Box fan mod ?? Any electricians in the house?

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dr.kevin

2[H]4U
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Feb 17, 2006
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i wanna take one of these box fans
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and cut the noise with a voltage mod?

It runs on 110v. If I buy a 220>110 step down converter (not transformer) and plug it into my 110v outlet, will that cut the voltage down to 55v to make it spin slower?

And if that works, what about current? Do fans play well with jacked up current ?
 
What exactly are you trying to do? There's probably a better solution. Maybe a different/better fan?

Usually 220 and 110 use different connectors, and I'm pretty certain it doesn't work like that.
 
1. What are you trying to do with this fan? If you are at the point you need a box fan to keep your computer cool, you are doing it wrong.
2. Why modify one of those fans to run slower in the first place when you can simply buy a better, quieter fan?
3. Electrical questions regarding house hold appliances are better asked in this part of the forum.
 
Thank you Capt ... beat me to the link there :p


Not exactly a coolign question, this is a electrical one.... But as stated, find another fan, You can find larger fans with variable speed for sub 15 bucks, like 3 if you go to a garage sale typically, and it will do what you want without messing around with modifying a crap fan to begin with.
 
I have successfully slowed down a house fan with a regular dimmer before. The dimmer gets pretty hot though and is NOT designed for it, but it does work. A variac is a better choice.

Some AC motors rely on the 60hz frequency to operate though so your mileage may vary.
 
timta2 said:
What exactly are you trying to do? .
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make this big fan quieter.

I was hoping something similar could be done like my voltage mod for case fans. But I need something safe.

I know a dimmer should not be used for fans.

I'm not sure if a stepdown voltage converter runs the same way as a dimmer.
 
Since this seems to have nothing to do with computer cooling, im going to move this to where it might be a little more ... on topic
 
Running any AC motor outside of spec is a good way to burn your house down,
Also keep in mind that box fan motors range from total crap to somewhat crappy and you have even more issues.
 
Yeah, normal box fans with variable speeds do it by having three taps on the motor windings--not exactly a DIY job unless you have a lot of spare time on your hands.
 
if you really wanted to get fancy you could use a variable frequency drive
 
You could probably make your own using a PWM generator and a decent amp capacity transistor or a solid state relay. But yeah, that's getting pretty fancy either way. :D
 
Red Squirrel said:
You could probably make your own using a PWM generator and a decent amp capacity transistor or a solid state relay. But yeah, that's getting pretty fancy either way. :D
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Only if it's a DC fan, which this certainly is not :D
 
Those box fans don't put out enough air on the low setting as it is... why bother slowing it down even more?

Just get a better fan. Not worth the time wasted to modify it to run at an even lower speed.
 
Mohonri said:
Only if it's a DC fan, which this certainly is not :D
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Hmm can't you get PWM generators that do AC as well? But yeah I guess most solutions would only work with DC. Unless you can throw in some kind of DC offset to turn the DC wave into AC. No idea how/if that would work.

Is this fan going to be for a permanent cooling solution? I would look at using an inline fan instead, they're extremely quiet and probably move just as much air, if more. They're meant for being in a ducted situation though but nothing stops you from rigging it as a cooling fan and have some louvers that move back and forth or something.
 
For AC variable speed, it's not PWM, but varying the frequency that's needed. And it doesn't work so well with all types of AC motors. Read up on induction motors, there are many types.
 
There are variable frequency drives (VFDs) that use PWM, but they first rectify the input AC power to DC. They use PWM on the DC bus to control the voltage and frequency of the DC power that is fed to an inverter inside the drive, which then goes to the AC motor.

And yeah, not every AC motor likes being fed this way. There are inverter-rated or induction motors like Fenris_ULF stated for the job.
 
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