Attach a resistor to the fan power cord

[Morannon]

Hi!

I don't like fan noise one bit. I don't want to hear the fan while I'm idling or just doing light stuff in Office! I'm starting to regret buying the s10e. Yeah, I should have researched better. Anyway, my proposed solution to this is to attach a resistor to the fan's power cord.

Q1: What are the fan's voltages and it's current?
I don't know, do you?

Q2: How will the temperature controlled fan react to the resistor?
I don't know how many speeds/voltages the fan has but I assume it's more than one. Since the lower voltages probably wont keep the temp below ~45 C anymore, I guess the fan will increase voltage until it gets there. Is that right?

Q3:How much should I lower the voltage?
Assuming I'm right at Q2, the resistor should be strong enough to make the fan's highest possible voltage spin the fan slow enough so that I can barely hear it.
Let's say the fan's max is 5V. Then my pure guess is I should lower that to about 1,5-2V. how does that sound?

[Dennis]

I don't know the fan details but I think I would try series diodes in-line with it to slow it down ... If the fan is 5v you could drop it's speed by approx 12% with each forward biased diode placed in series ... You can place an ammeter in line to measure the current and select the diodes accordingly ...

[jaqiefox]

the diode is a good idea, but remember this fact very clearly: voltage and fan speed do not vary linearly, and below a certain threshold fans just stop spinning up. the lowest you should ever take the fan is 60% of it's original voltage, below that it might not spin up even when set to near full speed by the system.

And IIRC somewhere it was said to be 5v max, but before you do this project you need to verify it with a multimeter.... you were going to do this project with one, right?

[Morannon]

I was hoping someone already knew the voltages of this particular fan, but I guess no one does so I'm gonna use a multimeter yes. The only way to measure is to cut the cord, get the multimeter in there and fire up the computer right?

I've never dealt with diodes before. From my knowledge they just restrict the current to one direction and have insignificant resistance. How can they help me?

Edit: Well I checked about the diodes and they do have significant resistance!

[ayt999]

Q1: What are the fan's voltages and it's current?
I don't know, do you?

ADDA part number AB5005UX-R0

5VDC 0.40A

as listed on the fan. I've posted this info a few weeks ago elsewhere on the forums fyi, but I know search sometimes doesn't work when you don't know what the right search terms are.

if you are talking about variable voltages sent to the fan, that's not a function of the fan but the system motherboard. the fan is rated to run up to a maximum of 5VDC and uses up to 0.40 amps of current, and can accept anything up to that (well, higher, but it's not guaranteed to work beyond that). I don't think the S10 has a variable fan speed controller, or at least I've never heard it do anything other than on/off.

fans (which are basic motors if you break it down) require a minimum voltage to start. this is higher than the minimum voltage required to keep it in motion. 1.5~2 would most likely be well below either thresholds.

[Morannon]

Great replies all of you!

Good news about the fan probably not having more than on/off. That makes things nice and simple. Do you have any idea if the motherboard is putting out 5V to the fan or is it lower? The reason I'm desperate to know is that I've never used a multimeter before and it sounds risky to turn on the comp while it's in parts. I'm probably gonna take a chance and assume it's always at 5V.

I've concluded that diodes are the way to go. However, I find varying specs on the voltage drop from different sources. In some places it says they drop ~0,7 V. But at my local electronics store's website it says 1-1,1V. If I use 2 of those diodes I'll end up at about 60% of the fan's max (If the fan is normally running at 5V that is). What do you think, should I use 2 of those?

And ofc I'll remove that stupidly dense mesh in front of the exhaust while I'm at it.

[Dennis]

Most forward biased silicon diodes drop between .6v and .9v ... Some maybe a little more. The forward biased voltage drop remains approximately the same regardless of the current. Since that voltage drop is across the diode, it must dissipate the voltage dropped times the current passed ... that is why you need to know the current capacity of the diode. It is doubtful the max voltage capacity will be an issue.

As for how many to use ... try both one and two ... not knowing the characteristics of the fan or the fan driving circuit, it's impossible to know ...

Experiment with it and see if you like what you see ... Almost any silicon diode of any moderate size will probably work ... Remember it must be in the forward biased direction ... if it is backwards, nothing will be hurt, it just won't run the fan ... so turn it around ...

PS: I am NOT saying lowering the fan speed will be safe for the longevity of the components it is designed to cool ...

[Morannon]

The mod is done... and it's a total success!

When the temp hits 46C, the fan kicks in like normally but it's now actually a bit quieter than the hard drive. The air flow is so small that the only way I can detect it is if I put my ear right next to the vent.The fan never powers down after the temp hits 46. The highest temp I've seen so far while using the comp at it's full potential is 51C.

What I did was:
Attach 2 silicone diodes (1N4001) to the fan's red cord. Each diode was said to lower the voltage by 1,1V. I also cleared away the mesh and the plastic bars in front of the exhaust to help the air flow. But there is still no way anything could damage the fan since it has protection on it's own.



I recommend this mod to anyone who finds the fan annoying. Because the HDD is a little loader now, it wouldn't hurt if the fan was spinning a little bit faster. If you do this mod you might want to try diodes with a voltage drop of about 0,75-1V each. This website was helpful: http://www.cpemma.co.uk/diodes.html

Thanks to everyone in this thread!

[scottyinco]

The mod is done... and it's a total success!

How did this mod affect your battery life? I assume it would be shorter since the fan never turns off, but since it's drawing less current, maybe not. Can you report back on that?

Scott

[BrendaEM]

As you hinted at, I wonder what a happy medium would be between the stock situation and your mod. I certainly wouldn't mind the fan being a little louder than the hard drive, but still quieter than what it is now.

I'm going to call Lenovo today.