high-power rheostats

[minameismud]

anybody know where to pick up some high-power rheostats? i'm talkin 12 watts or more. not a full bay device, just single rheostats, prolly around 100 ohms. i've looked at jameco, digikey, parts express...and many computer modding sites - svc, coolerguys, frozencpu, caseetc, azzo, etc. target usage is for an 80mm vantec tornato fan - .76 A @ 12 V.

 

[eternalspire]

Hate to tell you but when you are talking about disipating that much power you usually don't need that much resistance because the currrent is so high. You might want to re check your calculations. Best I can do is these:

http://www.allelectronics.com/cgi-bin/category.cgi?category=470015&item=RHE-15&type=store

I have one of those powering two 120mm 105 cfm fans and it works out pretty well. (suck 5w each I think). The two of them combine is about the same as your tornado and they work quite nicely.

P=IV =.76*12 = about 9 watts

voltage drop = (voltage input - desired voltage)/ current

= 12 - 5(trust me this is as low as you need)/.76 = 6 ohm

15 ohm is more than enough. You will end up stalling your fans.

 

[Vertigo Acid]

www.mouser.com has basically the largest selection in the world. If you can't find it there, it doesn't exist.

 

[blindviper]

http://www.radioshack.com/product.asp?catalog_name=CTLG&product_id=271-265

I used one of those for 1 80mm tornado, 4 ultra high output sunon 80mm's, and 1 x 120mm 130 cfm ystech
i did however put a 1 x 1 in heatsink on the back

 

[eternalspire]

woah I'm surprised whatever you mounted that ratshack one to didn't melt

 

[crap]

ive been using those 3 watt radioshack rheos for years and ive never had any problems. right now i have a 80mm tornado and a 92mm tornado hooked up to 2 of em and its working fine. the rheo doesnt completly shut down the fan but you will get full power out of it. you will however need some sort of cooling on the rheos or at least use some heavy duty knobs as the metal part on it gets too hot to touch

 

[eternalspire]

yea that means your over powering them.