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/...-a-thermistor/ with a link to his schematic here: http://microblog.routed.net/wp-conte...6/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...n_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.

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

How about the MAX6643?

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

It doesn't require too many external components.

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.

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"

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.

Where would I be able to buy a MAX6644 unit (in small quantities) if I chose to go that route?

Request a couple of samples from Dallas Semiconductor. They will be free. You can do that from their web site.

I don't see any 555 device there.

I guess my inexperience is showing. When I looked up the LM317, I thought I saw something about it being a 555 timer based component, but, I see that I was incorrect. Sorry.