PC70 Fan Speed Controller Circuit

I'm planning on buying six Sunon 80mm 50CFM fans to replace the current 80mm. The two front fans will be using the circuit or maybe having just one Delta EHE 80mm 80CFM, HS, connected to the circuit so I could controll the RPMs. How do I check if the Fan Speed Controller Circuit can handle the power requirements of the higher capacity fans?

Options;

a. 2 X Sunon 80mm 50CFM on the circuit;

b. 1 X Delta EHE 80mm 80CFM on the circuit for the HS.

I just need to make sure.

Well, it depends whether you want to hear. I would go with the sunons, I have 3 of them in my PC65 case...and they are wonderful. Not to loud either!

Rezman5 said:

Well, it depends whether you want to hear. I would go with the sunons, I have 3 of them in my PC65 case...and they are wonderful. Not to loud either!

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My question is about the working capacity of the Fan Speed Controller Circuit for the pair located in front of the case. Did you connect them to it & do they work properly with the controller?

Look at one of the stock fans and tell us everything printed on the label that looks like it relates to voltage, current, or watts. Then do the same for the new Sunon 50cfm fans. I searched high and low for a specification on the Lian Li PC70 fan controller, but could not find a specification. Lastly, if you have a digital camera, take a close-up picture of that controller and post it here. We may be able to determine something about its capacity by the components.

Hoot

The stock fans are 12V, 3W & .25Amps. Sunons are 12V, 4.32W & .36Amps. Delta 12V, 10.8W & .9Amps. If I change the resistor to a higher capacity could I then wire 2 Sunons on one header split by a Y connector then have the Delta on the other header. What would be the value needed? Here is the picture of the circuit;

I forgot to say which colors in the pic

Okay, so they are using 47 ohm resistors that look like 2W metal film, but they could be 1W. Radioshack.com has a 5W 47 ohm resistor for $.34 each. (SKU 900-0937) http://www.radioshack.com/searchsku.asp?find=900-0937

Unfortunately, this value is not stocked in their stores and must be ordered online, but that's the way Radio Shack has become lately. More appliances, less parts.

I'm sure if you had an Electronics Surplus store near you, you could find them there.

The problem you run into is that the 47 ohm resistor is adequate for dropping the speed of one .25A fan. If you put two of those fans in parallel, then 47 ohms is too much. Worse even yet for that .9A Delta. Likewise the new fans at .37A. The more current a fan or combination of fans draws, the less resistance you need to drop the voltage reaching that fan(s) to the same point. You don't want to slow them down too much or they become ineffective.

Lets look at ratios for a second. If 47 ohm is ideal at .25A, then (.25A/.37A)*47= 32 ohms for the new Sunon fans. I'm going to disregard that Delta fan because it is inappropriate for a case fan. 32 ohms is not a standard resistor value, but 30 and 33 are. Radioshack.com has the 33 ohm (SKU 900-0933) for $.34 each also. http://www.radioshack.com/searchsku.asp?find=900-0933

Personally, I think all those 80mm fans you are planning will be sufficient for adequate case ventilation. In searching for information on the Lian Li PC70 last night, I did stumble across a case mod to use 92mm fans in place of the intake 80mm ones. That's what I would use. Yes, it involves nibbling out the holes on your nice (expensive) case, but if approached with some forethought and performed with care, it will not detract from the appearance. I would think that using a pair of 92x32mm Sanyo Denki Mini Ace 32 http://2cooltek.safeshopper.com/27/198.htm?708 fans on the front intake and four of the stock fans on the exhaust, along with your PSU fan would yield an excellent setup with tolerable noise. In that case, you would control the two S.D. fans speed to yield a slight positive pressure. The Sanyo Denki Mini Ace 32 is in my honest opinion the best fan for case cooling ever made and I don't make such absolute statements very often.

Hoot

Hoot said:

The problem you run into is that the 47 ohm resistor is adequate for dropping the speed of one .25A fan. If you put two of those fans in parallel, then 47 ohms is too much. Worse even yet for that .9A Delta. Likewise the new fans at .37A. The more current a fan or combination of fans draws, the less resistance you need to drop the voltage reaching that fan(s) to the same point. You don't want to slow them down too much or they become ineffective.
Hoot

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I forgot to mention that the controller has 3 speed settings, low & medium using the circuit & fast is probably a "pass thru".

Hoot said:

Lets look at ratios for a second. If 47 ohm is ideal at .25A, then (.25A/.37A)*47= 32 ohms for the new Sunon fans. I'm going to disregard that Delta fan because it is inappropriate for a case fan. 32 ohms is not a standard resistor value, but 30 and 33 are.
Hoot

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My ideas are;

a. Use one header for 2 Sunons. what value of resistor to use? Also;

b. Delta 80mm 80CFM on the other header for the CPU heatsink that would also have 3 speeds like the sunon fans. Three speed are not to high on my list but at least have 2 options; LOUD & not too loud.".

Hoot said:

In searching for information on the Lian Li PC70 last night, I did stumble across a case mod to use 92mm fans in place of the intake 80mm ones. That's what I would use. Yes, it involves nibbling out the holes on your nice (expensive) case, but if approached with some forethought and performed with care, it will not detract from the appearance. I would think that using a pair of 92x32mm Sanyo Denki Mini Ace 32 fans on the front intake and four of the stock fans on the exhaust, along with your PSU fan would yield an excellent setup with tolerable noise.
Hoot

Click to expand...

The front fans are still covered by the face plate that have a grill for the air to pass thru but for now I would preffer to stick with the 80mm. The loudest fan by far in my system is the 120mm 131CFM YS-Tech.

I'm working in the blind here since i don't have one of those cases, nor the speed controller schematic. Okay, there are two headers. I'll assume that originally, one 80mm fan went to each header and that changing the setting effected both fans the same. If that's the case, you will not be able to split off the headers to two different functions. Whatever effects one header, effects the other header in the same way. Lets assume a little further with some of these possible scenarios:

Fast = no resistors used (pass-through)
Medium = both 47 ohm resistors in parallel = 23.5 ohms, in series with both fans
Slow = one 47 ohm resistor in series with each fan

-or-

Fast = same as above
Medium = one 47 ohm resistor in series with each fan
Slow = two 47 ohm resistors in series = 94 ohms, in series with both fans

-or-

Who the heck knows

You see my dilemna advising you from in the blind? There are a number of possible combinations of those two resistors to control the fan speeds. Without access to the controller or a schematic, I am shooting in the dark here.

That Delta fan for your HSF (sorry about the confusion) should have its own speed controller or rheostat as It draws considerably more current than the case fans.

Hoot

Thank You for all the info. I will take your advise, change the resistors to 33ohms or 30ohms & have the Delta on a Seperate rheostat which I'll probably mount at the rear so I don't change the look of the case. I've been trying to go for a non-moded look with faux covers for the CDROM, CDRW & Floppy except for the 120mm fans filter that shouldnt be hidden anyways so as to not restrict it's airflow requirements. Thank You for the knowledge that will take me further than I would have without your help