about DC motor control

[Boogity]

Agrajag,

Very interesting write-up - thank you.  I have been using a variac and have had no problems over approx, two years of use, but I really like the idea of varying the fan speed with the slider in Artisan.  I am using a Phidget to monitor BT, ET and MET.  I have never used an Arduino and am not familiar with them.  Can you use a Phidget and Arduino and the same time?

Any other information about the source of components, cost with links, and how to connect everything would be appreciated.  Thanks.

[Agrajag]

I'm not familiar with the phidget but as long as you have a spare USB port you should be able to use both. I'm actually waiting on some more parts for my arduino (thermocouple interface) so then will be doing everything through the arduino. I might document this when I'm done if it all works, as it's much cheaper than getting a phidget/tc4/whatever. Arduinos are super cheap and the thermocouple interfaces are about $2.

The only parts you need other than the fan are a power supply and the arduino. The power supply voltage needs to match the fan (I just used an old 24V DC power supply I had lying around from an old laptop or something). There are red/black wires from the fan, you just join them together to the power supply (you may want to wire in an on/off switch so you don't have to go to your power supply. Then you have the other 2 wires from the fan, one will be the control wire, the other will be the RPM sensor (so you can get a current RPM reading to the arduino as well.)

The arduino I used is a mega version, an uno would do but I wanted to make sure I have enough pins for other things I might want to do. E.g. http://www.dx.com/p/improved-funduino-mega-2560-r3-module-compatible-w-official-arduino-mega-2560-r3-blue-black-256335

Now to control the fan you need to send a PWM signal on the control wire. Arduino pins already do PWM, so as long as it's the right frequency (check the datasheet for the fan, the input it wants is normally a range, mine will take anything between 500Hz and 5kHz) then you're good to plug it straight in. Since pin 4 on my arduino (a mega2560) outputs a 980Hz PWM signal which is within the range, I just plugged the control wire straight into the arduino pin. The other important step is connecting the power supply/fan/arduino ground wires together, as they need to share a common ground so that the fan has a reference for 0V.

To set the fan speed in your arduino program all you need to do is analogWrite(PIN, VALUE), where in my case PIN is 4 and VALUE is between 0-254, where 254 is 100% and 0 is... 0%. I will post the source for both the arduino code and the program artisan calls when I've tidied it up a bit, but it is very simple.

Hope I haven't made that sound too complicated, it's not too hard. Happy to answer any other questions.

[brew]

This is very cool!  I thought I was clever making a box for all my controls!  It's nice to know that this is an option.  If I hadn't already set up ac fans and variac I would do this!

[Chert]

Replying to myself... after some more research I found this a 172mm 24V DC fan which was fairly cheap on ebay: PM240-24D-1751B-2TP. It can do 250CFM which is enough.

According to the pictures and datasheets it looks like it has 4 wires, one marked as CTRL which I would assume works similarly to 4 wire computer fans, so it's better than just plain DC voltage varying. The datasheets aren't very useful as far as how to actually control it though. I'm hoping to use an arduino and do pwm to that, will have to figure out what it needs. If anyone has any pointers on that part, let me know.

Interesting.  My arduino UNO connected to the TC4 controls the DC fan but I had to wire in a MOSFET for controlling the AC with the PWM.  I did not know that a fan that has the control circuit built in could be an option.

[day]

OH my goodness. I just ordered a variac and am going to have to turn it around and sell it. This is what i want man. However, I havent actually used Arduino yet, my brother is proficient and can help me. I am going to pm you for details. Love this concept here.

[CGwynne]

Bumping this old thread since I just found it, Great work Agrajag!

I have a Phidget 1065 DC motor controller I intended to use for this. The arduino route would have been far cheaper. But I never got around to this project and am now thinking about returning to it.

I tried looking for the fan you mentioned and it looks like it has plastic blades whereas the Huky included ones are metal and offer better thermal protection.

Have you had any problems with high exhaust temps affecting your fan?

[Chert]

Bumping this old thread since I just found it, Great work Agrajag!

I have a Phidget 1065 DC motor controller I intended to use for this. The arduino route would have been far cheaper. But I never got around to this project and am now thinking about returning to it.

I tried looking for the fan you mentioned and it looks like it has plastic blades whereas the Huky included ones are metal and offer better thermal protection.

Have you had any problems with high exhaust temps affecting your fan?

Sorry I missed that question.  The fan continues to work quite well.  Despite all the coffee stuff chaff that goes by it.