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February 13, 2012 / hrafnkell

DIY stirplate

I recently started acquiring everything I need to be able to slant and propagate yeast. I’ve never used liquid yeast before, so the first order of business was building a stirplate to be able to step up slants and make starters.

Stuff you need

  • A fan – Many people use 12v 120mm or 80mm computer fans
  • 1 or 2 strong magnets. I used one from an old hard drive, and some epoxy to attach it to the fan
  • 12v power supply (wall wart) Make sure it is at least 500mA, preferable 1A
  • Project box – make sure it’s large enough to hold the fan + components. You can get a cheap tupperware box from somewhere, or you can go fancy and buy an electrical box from eBay or radio shack.
  • For the speed controller:
    • Potentiometer, 1k resistor, 1uF electrolytic capacitor, 0.1 uF ceramic capacitor, protoboard, LM317 voltage regulator
  • You’ll also need some tools to assemble everything, f.e. soldering iron, drill, screws, glue and a few screws

Let’s start with the speed controller

I followed the instructions from here to arrange the components on the strip board. In retrospect I should probably have gone with a PWM speed controller in order to have greater flexibility with setting the speed. Maybe next time.

As for assembling everything in a project box, a picture is worth a thousand words:

<pic here>

Depending on what box you will pick your mileage may vary.

Next on my yeast propagation todo list

Before I’ll be able to make yeast slants I have a few more things I need:

  1. Buy a pressure cooker to sterilize everything, including yeast slants
  2. Buy some yeast to use. I’m thinking I want to do a wit beer, some kind of belgian trappist and more. There are no home brew stores in Iceland that sell liquid yeast, so I will have to order from abroad and cough up some cash for express shipping and cold packs
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