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Take 3-pin off old fan, solder multiple fans to it?

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SwishBish33

Registered
Joined
Jun 15, 2003
I'm a n00b to wiring and the like, but I want to know if I can cut a 3-pin connector off of an old case fan, leave a little bit of wire coming out of it, and then solder the bare leads of two fans to the now-bare wires of one 3-pin connector. I want to hook two H1As to one 3-pin connector, plug it into a rheobus, and then control the two fans together off one channel on the rheobus.

Something like this:

RHEOBUS+[3-pin]----[solder point]====== (bare leads of two fans)

Is this possible? Any dangers? THANKS
 
It's possible. How much wattage the rheobus can handle? It is dangerous if you run it out of spec.
 
It would work, but if it's connected to any pcb, it could very possibly burn out the traces. Additionally, it's not likely that the fans will recieve the full voltage, since you could get quite a bit of resistence.
 
Actually if he connects them in parallel the board will "see" less resistance which is why it will draw more current. But since he is connecting them to a rheo bus, as long as the wattage of the two fans added together is within the power capabilities of therheo bus, it should be safe.

LA
 
LA -

So it should be safe? Is what I want to do similar to buying a 3-pin splitter? Or does the splitter afford me some sort of safety/advantage? I'm simply trying to avoid spending the money to buy 3-pin splitters when I have burned-out case fans with 3-pin connectors that I could use. Any other expertise? Thanks.
 
It doesn't matter if use splitters or take connectors from old fans. Only thing that matters is the rheobus' maximum wattage. You should get that information from somewhere and then with amperages from fans, we can calculate if it blows or not.
 
John LA said:
Actually if he connects them in parallel the board will "see" less resistance
Well, the board will see less, but the fans will see more: You're pumping two fans worth of power through one wire. Neither of the fans will hit quite what they would if they were on their own wires. This may not be a bad thing, but I'm just saying that it's going to happen.
 
Caffinehog,
With respect for your knowledge I submit the following:
I would agree with the fans not running as fast together as they would seperately due to the following condition - Since the single wires are now being required to carry approximately 2 times the current required for one fan, the voltage drop in the wire will be higher which will cause a lower voltage to be available to the fans.
That and the increased connection resistance will cause the fans to run slightly slower.


LA
 
SwishBish33 said:
LA -

So it should be safe? Is what I want to do similar to buying a 3-pin splitter? Or does the splitter afford me some sort of safety/advantage? I'm simply trying to avoid spending the money to buy 3-pin splitters when I have burned-out case fans with 3-pin connectors that I could use. Any other expertise? Thanks.

It will be safe as breez said as long as the power rating of the rheo bus is higher than the two fan's wattages added together. The splitter does not provide any safety advantage.

LA
 
I don't believe in any noticeable voltage drop using two fans with same wires. There's just not that much resistance.
 
1) IMHO, if you're talking about regular case fans - you can safely connect 10 of them to one rheobus port. They ain't that powerful. Just don't stack Deltas :D

2) IMHO, in this case that wire resistance is negligible, so you're not going to see a significant performance decrease. However, it's easy to check:

1. Connect your fan to Mobo and measure its RPMs.
2. Connect two voltage wires of the fan to your splitter (either manufactured or hand-made) and leave tacho wire connected to Mobo. Measure RPMs again...
 
The rheobus I have handles 20W per channel. The max number of fans I'm going to hook to one channel of the rheobus is 2 80mm Panaflo H1As. Would it be better to build my own splitters? For instance, getting the 3-pin head and putting my own wires in? Is this difficult? Thanks to all.
 
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