How-To: PC Fan Stir Plate

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By Matt Richardson
Posted 2012/01/30 @ 12:30 pm
Category Electronics, Food & Beverage, Science

Liam made this cool DIY variable speed stir plate for creating yeast starter for his homebrewed beer. To control the speed of the magnetic stirrer, he used an ATmega328 with the Arduino bootloader connected to a PC case fan. Liam even made use of the LEDs that you can sometimes find on fancy fans to give his stir plate nice lighting effects. If you’d like to get started on your own, check out his site for an easy to follow wiring diagram and the code. [Thanks, Natalie!]

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6 Responses to How-To: PC Fan Stir Plate

tehsnarf on January 30th, 2012 at 12:42 pm said:

Not sure how I feel about the one I made now… Used:

25 ohm Potentiometer: http://www.radioshack.com/product/index.jsp?productId=2062299
Toggle switch: http://www.radioshack.com/product/index.jsp?productId=2062494
Project Enclosure: http://www.radioshack.com/product/index.jsp?productId=2062283
2.1mm DC Barrel: https://www.adafruit.com/products/373
80mm PC Fan: …
6 rare earth magnets: http://www.suntekstore.com/goods.php?id=15005471

Goes from half speed to full speed, no fancy lights. Will be putting it to work Wednesday for my first run.

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Roy on January 30th, 2012 at 1:29 pm said:

That’s neat, but a microprocessor seems like massive overkill to control the fan speed. It’s easy to do with just a simple three-pin LM317 analog voltage regulator, a potentiometer, and a few passive components
http://mynerdlyendeavours.com/2011/homebrew-stir-plate-for-growing-yeast/

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erasei on January 30th, 2012 at 1:34 pm said:

Cool project but there are a couple of things worth mentioning. The arduino isn’t really necessary. You can make the same thing with a pot and a few parts for much less cost. (see: http://stirstarters.com/instructions.html) [no affiliation].

Also, you should ditch the airlock and cover loosely with foil. The purpose of the stir plate is to both allow CO2 out, but to get oxygen in. The airlock prevents anything from getting in, including oxygen. On your fermenters, you definitely want to airlock to prevent oxygenation at that stage, but for your starter, you want oxygen getting in.

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- Whit on February 1st, 2012 at 4:31 pm said:
  
  Letting oxygen in allows for possible contamination. Yeast needs very little oxygen for homebrew batch sizes. Boil water and sugar to sterilize it, then shake it vigorously to aerate. Throw a fermentation lock on it and wait for it to cool to add yeast. Definitely want to keep the lock on it though.
  
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vladsinger on January 30th, 2012 at 9:44 pm said:

Used a similar apparatus to spin coat PVA onto glass slides in a materials science lab class at Cornell.

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Sparky on February 1st, 2012 at 11:20 am said:

Made one with a 12V rated fan but gave it 5V direct from a wall-wart so it did not go too fast. Our kids think having a ‘water tornado’ on the counter is crazy cool.

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