Sunbeam Rheobus fan controller, Thumbs down!

[Navid]

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Measurements
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Used an 80mm papst 37mA fan and a Yate Loon 120mm 0.30A fan for measurements.

At maximum setting, the 80mm and 120mm fan voltages measure 11.46 and 11.31V respectively.
Lowered the setting. The 80mm and 120mm fan voltages measure 9.12V and 7.46V respectively.
Lowered the setting more. The 80mm and 120mm fan voltages measure 6.53V and 4.79V respectively!

Adjusting the RPM is very difficult because the control knob is very sensitive. This is expected since half of the control range of the knob is useless (< 5V).
There seems to be no voltage regulation!


I performed the same measurements on a Cooler master Aerogate I. This is a very old fan controller, which is not sold anymore. But, it is the only other controller I have.
I used the same 2 fans for my measurements.

At max setting, the 80mm and 120mm fan voltages measure 11.51 and 11.32V respectively.
At mid range, the 80mm and 120mm fan voltages measure 9.19V and 9.15V respectively.
At minimum setting, the 80mm and 120mm fan voltages measure 7.54 and 7.56V respectively.

Adjusting the RPM is very easy (better resolution) since the entire control range of the knob is usable.
There seems to be a reasonable voltage regulation.




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Schematic
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It turns out most of the circuitry on the printed circuit board, including the 2 ICs, are for controlling the LEDs!

The fan RPM is controlled by a 10K potentiometer connected between the 12V and ground. The center tap is fed to the base of a BJT NPN transistor TIP31C. The transistor drives the fan so that the potentiometer does not see the load. But, the transistor has a limited gain. That is why the output voltage is still sensitive to the load (80mm fan versus 12mm fan).
But, there is no voltage regulation.




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Observations
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If an RPM is accidentally turned down too much, the fan completely stops! This could result in overheating of the CPU or graphics card depending on which one got turned off!
The controller does not regulate the output voltage.
The adjustment knobs are too sensitive (not enough resolution).
The LEDs are too bright.



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Conclusion
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I do not recommend this controller. I would not have bought it if I had known!
The output voltage can be reduced to 6V or 5V. That is good! But, the side-effect (possibility of complete turn off) is too bad!
Ideally, you would have a regulated output voltage that could go as low as 6V.






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Mod
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I am inserting a 20k resistor between each potentiometer and ground.
This increases the minimum voltage so that the entire control range of the knobs become usable.
This is an extremely difficult (and somewhat destructive) mod. I do not recommend it.
The LEDs can be disconnected easily to turn them off. I plan to completely disable their circuitry to avoid wasting power.





http://forums.anandtech.com/me...=2244388&enterthread=y

 

[Deathawk]

For what I paid for mine, I have no reason to complain. It does everything I want, and then some, and for the 13 or so dollars I paid for mine, things could have been worse.

But YES, those LEDs are WAY too bright.

 

[Zepper]

Well, for the cost one wouldn't expect tight regulation (and one would know for sure had s/he done his/her homework) - plenty of reviews of the Rheo out there so some should be technically competent. And you always lose some voltage unless it is a fully passive (rheostat only) control - and everyone knows that the Rheo offers full range control from 0 to Max. A higher resistance (low load) fan like the Papst will show a slightly higher voltage when set to the same resistance on the pot than the fan with the higher load (lower resistance) like the Yate. I use my Rheobus all the time for testing fans. If you use the setting where the LED just turns from blue to red, it will always be just under 7V for a fan of any load. If you want repeatable settings and a modicum of safety, use a PWM controller instead, but some fans (I understand the Panaflos are sensitive) don't like PWM and will whine or buzz (ball or sleeve bearings respectively). Seem to me to be a waste of time to complain about a gadget that works just the way one of its design (well known) should...
. Or you could replace the power transistors in the Rheobus with variable voltage regulators instead. Of course, the rest of the circuitry may need to be changed to some degree as well. And unless you could find some low differential (diff between the supply voltage and the max output voltage) V regs, you'd also get a lower top voltage than the Rheobus or PWM controllers manage.
. My Rheo gets a big thumbs up from me - best you can get for the money. If you need to lock in the settings, either put a reference mark on the knob or the face of it or tack the knob in place with a dab of hot glue (easy to peel off if a change is needed). I don't recall ever accidentally changing the knob settings on my Rheo, but doing that is certainly possible.

.bh.

 

[BonzaiDuck]

I have an "Aluminum" one and a black one. They've served to do what they're supposed to do, but they're manual controllers, and I choose more simplicity with key fans controlled through the motherboard plugs. These mobos now will let you thermally control up to 5 fans, and you could probably put two fans of same make/model wired in parallel, one tach wire only connected to mobo, and the double-amperage would still be comfortable for the mobo.

I know that "real men don't eat Kisch," but like the Swiss chef once told me, "Simple is best." so if some fans have a size with top-end rpm around 1,500 and 30-ish dBA noise-rating, you could even run those right off the PSU and "fah-get about-it."

 

[Navid]

Originally posted by: Zepper
And you always lose some voltage unless it is a fully passive (rheostat only) control -

A passive control is the one that loses voltage. Active control (negative feedback with gain) would not lose voltage!

A higher resistance (low load) fan like the Papst will show a slightly higher voltage when set to the same resistance on the pot than the fan with the higher load (lower resistance) like the Yate.

I would not call 6.35V versus 4.79V a slightly higher voltage.

If you use the setting where the LED just turns from blue to red, it will always be just under 7V for a fan of any load.

Have you performed measurements? Can you provide results? May be I made a mistake in my measurements because my results (reported in the first post) clearly show that when the low-current fan is at 6.53V, the high-current fan is at 4.79V. 4.79V is not just under 7V.

If you want repeatable settings and a modicum of safety, use a PWM controller instead,

Why? I use a controller that I bought for a similar price and does it right (Aerogate).

Seem to me to be a waste of time to complain about a gadget that works just the way one of its design (well known) should...

It may be but since it is my time, I spend it the way I wish.
This is not a complain. This is just a report of some measurement results and some opinions.
Feel free to disagree with the opinion.
But, if you feel it is a waste of your time, please don't spend time reading it. No one is holding a gun to your head.


Edit: Spelling

 

[Navid]

If you have a different fan controller, would you please make a few measurements and report?

Adjust the output voltage to 7V while driving a low-current fan like 40mA. Then, without touching the setting, switch the fan to a high-current fan like 300mA. What is the output voltage now?

 

[Zepper]

No, a passive unit is one with no active components (transistors, ICs etc.). A rheostat (used as a series variable resistor) will pass full input voltage when up against the input end stop - just like turning on a switch.

.bh.

 

[aigomorla]

wow... you really did your research.

I like the rheobus, because its cheap, its built solid, and i never had any problems with it. I dont have the need to turn my fans lower then 7V. Yates sounds at medium vs. High is almost nothing inside a case mounted on a radiator.

But Navid, great work... What controler would you recomend then?

 

[Navid]

Originally posted by: Zepper
No, a passive unit is one with no active components (transistors, ICs etc.). A rheostat (used as a series variable resistor) will pass full input voltage when up against the input end stop - just like turning on a switch.

Oh, you mean at the maximum setting. OK, I see.

The two units I have compared perform almost the same at maximum setting.
The difference shows up at medium and minimum setting, where Rheobus's output becomes dependent on the fan, while that of Aerogate remains constant.

 

[Navid]

Originally posted by: aigomorla
... What controler would you recomend then?

This was one of the reasons I started this and I see now that I may have chosen a very strong title for the thread!

I loved the Cooler Master Aerogate 1. But, it seems like Cooler Master have stopped producing fan controllers.:brokenheart:

I cannot recommend anything now because I do not have experience with any other controllers yet!

 

[Zepper]

Aigo,

Nothing wrong with the Rheobus Aigo - The one Navid studied works just the way it would have to given the design. You can easily work around its few shortcomings if desired. As I wrote up there a ways, can't beat it for the $$s.

.bh.

 

[aigomorla]

Originally posted by: Zepper
Aigo,

Nothing wrong with the Rheobus Aigo - The one Navid studied works just the way it would have to given the design. You can easily work around its few shortcomings if desired. As I wrote up there a ways, can't beat it for the $$s.

.bh.

yeah, but if someone was to ask for one that can be downvolted to near 5V, i cant recomend this fan setup anymore.

Also you sure its not the fan and the fan controller? I noticed some fans dont like to start at 5V period.

 

[Navid]

Originally posted by: aigomorla
yeah, but if someone was to ask for one that can be downvolted to near 5V, i cant recomend this fan setup anymore.

You can still use this to downvolt to 5V.
Please explain what you mean!

 

[Binky]

Wow. You did a bit of work here. I still like my crappy little Sunbeam unit. It works fine for what I need it for, and I've used it for about 2 years.

Like i said in my post in another thread - do NOT turn it down below 12:00 or most fans just shut down completely. Once you learn this it's pretty easy to keep the knobs at 12:00 or higher (use white-out to enhance the visibility of the notch on the knob). I think this is your major issue with this unit.

But seriously, we're talking about a $13 part here with a stated output voltage of 0-12v. I'm not surprised that there is ineffective or completely absent voltage regulation.

Linky

 

[VinDSL]

Originally posted by: Navid
I cannot recommend anything now because I do not have experience with any other controllers yet!

Heh!

How about trying a Scythe Kama-Meter next?

I about crapped when I found out they were available in the States, but haven't bought one yet...