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Question about Rheostat resistance rating.

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QSW

Member
Joined
Dec 20, 2000
I have searched high and low everywhere reading about building a rheostat baybus, altho I am not electroncally inclined, I figured I have nearly all the information I need to build a external rheostat baybus. Basically get one with a enough wattage to handle the rated wattage of the fan/s. But most posts and articles rarely mentions about ohm rating of the rheostat. How does a higher resistance affect the rheostat? I can easily find 5W 10ohm and 5W 100ohm rheostats at radio shack, are they the ones I shoud buy? They have the 25W rheostat too, but they are expensive!

Here's what I plan to hook it up to:

1st rheostat control 2 120mmPanaflo L1A (4.32W total)
2nd rheostat control panaflo 92H1A and 120mm L1A (4.86W)
3rd rheostat control a Delta 80mm fan (6.96W)
4th rheostat for 120mm Sanyo Denki fanb(6.24W)
 

Hoot

Inactive Moderator
Joined
Feb 13, 2001
Location
Twin Cities
I could work each problem out for you using Ohm's law, but essentially, use a 10 ohm rheostat for each combo. You can buy them with either a real short shaft with a screw slot in the end or a long shaft to allow an easily accessed knob to be mounted on the outside of the case for each one. I use a long shaft with a knob on the end. It's a great "sound gag" when someone is visiting, to reach over and turn up the speed /sound while saying "Let's just turn up the processing power a bit..." ;D

Hoot
 
OP
Q

QSW

Member
Joined
Dec 20, 2000
Thanks Hoot[img="http://"]
I will get the 10 ohm rheostats tomorrow. My buddy told me that the resistance will only affect the range of the knob but he couldn't figure out if the 10 or 100ohm is better for my project.