BayBuses/FanBuses/Rheostats explored

[Garet Jax]

Hello all,

Thanks to ericd for getting me the original information/links to enable me to do this research.

I have been interested in building a new OC'd machine. As a result, I have been researching everything from cases to MBs to CPUs to RAM etc...

I came across the term baybus in a post by ericd and asked some basic questions of him. Since then I have been able to track down a little more information that I thought I would share with others. Hopefully this is useful.

First off, baybus and fanbus are interchangeable terms. To the best of my knowledge, they mean exactly the same thing.

Secondly, a baybus refers to a mechanism that allows someone to install multiple fans (or other low voltage h/w) within a computer without using all of their 4 pin molex connectors. In addition, more advanced baybuses allow someone to install switches to individually turn the attached h/w on and off or even to actually control the voltage sent to it.

There are two options with BayBus. You can build one yourself or you can buy one prebuilt. To build one yourself, refer to Cliff's Page. For pieces to build one, refer to this online vendor.

However, having said that there is one baybus that ericd pointed me to that is prebuilt and looks to be very well put together. Refer to this online vendor for a brief description, some pictures and three very good reviews.

Thanks again to ericd for all of the above links.

I found that the reviews and FAQ didn't answer all of my questions so I sent an email to their customer service. Here they are with the responses:

Questions:
1) How are the trimmer pots adjusted to vary the voltage to the hooked up device? Is it simply turned using a screw driver?
2) Can I accidently adjust it to go below 5.5V or above 11V? If not, how is this prevented?
3) I know that I need to screw stripped wires into the baybus, but what do I need to do to connect the fan to the stripped wires? Most fans that I have seen come with a 4-pin molex connection. Do I need to remove the molex and attach the strip wires to the red and black wires on the fan?

Answers:
1) The pots are adjusted by using a small cross point or common screwdriver, or equiavalent tool.
2) The range of adustment varies slightly with the load. A good rule of thumb is that the highest range possible is approximately from 5.5v to 11.5v. Increased load skews the lower and higher limits downward slightly. So, you CANNOT adjust the upper limit higher than 11.5v. If you have a large load, you CAN adjust the lower limit slightly below 5.5v.
3) Exactly. If you have fans with 4pin molexes on them, simply snip the molex off, strip the wires, and attach to the wire terminals on the baybus. Then you are ready to rock and roll.

Hope this helps at least someone.

 

[ericd]

For the most part you are correct. However I have one correction. Generally a fanbus is just a device used to connect multiple fans to one four pin power connector. Fanbus do not have controls to switch the amount of voltage going to the fan. Baybus are much like Fanbuses except that they generally have on/off controls with possibly multiple voltage settings. Baybuses are usually mounted on a 5.25" drive BAY cover....hence the name. Otherwise you are correct.


Eric

 

[fitzhue]

Thanks Garet Jax
Those were some of my questions that I had. One question though, is a rheostat basically just a baybus but modified to be used with rheostats to further allow voltage adjustments? I get how you hook up the fans, is it the same with a rheostat? The unit i am looking at is right here
Would I be able to run all my fans at 12v and all the way down to 5.5v?
If you don't have this info that's fine. If you do that it would help to out a lot.

 

[ericd]

A good FAQ and tutorial for Rheostat is included on Cliff's Page. Basically the principal is the same as a baybus except you have variable voltage control on the front panel intead of just 2 settings that you would have with a switch based system. Rheostat setups are in my opinion a hell of a lot easier to wire than a switch based system. The only thing that you have to keep in mind is that Rheostats have a maximum wattage that you have to stay under, this maximum is 5 watts on most Rheostats. You can use multiple rheostats on seperate circuits to get past this limitation but it does make it more complicated and IMO a little less convenient. As far as the voltage limits I can't answer with absolute certainty but I believe that with a Rheostat the range is around 12V to 3 or so. Regardless of what the low end is it is low enough to choke almost any fan. In a rheostat fanbus you basically attach the fans in the exact same manner as a switch based bus. For more info I would once again suggest checking out fanbus.com.

Hope this helps.

Eric

 

[Garet Jax]

I have updated the title to more accurately reflect the discussion. In terms of rheostats, pcmods customer support said that they are currently trying to develop one similar to their baybus. They even sent me a picture of what one looks like. It drives home the description that ericd gave. If you are interested in seeing it, send me an email to garet_jax23@hotmail.com

Fitzhue,

Thanks for asking the questions regarding an obviously overlooked piece of hardware.

Ericd,

Thanks for setting me straight on the difference between a fanbus and a baybus as well as answering the question fitzhue asked.

 

[fitzhue]

Thanks a lot guys. While on my search for rheostats and information on them, I stumbled upon the dual voltage baybus @ pcmods.com here
This thing looks really sweet. I read the review at virtualhideout and it seems it has three selections. On, off, and "variable speed" It says that when on variable speed it can control between 11-5v. Well isn't basically the same principle as a rheostat controlled baybus? It actually seems a little bit nicer than a rheostat. The price is rather good I think. I think i might go ahead and purchase this as it will do basically what I want it to do. Installation seems to be a lot easier too. If anyone has any comments on this it would be great. Does anyone also know how the variable speed works with only flip switches?

 

[ericd]

Yes it is EXACTLY the same principle as a rheostat. Actually another name for a rheostat is a potentiometer which is what the PCMods baybus uses to creat that variable voltage setting. They just use a miniaturized version of what you would use for a rheostat baybus. I actually own the PCMods baybus and can tell you that overall easier and believe it or not cheaper than building your own baybus particullarly if you have to buy any tools or wire. I still like the idea of the rheostat baybus because of the fact that you can adjust the voltage "on the fly" where you have to take the bay cover off your case and use a screwdriver to adjust voltage. Either way is great and both have advantages so pick your evil and go with it.

Eric

 

[fitzhue]

Thanks a lot ericd
One more question, on the pcmods baybus, do you have to take the cover off and use a screw driver to adjust the voltage setting? I'm thinking that wouldn't be very practical. Thanks for your help

 

[Garet Jax]

fitzhue,

To my understanding, that is exactly what you need to do. If you see yourself needing to do this a lot, you may want to wait until pcmods releases their rheostat. Otherwise, leave the case cover off, please with the trimmer pots until you get the custom setting as desired and then put the case back on.

 

[fitzhue]

Thanks Garet Jax,
I think what I'll do is just run this thing as basically a dual voltage baybus. I'll set the "variable speed" to something probably around 7-9v. That should basically give me what I want. I don't see myself needing a rheostat. I wouldn't that very large amount of small incremental increases. Thanks for all your help.

 

[sitka]

moffsets with a pot are the way to go, more efficient. Just wish I knew what sizes to get.

 

[fitzhue]

sitka
would you care to elaborate a little more on these moffsets?

 

[sitka]

OOPS.... spelling is mosfets. They are basically voltage gates. NPN I think is the cool name for 'em.
I was just hoping that someone would throw up a diagram. I've been looking all evening on how to build a mosfet 5 to 12V DC motor control but I don't speak electro-geek.
Anyways what happens is there are three leads on a mosfet. IN, OUT and control. The control can be low current so you can use a potentiometer. By varing the pot the mosfet becomes more or less conductive and finishes the current to the fan. The advantage is it changes the voltage more efficiently. Pretty simple but I don't have a diagram or build list and can't figure out the components. So keep your eyes open.

 

[SammyBoy]

Lets say I bought that nice baybus that they have at pcmods, and I wanted to connect my fop38, or any hsf with the black label alpha fan. I would want to run it at the full 12 volts for hardcore computing, and say 9 volts when I am surfing or not doing anything too cpu intensive. For some reason I thought that your motherboard would not run if the hsf wasnt plugged into its 3 pin outlet thing. can anyone verify this?

I am sure that I have heard of peoples new rigs not starting up and ananders telling them to plug their hsf into the proper outlet on their mobo. If not then doing what I said is no problem, and I think I might have to get one. Can any of you baybus geniuses tell me anything about this?

thanks a lot,
-Sam

 

[ericd]

SammyBoy- the only MoBo that I know of that requires a fan to be plugged in to the header is the Abit KT7A/A-Raid. Even with these motherboards the newer revisions of the Bios have an option to turn that safety feature off.

Eric

 

[SammyBoy]

thanks a lot eric, yeah thats right, a few weeks back i was reading up on the abit cuz I thought I was going to get it. Wow, this is so cool, i wonder why these werent popularized earlier (maybe they were, ive never heard of em). I am gonna get an Iwill MOBO so this will be great!

thanks for helping us all out guys

 

[Croton]

i got the pcmods baybus on my system and it is awesome!

 

[sitka]

Just bought THIS OooH Momma. Get them fans down to tick-over speed. It's called PWM for Pulse Width Modulation. See I wasn't lying.