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Computer/Arduino speed control of 12V DC centrifugal fan for coffee roasting application  

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Rickpatbrown
(@rickpatbrown)
New Member
Joined: 4 months ago
Posts: 4
2020-04-06 1:44 am  

Hi there!

I am trying to control a DC fan using my computer. This is for a coffee roaster exhaust system, so the fan needs to be able to tolerate tempertures up to 110-140°C. I will use a computer program called Artisan Scope, which interfaces with an Arduino/TC shield to measure multiple temperatures and send PWM signal through Arduino.

1) The fan I am interested in is like this (2.8amp 12V) https://www.grainger.com/mobile/product/DAYTON-OEM-Blower-3FRG6?breadcrumbCatId=3621&fc=MWP2IDP2PCP

2) The shield that I am using is this https://www.tindie.com/products/greencardigan/tc4-arduino-shield-v602/

3) And Artisan Scope is an open source program here https://artisan-scope.org/

I've had some success in configuring Artisan to control a small capacity PWM fan from an old graphics card, but all the metal body, high CFM fans lack PWM or use proprietary controllers. Also, I'm am pretty new to delving into electronics and find the "language" overwhelming. You guys are definitely in another world, lol. 

I just watched Bill's video on using an H-bridge and PWM to control DC motors. It was awesome! Definitely, the clearest, most understandable presentation I've seen yet.

His use of the mosfet h-bridge looked promising. I don't need the directional control (in fact, I think it could damage the motor).

Does this motor and the cytron MD10C https://www.cytron.io/p-10amp-5v-30v-dc-motor-driver work together nicely? If not, what specifications should I look for in a motor?

Can I just omit the directional input?

Or is there a better board to use?

 

Thanks in advance for any input!


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Ruplicator
(@ruplicator)
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Joined: 4 months ago
Posts: 108
2020-04-06 5:58 pm  

I'm pretty new at this but you might take a look at using a simple Mosfet transistor circuit tied to one of the PWM outputssince you don't need directional control. If you don't feel comfortable designing your own here is a very inexpensive example that is available

https://www.dx.com/p/high-current-mosfet-switch-module-dc-fan-motor-led-strip-driver-steples-speed-for-arduino-avr-2044998.html#.XotXoIhKhEY

Here is its internal design:

http://pan.baidu.com/s/1o60VhYa

 

 


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Rickpatbrown
(@rickpatbrown)
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Joined: 4 months ago
Posts: 4
2020-04-06 11:19 pm  

@ruplicator

Ok. Last night I saw noticed that a transistor can do exactly what I need. I assume that the resistors and capacitors are just to adjust the current for the whole circuit to operate. I'd love to solder some stuff together and make my own, but it would probably look pretty hideous. A board would be cleaner.

I think that the MOSFET board you linked is along the line of what I need, but I will need a higher amperage board. It says 3 amp, but I think that is peak. The document says 1.5 amp. I'd rather have something in the 10 amp range to make sure it is safe.

 

What does "input logic voltage" refer to? I notice this on spec sheets. Is this the voltage that the logic gate responds to?

 

...oh boy. Off to learn about transistors!


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Ruplicator
(@ruplicator)
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Joined: 4 months ago
Posts: 108
2020-04-07 12:17 am  

@rickpatbrown

In reference to the "input logic voltage": Motor controllers can have separate power requirements. One to power the actual load (or motor in your case) and the power to run the internal circuits of the controller. 

I completely understand wanting to use a pre-made controller for its ease, speed to project completion  and reliability. However, one of the reasons your on this site is your interest in building things. Maybe you don't start with your final project until you get some experience with a smaller and simpler prototype. There are a lot of tutorials and plans available on the web that relate to what you are trying to do and could step you in the right direction. Good luck with whatever you decide.


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byron
(@byron)
Reputable Member
Joined: 1 year ago
Posts: 307
2020-04-07 12:45 am  
Posted by: @rickpatbrown

What does "input logic voltage" refer to

Logic level refers to the voltage of the logic signal and by that we me on or off or high or low.  So a 5 volt logic level is where off and on is represented my 0 volts (off) and 5 volts (on). This is the logic level of an Arduino.  The logic level of a Raspberry pi is 3.3 volts. So 0 volts for off and 3.3 volts for on.     The voltage that a motor controller board needs for its power input to send to its motors is an altogether different thing.  Motor controller board are usually controlled by logic level signals sent from the likes of an Arduino.   There's more to all this of course, but thats the simple view.


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Rickpatbrown
(@rickpatbrown)
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Joined: 4 months ago
Posts: 4
2020-04-07 9:17 pm  

Ok. Thanks to both of you. This gets me started. 

I bought a bunch of these MOSFET modules to play around with 

https://www.amazon.com/dp/B07WTN72HF/ref=cm_sw_r_apa_i_j9nJEbKX08ZVP

They dont seem to have a fly back diode installed, so I also bought this kit with some 10amp rectifier diodes.

https://www.amazon.com/dp/B07BPW7MTF/ref=cm_sw_r_apa_i_e4nJEb9EEZ87Q

I have a cheap, plastic blower fan coming so I can experiment and get a handle on things, before shelling out $75 for the proper metal fan. 

I'll keep updating on my adventure as things progress 😃


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Ruplicator
(@ruplicator)
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Posts: 108
2020-04-07 11:22 pm  

Great! sounds like a good start.


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