Pwm Fan Controller Help

Dear all,

I have a very very basic knowledge of electronics and would like to try learn more, i want to start my own project.

What I'd like is two temp sensors and when they hit 25 degrees to trigger 4 fans which are Pwm controlled. As the temp increases the fan speed increases.

Board needs to run on 12v Need two sensors to monitor temperature 4x Pwm Fan outputs, min of 1amp each Get some nice little boards made up

Anyone willing to offer advice on where and how to start this project?

Anyone willing to offer advice on where and how to start this project?

The project sounds, from a programming point of view, almost trivial. The requirements are incomplete.

As the temp increases the fan speed increases.

By how much? If the temperature is 25, should the fan PWM value be zero? Does a 1 degree temperature rise cause the PWM value to increase by 1? By 10? By 100?

What part of the project do you need help with?

I'm sure it is trivial if you know what your doing and probably someone could knock something up in a few hours.

I'm thinking 25 degrees 25% fan power, 27 Degree 50% fan power, 29 degrees 75% power and 31% full power Fans stay on till temp goes back down to 25 degrees.

I need help with every single thing i pretty much know nothing

http://embeddedsystem1.blogspot.in/search/label/lm35

Many thanks I'll take a look at that

Not exactly what I want but a good start for learning

was hoping to use an ATiny chip (something nice and small) to control everything and this type of sensor

http://www.ebay.co.uk/itm/5pcs-DS18B20-Digital-Temperature-Sensor-Chip-Dallas-TO92-Thermometer-Thermal-/281210872708?hash=item4179796384#ht_2380wt_1275

was hoping to use an ATiny chip (something nice and small)

Why? Your fan motors are going to be relatively large.

Anyway, get it working with a real Arduino first. Then, you can think about a smaller chip. Or more features.

There is a library for reading that sensor - a really good starting point, since it comes with examples.

120mw fans
?? Cos I want the final board to be nice and small

Ok will do cheers

You should probably start by buying a PWM controllable fan, an Arduino, and a temperature sensor and work on having the temperature sensor control the fan. If you run into any problems, you can ask, but we are mostly unwilling to do the project for you, especially if you aren't going to put any effort into it. We will help when you get stuck.

I am willing to put the effort in and thanks to the forum I now know where to start.

I'm not a lazy person just a little clueless on how to start such a project

Well start by what I said, get an appropriate PWM fan, an arduino and a temperature sensor. And it sounds like you have the temperature sensor picked out.

Have you chosen out fans? If not check http://www.digikey.com or any of the other electronics distributors. Figure out what kind of size you need, and how much airflow. Make sure it has a PWM input, that way you don't have to include complicated extra hardware. As for air flow, what are you trying to cool?

I will do thanks.

I have some ATiny chips and usb flasher already, is it a bit to advance to start off using them?

Going to start with some 60mm Pwm fans, cooling an ally heat sink. I know what fans I'm looking for so it's fine

While we can give you pointers, I'm not sure any of us will want to bother helping you program ATTinys, since they are not really Arduinos and have significant changes to be made to support the arduino format. I would go ask for help on AVRfreaks instead. These are the arduino forums after all. It would be far simpler for you to use an arduino at the beginning and then see about translating it to the smaller device. Or built it for the smaller device to begin with, but ask around on AVR Freaks. Most of us are going to tell you to use libraries you won't have access to on the ATTIny.

sorry that my lack of knowledge showing, i thought they were all the same thing.

once gain thanks for the advice