Fan Wiring Help

salty cheese

salty cheese

Active Member
I bought a fan and power adapter from Radio Shack, but I don't know how to tell which wire on the adapter is positve.
I don't want to fry the fan so if anyone has done this before HEEEELP:D
 
nas19320

nas19320

Active Member
I've hooked them up backwards many times and haven't had any problems. They just don't spin, I don't leave them for long like this though.
 
B

bluedolphi

Guest
Generally the positive lead will have a stripe or as mentioned may have some writing on it.
 
B

bluedolphi

Guest
I've never had a fan turn if NOT wired correctly. Mine have always insisted on positive to positive. DC fan will turn no matter how it is wired?? :rolleyes:
 
salty cheese

salty cheese

Active Member

Originally posted by eric41177
what fan size did you get?
I got the 120mm, 3k rpm, 85cfm model 273-238.
Originally posted by obtusewit
Fans don't care if they are DC, which most are. DC motors will turn both directions
I beg to differ, I tried reversing the wires and the fan wouldn’t spin.
 
viper_930

viper_930

Active Member
I beg to differ, I tried reversing the wires and the fan wouldn’t spin.
Hmmm, that's weird. I have been dealing with many DC motors in another hobby of mine and it doesn't matter which way the leads are connected.
 
salty cheese

salty cheese

Active Member
It's got to be the type of fan and what it is used for, in computer and electronic applications the fan only needs to blow in one direction, so the way you mount it depends on what you need. i.e. one fan pushing air in the front and one pulling air out the back.
 
scribben

scribben

Member
the fan shouldn't be polarity sensitive. set your multimeter to ohms and check the fan should be anywhere from 5 to 35 ohms id guess
 
B

bluedolphi

Guest
Fans like those used in computers WILL NOT TURN if you reverse the leads. Positive MUST go to positive, and neutral to neautral.
I have installed hundreds.
 
masterreef

masterreef

Member
Everyone is right . . . to a point. DC motors are reversible but some are manufactured with a diode or other circuit to protect against reversing the air flow (disasterous on a PC for example). Using a multimeter on a fan like this would show a few hurdred ohms in one direction and no connection the other. If your fan has a temp sensor or other additional circuitry it will be polarity sensitive as well . . .
 
scribben

scribben

Member
my bad master reef my brain works on three phase and and single phase high voltage i didnt even think about the dc conversion at the power supply hope i didnt make anyones day more confusing
 
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