Fan Voltage Question

[Armageddon415]

If I have 5 fans strung together using spliters, and I wire a 12V/7V switch to the lead fan (the one getting power from the power supply). Will the switch be able to control all the fans that follow the first one?

 

[OulOat]

If my knowledge of circuits is right, then this is just a simple case of fans hooked up together in series. Whatever that affects one fan will affect the fans after it. So the answer is yes, I believe so.

 

[Armageddon415]

Thats what I thought too, but I wanted to get a second opinion.

 

[Drewpy]

actually the fans will be hooked together in parallel. And if the switch is between the fans and the power supply you should be fine. The only thing to look out for is that you don't exceed the power rating of the switch. Doing this can cause some nasty consequences

 

[Armageddon415]

Would 5 fans exceed the power rating of a switch rated at 6A at 125VAC, 3A at 250VAC?

 

[Drewpy]

Highly unlikely, an 80mm Panaflow L1A is rated at 0.068A, so 5 would only a third of an amp of current. This would be far below the rating of your switch.

Unless you are using freakishly huge fans, your switch will handle your fans no problem

 

[OulOat]

I wondering, how would it be in parallel? Between each fan should be a node, disconnect the first fan and the none of the other fans get any power, which is unlike parallel since parallel stuff is all connected to the same node.

 

[Drewpy]

its the same as splitters for your power supply. They work in parallel too.

If the fans were connected in series the first connection would be the positive lead of fan1 to the positive lead of the power supply. The grounding lead of fan1 would connect to the positive lead of fan2, grounding lead of fan2 to positive of fan3... and so on. Then the grounding lead of fan5 would connect to the ground on the power supply.

Note that by power supply I mean either a molex connector directly from your power supply or a motherboard fan header.

Thus if these are all 12V fans eash one would only recieve 1/5 of the power they would get if connected normally or in parallel. (if they are identical fans). And this would not likely be enough power to get the fans to start turning (equivalent of runing each fan at 2.4V).


And as an afterthought, I do hope that you are connecting from a line directly from the power supply. Your five fans could be too much current to draw from a motherboard fan header and fry some circuitry.

 

[L00PY]

Originally posted by: OulOat
I wondering, how would it be in parallel? Between each fan should be a node, disconnect the first fan and the none of the other fans get any power, which is unlike parallel since parallel stuff is all connected to the same node.

That's because you're disconnecting more than just the fan when you unplug the molex; you also break the parallel circuit. If you were to cut only the two (or three) wires leading directly to and from the fan, the rest of the fans would still be powered. If you have Panaflo fans, you can do this just by disconnecting the white connector near the fan hub.