Panaflo L1A @ 1-2V???

brianLp518 · Post by **brianLp518** » Thu Mar 03, 2005 9:04 pm

Hey guys, just seeing if I'm correct here... I just Panaflo L1A'd ( made in china =\ ) my Antec Smartpower 350, and i didnt' have any resistors besides two Zalman RC56's.... so I tried one [which is @ 7V (0.1A *56ohms= 5.6V drop) and it was still tickin and whoosy. So i decided to try two in series...

There was about a 50% drop in RPM speed (eyeballin it), but a HUGE decrease in sound... It did turn twice prematurly and then started up, but it did the same for every trial i plugged it in. I bent the slats in the PSU and there seems to be plenty of airflow with temps around 30-40C from the exhaust....

Anyways... 56ohms + 56ohm = 112 ohm. 0.1A * 112ohms = 11.2V drop??? I don't think this could be possible is it??? i was reading somewhere where the voltage drop for a panaflo is less actually (3V voltage drop across a 56ohm resistor). So do i have a 2V panaflo or a 6V one???

PS... where's a good dealer to get a nexus 120mm fan in the US??? Can't find 'em... Thanks

Michael Sandstrom · Post by **Michael Sandstrom** » Thu Mar 03, 2005 9:09 pm

Silicon Acoustics is a good supplier for the 120mm Nexus.

sthayashi · Post by **sthayashi** » Thu Mar 03, 2005 9:13 pm

You can't assume that the current remains constant. In fact, when you drop the voltage on a Panaflo (or most fans, as far as I'm aware), you drop the current too. So the fan can be modeled as a resistive load.

Using V=I*R, we can say that 12v/0.1A = 120 Ohms. Actually, I think the value is closer to 150 Ohms, based on my experience with it, so let's assume that, if you don't mind.

150 Ohms + 112 Ohms = 262 Ohms. 12V / 262 = 0.0458A

Again, since know the Panaflo acts as a 150 Ohm resistor, we can say that the voltage is 0.0458 A * 150 Ohms = 6.87 V.

brianLp518 · Post by **brianLp518** » Thu Mar 03, 2005 9:24 pm

cool... Thanks...

Quick question... should i just get a zalman fanmate to control the RPM's to 5V??? would a panaflo L1a @ 5V be enough to cool my SmartPower 350W?

cpemma · Post by **cpemma** » Sat Mar 05, 2005 3:56 pm

sthayashi wrote:Using V=I*R, we can say that 12v/0.1A = 120 Ohms. Actually, I think the value is closer to 150 Ohms, based on my experience with it...

I checked one just received (good service, DB

), 145R @ 5.3V. But 176R @ 11.5V.

The other fan (Fanner Tech (Shen Zhen) Co.) came on a cheap (but very effective) Speeze HS, nominally 90mA but a bit noisier than the L1A. Impedance change goes the other way, 147R @ 5.3V, 127R @ 11.3V.

edit: Added the 80mm Vantec Stealth, it's almost perfectly ohmic at about 170R, and like the Panaflo draws much less current than the 0.1A rating.

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