I have a 5v usb fan and I want to reduce the speed.

rayjai over 13 years ago

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

the fans on my laptop cooler is too loud.

thanks

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YT2095 over 13 years ago +1

you could also use a simple 1n4001 diode in series with the positive wire, to drop .7 of a volt for each diode you use, doing it this way still lets you draw exactly the same amount of current (about 500ma…

0 RaymondDay over 13 years ago

You could put a big size resitor on the 5 Volt side.
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0 Former Member over 13 years ago in reply to RaymondDay

Use PWM
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0 Catwell over 13 years ago

Rayjai,

Raymond day is correct. However, I would place a 100 ohm potentiometer in series with the fan and its power supply. This will drop the fan voltage between 1V and 5V.

Good luck.

Cabe
http://twitter.com/Cabe_e14
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0 Former Member over 13 years ago

Simplest thing to do might be to replace the 5V fan with a 12 volt fan that is the same size. The 12 volt fan will run slower from 5V. Just be sure it is not a brushless DC fan.
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0 Former Member over 13 years ago

Something like this:
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0 YT2095 over 13 years ago

you could also use a simple 1n4001 diode in series with the positive wire, to drop .7 of a volt for each diode you use, doing it this way still lets you draw exactly the same amount of current (about 500ma), and it Purely drops voltage and nothing else, whereas a resistor in line will have an effect on current also.
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0 Former Member over 13 years ago in reply to YT2095

Do you want to regulate only the fan speed or to regulate the speed of the fan based on the temperature of the surrounding ? Or you just need to reduce the speed without the possibility of regulation ?
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0 Former Member over 13 years ago

Can the bearings be taken apart and lubricated?
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0 Former Member over 13 years ago

the easiest way it to use a poteniometer wired in one of two ways.
you can wire each fan to a potentiometer and mount them to a a project box and there you go a fully customizable fan control system. One thing make sure you use a 100 ohm potentiometer.
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0 YT2095 over 13 years ago

IF you`re going to use a pot, then you should also use a transistor, a pot alone is a filthy dirty trick that will just about get you by until something goes wrong, and is certainly unsustainable in the long term.
put the pot Across the 5V rail and then use the center wiper pin to feed the base of an NPN transistor via a resistor, where the Collector is connected to the +5v rail, and the Emitter feeds your Fan input.
this will give you a Very crude voltage regulator and leave your current intact, it`s the Voltage you need to regulate here, and NOT the current!

I`m sorry but I can hardly believe I`m reading some of the above from "Engineers"?
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