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

[emjay]

If I use a 12V power cable and a 12V switch, would it just limit my fan to this voltage, essentially making it work as a 12V computer fan?

Not quite. Reducing the voltage will slow down the fan. At a certain point, it won't have enough voltage to start up.

SOME fans (ie one that has a higher startup voltage requirement than its minimum voltage requirement) can be "helped" along by applying the power to it and manually giving it a quick spin to get it started (kinda like a rolling start with a vehicle). Obviously, operating it like that isn't really conducive to its use in a stirplate.

And even then, there will be a minimum voltage at which it will be able to CONTINUE spinning. 12V is probably below that minimum voltage - to give some perspective, it's like operating a 12V fan a 3.4V. I have never personally seen a 12V fan able to run at that kind of voltage.

And EVEN IF ONE COULD, it would be so close to its minimum voltage that speed control would be practically non-existent. Let's say that this fan had an astonishingly low voltage at which it could startup and maintain spinning of 3.0V. The minimum to maximum would therefore be 3.0V to 3.4V, meaning you have a usable range of 0.4V - or roughly 3% of its voltage rating. That's essentially negligible when it comes to controlling the RPM. Scale all these things up by a factor of 3.5, and you can say the exact same thing about a 42V fan.

I'm guessing the stainless steel washer is being used to shield the magnet from the magnet in the DC motor

Not really. It's just to make it easier to position it well. Trying to fine tune the placement of one neodymium magnet onto (essentially) another one is not an easy thing, and can really hurt if you're not careful!

 

[JayMac]

Not quite. Reducing the voltage will slow down the fan. At a certain point, it won't have enough voltage to start up.

SOME fans (ie one that has a higher startup voltage requirement than its minimum voltage requirement) can be "helped" along by applying the power to it and manually giving it a quick spin to get it started (kinda like a rolling start with a vehicle). Obviously, operating it like that isn't really conducive to its use in a stirplate.

And even then, there will be a minimum voltage at which it will be able to CONTINUE spinning. 12V is probably below that minimum voltage - to give some perspective, it's like operating a 12V fan a 3.4V. I have never personally seen a 12V fan able to run at that kind of voltage.

And EVEN IF ONE COULD, it would be so close to its minimum voltage that speed control would be practically non-existent. Let's say that this fan had an astonishingly low voltage at which it could startup and maintain spinning of 3.0V. The minimum to maximum would therefore be 3.0V to 3.4V, meaning you have a usable range of 0.4V - or roughly 3% of its voltage rating. That's essentially negligible when it comes to controlling the RPM. Scale all these things up by a factor of 3.5, and you can say the exact same thing about a 42V fan.


Not really. It's just to make it easier to position it well. Trying to fine tune the placement of one neodymium magnet onto (essentially) another one is not an easy thing, and can really hurt if you're not careful!

Thanks! I guess I'll go buy a 12V fan from a local computer store. So you're saying I could just flue it right onto the center of my fan? If so, I'd rather due this, to make things easier.

 

[mojo2008]

I built my stir plate several weeks ago and it works ok, but I can't really get the speed that I expected out of it. As a matter of fact, if I bump down the potentiometer even just a little bit it stops turning. I'm using a 12VDC CCTV camera power cord and a 12V fan, but the current rating on the power cord is only 500mA.

I've ordered AC fans for my lagering chamber and they get lots of juice straight from the wall. It seems to me that my potentiometer would work just as well for an AC circuit, but I'm afraid that it's max resistance isn't enough to really even slow the fan. Has anybody built one of these with an AC fan?

Thanks,
Andy

 

[brewinitup]

I built my stirplate using a 12vdc fan and it works just fine. Obviously you could use a 120vac fan, but you'd need to get a new potentiometer and rocker switch. You really don't want to use 12vdc equipment on a 120vac circuit.

 

[mojo2008]

I built my stirplate using a 12vdc fan and it works just fine. Obviously you could use a 120vac fan, but you'd need to get a new potentiometer and rocker switch. You really don't want to use 12vdc equipment on a 120vac circuit.

That's what I suspected. I imagine it's not rated for that kind of current and it will burn it up. Thanks!

 

[Justintoxicated]

That's what I suspected. I imagine it's not rated for that kind of current and it will burn it up. Thanks!

You could use a dimmer switch to adjust the fan. Just be careful when dealing with direct 110v!

 

[emjay]

You could use a dimmer switch to adjust the fan. Just be careful when dealing with direct 110v!

I wouldn't use a typical dimmer for this, if for no other reason than that it's going to make a really annoying buzzing sound (has to do with how it alters the voltage sine wave). I would go with a switch that is *intended* for adjusting fan speed.

 

[Justintoxicated]

So my stirbars came in. I got a 1" and a 1 and 3/8th inch. I think I like the 1 and 3/8th inch better but please advise.





Not sure why I would need to turn it down, perhaps it will ferment too much and need to be slowed down?

 

[Huaco]

I started a 3L starter last night of Wyeast German Ale 1007 in my 5L flask. This morning I looked at it and it had developed a thick Krausen and almost blew out the top! Be careful with the 2L flask in the video...

 

[troyh]

So my stirbars came in. I got a 1" and a 1 and 3/8th inch. I think I like the 1 and 3/8th inch better but please advise.

Video Link: http://www.youtube.com/watch?v=huG9MVZspUk

Video Link: http://www.youtube.com/watch?v=RapsolLdp5Y

Not sure why I would need to turn it down, perhaps it will ferment too much and need to be slowed down?

It's my understanding that a big vortex is unnecessary, a small dimple is good enough. So either should be fine.

 

[Lumpyyyyy]

Where to buy a 2L flask in the cheap?

 

[troyh]

Where to buy a 2L flask in the cheap?

I got two 2L flasks from Amazon for $28.50. They seem to be more expensive now at $22.50 each:

http://www.amazon.com/gp/product/B005QDP82Q/?tag=skimlinks_replacement-20

 

[Justintoxicated]

I started a 3L starter last night of Wyeast German Ale 1007 in my 5L flask. This morning I looked at it and it had developed a thick Krausen and almost blew out the top! Be careful with the 2L flask in the video...

Oh great, the starter I have on the plate at home is over the 2000ml mark. However I didn't notice any fermentation when I woke up this morning. Perhaps the yeast is not viable

 

[Huaco]

Oh great, the starter I have on the plate at home is over the 2000ml mark. However I didn't notice any fermentation when I woke up this morning. Perhaps the yeast is not viable

What yeast did you use? 1007 is a pretty active top yeast. May just be this strain. I have had krausen before but not this big!

 

[troyh]

Oh great, the starter I have on the plate at home is over the 2000ml mark. However I didn't notice any fermentation when I woke up this morning. Perhaps the yeast is not viable

In my experience, you don't see a big krausen when stirring. Almost all my starters looked like this while on the stir plate and they've all been very vigorous fermenters.

 

[Huaco]

I use a 10:1 ratio of extra light DME to Water. What is your ratio? Example... 3000 mL of water gets 300 grams of DME.

(this is not a thread about starters though... lets keep this discussion short)

 

[Justintoxicated]

I use a 10:1 ratio of extra light DME to Water. What is your ratio? Example... 3000 mL of water gets 300 grams of DME.

(this is not a thread about starters though... lets keep this discussion short)

200g DME & 2000ml water (about 2 cups DME) if put into a mesuring cup.

I was wondering if the stir plate is hiding the fermentation or not. I guess I will put it in the fridge tonight and see how much yeast I have created, if not enough I'll have to overnight ship some greenbelt yeast from somewhere.

This would be my second failed starter.

http://www.austinhomebrew.com/product_info.php?products_id=12720

 

[Huaco]

Is this a dry yeast, smack-pack, or vial? I have never heard of "Greenbelt"
If it is dry, DO NOT make starters with dry yeast. I have it on pretty good authority that making a starter with dry yeast is detrimental to the yeast. I've got now empirical evidence to support this off-hand, but this comes from a guy that KNOWS yeast and KNOWS homebrewing.

 

[ennis2000000000]

Iv always made starters with dry yeast and its always turned out great

 

[Justintoxicated]

Is this a dry yeast, smack-pack, or vial? I have never heard of "Greenbelt"
If it is dry, DO NOT make starters with dry yeast. I have it on pretty good authority that making a starter with dry yeast is detrimental to the yeast. I've got now empirical evidence to support this off-hand, but this comes from a guy that KNOWS yeast and KNOWS homebrewing.

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.

 

[troyh]

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.

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.

 

[Justintoxicated]

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.

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?

 

[raindogxx]

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

 

[mojo2008]

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?

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.

 

[rales]

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.

 

[stjackson]

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!

 

[sctocinci]

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.

 

[starsman20]

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

 

[mcbaumannerb]

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!

 

[nmfree]

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

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.