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

[jtucker101]

I think it would work fine...but it probably won't turn the fan at the lower voltages. I'd prefer to go with a 12V supply rated at about an amp or so, but that's just my opinion. I've seen this same type of supply listed in one of these DIY stir plate threads, but maybe someone could explain what the benefit is of having the lower voltage levels (unless their fans are rated at less than 12 volts)?

I remember reading that some people are using dc supplies that give them a bit more than 12 volts...that way if you slow the fan down your voltage drop across the pot will still give you close to 12 volts.

 

[ClaudiusB]

fermenator wrote:
adjustable voltage from 3-12v, i would assume this could work, no?

Will work with fixed and adjustable speed control.
Two of my stir plates are fixed speed and I use the selectable supply to get
the optimum voltage/ speed for my flasks.




Cheers,
ClaudiusB

 

[fermenator]

Thanks for the feedback, I will be chopping up that adapter this week!

 

[fermenator]

I have a question, i know i can use extra 10/32 nuts for spacers (btw, how many?) but what are the "¾ inch stand offs"? Can these be bought at Lowe's or Home Despot or is this just something you had on hand??

Thanks and I apologize for the stupid questions!

 

[chumprock]

Thank you for this, I just built mine today and it works great.

Only issue I had was being lazy and going the solder-less route, the 3/16 connectors dont really fit on the LED rocker switch. I had to "stretch" out the female connector like a two-bit floozy from Jersey.

 

[jtucker101]

I have a question, i know i can use extra 10/32 nuts for spacers (btw, how many?) but what are the "¾ inch stand offs"? Can these be bought at Lowe's or Home Despot or is this just something you had on hand??

I don't think Lowes or Home Depot has these (but I could be wrong). Best bet is to try Radio Shack or some sort of electronic components store. They look similar to this:

Use them for raising circuit boards off a surface (or in this case, I think they were used to raise the fan off the inner surface of the enclosure). You can get the same effect with long screw and the 10/32 nuts you mentioned.

 

[JVD_X]

Yes - Lowes carries them... I used them on my stirplate.

 

[Travel_mon]

Hello,

I just finished my stir plate build per page one of this thread, everything works, yet I can't get my 2" stir bar to spin fast enough in my 2L flask. It will spin and get the fluid moving, but not like the tornado pictures I see posted here. So my question is, I am using an old computer fan and a cell phone adapter (5v, 0.7a) do I need to replace my power cord with something in the 9v range or more??

I'm by no means an electrician, so any insight would be greatly appreciated.

Thanks.
Travel_mon

 

[chumprock]

No. I'm using a 5v power supply and I'll kick the sitrbar if I turn it up too high.

Is it a really old, smaller case fan? It might not have the chutzpah to move faster when there's a load (the stirbar) putting weight on it spinning.

 

[Travel_mon]

Hey Chumprock,

My fan is a 12v DC / 0.12a computer fan, is that my problem?? I've used to earth magnets and that had no effect on how the bar spun.

Thanks.

 

[chumprock]

I think all the pc fans are 12v. but if its a smaller fan it might be an issue.

IIRC, most case fans are 80mm. I'm using a 120mm from an old IBM server because it seemed to be a bit sturdier, and it already had a metal face that the magnets were at home on.

I just know that my little 5v phone charger cords works fine, so it's not likely to be your voltage.

 

[fermenator]

Yes - Lowes carries them... I used them on my stirplate.

Thanks guys, if anyone has trouble finding these, at Lowes they are in the "specialty section" in hardware labeled "nylon spacers" or "steel spacers". They did not have 3/4" as suggested in the instructions (they do however have 1/4". 1/2" and 1" spacers). I picked up the 1" spacers and figured I could cut them down if needed.

Anyone have any experience using different heights for the spacers?

 

[jackson_d]

I am working on my first build of this right now. The flask and stir bar are due to be delivered to me on monday morning so I'm not ready just yet to seal everything up... One thing I did was mount the switch and the potientiometer backwards. I have the pot on the left and the switch on the right. it still works just fine, but being a bit of a perfectionist, I wish I had mounted them in the oppostie direction. Working upside down while installing everything threw me off. Otherwise its working great and the neodymanium magnets are quite impressive too... Fun build and i cant wait to see a little tornado in my new flask on monday morning. Thanks from Chicago for this thread..

 

[BrewBeemer]

I cardboard box assembled my 12 volt 720 mA fan for testing with a 12 volt 1000 ma cube, added a hollow air cooled 10 watt Ohmite with a sliding center tap. It had a range of less than 1 ohm to 10 ohms which was great from a stalled starting fan motor needing a spin to start at 2.81 volts under load to full speed. Then thru my junk pile I located a 0-500 ohm pot and ran it for a short while. This I mean by less than 3 minutes as i left the room and before I returned it let the smoke and quit. I had a 1/8' glass plate above one of the .140" computer drive magnets I have with a mason jar and 1" magnet bar to play with water. Regular small pots are not rated to handle 8.64 watts at 12 volts which I had a reading of plus the reading of 13.47 volts under load for 9.698 watts with a 1500 mA cube power supply. This under load wattage was way beyond the operating current of these small pots. These pots will work within their current range if they are used properly like controlling a LM317 voltage control regulator not a fan motor directly unless you have a 120 or 200 mA 12 volt fan. I know there are 12 volt 120mm fan motors that have a lower rated amperage but these lower mA motors will also have lower torque outputs at the reduced voltage applied that is needed for these stir plates. I would rather build a stir plate with a infinate voltage control if i'm going thru the trouble of building one to use a LM317 to allow for correcting the stir bars speed as the viscosity of the starter changes. With the chance of letting the smoke out is not a very reliable DIY to built project for me. This is my findings.

 

[Catt22]

That's why I'm using a 120 AC muffin fan with a light dimmer. Been using it for years now without a hitch. It doesn't have to be complicated. It doesn't let the smoke out either.

 

[wwwdotcomdotnet]

question about actually using the starter: once you have the starter going do you guys just dump the entire thing into the carboy/bucket, or do you pour of the top into the fermentor and leave the trub in the bottom and get rid of that?

 

[Catt22]

I pour off the top spent wort portion, but I don't dump it into the beer. I dump it down the drain and pitch the thick yeast slurry on the bottom. What you are referring to as trub is largely the yeast. That's the portion you want to keep and pitch. I like to retain about 100-200 ml in the flask and shake it up to mix with the yeast sediment then pitch that mixture into the fermenter. The yeast sediment can become very thick and difficult to pour out of the flask unless you mix it up a some.

 

[wwwdotcomdotnet]

thank you!

now i understand why big starters are worthwhile, more yeast! i never really understood the 1 gallon starters some of you guys would do, i figured it all got poured into the fermenter haha. this was one of those "ooooooooh" moments for me!

 

[Catt22]

thank you!

now i understand why big starters are worthwhile, more yeast! i never really understood the 1 gallon starters some of you guys would do, i figured it all got poured into the fermenter haha. this was one of those "ooooooooh" moments for me!

It's guaranteed not to be the last "oooh" moment. I've had many of them in this hobby, some recently.

 

[wwwdotcomdotnet]

also, how long before pitching do you guys turn off your stir plate? i am assuming the yeast needs to settle a bit before? could you throw the flask in the refrigerator to help separate the yeast?

 

[Catt22]

also, how long before pitching do you guys turn off your stir plate? i am assuming the yeast needs to settle a bit before? could you throw the flask in the refrigerator to help separate the yeast?

As usual, it all depends. When you have the time, put the flask in the fridge and let it settle overnight. When you don't have the time, a few hours or even less will let much of the yeast settle.

Yes, cooling speeds up the the settling of the yeast, or at least it appears to do that. Lager yeast are a little different. They enjoy cooler temps and won't settle out as easily when the flask is cooled. I always allow enough time for a lager starter to finish out completely. I thien chill it for 24 hours before decanting and pitching.

You can leave a little wort in th flask after decanting and use the stir plate briefly to mix it up some prior to pitching.

 

[springer]

I got mine together last night and did a trial run. I don't know why but at times the stirbar seems to clatter but only on high. I used the K&J magnets that Anthony recommended I had to space about 3/8's of an inch apart on the washer . The power source is a 12v charger for one of those booster battery packs to jump start cars . Here is a video of it in action

 

[tipicreeper]

Looks really good!
Thanks for the video!
I believe the chattering you hear is the vortex reaching the stir bar and sucking air creating turbulence, very similar to pump cavitation.
Of course, you won’t be running the vortex that violently while making a starter. Just an inch or two from the surface, enough to keep the yeast in suspention. You may want to see if your power supply will allow the stir bar to turn slow enough for that.
Cheers,
-David

 

[springer]

On slow it will only make the vortex about an inch. Its also spinning 2000ml of plain water I would think that wort with yeast would be a little more viscous

 

[gingerdawg]

Mine clatters a little when the flask isn't centered over the fan. I can often move the flask just a bit and it quiets down.

 

[joety]

On slow it will only make the vortex about an inch. Its also spinning 2000ml of plain water I would think that wort with yeast would be a little more viscous

I can always tell when the fermentation has taken off as my stir plate has a more difficult time maintaining a full vortex. Must be the viscosity issue you allude to.

 

[Anthony_Lopez]

The chattering is definitely either the bar not being centered in the flask or (most likely) the air being pulled into water/solution. U should be able to hear it in the original video I posted.

 

[Schnitzengiggle]

I found that positioning the magnets while the stir bar is on top helped me find the magnetic center and the rotational center.
This is a magnet and the 1" stir bar configuration that works.

So that lead me to take a couple of smaller magnets and spread them out. Now the configuration looks like this for a 2" bar with a 2" magnet spread.

I ordered my magnets and stirbar today, going to Radioshack to pick up other components tonight. I bought from K&J magnetics, I got two 1/2" x 3/8" N42 discs that I am going to try and make work with the 2" stirbar I ordered.

If I remember correctly the distance between the magnets must be at least the length of the stirbar (like in the quote)?

 

[wwwdotcomdotnet]

Can anyone post a link to a 25 ohm potentiometer (linear) in a 16mm or 24mm case from Mouser or Digikey? I've ordered plenty of parts from both vendors in the past, but I'm having trouble finding anything less than 100 ohms.

I tried RS, but you know how that goes...

 

[wwwdotcomdotnet]

I did find the part on the RS website, but I'd prefer to order from another place where I can get a bunch of other stuff for unrelated projects to justify the shipping.