you plan to use the fans on between the active push fan and the passive sensor fan.

For P-P, just add the second active fan after the passive fan.

You can also evaluate how much effect adding a filter might effect your airflow.

The display is set up so that the top row right reading is the push fan rpm,
The top row center reading is the sensor fan rpm,
The top row left reading is the pull fan rpm for P-P setups.



Here's some quick tests:

BGears in push only:




and in P-P:





Aerocool Sharks in push only:



and in P-P:





Prolimatech Aluminum Vortex in push only:



and in P-P:





And an older pic of a 280 GT-X with a pair of 38mm San Aces:

These suckers rock!

You can see that the rpm equivalent is right at ~1300 . . . that's about what the bgears made in P-P Without anything between them but the sensor fan.



Edited by IT Diva - 11/23/13 at 3:09pm
post #3 of 3
Wow, this is real interesting. Thanx for making this thumb.gif
    
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CPUMotherboardGraphicsRAM
4930k Rampage IV Black Edition w/EK Clean CSQ Block PowerColor 290x BF4 (2 More Coming) G Skill Trident X 
Optical DriveCoolingCoolingCooling
Silverstone Slotload Bluray Burner EK Supremacy Clean CSQ Alphacool XT45 360 XSPC EX360 
CoolingCoolingCoolingCooling
Alphacool ST30 240 3 x Phobya NB E-Loops (1600RPM) Alphacool UT60 120 (White Edition) 7 x Gentle Typhoon AP-00 (2150) 
CoolingCoolingCoolingCooling
3 x Gentle Typhoon AP-15 6 x Phobya G1/4 Inline Temp Sensor Coupler (2 P... Aquacomputer G1/4 High Flow Meter Swiftech MCP35x 
CoolingOSPowerCase
XSPC Photon 170 Reservoir Windows 7 + Linux Antec HCP-1300 Platinum CoolerMaster HAF XB (Modded) 
OtherOtherOtherOther
Silverstone FP58 Thermaltake Max 5 Duo Phobya 6 x 16mm Vandal Switch Plate  6 x 16mm Vandal Switches (ModSmart & Lamptron) 
OtherOther
LC Telios Red/Black Fusion, White, & Gray More To Come... 
  hide details  
Reply
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