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In December of 2005, I was listening to a broadcast of The Brewing Network, and I heard about someone making a homemade stirplate.
I have always wanted to find ways to make my yeast perform better, and although the starters I have been making have helped, they needed a little 'kick'. I was not swirling it nearly enough (by hand), especially on the days when I had to go to work.
So, I decided to build my own. Here's what I did... (Click on any of the thumbnails for hi-res pictures).
- Scrounged around for a 'box'. This was a gift last Christmas, that came with a bunch of chocolate-covered nuts and stuff. This box should allow me to install a second fan/magnet/potentiometer, for a dual-stirplate later.
- Scrounged around for a 12V supply. I think this was from some old cell phone we had or something. It's easy to cut off the connector, strip the wires, and hook it up. Remember, red is positive and black is negative... (hahaha, we needed a little humor, right?).
- Scrounged around for an old hard disk. This is a great source for the rare-earth magnet. For those of you that have never experienced the magnetic power of a rare-earth magnet, boy, will you be in for a treat! If I get a chance, I'll open up another hard disk, and give you a play-by-play of where it can be found, and how to get it out. The hard disk I had was equipped with 2 of the magnets.
(Sorry, no picture).
- Bought a 4-inch fan from Fry's Electronics. I think it cost me $10.99. I opted for the 4-inch, because it's bigger than most of the standard 3-inch ones in PCs, had a bigger hub for mounting the magnet, and was a little stronger.
- Bought a 500 Ohm potentiometer from Fry's Electronics. This was about $6.99 or something. The potentiometer is used to limit the electric current going to the fan (with resistance). I think if I add a resistor to the circuit, the potentiometer can be used for fine-tuning. Right now the difference between the correct spinning speed and off is only a small fraction of a turn (something like 1/20th).
- Closeup of magnet on fan. This view also shows a bunch of wires. I plan on using plastic-coated staples to secure the wires inside of the stirplate, but for now, electrical tape will do. I also plan on getting some o-rings to use with the screws for the fan, to help silence any vibrations. With the magnet centered, the vibration isn't bad, but every bit of cushioning helps.
The magnet pretty much holds itself on (as long as it's centered, and you don't turn the fan up too fast). I tried super-glue, but it didn't adhere to the magnet very well. I'm guessing that epoxy would work better. I have some JB Weld that I think I'm going to use.
I drilled a hole in the front of the box for the potentiometer, and then whittled out a little bit of the wood in front, so I could countersink the nut.
- Completed stirplate (well, close). I still need to pick up a knob for the front. I didn't need to install an on/off switch, as the potentiometer can put the fan at full-speed, all the way off, or anywhere inbetween.
- Yeast starter happily whirlpooling away. I didn't take a picture of the stirbar I bought from Beer, Beer and More Beer, but it was a little 1-inch one.
Free - Box
Free - 12V Supply
Free - Magnet
$10.99 - Fan
$6.99 - Potentiometer
$7.99 - Stir bar
Total - About $26.