This article will describe the making of a home built RheoBus. A RheoBus is a device that allows you to manually set the speed of the fans in your chassis by limiting it’s voltage input. The main difference between a RheoBus and a BayBus is that you set the voltage to the fans step less with a potentiometer when using a RheoBus, while a BayBus only has two or three preset voltages…

This article will describe the making of a home built RheoBus. A RheoBus is a device that allows you to manually set the speed of the fans in your chassis by limiting it’s voltage input. The main difference between a RheoBus and a BayBus is that you set the voltage to the fans step less with a potentiometer when using a RheoBus, while a BayBus only has two or three preset voltages. You’ll probably want better cooling when you are playing or doing things that use a lot of CPU-time and the computer generates more heat, but there are times where you want to sacrifice that cooling and run the computer silent, when you are sleeping or watching movies. A RheoBus is the perfect device for this purpose, and since there are prefabricated ones priced at 50$+, I simply had to design my own one to a much more reasonable price.


Description Quantity Price Elfa number
Light Emission Diode x 3.64 EL264-7SRC
Resistor 300 Ohm x 3.24 60-716-66
Resistor 240 Ohm x 3.24 60-715-59
Potentiometer 2.2k Ohm x 15.5 64-262-74
LM317t Voltage Regulator x 10.9 73-120-77
Heatsinks x 7.96 75-612-36
Total:   44.48  

x is the number of channels. All the products are available from other companies, I only used Elfa as an example.

Price Calculator

The price for one channel is easy to see above, but you can check the price of your RheoBus by simply using the form below. Just write how many channels you wish, and the total price will be calculated for you. One channel can handle about 18w, thus allowing control of multiple fans on one channel.
You can only fit four channels on a 5.25″ faceplate, and three on a 3.5″.

Insert the number of channels below



Tools
  • Cutter
  • Soldering Iron

Buy the cheapest potentiometers that you can find, since they won’t suffer any current. Their purpose is to control the voltage regulators who will take all the stress.
The most expensive part of this device is the knobs on the potentiometers, I have not included the cost of these since they cost 3-4$ each. It may be a good idea to find options to the knobs, or try to find used ones since their only purpose is to look good.

Ideas for cheaper knobs

  • Be creative! Make your own using your younger sisters lovely colored clay, for example.
  • Small rubic’s cubes (you can find them in larger toy shops)
  • 40 or 60mm fans (if you have any broken ones)

Wiring Diagram

T1=LM 317t, R1=300 Ohm, R2=240 Ohm, R3=2,2K Ohm Potentiometer
Remember that this wiring diagram is for one channel only, if you want to use four channels you have to use the diagram four times. If you hold T1 with the written text towards you, connect +12volt to the right leg.

Veroboard design

Allting som behövs
My veroboard design

R1= 240, R2=300Ohm, R3=2,2K Ohm Potentiometer, D1=LED, T1=LM 317t. The arrow shows the knob on the potentiometer. The black rectangle is a break, where electricity should not pass. The light gray rectangle is a cable, and the black circles are connection points. Thus, the cable is supposed to be connected on the center of R3 and the right side of the LED, not on all the columns in between. The text of T1 should be turned the same way as the axis of the potentiometer (see picture below).

Allting som behövs
Two soldered, click to enlarge

It’s quite obvious that the voltage regulators will become hot, since they will handle all the current instead of the potentiometers. Therefore it’s a good idea to mount heatsinks on them, this is done with a regular m3 screw and an appropriate nut. The heatsink will have the same voltage and current as the output pin, and this will most likely cause a problem if the heatsink is in contact with anything metallic that is connected to anything. There are nylon washers and spacers to prevent this, another solution is to use nylon screws and nuts instead of using washers. These can most likely be bought from your local hardware store.


It’s a good idea to test the RheoBus before you mount your circuit board on a faceplate. Connect the channels to 12 volts and try to turn the potentiometers, the LED should vary it’s brightness. Try all the channels, and check your solders if it doesn’t work. Do NOT use your ohm-meter in order to check if two columns are short circuited, doing so may result in a broken voltage regulator.

Measure twice, drill once. Use a ruler to mark the positions of the LED’s and potentiometers on the faceplate, drill size for the LED’s is 3mm, and 7mm for the potentiometer. When this is done, simply push the potentiometers through the faceplates, and use the included nuts to mount them. Push the LED’s through their holes, and secure them with some glue or similar. Measure the potentiometers, and cut the axle to an appropriate length. Finally mount the knobs or whatever you chose to use.

Allting som behövs
Picture from the top

Allting som behövs

Allting som behövs

From the front

Allting som behövs
From the side

Final Words

This is the perfect tool to lower the noise if you are tired of loud screaming fans when you are listening to music or watching movies. You lower the voltage (and noise) step less, thus you can find your own tolerance level without any hassle. It took about 10 hours to complete the project, but I was very unfortunate spending more that three hours trying to find out why one channel didn’t work when the LED itself had broken. It’s always a load of fun to build something of your own, and this is not an exception. It is also much cheaper than a prefabricated one, a prefabricated RheoBus from PcMods.com costs about 50$ if you want LED’s, and it has four channels. If you instead choose to build one of your own, the bill settles at 18$. It is also easy to repair it yourself, since you know you built it. You can also choose the number of channels yourself, it’s not really necessary to buy a prefabricated for 50$ if you only desire to control two fans.

+Adjustable noise level for your fans
+The price is about 1/3 of a prefabricated one
+Easy to repair
+You can choose the number of channels you would like
+Up to 18 watts per channel

-None worth mentioning

Annons

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