Food & Beverage Science Technology
How-To: PC Fan Stir Plate


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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12 thoughts on “How-To: PC Fan Stir Plate

  1. 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.

  2. 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.

    1. 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.

  3. 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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Matt Richardson is a San Francisco-based creative technologist and Contributing Editor at MAKE. He’s the co-author of Getting Started with Raspberry Pi and the author of Getting Started with BeagleBone.

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