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

Justintoxicated said:

I linked the yeast above, it was in a smack pack. It's good to know that I might not see any fermentation when making a starter with a stir plate though, the yeast arrived almost hot though (cold pack was hotter than room temperature which was in the 80s) and felt heated to the touch.. So I still have my doubts.

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The small amount of foam in my photo is fermentation, it just dissipates before it can form a big krausen because of the stirring.

I've had a smack pack of yeast ordered online and delivered 7 days later already smacked and fat. It worked fine when I used it a few days later. I think yeast are pretty hearty, I bet yours are fine.

troyh said:

The small amount of foam in my photo is fermentation, it just dissipates before it can form a big krausen because of the stirring.

I've had a smack pack of yeast ordered online and delivered 7 days later already smacked and fat. It worked fine when I used it a few days later. I think yeast are pretty hearty, I bet yours are fine.

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So I dumped that yeast and started another starter with WLP085. Now that yeast was viable!

The starter overflowed and I have never sceen fermentation like what is going on in my fermentation chest now (have to go change the 1/2 gallon growler I'm using for a blowoff overflow because it's full!)

On the downside when the starter overflowed it seeped into the Stirplate and shorter it out. The LM317 was on the bottom of the box and is likely what shorted out. I waited till dry, but the stirplate is still broken. So whats the chances I just need to replace the LM317T? If its the potentiometer, I will need to solder up a new circuit, but the LM317T itself is replaceable.

EDIT:
So I determined it is the Potentiometer. I decides to play a bit and it shot flames out of it, but then it actually starter working again lol. Well I'm still going to replace it.
But how can I prevent this from happening again? Some sort of blowoff tube into another container?

Finally got my stirplate together. I ended up using a £0.99 PC fan speed controller in lieu of the rheostat listed in Anthony's opening post. Unfortunately Radioshack doesn't ship to Ireland and I've had very little success sourcing small parts here.

I powered the unit with a variable AC adapter set to 9 volts. 12 volts threw the stir bar too easily. I'm planning to make one or two more (gifts) and I'm sure they'll look a lot cleaner than this one but it does the job.

Cheers for the help

https://plus.google.com/u/0/photos/104618974056397434569/albums/5794718968070089393/5794718968230641250

Justintoxicated said:

So I determined it is the Potentiometer. I decides to play a bit and it shot flames out of it, but then it actually starter working again lol. Well I'm still going to replace it.
But how can I prevent this from happening again? Some sort of blowoff tube into another container?

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I suppose you could put a piece of thin rigid plastic between the stirplate and the starter so that it moves any overflow out beyond the stirplate itself.

I sometimes will use an aluminum drip tray between the flask and the stirplate to catch any overflow. Foam plugs for the flasks help also.

I bought some magnets from Radio Shack and I'm wondering if they will be sufficient for this project. The part number is 64-1895. Here's a link: http://www.radioshack.com/product/index.jsp?productId=2102642

I have four and planned on placing them across the center of my fan, ++--. Are these going to be strong enough to spin my bar? I've ordered a 2" stir bar from Amazon.

Thanks for the help!

I used 1/4 x 1/8 rare earth magnets that I got on ebay and those worked fine, so I would imagine that those would work as well.

Here is my build
Hard drive magnet -free
Pc fan -free
Scrap wire -free
Enclosure 4.99 at frys
Pot 1.99
Switch .99
Stir bar 4.99
Power supply from box of extras in closet - free
Total cost $13 bucks or so. Not bad

I put my stir plate together today in under two hours and less than $12.00. I had an old PCthat is about to get recycled so I yanked out the fan and hard drives. A few whacks with my hammer and I had the magnets. From RS I got the toggle switch, rheostat and knob; the power was courtesy of an old router and I used a discarded Robbermaid container for the box. The rest came from my jars of junk - some rubber spacers to give room for the magnet to spin, plus screws, bolts and the washer. With it running the only noise i hear is a slight rattle from the stir bar. The hardest part of the project was getting the fan up to speed to move the started without stalling or sending the stir bar flying!

Many thanks to the OP - I'm confident this will be the key to a successful RIS I'm brewing this weekend!

Mellow52 said:

This is a fool proof wiring diagram. All parts is obtainable from your local Radio Shack.

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Just got done building my own stirplate using these plans. I was going to just do it the simple way but I had to go to RS to get a potentiometer anyway, and I figured I might as well do it the right way the first time.

It spins nicely, and I can't wait to get a stir bar to see how well it actually works with a flask.

So I am taking my turn and putting together a stir plate... Originally I was going to use a 9v power supply, but it won't turn the fan. The fan is marked 12v, but I figured it would just spin slower. The only other PS I have is 19.5 DC, this spin the fan just fine. The problem is when I wire in the rheostat for speed control. It doesn't do anything. Is a 25ohm 3W too small for this PS, or did I wire it wrong? I went neg on fan to neg on PS, with pos on fan to outer leg of stat, and center leg of stat to pos on PS.

I want to get the wiring all figured out before I start mounting anything.

OK.. I found a 9v PS that was able to power the fan, but my rheostat still is not working. I have power from the PS going to the middle post, and the leg on the right going to the fan (this all the positive side), with the neg going directly from the PS to fan. Should this not work?

TBaGZ said:

OK.. I found a 9v PS that was able to power the fan, but my rheostat still is not working. I have power from the PS going to the middle post, and the leg on the right going to the fan (this all the positive side), with the neg going directly from the PS to fan. Should this not work?

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Sounds right but the rheostat is probably providing too high a resistance so it stops the fan completely. You can wire in an LM317 voltage regulator to provide more voltage but allow the rheostat to dial the voltage down from the full voltage. This thread has such a wiring diagram.

Note that some fans require a higher minimum voltage than others.

It's not that the rheostat stops the fan, it doesn't seem to slow it down enough.

So yeah, this rheostat is a dud, going to get another one. I picked up a few resistors and and if I put one in line instead of the rheostat it slows down like it should.

TBaGZ said:

So yeah, this rheostat is a dud, going to get another one. I picked up a few resistors and and if I put one in line instead of the rheostat it slows down like it should.

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Oh, then it doesn't provide enough resistance, it's not defective. Look into ohm's law to figure out how much resistance you need.

I was thinking that, but when I put a 10ohm 1w resistor inline it slows down. So why wouldn't the 25ohm 3w stat work?

TBaGZ said:

I was thinking that, but when I put a 10ohm 1w resistor inline it slows down. So why wouldn't the 25ohm 3w stat work?

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It probably did, just not enough to notice the difference. Testing my basic understanding of ohm's law....

Let's say your fan is 12V and .5A. To drop the current in half (.25A), you'd need a 48 ohm resistor. Just the 25ohm rheostat cut the current to .48A (12 / 25), so it barely did anything, only 4%. Adding a 10ohm resistor cut the current to .34A (12 / 35), or 32%, which may be enough to notice.

I'm talking the 10ohm resistor without the rheostat made a noticeable difference.

TBaGZ said:

I'm talking the 10ohm resistor without the rheostat made a noticeable difference.

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Don't know what to tell you then. Maybe you're right and the rheostat is defective, although that seems unlikely if it's new. Or maybe the 10ohm resistor is a 100ohm resistor (translating those color bands can be error-prone)?

Yes, it is a 10 (just took it out of the package). I also put a 100 inline and that made it too slow. I will just pick up another rheostat and try it. Maybe I should get a higher ohm one? Could it be that when I initially put it to the 19 volt PS I fried it?

It's possible, I guess. Did you notice it being hot or smelling burned? May as well try another rheostat.

Out of curiosity, what are the specs on the fan?

For what it's worth, a slow spinning stir plate is better than a faster spinning one. I keep mine at 25-30% speed at the most. When it gets too fast the stir bar gets spun off easily. You don't need a huge vortex, you just need to keep the liquid turning with a small dimple to get air into the solution. So the 100ohm may work well by itself, i.e., without a rheostat.

So I was messing around with magnet placement and whatnot with just using two sided tape for temporary mount until I knew where I wanted them permanently placed. As you see the magnetism pulled the stacks together and layers them down. So I figured what the heck and gave it a try. Seemed to work pretty good. Figure I will just have to raise it up closer to the lid, but that's it. Anybody ever put their magnets laying down?

Btw the fan specs are 12v .16a.

Just build a stirplate using this thread as a guide and it turned out awesome! Very very quiet. the only issue I had was that I bought a computer fan that came with a rheostat but I was unable to use the rheostat because of the way it was built (with little circuit boards attached). Now all I need is a flask... How many more days til Christmas?

Does anyone have a good method for centering a washer (to be glued) on the fan? I've built a stir plate but having a hard time getting the washer centered so the fan is wobbling quite a bit.

I've heard if people using a 60 second epoxy so that they have time to adjust it before it sets

Kirch3333 said:

I've heard if people using a 60 second epoxy so that they have time to adjust it before it sets

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That could work so set it, turn it on for a second to get spinning, adjust. I used krazy glue last time... Nope

Built it.. Turned out awesome and is spinning away a starter as we speak

Kirch3333 said:

Just build a stirplate using this thread as a guide and it turned out awesome! Very very quiet. the only issue I had was that I bought a computer fan that came with a rheostat but I was unable to use the rheostat because of the way it was built (with little circuit boards attached). Now all I need is a flask... How many more days til Christmas?

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Nice on making the removable part the top! Wish i would have thought of that.. could have saved me a whole lote of trouble with how many times I had to pull it apart to get it just right.

Kirch3333 said:

I've heard if people using a 60 second epoxy so that they have time to adjust it before it sets

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I used a 5 min epoxy.. let it set for a minute so it was slightly tacky and then fine tuned till my hearts content. Worked well for me.

I am looking to build one of these, but I wanted to check and see if anyone had a couple magnets or one hard drive magnet they would sell?

The ones linked to from the OP work really well.. quite pleased with them.. I'd recommend getting 4 though so you can double the power for larger stir bars... has a tough time holding onto a 2in

I'm using four magnets from two hard drives, and they will spin a 1 inch perfectly but not a 2 inch. However the 1 inch bar with a 12 V adapter has no problem stirring a 2 L starter in an Erlenmeyer flask. When I use a 9 V adapter it's not enough power and the bar gets thrown. I've learned in making this that no two are alike, there are a lot of factors in play and you really have to tweak it to get it just right. I'm using a cigarbox and what I'd like to try next is to cut out a square or circle in the lid to reduce the material between the magnet and the glass bottom. I'm hoping this will get better contact And a more powerful connection between the magnets and The stir bar

evolcoms said:

I am looking to build one of these, but I wanted to check and see if anyone had a couple magnets or one hard drive magnet they would sell?

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Man... Go down to your local 'craft' store. Michaels, Hobby-Lobby etc. They have packages of 6 rare earth magnets for a few bucks.

Huaco said:

Man... Go down to your local 'craft' store. Michaels, Hobby-Lobby etc. They have packages of 6 rare earth magnets for a few bucks.

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Hmm , ok ill have to go check them out.

So I went to all my Radio Shacks, and home improvement stores and they didn't carry to right size magnets. Here is my Stir Plate....minus the magnets :/
Top view



Bottom view



Side view


Thanks for the great tutorial!

Try your local hobby/craft stores. Michaels or Hobby Lobby

The clear case is a sweet touch

Roadliner said:

The clear case is a sweet touch

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Thanks!I found the case at walmart in the craft section with all the beads and jewelry equipment. I was going to for the " Look at my work" look. My dad has worked in electronics (Qualcomm) my whole life so I'm sure he will be happy with my little gadget. Although, i didn't do much, but follow instructions.

I also went to my local Michaels and they only had flexible magnets.

evolcoms said:

Thanks! I was going to for the " Look at my work" look. My dad has worked in electronics (Qualcomm) my whole life so I'm sure he will be happy with my little gadget. Although, i didn't do much, but follow instructions.

I also went to my local Michaels and they only had flexible magnets.

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Where did you get the clear case?

bizarrojosh said:

Where did you get the clear case?

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Walmart. Where they sell beads and jewelry making equipment. I also saw them at Michaels. Same general area.