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Help with a Circuit that Generates Analog Fan Speed Control

J

Jason C. Lamb

Jan 1, 1970
0
First, I am a neophyte when it comes to electronics, I know pretty
much nothing, and am just eager to wire up some components based on a
schematic.

I am trying to find a schematic to build a variable speed fan based on
temperature and found an app note at
http://www.maxim-ic.com/appnotes.cfm/appnote_number/1125
that does a pretty good job of documenting the circut that I would
like to build. The problem is that the ICs that are used in their
circut (MAX4402, MAX6003,MAX6605) are only offered in an SC70
packaged, which I found out is very small when I received my samples.

I looked for a replacement IC that would do something similar to the
MAX6605, but was unsucessful.

I've read some other posts in this group about the design similar
circuts, and I want to ensure everyone that I understand that it is
easier to leave the fan ON all of the time, or unplug it when I want
it off. But this circut seems fairly stright forward to build, and I
would hope to lear a LITTLE bit about electronics by building it. Can
someone please give me some simple instructions on how to build a
similar circut to the one found at maxim-ic's web site?

Jason C. Lamb
 
L

Luhan Monat

Jan 1, 1970
0
Jason said:
First, I am a neophyte when it comes to electronics, I know pretty
much nothing, and am just eager to wire up some components based on a
schematic.

I am trying to find a schematic to build a variable speed fan based on
temperature and found an app note at
http://www.maxim-ic.com/appnotes.cfm/appnote_number/1125
that does a pretty good job of documenting the circut that I would
like to build. The problem is that the ICs that are used in their
circut (MAX4402, MAX6003,MAX6605) are only offered in an SC70
packaged, which I found out is very small when I received my samples.

I looked for a replacement IC that would do something similar to the
MAX6605, but was unsucessful.

I've read some other posts in this group about the design similar
circuts, and I want to ensure everyone that I understand that it is
easier to leave the fan ON all of the time, or unplug it when I want
it off. But this circut seems fairly stright forward to build, and I
would hope to lear a LITTLE bit about electronics by building it. Can
someone please give me some simple instructions on how to build a
similar circut to the one found at maxim-ic's web site?

Jason C. Lamb
Jason,

It may be far simpler to drive the FET with a 555 timer and put a
thermister in the 555 circuit to decrease the pulse width as the
temperature goes down. By selecting two fixed resistors in the circuit,
one in series with the thermister and one paralleling that, you could
set hi and low power endpoints.
 
D

DaveC

Jan 1, 1970
0
First, I am a neophyte when it comes to electronics, I know pretty
much nothing, and am just eager to wire up some components based on a
schematic.

These guys make a religion out of modifying their PC's:

http://bit-tech.net/article/

Scroll down to the Cooling heading. Several simple construction articles for
fan speed control.

Good luck,
 
D

DaveC

Jan 1, 1970
0
http://www.cpemma.co.uk/

This page describes the why's and wherefore's of cooling. Scroll to the links
at the bottom of the page to see construction ideas.

Good luck,
 
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