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Where can I get a dimmer for my case fans?

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Mac42

Member
Joined
Dec 18, 2000
Ok, the people at Radio Shack are idiots...

"I need a dimmer for a 12V fan."

-"OK... what is that exactly?"

"A D-I-M-M-E-R... like they use for lights but smaller."

-"I've never heard of one of those... I don't think we have anything like that."
-------------------------------------------

Anyway, I have my case fans connected directly to my power supply, but sometimes they're just a little too noisy... I just want to be able to turn them down a little, and installing the mod would be no problem... BUT NO ONE AROUND HERE HAS HEARD OF A DIMMER. I'm sure it's possible this isn't the right term for it. If any of you know a part number for Radio Shack or a better store to go to (haven't tried Lowe's or Home Depot yet... that's a decent drive from here) them please enlighten me. Thanks.


-=mac=-
 

SickBoy

Inactive Moderator
Joined
Jan 13, 2001
Location
Minneapolis, MN
I built one from a 47 Ohm rheo from radio shack. just put it in parallel with the fan. they get damn hot though, I mounted mine on a old socket 7 heatsink and it still gets real hot. Works for CPU fans too.

SickBoy
 

Phil

Senior Member
Joined
Jan 13, 2001
Location
Bolton, UK
I took a really old joystick apart that had paddles built into it, they were basically variable resistors and they work fine on my fans, try asking for variable resistors
 

Valafar

Registered
Joined
Mar 10, 2001
Location
Hemet CA
Rheostats, variable resistors, variable potentiometers. Basically the same thing. RS only has 3W ones, not good for case fans. www.jameco.com has a 5W 100 Ohm, it is good for case fans, I have it controlling a 7.98W 120mm and it is warm when the resistance is up. If it is too hot, then something might burn up, like the resistor.
 

Colin

Arctic Silver Senior
Joined
Dec 19, 2000
Better yet buy a LM317 voltage regulator at the Shack and build the circuit on the back of the package.
 

dem1an

Member
Joined
Mar 19, 2001
Location
Suwanee
can you still monitor the fan speed with the mobo when using a rheostat? nobody has used the digidoc V?
 

Hoot

Inactive Moderator
Joined
Feb 13, 2001
Location
Twin Cities
So far, I have not seen using a rheostat cause problems with the tachometer output being readable, but that is just my personal experience.

Hoot
 

dgk

Member
Joined
Feb 2, 2001
Location
Delray Beach FL
Colin (Mar 29, 2001 07:54 p.m.):
Better yet buy a LM317 voltage regulator at the Shack and build the circuit on the back of the package.
I asked Hoot about this one. He says that the problem with using the LM317 is that the maximum it will let through (with 12V input) is 10.8 volts. It apparently eats the other 1.2. That doesn't allow the Delta to ever run at full speed.

I figure maybe at 12/7 switch wired into the red and yellow power wires should suffice. Sort of a summer/winter switch.
 

Colin

Arctic Silver Senior
Joined
Dec 19, 2000
dgk (Mar 30, 2001 08:38 a.m.):
[
I asked Hoot about this one. He says that the problem with using the LM317 is that the maximum it will let through (with 12V input) is 10.8 volts. It apparently eats the other 1.2. That doesn't allow the Delta to ever run at full speed.

I figure maybe at 12/7 switch wired into the red and yellow power wires should suffice. Sort of a summer/winter switch.

Try a SPDT switch with an LM317. This would give you OFF, LM317 and 12V. About switches, it's real handy to have a way to dial in your favorite speed and turn the fan on or off without changing that speed.
 
OP
Mac42

Mac42

Member
Joined
Dec 18, 2000
Would it be a bad idea to run multiple fans through any of these things, or would at least one of them handle it pretty well (4 fans max)?




-=mac=-
 

Hoot

Inactive Moderator
Joined
Feb 13, 2001
Location
Twin Cities
The delta fan on my MC-462A draws over .5A and the LM317 I built handled it no sweat with a small heatsink on it. Iwould wage that it can handle up to 12W of fans no problem. What you need is a control pot with a switch built in. Not the typical "closed when on", but one that is "closed when off". Then, when you turn off the LM317, the switch contacts could bypass it, giving you the full 12V.
 

SickBoy

Inactive Moderator
Joined
Jan 13, 2001
Location
Minneapolis, MN
Mac42 (Mar 30, 2001 11:38 a.m.):
Would it be a bad idea to run multiple fans through any of these things, or would at least one of them handle it pretty well (4 fans max)?

-=mac=-

First, find out the wattage ratings on all your fans and add them up. A rheostat with a wattage rating higher than all your fans' wattage ratings added up should work fine. Typically though, rheostats dont have wattage ratings that go that high, I anticipate you could get 2, maybe 3 fans on one rheo, depending on the fan.

SickBoy
 

SteenkyBastage

Member
Joined
Jul 9, 2001
Location
Land of OZ
i use those 3w radio shack rheostats on all my fans, and have found that they can run my 8w 120mm fans as well as a pair of 80mm fans together. when i turn the rheostat all the way down the fan does not shut off, it simply slows way down.

also i tend to put the rheostats right in front or behind the fan so that the air from the fan blows right over them keeping them cool. when i dont do that the rheo's tend to get pretty toasty.

hope this helps
 

SteenkyBastage

Member
Joined
Jul 9, 2001
Location
Land of OZ
just to clarify, i meant they can run a single 120mm fan, or they can run a pair of 80mm fans together... didn't mean to make it sound like i can do all 3 on one rheo (altho i haven't ever tried).