Review: Sunbeam Rheobus Fan Controller

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Manufacturer Sunbeam Company
Supplier Silicon Valley Compucycle (SVC)
Supplier's price US$18

The LEDs can all light red or blue. But they are very bright. Blindingly bright. You can, however, easily get them to look more like the photo below (in which only the center 2 LEDs are on, by the way). More on this solution below.

The Sunbeam Rheobus is actually a bit of a misnomer. Rheobus refers to a bus (or voltage line) of rheostats, which are a certain type of variable resistor. A rheostat is a passive device, the simplest type of voltage controller available. It has some distinct disadvantages, such as heating up, and not providing the same voltage control range with all fans. The Sunbeam does not actually use rheostats at all. Instead it uses 4 transistors in active electronic circuits to provide more efficient, repeatable fan voltage control.

As you might guess from the photo above, the Sunbeam has 4 independent channels. It is not limited to controlling 4 fans, however. Each voltage channel can be shared via splitters with more than one fan. As the power rating per channel is a generous 20W, this means a combination of fans rated for a total of up to 1.67 Amps can be accommodated on each channel. That's as long as the total 12V rating of the PC's power supply is not exceeded. The Sunbeam, like all the active (and passive) fan controllers on the PC market, is powered by the PC's power supply. For silent PC applications, the Sunbeam power capacity is probably much more than will ever be needed. Most of our fans rarely exceed 0.15A rating.

Another thing you might have guessed from the photos (and reviews at other sites as well as comments in forums) is that the LEDs are very bright. Bright enough to cause ghosting in your vision should you look directly into them for any length of time from any distance up to several feet at least. There is a simple solution. See below.

Manufacturer's specifications:

  • Power : 20 watt per channel
  • Input voltage : DC 12V
  • Output voltage: 0 ~ 12 V
  • Output current: up to 1.67 A
  • Dimensions: 148.5x 105x 42 mm
  • Weight (Net) : 184

Like most multi-channel fan controllers, the Sunbeam is meant to fit into a CD drive bay. The front consists of a brush aluminum panel with blue graphics. There are 4 knobs about 3/4" diameter and 5/8" deep. Each controls one voltage channel. A bright LED indicator lights up when the knob is turned clockwise, which turns a switch on with an audible click, much like a simple transistor radio. The LED starts out red colored but turns blue past a certain point. The knobs have a smooth slightly frictioned feel, quite pleasant to use.

A few more photos:

The brushed aluminum is probably not a bad match for aluminum front bezels, but depending on how picky you are, it may be close enough, or close but not close enough. Those with cases that have doors over the CD drive bays will be pleased to know that, at least on the Antec cases, there is enough clearance for the knobs; the door closes fine.

A thin layer of foam is affixed to the underside of the PCB. It can't possible have any acoustic damping function. Perhaps it is meant to protect the board?

The photo above shows the view from top: Power from the PSU is obtained via a 4-pin peripheral connector. Note the four 3-pin output connectors for fans with standard motherboard header connectors. This means an adapter or some rewiring is needed if you have fans with 4-pin peripheral type connectors. (Apparently an earlier version used screw set terminals instead of the 3-pin connectors.) The transistors for each of the channels is cooled by a fairly substantial heatsink, as befits the 20W / channel rating.

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