Turn on/off two rheobuses with one switch?

[MonroeM]

Hey everyone,

I have an idea that I've been pondering over (and searching the web & forums) for the last few days.


I would like to use a military-style toggle switch (red LED) to control the on/off power function of two seperate rheobuses in my case.

I already have the switch but am confused by a) if this is possible without frying anything and b) the wiring setup. The only specs I have on the switch is a "Connections" sticker on one side that reads "Power - ACC - Ground", each word over their respective connectors. It also reads "12v20A" on another side.



Any help would be much appreciated as even w/ the fans' speeds turned all the way down, they're still annoyingly loud.



ADD: I have 10 cooling fans in my system BTW, not counting PSUs, CPU or VGA =\

[Son1990]

When you say turning off your controller, you mean turning off all fans on that one controller as well while turning on other fans and another controller?

[MonroeM]

Yes, essentially. I want to completely cut the power to both controllers, effectively turning off all the fans and the blue LEDs on the controllers (a Nexus and Aspire Fanmaster... or something).

In theory, could cutting the power like this fry anything?

[Son1990]

I dont see why it would fry anything.

[MonroeM]

It just made me wonder 'cause I'm sure cutting the power to most other peripherals would fry them sooner or later.

I plan on using a molex splitter to connect to the toggle switch then connect both controllers to the splitter. I'm just not sure which lines to connect from the splitter to the switch.

BTW, thanks for the reply Son1990.

[Captain Slug]

You cannot toggle such a high-current load device. Fan controllers source too much current for you to simply turn them on while your machine is running. Doing so would result in a sudden voltage drop on the 12v rail causing your power supply to reset your computer. You would need a capacitor to act as a current buffer in order to do this safely.

If your fans are loud, use different ones or change your setup.

[MonroeM]

Thanks for the reply Captain.

Well since that wont work, would it be possible to wire up a toggle switch to only one fan that connects to the controller and be able to toggle only that one fan on/off? I wouldn't mind individually wiring up a few more switches for the fans I'd like to be able to toggle.

[Captain Slug]

That should work. The safety of doing so will depend on the configuration of the fan controller (like what rating of capacitors it has) and the amperage draw of the fan.

Theoretically PWM fan controllers could be capable of reducing a fan to a halt, but none are designed to do so.

[MonroeM]

Good deal, thanks for the info Captain.

So if I can get the specs for the fan controllers and the fans, how would I judge the "safety" of this project?

[Captain Slug]

As a rule of thumb it's best to avoid switching on/off any devices that draw anything more than 0.5amps, but weaker Power supplies can't manage even that safely. At most you'll experience a hard reset if the fan draws too much current when switched on.
Most fan controllers with capacitors should presumably be able to tolerate and buffer the toggling of low to mid power consumption fans.

I had this problem when I wired a video LCD to a toggle switch. No damage was done, but it will force your power supply to reset. The only instance where damage is a potential would for example be if you tried to toggle a fan plugged into a motherboard header.

[Randyman...]

I use an old USB enclosure Power Supply for my 3 case fans. This was an old USB enclosure that I used the USB bridge board for another project, and the PS was the "Built in" type (NOT a wall wart). It is very compact, had ample amperage :) , and fit perfectly right by the PCI port area on the rear of the PC case (took some cutting). It has a small cooling fan of its own that exhausts out the rear of my PC's case (it is quiet), and the AC cord plugs in just like the PC's main P.S. I could hook it up to turn on/off with the main PS (using a relay), but I leave my PC on 24/7, so I just leave the fans' power supply on 24/7 as well...

This way, I NEVER have a chance of crashing my PC when I'm messing with the fans. I did leave one fan (the CPU fan) on the MoBo's fan header just in case the extra PS had issues (failsafe).

I doubt this one could power 10 fans (I think it is a 2.5 Amp PS), but you could easily find an inline "Brick" type power supply (like the X-Box's) that provides 5-7 amps at "All Electronics.com"

One man's solution :)

:cool:

[MonroeM]

Thanks for the info fellas, I think I know what I'm going to do now.

After thinking about it over the holiday, I've come to the conclusion that my fans' placements and arrangements aren't the greatest for taking in cool air and blowing out hot. I'm going to test some different arrangements and possibly remove some of the loud fans.

Almost all of my fans are 3-pin and I have dozens of 3-pin extension cables so I think I'll test the idea of wiring up toggle switches for individual fans. Then again it may be easier to sell one of my controllers and buy one that already supports fan toggling and speed handling. But what do I learn from that? :)


Just for some idea of my setup, I've attached a couple pictures below. The first picture is of my current arrangement (taken earlier this year) and the approximation of airflow. The second picture is the arrangement I am thinking about.

NOTE: On the left side panel, there is a 120mm fan blowing on the PCI/AGP-card area. On the right side panel, there is another 120mm fan blowing onto the back of the CPU socket on the mobo. With my current setup, I idle at around 51c w/ case temp of 31c. =