My Stirplate... Cheap and Easy Build...

I went to radio shack last night and, at least here in Tucson, they have discontinued the 3 watt 25 ohm potentiometer/rheostat. It is still available on-line though. I was told, by some huge slovenly man-boy, that they would not be carrying rhem "in-store" any longer. He looked real lazy, so I don't know how credible his info was. I purchased on line from RS because any order over $10 is shipped free, the tax was less than I would have paid here in-town (because they tack on 2% in the city) and of course, they carry everything except the rheostat! F@ckers!

im going to try another RS by me tomorrow, otherwise ill just order through them online. thanks!

I changed out the 12v power supply with a 9v from an old cordless house phone works much better. I have some Hoegarden yeast that I am trying to cultivate on it now.

I will be rocking this out tomorrow! Thanks.

glad to hear everyone is enjoying this thread...

I got a 120x120x25mm fan (4.75in x 4.75in) from a friend today. This should fit in the 7x5x3" enclosure I got from RS (its at home right now and I'm at work), however I will likely have to mount the controls on the side due to space limitations. Is anyone else using this size fan with success?

Here it is:

What drill bit size is necessary for the switch holes?

I have mix and match drill bits at home, but I gotta stop by ace to get my few remaining parts and wanna pick up the correct size drill bit so I can get this completed tonight.

wwwdotcomdotnet said:

I got a 120x120x25mm fan (4.75in x 4.75in) from a friend today. This should fit in the 7x5x3" enclosure I got from RS (its at home right now and I'm at work), however I will likely have to mount the controls on the side due to space limitations. Is anyone else using this size fan with success?

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Yes. Mine even had a metal housing on the fan face so I didnt even need to epoxy a washer on the thing. Works like a champ!

chumprock said:

Yes. Mine even had a metal housing on the fan face so I didnt even need to epoxy a washer on the thing. Works like a champ!

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Nice, thanks!

wooo, got mine working. I ordered from k&j and got cylindrical magnets for the stirbar. works like a charm!

Mocked mine up last night, gonna borrow a soldering iron froma buddy tomorrow to solder all of my connections, it is cramped in there with the male/female connectors I bought. But got it working, I am waiting for my stirpar to arrive and then all I wil have to do is Epoxy my magnets down.

Getting that washer dead centered is a task with in itself.

I don't remember reading it anywhere here, but my switch dims as I turn the pot up and down is this normal, I would assume so, but I'm not sure.

I don't remember reading it anywhere here, but my switch dims as I turn the pot up and down is this normal, I would assume so, but I'm not sure.

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If your light is connected at the fan side, the brightness will change according to the fan voltage.

Cheers,
ClaudiusB

I have it wired up like Anthony's pics show, does everyones lighted switch dim with the potentiometer?

I was never able to get my washer properly centered. Its still a little off, but its not that big of a deal for me. I'd rather just use it as is then find/buy another fan.

If a little out of balance use a small piece of a stick-on alloy wheel weight is all that is required. A little time and a razor blade to trim the weight for a simple fix.
Connect the led off the power supply to read the full cube voltage all the time for constant led brightness no matter the fan speed control setting.

Mine may be a tad out of balance as well, but I figured it's pretty easy to replace the fan if it burns out prematurely. We've got piles of them here at work.

Would a 50ohm rheostat give you a better rpm range with the fan?

A 50 ohm would give you a wider range.

As for the power switch dimming, mine does not changed. I'd verify your wiring. The power from the supply should be going into the switch and then out to the potentiometer. From the potentiometer, the power should be going into the fan.

I would like to build a stir plate and I feel this design is a very good one so I would like to follow it as close as possible. The only thing I'm having difficulty with is finding a PC fan. I don't have access to old PC fans but I can easily buy one off of newegg.com. Unfortunately there are about 1 billion of them on the sight and I am unsure which to buy. Does anyone have part numbers for fans that work well and have enough power, will run on a 12v supply and still fit in the enclosure listed in the materials for this build. As always thanks!

mnm129 said:

I would like to build a stir plate and I feel this design is a very good one so I would like to follow it as close as possible. The only thing I'm having difficulty with is finding a PC fan. I don't have access to old PC fans but I can easily buy one off of newegg.com. Unfortunately there are about 1 billion of them on the sight and I am unsure which to buy. Does anyone have part numbers for fans that work well and have enough power, will run on a 12v supply and still fit in the enclosure listed in the materials for this build. As always thanks!

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I got a used one at the local PC repair shop it was covered with dust but worked fine. Cost me 1 bottle of HB

I tried a 12v supply but went with a 9v from and old cordless phone. While it didnt throw the stir bar even at high it was sucking the vortex all the way down. it was even huge at low see my the video in post 232.

Anyone tried a starburst stir bar? Just bought one on ebay here I hear its gives a wider vortex. Figured what the hell.

johnnyc said:

Anyone tried a starburst stir bar? Just bought one on ebay here I hear its gives a wider vortex. Figured what the hell.

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Keep in mind that you have to get that thing down the throat of a flask (assuming you are using a flask) and it might be too wide to fit. Otherwise, the price is right and I would say go for it.

Looks like its 1.5" diameter which FYI would fit in my 2000ml flask no problem.

Thanks for the great thread. Mine is all together and running. But its a little too fast and throwing my 2" bar. I'm using a 4.3v power supply and the recommended rheostat but its cruising as soon as power is applied. My question is can I place an in line resistor and if so, what size should I use? Thanks again for the information.

I would bet that the speed is not the real issue as to why it's throwing your stir bar. I had issues when I firsted tested it out as well, went with longer magnets, and the stir bar now stays centered at any speed. You're going to want that speed, particularly when the yeast kicks in and it's tougher to maintain the vortex.

after reading a few more post I decided to try the 1" stir bar before changing voltage. My magnet is small, but powerful little sucker.

Yep, I can't hold a 2" bar on mine, but my 1.5 will run all day.

Thanks for the great tutorial Tony. I got it up and running with only a few problems.

One question, when the vortex gets down to the bottom the stir bar kicks a bunch of bubbles around, but this isn't sustained. Normally the vortex is smooth and just barely reaches to the stir bar. Is this how it is supposed to be? or do you want the flinging action? I'm not sure if my fan is running fast enough or the magnet is strong enough to get the sustained bubbling action. My power source is 9.6v.

Great plans!

Received my 1" stir bar yesterday. Works like a champ. Still have a vortex at the lowest setting in water.

beeraroundtown said:

Thanks for the great tutorial Tony. I got it up and running with only a few problems.

One question, when the vortex gets down to the bottom the stir bar kicks a bunch of bubbles around, but this isn't sustained. Normally the vortex is smooth and just barely reaches to the stir bar. Is this how it is supposed to be? or do you want the flinging action? I'm not sure if my fan is running fast enough or the magnet is strong enough to get the sustained bubbling action. My power source is 9.6v.

Great plans!

Click to expand...

A vortex - any vortex is good. Oxygen transfers thru the surface of the water and that's always changing with water movement...plus the movement should keep all (many?) your little friends in suspension...

Huge +'s on this - my total cost (including washers/nuts/bolts AND a $3 power receptacle so I didn't have to cut the power supply cord) was just under $27. Just received my 2000mL flask and 1" stir bar from Midwest and thought 'no way that'll work - I'll have to spring for a 2"'. Looked tiny.

Vortex reaches the bar with 2L of H2O and I can sustain it within an inch of the bar - 10v power supply. Love it!

Thanks for the plans/instructions/pics!

My bar won't spin fast enough to get a vortex to the bottom. I am using a 1" bar and a 1.5" bar. I have a 9v power supply and the computer fan/hard drive magnet setup. I do not know if the power of the magnet is pulling up on the fan hard when the flask and bar are on the stirrer and the friction is slowing the bar or what. It spins fast when the bar is in an empty flask so maybe I just have a weak fan?

I would like some opinions before I open it up and solder another fan in.

You don't need a vortex to the bottom, you're just trying to keep the yeast in suspension -
However, some folks here (myself included) have spaced the magnet off the fan some. The magnet definitely interferes with the motor, and depending on magnet and motor, your motor may overcome that or not.

Mine wouldn't spin slowly until I moved the magnet 3/4" off the hub. It was all or nothing. Now, I can slowly crank up the speed and get a nice small vortex, or work it slowly up the scale and get a pretty good sized one.

Thanks to everyone keeping this alive and posting about their successes or problems... Someone in my homebrew club pulled one out of his gear tool box, and said he found this thread here, and built it according to specs. He had no clue that it was me...

Hang Glider said:

You don't need a vortex to the bottom, you're just trying to keep the yeast in suspension -

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Doesn't the vortex help aerate the starter?

Hmm, will need to stop at Radioshack after work. I have most of these parts already. I bet i can get a stirbar at my LHBS next time I am there.

TommyBoy said:

My bar won't spin fast enough to get a vortex to the bottom.

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You need to drink 12+ beers to get your bar to spin.

TommyBoy said:

Doesn't the vortex help aerate the starter?

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It probably does, but it isn't necessary at all to have a vortex. A sufficient gas exchange will occur at the wort surface. Stirring the wort keeps the wort "turning over" so that fresh wort will be exposed to the surface continuously. Stirring also keeps the yeast in suspension where the food is more accessible. I'm pretty sure that a vortex won't do any harm, but it isn't the holy grail either.

I just used mine for the first time last week, made two starters, I am able to get a vortex about 1/2 way down my growler for a 1 liter starter with a 2" stirbar.

I am using a 6v cell phone charger, but a buddy of mine has a bunch of old cordless phone chargers one is 9v and another is 10.5v.

I was wondering if using one of these would give my fan a little more power to pull the vortex down a bit further?

Also, if wattage is listed on the charger does that make a difference?

I think the 10.5v charger states 14 watts, and the 9v might be like 2 watts, I'm not certain, my cell phone charger that I am using now is .5 watt.

Can higher wattages burn out my fan if the charger is 12v or under?

The wattage rating is probably for max output. IOW, the transformer is rated at 1.3 amps max draw at 10.5 volts. Don't confuse the power consumption rating that is usually listed on the transformer too. This will typically be a very low number like the 0.5 watts one that you mentioned.

So, I would ignore the wattage ratings and focus on the voltage only. So long as you do not exceed the 12 v fan rating you should be safe and not burn it out.

Forget the vortex. So long as you are stirring the wort it will work perfectly with or without a vortex. The bes thing you could do for an improvement would be to get a larger 2 liter flask. IMO, a 1,000 ml flask is pretty much a waste of time and effort. The one liter flasks just don't have enough wort to support a large yeast population growth. It's better than nothing, of course, but bigger would be better in this case.

I don't really have anything meaningful to add, but +1000 for the hard drive magnets. I tried a setup with just two little round magnets on the fan and while I could get it to work, it was very sensitive and would throw the bar regularly. So I took a hammer to my old desktop computer and salvaged one of the hard drive magnets and it worked like a charm.

Top speed and no throwing the bar at all and it can pull a vortex down all the way in 2L without a problem. After my build I was about ready to throw everything out the window but a better magnet basically solved all of my problems.