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Simple fan control

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joshua_33

New Member
Hello

I've come from a background where I constantly played with the electronics in my toys, scalextrics and any little motors I could get my hands on.

After many years of dormant activity, I've decided I'm going to go back to it, albeit with more exploration and practicality.

I'm looking for a variable/adjustable power supply that can output perhaps 30v (nothing to a level that I could hurt myself with). I'm hoping to build a custom air duct for my window. I will probably use a cheap PC case fan in-conjunction with the variable power supply to give control over the power so that I can decrease the voltage if it's too loud.

I may look into larger fans but for now I'll go with the cheaper option, just in case it all goes down the pan and the idea turns out to be useless.

Any help would be appreciated.


Thank you.


p.s. I'm from the UK and the site CPC | CPC - Over 100, 000 products from one of the worlds leading distributors of electronic and related products. has a lot of useful products which may be useful if you find a product I should buy.
 

Hero999

Banned
I wouldn't recommend using a variable voltage supply just to control the speed of a fan. I'd recommend a PWM (Pulse Width Modulation) controller.

What's the maximum voltage rating of the fan you want to use? 30V sounds like the absolute maximum rating for a 24V fan.

Do you want this to be mains or battery powered?
 

BrownOut

Banned
Make sure of the control method. Some PC fans are controlled by the driving frequency, so neither vairable voltage nor PWM will work.
 

joshua_33

New Member
I'm quite new to this subject area despite playing with it as a kid so you'll have to bear with me as I research into the things you guys mention.

I want this to be as easy and as quick as possible so if there's an off-the-shelf PWM with integrated power supply (or can easily be connected to a 12v DC power supply) then that would be welcome.

Ideally, I won't have to do any soldering or very little if possible - that way I can just pop the connectors together (bit of a bodging) and bingo, I got my set-up ready to then build a tube to go from my window into my room.

Hero999
- The volts for a PC case fan comes at typically 12v, however I'd like to be able to go past it's standard voltage recommendation as I'm a bit crazy like that and enjoy pushing things past their limits. Either way, I might find myself being able to move more air quicker by increasing the amp/wattage by a little amount that's over the recommended level to a useful degree (and thus saving money on buying a more expensive fan).
- It will be mains powered.

BrownOut
- Perhaps I should use a different fan altogether. I don't care if I happen to buy a PC case fan and it doesn't work, they are only 99p


Thanks a lot for your replies, I'm really excited about this!
 

BrownOut

Banned
BrownOut
- Perhaps I should use a different fan altogether. I don't care if I happen to buy a PC case fan and it doesn't work, they are only 99p
I don't know anything about your fan. I"m only suggesting a little research on it's operation before putting in the effort of building something that will only result in frustration.

Good luck!
 

Hero999

Banned
A cheap fan should be easy to control with PWM.
 

joshua_33

New Member
Thanks for the link. Is there any reason why it's so expensive?

Oh and, would I be able to almost blow up a PC case fan (by going very fast) with this if I was so inclined?

I'm interested in buying a bigger and more powerful fan if my objective cannot be achieved and I'm wondering whether the component you linked would be capable of something like this.

Thanks again.
 

pcbheaven.com

New Member
Thanks for the link. Is there any reason why it's so expensive?

Oh and, would I be able to almost blow up a PC case fan (by going very fast) with this if I was so inclined?

I'm interested in buying a bigger and more powerful fan if my objective cannot be achieved and I'm wondering whether the component you linked would be capable of something like this.

Thanks again.
30$ is not expensive. It controls 30 Amps. There are also ready made from thermaltake or other companies for PC coolers, with fancy pots and LCDs, designed to fit in single or double 5.25 cases. They start from 35 and go higher,
 

Hero999

Banned
Thanks for the link. Is there any reason why it's so expensive?
Because it's designed for 30A, your fan probably only uses 300mA (1/100th of the current) so it's really overkill but will work. Most motor controllers will be designed for large motors, there isn't much demand for small motor controllers.

Oh and, would I be able to almost blow up a PC case fan (by going very fast) with this if I was so inclined?
Only if you do something stupid like connect a 12V fan to a 24V supply.

I'm interested in buying a bigger and more powerful fan if my objective cannot be achieved and I'm wondering whether the component you linked would be capable of something like this.
With a 24V supply the controller can power a 720W fan, nearly 1HP and with a 12V supply it can power a 360W fan. A 720W fan will probably blow your computer to pieces.:D
 

joshua_33

New Member
Because it's designed for 30A, your fan probably only uses 300mA (1/100th of the current) so it's really overkill but will work. Most motor controllers will be designed for large motors, there isn't much demand for small motor controllers.

Only if you do something stupid like connect a 12V fan to a 24V supply.

With a 24V supply the controller can power a 720W fan, nearly 1HP and with a 12V supply it can power a 360W fan. A 720W fan will probably blow your computer to pieces.:D
I'm interested in buying a fan or multiple fans depending on how much air I can push. This is so I can make my own custom air duct leading from my window into my room. I'll install a filter for flies/nats and take it from there.

I'm heavily considering buying this product now due the ability to rank up the volts if needed. Perhaps I could even power a whole house fan, or one of those smaller fans which I've forgot the name of that are used in kitchens.
 

audioguru

Well-Known Member
Most Helpful Member
Why blow around hot air with a fan?
Get an air conditioner instead.
 

audioguru

Well-Known Member
Most Helpful Member
It is often cold outside and hot inside the house.
What is heating your house?
Maybe your house has poor insulation and heats in the daytime by the sun.
Maybe you need awnings over the windows on the sunny side.
 

Hero999

Banned
Turn the heating off if it gets too hot in winter.

Where are you going to get 24V at 30A from? A 720W SMPs isn't going to be cheap.
 

BrownOut

Banned
I live in a thinly insulated house on Monte Sano mountain in northern Alabama. It was built back in the 1950's by the rocket engineering community that was so vital to the area at the time. Here, the temp routinely gets into the hight 90's in the Summer. The morning Sun heats my house from the exposed East, but in the afternoon, I can cool by drawing air from the shady side and moving it through the house with fans. It takes a little energy to run the fans, but waaaay less than the A/c would use. In the 8 years I've lived here, I've only run the A/C three or four days.
 

Hero999

Banned
I don't know about where you live but here in the UK you can get government grants to help you insulate your home if you can't afford it. If you can afford it you might be able to save enouhgh money on your annual heating/cooling bill to pay for the insulation in a few years.
 
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