For those in search of a PWM-less fan controller...

meglamaniac · Post by **meglamaniac** » Thu Oct 07, 2004 12:10 am

...I've heard various reports that the Akasa Fan Controller FC03 uses good old resistors, not pwm.
If anyone could confirm, that'd be pretty cool.

silvervarg · Post by **silvervarg** » Thu Oct 07, 2004 12:33 am

I haven't looked that closely on that controller, but with a rating of 17W per channel it would need huge heatsinks to be able to operate with just resistors. The resistors would be very big and expensive as well.
It could possibly use voltage regulators, but I strongly doubt even that solution with 17W per channel (expensive to build).

scara · Post by **scara** » Thu Oct 07, 2004 3:59 am

I have one of those and it makes absolutely no noise. That means it must use resistors right?

meglamaniac · Post by **meglamaniac** » Thu Oct 07, 2004 4:28 am

It's not so much if IT makes any noise, although some PWM controllers do exhibit a buzz/click at lower levels, especially the some of the Vantec ones.
It's more to do with whether it makes the fans noisey. Many fans don't cope very well with PWM at low speed - they're not designed to have short bursts of full current - this makes them click or buzz as well.

If you could try raising and lowering the current to one of your fans and report if you hear anything like that, that'd be great. Better still if you can tell us what fan it is

Thanks

scara · Post by **scara** » Thu Oct 07, 2004 5:26 am

Oh, I didn't realise only some pwm controllers made a noise. I thought they all buzzed/clicked when turned down.

When I first put this system together I messed around with the fan voltage levels to get the noise/heat balance and never heard any buzz or clicks from the unit or the 3 Nexus fans it controls (see sig) at any v-level combination. Also I had the GPU fan unplugged and the PSU was unloaded so there were no interfering noises.

Just turning the fans up and down now.....only a definite air-turbulance noise change.

Hope thats what you're after

Atmos · Post by **Atmos** » Thu Oct 07, 2004 9:24 am

http://www.casetech.co.uk/product_info. ... cts_id/716

I bought one of these which look to be the same and it contains 4 voltage regulators.

meglamaniac · Post by **meglamaniac** » Thu Oct 07, 2004 2:42 pm

Heh, that does look surprisingly similar doesn't it.
So, are voltage regulators good (ie. non PWM)? I'm not fully on top of all the various different regulation methods.

sthayashi · Post by **sthayashi** » Thu Oct 07, 2004 8:02 pm

meglamaniac wrote:So, are voltage regulators good (ie. non PWM)? I'm not fully on top of all the various different regulation methods.

There ARE a couple downsides to Linear Voltage regulation. They're the least energy efficient, burning off the energy you don't use. e.g. if you have a fan that draws 0.05amps @ 7V, then the regulator puts out (0.05 * (12-7)) = 0.25 Watts. It's a drop in the bucket compared to all the other heat generators in a CPU case. With ridiculously powerful fans, it might actually be a problem, but we silent PC users NEVER use ridiculously powerful fans.

The other problem with linear regulation is that you can't get full range out. The maximum voltage is around 11V +/- 0.5v depending on implementation. Often, there's a lower limit of 5v as well.

Another common form of voltage regulation are rheostats, though I'm not as familiar with their pros and cons.

mathias · Post by **mathias** » Thu Oct 07, 2004 8:27 pm

sthayashi wrote:
meglamaniac wrote:So, are voltage regulators good (ie. non PWM)? I'm not fully on top of all the various different regulation methods.
The other problem with linear regulation is that you can't get full range out. The maximum voltage is around 11V +/- 0.5v depending on implementation. Often, there's a lower limit of 5v as well.

That could be fixed with a simple switch to bypass the resistor. And the lower limit could be worked around by switching from the +12 to the +5 line.

sthayashi · Post by **sthayashi** » Thu Oct 07, 2004 8:55 pm

mathias wrote:That could be fixed with a simple switch to bypass the resistor. And the lower limit could be worked around by switching from the +12 to the +5 line.

Depending on the linear regulator, the results become a little on the unpredictable side. Look around for posts of people who have wired 2 Fanmates in series.

meglamaniac · Post by **meglamaniac** » Fri Oct 08, 2004 3:19 am

Oh well that sounds good enough for me anyway - I can't see any reason to want to run at 12v, and if it won't let me switch them off all I need is a little fiddling with a switch from a hardware store and a drill if it turns out I need that ability.

Just so long as there's no buzzing!