Need some Incubator advice - Controlling CPU fan speed.

I am working on a new homemade incubator. I've got everything going pretty good. But I would like to have the option of slowing down the computer fan I've rigged into it. Ive looked into dimmers(heard this is a No-No for fan speeds), rheostats(cant seem to find anyone that sells them in Toronto Ontario, CAN.) Im just wondering how everyone manages?

Any input is appreciated.

Why would you want to slow down the fan?

I currently have a 12V 300mA CPU fan running(mounted inside my cooler incubator). It is powered by a 120vAC 5vDC cellphone charger. Even under powered the fan is pretty noisey and blowing excess air than needed. That is why I would like to slow down the speed.


I have found a 3watt rheostat at The Source.

http://www.thesource.ca/estore/produ...roduct=2710265

Im not sure if thats exactly what I need. I am googling as much as I can, but there is so much info out there and its all headed in different directions. If anyone can chime in feel free to do so :) .

Why not just buy a smaller fan from radio shack, they are rather inexpensive

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Originally Posted by llovelace

Why not just buy a smaller fan from radio shack, they are rather inexpensive

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Could you recommend one that is small enough, not very powerful(and/or has speed control), and can be mounted?

Couldn't find any that fit the bill.

Lots of people use cpu fans. Im just wondering how :rolleye2:

There has got to be a few people out there that didn't accept one speed for their fan as an option and took it to the next level!

check out the DIY section for incubator builds, there is tons of information there, about types and how to wire.

Ive searched through many stickies and regular threads. None go into detail about fan control. Most just say "slap wires together and presto fan works" more or less.

So, Ill make it my mission. To figure out how to jerry-rig a CPU fan with some control to it. Im sure there's more than a few people on here who can benefit from it. :gj:

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Originally Posted by llovelace

Why would you want to slow down the fan?

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Because the fan speed has everything to do with how stable the temperatures are shelf to shelf, that and our fan is a lot larger bathroom ceiling fan and had to be slowed down.
If the fan runs too fast it makes the bottom of the incubator hotter than the top :P

Micro-managing the fan lets me dial in all 3 shelves to the same temperature.
We fought shelf to shelf temperature differences until plugging the fan into a rheostat.

Our incubator is a 24 cubic ft. true cooler and for now we use 3 shelves that will hold six 7qt tubs. To get the same temperatures on all three shelves we just move the fan speed up and down until the temps are equal on all shelves.

Bathroom ceiling fan plugged right into a zoo-med rheostat facing backwards to blow against the back of the inc.
http://i968.photobucket.com/albums/a...s/PICT5483.jpg

Sorry, I do not know how to do the same with a computer fan :rolleye2:

I know, he said computer fan Jerry, but I can see why you had to dial back the fart fan

buy a fan with less cfm

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Originally Posted by snakesRkewl

Because the fan speed has everything to do with how stable the temperatures are shelf to shelf, that and our fan is a lot larger bathroom ceiling fan and had to be slowed down.
If the fan runs too fast it makes the bottom of the incubator hotter than the top :P

Micro-managing the fan lets me dial in all 3 shelves to the same temperature.
We fought shelf to shelf temperature differences until plugging the fan into a rheostat.

Our incubator is a 24 cubic ft. true cooler and for now we use 3 shelves that will hold six 7qt tubs. To get the same temperatures on all three shelves we just move the fan speed up and down until the temps are equal on all shelves.

Bathroom ceiling fan plugged right into a zoo-med rheostat facing backwards to blow against the back of the inc.
http://i968.photobucket.com/albums/a...s/PICT5483.jpg

Sorry, I do not know how to do the same with a computer fan :rolleye2:

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Thank you. This shed some light on my situation. It seems that rheostat I posted earlier is what I need. Lucky its the right wattage I need to, its the only type of raw rheostat I can find right now.

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Originally Posted by seang89

Ive looked into dimmers(heard this is a No-No for fan speeds), rheostats(cant seem to find anyone that sells them in Toronto Ontario, CAN.)

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I just noticed, you do know most cheap light dimmers are rheostats.....

I ended up wiring a CPU fan to an old answering machine transformer and then simply plugging that into my Herpstat. My thought process was that the fan speed would be regulated by how much demand there was to increase the temps throuigh the Herpstat. So far I've hatched 7 out of 8 clutches with no issues :)

And as far as buying CPU fans .... Just head down to a small computer repair shop and ask for a couple differant CFM CPU fans. They will likely give you several used fans for just a couple dollars if not for free. I picked up 5 differant fans locally for free. They were only ask 50 cents to $2.00 for them but after I explained to them that I wasn't sure what CFM I wanted they just gave them to me.

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Originally Posted by 88Snakes

And as far as buying CPU fans .... Just head down to a small computer repair shop and ask for a couple differant CFM CPU fans. They will likely give you several used fans for just a couple dollars if not for free. I picked up 5 differant fans locally for free. They were only ask 50 cents to $2.00 for them but after I explained to them that I wasn't sure what CFM I wanted they just gave them to me.

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Thanks for sharing that, good to know

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Originally Posted by OhhWatALoser

I just noticed, you do know most cheap light dimmers are rheostats.....

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Have you tried yourself using a cheap light dimmer to get it work with a fan? It doesn't work. Not the way I am inquiring about. The dimmers you buy for regular household use are rated for a certain amperage, It wont work on this small scale cpu fan.

What was the point of telling me this? Got any other info?

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Originally Posted by seang89

Have you tried yourself using a cheap light dimmer to get it work with a fan? It doesn't work. Not the way I am inquiring about. The dimmers you buy for regular household use are rated for a certain amperage, It wont work on this small scale cpu fan.

What was the point of telling me this? Got any other info?

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as a matter of fact I have used a light dimmer on cpu fan before, common 120mmx120mm, way back in 5th grade. :) part of a rube goldberg machine

amperage doesn't matter one bit, rheostat is just a variable resistor, they come in different ranges of resistance, I don't know the specs of the rheostat or fan your trying to use or what range a common dimmer is, but you broadly say rheostat, which light dimmer falls under that category. hence my confusion on why you said it wouldn't work. sorry for trying to help, ill be quiet now.

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Originally Posted by OhhWatALoser

as a matter of fact I have used a light dimmer on cpu fan before, common 120mmx120mm, way back in 5th grade. :) part of a rube goldberg machine

amperage doesn't matter one bit, rheostat is just a variable resistor, they come in different ranges of resistance, I don't know the specs of the rheostat or fan your trying to use or what range a common dimmer is, but you broadly say rheostat, which light dimmer falls under that category. hence my confusion on why you said it wouldn't work. sorry for trying to help, ill be quiet now.

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Maybe dimmers that had variable transistors worked with the fans back in the what? 90's? but today, they only use the variable transistor as a mechanism to make the overall dimmer work the way want it to ( to not waste energy/cause unwanted heat). So the variable transistor doesn't complete the dimmers main funtion, just aids it.

So when I said Dimmer, I meant what common people know as a light dimmer.

When I said rheostat, I meant Potentiometer/Variable Resistor/Rheostat. There is and isn't a difference, it depends if you play semantics or not.