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Need to undervolt some fans, plz help.

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tripwire

Member
Joined
Jul 3, 2002
Location
Dixon, California
Hey guys, I have a 2x120mm fan combo blowing on my heatercore. Problem #1, they are 115v fans, problem #2, they are BEYOND loud. Can anyone help me find the right rheostat so that the I could drop the voltage to say around 50v to one extreme, and 115v at the other. I assume someone around here can help me, you guys/girls are all geniuses. thanks for everyone's help in advance.
 

eliya

Registered
Joined
Oct 12, 2002
what's the wattage of the fans? (or how many current they draw?)

just putting in a resistor in series "blindly" could result in a burnt resistor. we need to know what these fans' resistance is. (i also assume that 30-40 ohms will drop the voltage only a few volts down).

i think the best thing would be to use a transfomer with 4:3 ratio or something like that.
be careful when working with ac voltages!!!

about permanent effect: you could also make a by-pass switch so u can use the fans through the transformer or directly
 
OP
tripwire

tripwire

Member
Joined
Jul 3, 2002
Location
Dixon, California
honestly, Im not sure of these fans amperages... they are not stated any where on the fans. could have my dad check the resistance of them at 115 later tonight, but, as of right now.. Im not really sure.
 

550M

Member
Joined
Feb 10, 2002
Location
Oglesby,IL
i use a dimmer switch for mine works really well, but you have to use a metal box for it or it might screw stuff up with emf. they're pretty cheap from places like menards