windows freezes when i switch my fans on my 4 switch fanbus...

[Detoyminador_]

i built and installed the same 5volt/12volt four switch fanbus like the one at virtual hideout, except it has no led's or an off setting, so it switches the fans from 5v/12v. all 4 fans (front intake, back exhaust & 2 cpu's fans) all work great switching from 5v/12v, it's lowered the noise of my pc a heap. my problem is sometimes when i switch a fan 5v/12v the light on my hard-drive comes on and windows then locks, don't tell me it's a heat problem because it's not.

 

[Detoyminador_]

it's not just in windows either, during boot-up i flicked the switches and it locked, so it'a system lock. i've got a 300watt power supply also, could it be a current draw problem that locks the system? thanx for the reply's :-(

 

[SubzeroPC]

If I understand correctly the problem happens when you increase from 5v to 12v. If that is the case, it seems like the fans are using too much power to spin up. Kind of an artifficial brownout in your system. You might want to try setting up the fanbus to spin the fans up in different groups or individually. Fans draw more power when they are spinning up than they do once they get to full speed. Just like a car needs more power to accelerate than it does to maintain speed. Good luck Detoyminador_.

BTW: how big are the fans and what kind of fans are they?

 

[Detoyminador_]

2x 80mm Sunon fans
2x 60mm Y.S. Tech fans

thanx

 

[Mday]

i am hoping you did not wire your CPU heatsink's fan to the switch.

 

[Detoyminador_]

why's that??? i run 1 cpu fan at 5volts and the other at 12volts while browsing and desktop work. it's currently 21c room temp, cpu temp is 31c and system temp is 22.

 

[Jhhnn]

Definitely seems like a power problem. This happens when switching from 12 to 7v or from 7v to 12v on any switch, right? Checked the diagram at virtual hideout, and I may have found an answer, switch overlap. For proper operation, one set of contacts should break before the other one makes, switches with center position "off" always achieve this, while the single throw switches you are using may not. If so, 5v and ground will be momentarily shorted-- a bad, bad thing.

You may be able to detect this with an analog voltmeter as a momentary dip in the 5v line, or it may be too fast for anything except a graphic type recording multimeter.

Try center off switches, DPDT, rather than your DPST units.

 

[fast_eddie]

Jhhnn;
Good point! There some switches that make contact, before breaking the previous contact; they are called 'make before break' type contacts. Definitely not the type to use! I don't think a center-off type switch is absolutely necessary though; a 'break before make' type of DPST switch should work fine. Most DPST (and DPDT too) switches are of the 'break before make' type; a person would have to be very unlucky (or have ordered the wrong type of switch to start out with) to get a 'make before break' type of switch as they are somewhat rare to accidently find!

Detoy.....;
Are you 'starting' the fans at 12v, then cutting them back to 5v? Most 12v fans will run at 5v OK, but they need more like 6 to 7 volts to start up. Virtual Hideout has a new project for a 7v/off/12v FanBus. A bit of caution though, the switches Wolf used for his project are a non-standard variety of switch probably originally manufactured for a special OEM application; they are not standard DPDT switches! In a few days Wolf will have a wiring sketch for standard type DPDT switches that are available from RadioShack and other vendors.

 

[Jhhnn]

Hhmmm...I may be suffering from an accidental cranial-anal insertion, but let's try this again. At Virtual, I found only the 7v/off/12v article w/schematic, no reference to a 12v/5v design, so I figured that this was Detoyminador's reference. With that design, I was referring to the possibility that the two poles of the switch might not be perfectly co-ordinated, that the 5v side might not break before the ground side made. A center-off switch would eliminate the possibility. Virtual currently has a seemingly better design on their front page, attributed to Ed Heinrich. It could be even simpler if 5v led's were used, no resistor. A little clarification from Detoyminador could help me out.