I have a 5v usb fan and I want to reduce the speed. how would I do it? thanks?

I have a 5v usb fan and I want to reduce the speed. how would I do it?
The fan on my laptop cooler is too loud and I need to lower it.

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Re-design6 years ago
A smaller resistor. Try a few hundred ohms. You may only need 10 ohms.
rayjai (author)  Re-design6 years ago
I think I tried a 150ohms resistor gold, brown, green, brown? it's the only resistor I have on hand.
jeff-o rayjai6 years ago
You're reading it backwards, it should be brown (1) green (5) brown (x10) gold (5% tolerance). But yes, 150 ohms. If the fan stopped use a smaller resistor. If you have a second 150 ohm resistor, connect them in parallel to create an effective resistance of 75 ohms.
rayjai (author)  jeff-o6 years ago
Thank you it worked! I didn't know I could do that.
I put 4 in Parallel to get the fan working. How many ohms is that?
jeff-o rayjai6 years ago
About 37.5 ohms. In this case, since they are the same value, the calculation is simply 150/4.
Just for the record this only works when the resistors are the same value.
rayjai (author)  Re-design6 years ago
Thank you!
Re-design6 years ago
Put a resistor in series with the fan.
rayjai (author)  Re-design6 years ago
I tried that and the fans stopped working. what resistor should I get?
Feed lower voltage to it like say maybe 3.5 volts that might slow it down. pm me if this doesnt work