Open source DIY TEC and Fan controller

[Ultrasonic2]

Right im gonna create a relatively simple TEC controller from off the self-parts, based around the Arduino UNO board. The idea is that pretty much anyone will beable to follow this thread and build the same controller, But of course change it to suite what you want.

The cool thing about the Arduino is that you can program it in C++ (I will make the code available once done) and therefore anything is possible. All you need to do is buy the correct plug in boards and tell it what to do.

The cost of this will be about $150NZD. I wont be selling these, you can just make your own. While im on the topic of selling things some of you guys will know I’ve shut down my TEC shop. It’s highly unlikely that I will ever return to that. However I do intend to make all my Solidworks drawings available to people to down load and they can choose to change it or simply take it to a milling machine shop and get them to mill one for you.

For me quite running and Consistent running temperatures ( the point of having TEC’s ) is essential. I like to pic a hotside water temp and auto adjust the fan speed to keep the hot side at X value.

Now I’ve had T-balancers for years however they haven’t ever worked very well in my opinion, As the fans would constantly hunt when given a target temp to achieve. Having the fans constantly changing speed was very very annoying so I will (already have) fix this while still maintaining responsiveness when a large load is applied and the temps start rising.

To achieve this I wrote a VB application to simulate an inconsistent load and a radiator and fans trying to cool it. This has enabled me to create a pretty good logarithm(imo). In essence when the temp starts increasing the fan Duty increases with it and when the temps start falling the Duty also falls However the rate the duty falls is 20 times slower which prevents the bouncing. I’ve written this for the T-balancer and it works perfectly.

TEC Temp Controller.jpg

I have also implemented a MIN and MAX duty which will prevent the fans from automatically slowing down below or speeding up above this value. This has been done because some fans are just to impractically load at full power and some are already very quite at 50% so there’s no point in going below that. Also most fans wont run below say 25% duty and that really throws everything out when the app assumes the fans are always spinning.

I have my min at 35 % and max at 94% so the fans are automatically adjusted between these 2 values.

Now I’ve already completed the above and tested it by reprogramming the T-blancer, though I did it in VB not C

TEC Temp Controller graph.jpg

I of course will repeat the whole process for the cold side.

At this stage I will probably have a humidity and ambient temp sensor, which will only be there for reference sake. In my opinion adjusting the cold side temp to just over dew point AUTOMATICALLY is pointless and therefore I wont be doing it. You guys can of course come along after and do that if you want. The reason im not doing this is I want consistent temps so I can have consistent over clocks. If the cold side was automatically adjusting all the time it would result in wildly different cold side temps based on changing humidity and ambient. I much prefer picking a cold side temp that is always over the dew point. This sometimes means it’s actually over the ambient temp. ie on a cold winters morning the plus side is that in cases like that the total system noise will be very very quite and only really working hard at the heights of summer.

Im obviously going to be connecting a screen to display all the relevant information , which should be hot side temp , hot side duty , ambient temp, cold side, temp duty and dew point.



UPDATE TIME
25/06/2012

Controller Arduino Nano v3
http://www.dealextreme.com/p/nano-v3...-118037?item=8
sku_118037_3.jpg


Screen DFRobot I2C / TWI 4x20 LCD Module
http://www.robotshop.com/dfrobot-i2c...cd-module.html
dfrobot-i2c-twi-lcd-module-1.jpg


Two of ZX-Thermometer Temperature Sensor thse for monitoring the Hot and cold side water temps
http://www.robotshop.com/productinfo...-43&lang=en-US
inex-zx-temperature-thermistor-sensor.jpg

One of these DFRobot DHT11 Temperature and Humidity Sensor
http://www.robotshop.com/productinfo...-64&lang=en-US
dfrobot-dht11-temperature-and-humidity-sensor.jpg


Some jumpers
http://www.robotshop.com/productinfo...100&lang=en-US
sfe-170mm-ff-premium-jumper-wires.jpg

Thats all thats required to get the controller working


Powering the Arduino AND Fan Mosfet with Lowpass filter (You HAVE to have a lowpass filter for the fans)



Four 16v 1000uf Caps

1 of these resisters PWR263S-35-R270F for the lowpass
http://newzealand.rs-online.com/web/p/products/7332694/
R7334704-01.jpg

1 of these MOSFET's BUK9608-55 (The mosfet i will be using will be abit different to this one)
http://newzealand.rs-online.com/web/p/mosfet/6531746/
D2PAK-03.jpg


Powering the TEC's Type 1
TEC Mosfet with Lowpass filter the result is an analogy output (a change in voltage)

The diagram is the same as the fan controller i have used 50v caps cos i was building this for 50v but if you want to control a lower voltage you can use lower voltage caps which will make them smaller

Four 50v 2200uf Caps (yes they are big)

3 of these resisters PWR263S-35-R270F for the lowpass
http://newzealand.rs-online.com/web/p/products/7332694/
R7334704-01.jpg

one of these HEX MOSFET's IRLS3036-7PPBF (DO NOT JUST USE ANY OLD MOSFET)
http://newzealand.rs-online.com/web/p/products/6887254/
L0464362-01.jpg

Powering the TEC's Type 2
TEC Mosfet the result is a digital output (a change in Current)



one of these HEX MOSFET's IRLS3036-7PPBF (DO NOT JUST USE ANY OLD MOSFET)
http://newzealand.rs-online.com/web/p/products/6887254/
L0464362-01.jpg

Now like everything I’ve ever done it will change widely so we’ll see how it all turns out