Case fan volt mod, 5v or 7v

[kaiweiler]

Hello, I havn't visited the boards since late in '05, been quite busy.
Anyway, I want to know if anybody can help me mod a DC San Ace 120mm 12v fan to run on 7v or 5v.
I have in my posession 4 of these fans with great blowing potential. Only problem is that they sound like a jet engine.

The fan

DC San Ace Brushless made by Sanyo Denki

120mm x 38mm
Blows 102.5 CFM at 2600 RPM
Loud at 39 DB

It runs on the 3 pin. I have searched and found lots of tutorials on molex connected, but not for the 3 pin.

Somebody has to know how to do this.

Thanks.

[Virtualbody1234]

On your fan there are 3 wires. Leave the yellow where it is (speed indicator).

Connect the black and red as per these instructions below.

http://www.cpemma.co.uk/7volt.html

[kaiweiler]

This is again for the fans with a molex connector.
Is cut and splice the only option for the 3 pin connectors?

[Virtualbody1234]

All you really have to do is cut the black wire and connect it to a +5Volt source.
The molex connector is just an easy access to +5V.

[clocker]

Since you can't plug that fan into a motherboard header anyway (too much current draw), you can either just switch it to a Molex or get a Molex>fan header adaptor.
Before you finalize the wiring though I'd just temporarily jury-rig it and make sure the fan will start from 7v- lots of fans won't.

Your easiest option in either case would be to plug it into a fan controller.
Sunbeam makes the best (and, oddly enough, one of the cheapest) I've ever used.

[kaiweiler]

Alright clocker, thanks for the advice. Good to see you are still around these forums. Same to you VB1234
I think a fan controller is going to be my best option. Then I can start them at full power and once they are spinning, then decrease voltage.

[kaiweiler]

Well I found a couple 3 pin -> 4 pin adapters so I tried the 7v mod. The fans start up with ease and are actually quite quiet while still moving a fair amount of air. I am very impressed.
The mod also took about 3 minutes to do and required no soldering or anything. Very easy, and free

[Virtualbody1234]

[kaiweiler]

I also used a multimeter and the fans are indeed running at 7v. Unfortunately it is not digital so I do not have exact readings, but it's in the ballpark

[Seedler]

Can't you like, plug it into your AC current?