Help me design my next stir plate

[devils4ever]

I have a simple stir plate now that I built a few years ago. It works okay, not great. It uses a simple voltage regulator to control a computer fan. The problem is it is very touchy. If I set the speed too low, the fan will eventually stop. Too fast and it throws the bar. So, I think it's time for a new design.

At first I was thinking of using a 3-wire or 4-wire PC fan and an Arduino to control it. Then, I thought of using a stepper motor and an Arduino for control. The stepper motor is easy to control with an Arduino, but I'm not sure it's fast enough. Does anyone have experience in this? I'm thinking I need at least 10 rps or 600 rpm.

Now, I see these controllers out there that are pretty cheap: https://www.amazon.com/gp/product/B00QLYO7XU/ref=s9_dcacsd_dcoop_bw_c_x_3_w. I'm thinking this might be the way to go and it's probably cheaper than I could build one myself.

Thoughts? Comments?

 

[gromitdj]

That's probably about as cheap as it's going to get. I was going to recommend this PWM Build or the one I did, using the LM317 Voltage Regulator (Similar to This One). But you probably couldn't order the parts for either one of those for the price of that unit. And it comes with a fancy display!

 

[devils4ever]

Well, I just received my "uniquegoods 6V 12V 24V Digital Display LED DC Motor Speed Controller PWM Stepless Speed Control Switch HHO Driver - Black CCM5D" from Amazon and I am very pleased with the results. I've read that the stir plate is a little sensitive keeping the bar moving and not throwing it at 12V. I think I read the controller is set at around 13% or something. So, I decided to run this at 6V instead giving me more range. It works great! I have it set to 75% and the stir bar moves at just the rate I want.

Success!

I'm buying another to make a pair of them so I'll have two stir plates for when I do doubleheaders!

It's definitely not worth building an Arduino based version in my opinion. It would cost at least triple the amount.

 

[tracyk]

On your 6V power supply, how many mA do you have?

 

[devils4ever]

My fan is rated at 12V, 0.68A. I bought this power supply https://www.amazon.com/gp/product/B01CFJH2U4/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1 since it has multiple output voltages and is rated at 30W. So, at 6V, it can put out 5A. Obviously, I didn't need that much, but I wasn't sure and I may wind up powering more than one of these stir plates from the same supply.

 

[Jeff_T]

This plate sounds exactly like something I'd like to build, do you have a pic @devils4ever?

 

[devils4ever]

This plate sounds exactly like something I'd like to build, do you have a pic @devils4ever?

I'm almost done. Pics to come along with more details.

 

[devils4ever]

Here's the finished project. Fans are 120mm 12V. I used 3/8" Baltic Birch plywood for the sides and 1/4" Plexiglass for the top. For the magnets, I used K&J Magnetics discs 1/2" x 1/8" thick, N42 and Superglued them to the fans. I used the Uniquegoods 6V 12v 24V PWM controllers.

 

[philjohnwilliams]

A bit of an old thread, but I just built a stirplate with this controller and it was so easy and it works great. I bought the controller on ebay for about $5, and the rest of the parts I had lying around.
https://www.ebay.com/itm/DC-6-30V-1...337371&hash=item283de85eee:g:CL4AAOSwAyBZn7b0

 

[Will_the-new-brewer]

I'm almost done. Pics to come along with more details.

Did the equipment you bought come with a wiring diagram, or did you know all of that yourself? I like your build and will eventually need a stirplate--just trying to get ahead of it and know what I am getting into before I take the plunge.

 

[devils4ever]

Did the equipment you bought come with a wiring diagram, or did you know all of that yourself? I like your build and will eventually need a stirplate--just trying to get ahead of it and know what I am getting into before I take the plunge.

No wiring diagram, but it's pretty simple and straightforward. Of course, I'm an electrical engineer which doesn't hurt.

 

[Will_the-new-brewer]

No wiring diagram, but it's pretty simple and straightforward. Of course, I'm an electrical engineer which doesn't hurt.

Yep, you make it sound so easy--why wouldn't I take a stab at it! LOL.

I do plan on doing exactly that...will start researching everything now and probably buy the parts in a couple months. Maybe I will find a good deal between now and then.