Universal fan low speed resistor

Sun Apr 19, 2015 6:02 pm

What resistor do people use for low speed on universal 80w fans?

Thanks

Mon Apr 20, 2015 7:07 am

Aux. fan wiring diagram says 50 Ohms. So I guess you need a 50 Ohm, 25 Amp resister?

Mon Apr 20, 2015 7:26 am

Ah thanks. I did look for info before asking but couldn't find it. Thank you

Mon Apr 20, 2015 10:12 am

That sounds an extremely high value to me!
If the fan input is 80W, it will draw around 7A at full speed, but the absolute maximum current it could draw through a 50 Ohm resistor is around 1/4 A. Sure it's not 5 ohms?
Resistors are rated in Watts, not Amps - no such thing as a 25A resistor. A 50 ohm resistor would only need to be rated at 3W, while a 5 ohm one will need to be around 25W.

Wed Apr 22, 2015 11:27 am

Brianmoooore wrote:That sounds an extremely high value to me!
If the fan input is 80W, it will draw around 7A at full speed, but the absolute maximum current it could draw through a 50 Ohm resistor is around 1/4 A. Sure it's not 5 ohms?
Resistors are rated in Watts, not Amps - no such thing as a 25A resistor. A 50 ohm resistor would only need to be rated at 3W, while a 5 ohm one will need to be around 25W.

Sorry I was talking tosh. Need to stop quoting shoit from memory and start checking stuff. Just checked up wiring diagram and it's 6 Ohms, not 50 Ohms. Makes far more sense. Thanks for correcting me Brian