PWM Fan Controler

Rather than joining a new forum for this question, I thought I'd post here.

I'm looking to make a very simple PWM fan controller for my computer. I've been searching all day, and it seems like everything is either too complex, parts are discontinued, or it's user controlled rather than temperature controlled. Finally, I've found a design that looks fairly simple and easy to make, but I've run into a problem, I don't know where to find the MOSFET (I think ?).

The designers page is here: http://microblog.routed.net/2007/06...re-based-fan-controller-without-a-thermistor/ with a link to his schematic here: http://microblog.routed.net/wp-content/uploads/2007/06/temp-fan.pdf

What I'm looking for is just a simple PWM, temperature dependent fan controller. I don't need anything complicated like RPM meters or anything, so I'd like to be able to use the simple 2 wire case fans.

This so far looks the best to me because of it's simple design, and I was able to find quite a few of the parts at Parts Express.

Does anybody have help for me on this design or have suggestions for a different design?

PS - noob to electronic design and soldering - KISS would be appreciated.
 
This design (http://www.bit-tech.net/modding/2001/12/03/pwm_fan_controller/1) also looks very enticing, mainly because, in addition to variable speed controlled by temperature this controller will also turn the fans off entirely when not needed. However this design uses the discontinued (as far as I have found) MIC502 chip. Is there a replacement for this design?


Either of the two designs I've posted would be fine with me.
 
Why can't you use a small microcontroller with A/D like PIC12F675 with a NTC for temperature sensing and a couple of transistors and a LC filter to get smoothed power PWM from one output pin? You could control three fans with three temperature sensors with this micro. It would be mostly a software job.
 
Eva said:
Why can't you use a small microcontroller with A/D like PIC12F675 with a NTC for temperature sensing and a couple of transistors and a LC filter to get smoothed power PWM from one output pin? You could control three fans with three temperature sensors with this micro. It would be mostly a software job.

Unfortunatly, I know nothing about software programming, IC or PC. If it is something I could learn in a short period of time and without much investment in tools, it sounds like a good possibility.

soongsc said:
I wonder if 555 based RC motor controllers might work or not?

If one looks at the design for the controller in my first post, there is a 555 timer in the design, but what I don't know how to find is the part labeled "TLV3272"

theAnonymous1 said:
How about the MAX6643?

http://www.maxim-ic.com/quick_view2.cfm/qv_pk/4317

It doesn't require too many external components.

I'll have to try to work my way through the datasheet. I doubt I'll understand what most of it says, but if it's similar to either of the designs I linked to, and the parts are readily available, it could be another good possibility.
 
Eva said:
PIC12 family is very easy and programming is less messy tan dealing with breadboards and analog electronics.

Well, I found a datasheet for the PIC10, PIC12, & PIC16 Family chips, and from the looks of it, they only mention the PIC16 family for fan (and motor), PWM control. Despite the fact that they only mention the PIC16 for fan control, I get the feeling it has many more features than I need and that PIC10 or PIC12 will be a better choice since I have a very simple (at least in number of operations) device to create. Am I overlooking something?
 
Some PIC16 devices and more complex ones have PWM in hardware that produces periodic timed pulses automatically while the CPU is free to do other tasks.

You can also do PWM with simpler PIC10 and PIC12 devices but the pulses have to be produced and timed in software (that is by your program). This is not so hard considering that instruction execution takes 1us (2us for jumps) on most PIC12 with internal oscillator, and that the only other thing that the micro has to do is to sense temperatures and calculate pulse widths accordingly.
 
did you find this one in that link?
http://www.cpemma.co.uk/pwm_erg.html

I like this one (Bells and Whistles version at the bottom) based on a dual comparator:
http://www.cpemma.co.uk/thermal.html

But as with all these stop/start controllers, one must run them from a dedicated PSU to help avoid interference getting into the audio and even then some may leak through.
 
If nordic is thinking of the same ones I am then you may be overlooking some obvious choices.
There are a dozen sites/pages like the following if you ask google the right questions

http://www.sidewindercomputers.com/fancontrollers.html
http://www.acousticpc.com/fan_controllers.html

unless I've misunderstood your aim, this one looks like it would do what you need for twenty three bucks.
http://www.sidewindercomputers.com/seonecobllcd.html

Some of these are user controlled, some are temp controlled with leads and thermistors (like the linked one above). Unbelievably (in my humble opinion) there seem to be enough millions of people willing to hotrod their computers with liquid cooling and the like, and demanding this sort of thing, that the economies of scale have made it pretty tough to justify building your own controller. In other words, some of these are astonishingly inexpensive for what they do. Don't get me wrong. I don't see anything wrong with this. But if someone five years ago had offered me stock in a company catering this stuff I would have laughed. It's really suprising how big it's become.

There are many many "overclockers" forums on the web to get advice on this stuff too.