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

Apoxbrew said:

okay... so i've got mine wired up and working. problem now is that i can't figure out how to keep the bar from getting thrown to the outside. no matter what i try i can't keep the stir bar in the middle of the flask and spinning, it just gets thrown to the outside. any ideas?

Click to expand...

Does it throw the bar with the rheostat all the way down?
Maybe you need to move the fan closer to the surface of your flask.
Reposition the magnet/s to the length of your stirbar.
Make sure the magnets are centered on the fan
Get stronger magnets.

Apoxbrew said:

can you do this without the switch and just the rheostat? i don't really want an on off switch... i'll just unplug the power supply.

Click to expand...

Sure, you can run the stir plate without the switch.

Apoxbrew said:

okay... so i've got mine wired up and working. problem now is that i can't figure out how to keep the bar from getting thrown to the outside. no matter what i try i can't keep the stir bar in the middle of the flask and spinning, it just gets thrown to the outside. any ideas?

Click to expand...

Like Chefencore says, we need more information to help diagnose your issue. What kind of magnets (hard drive, disc, bar)
How are the magnets positioned
Pictures couldn't hurt.

try putting the magnet right on the surface of the stirplate without a flask.

thanks gents.

i think i need stronger magnets. i didn't have a spare hard drive so i bought some of the Neodymium magnets. they're little discs and i'm using 3 in a straight line in the center of the fan. given that if i just set the stir bar right on the stir plate surface it seems to work okay (not great but okay), but not at all when in the flask, i think the magnets just aren't strong enough.

i'll try and take some pics tonight and post.

i'm also a little concerned because my power supply (cell phone charger) seems to be heating up quite significantly when running the fan... not sure if there's a way to alleviate that.

Apoxbrew said:

they're little discs and i'm using 3 in a straight line in the center of the fan. given that if i just set the stir bar right on the stir plate surface it seems to work okay (not great but okay), but not at all when in the flask, i think the magnets just aren't strong enough.

Click to expand...

Try taking out the center magnet, and make sure the other two have opposite poles facing up (I’m sure they do, but ya never know). That way the middle magnet isn’t trying to pull on either end of the stirrer. If you need more strength, stack the magnets.

Apoxbrew said:

i'm also a little concerned because my power supply (cell phone charger) seems to be heating up quite significantly when running the fan... not sure if there's a way to alleviate that.

Click to expand...

You say you did install a rheostat? If it can’t handle the voltage your power supply is putting out, it can burn it out. Check the packaging for any info, or call the Shack. I had this happen with the first (and only) switch I bought.

thanks! got it.

so, i pulled the middle magnet and stacked two so instead of like this - 000, now it's like this - 0 0

as to the power supplies. i have two i've tried now. one didn't seem strong enough to power the fan unless the rheostat was on full blast the other seems to overload the rheostat (smoke started to come out!). here's the output specs on both:

lower power = DC 9v, 100mA
high power = DC 12v, 500mA

how should i proceed you think?

Apoxbrew said:

here's the output specs on both:

lower power = DC 9v, 100mA
high power = DC 12v, 500mA

how should i proceed you think?

Click to expand...

I actually had to go down to a 5v supply or it threw the stir bar.

But, I assume that the strength of my magnet also played a factor.

I'm using a 12v 1.25A supply. It won't pull a vortex to the bottom of my 2L flask on high.
Have you put some water in your flask and tried it out? If it works with the lower power supply, use it.
Keep the other supply for your next project!

Apoxbrew said:

thanks! got it.

so, i pulled the middle magnet and stacked two so instead of like this - 000, now it's like this - 0 0

as to the power supplies. i have two i've tried now. one didn't seem strong enough to power the fan unless the rheostat was on full blast the other seems to overload the rheostat (smoke started to come out!). here's the output specs on both:

lower power = DC 9v, 100mA
high power = DC 12v, 500mA

how should i proceed you think?

Click to expand...

Whats the specs on the rheostat?

specs on the rheostat is 25-ohm ±20% tolerance wirewound 3-watt variable. doesn't look like the shack sells anything other than that one rheostat either so i need to figure out something to keep the thing from smoking when using the 12v power supply.

i'd use the 9V, but it was heating up significantly and didn't seem to have the power to run the fan (had to crank the rheostat up nearly all the way to get the fan moving).

maybe i need something with lower volts but hither mA... like a 9v 500mA ????

Are you sure you don't have a short somewhere that is causing it to pull a lot of amps? The fan by itself should not be pulling that much of a load that it would cause the rheostat to smoke, plus now that it has smoked it may be damaged.

perhaps. here's how i've hooked it up... is this right?

i have the positive from the fan and the power supply going to the right hand terminal on the rheostat. i have the negative from the fan and power supply going to the middle terminal on the rheostat.

sound right?


EDIT: okay... it's working!!! main problem i think was that the magnets had the same poles facing up. i reversed one of them and all is working well now. got a great vortex (or whatever you want to call it) and can even crank it up full speed without throwing the stir bar!!

that said, i'm still having issues with the rheostat. i put a new one in, redid the wiring (put new connectors on the wires) and i still had smoke in the rheostat. i think, though, it's only happening when the rheostat is in the full-off position. what is causing that? see above for wiring and let me know if i've wired the thing wrong. it seems as though when i crank the rheostat up a bit, the smoking stops and all is well. would love to know this thing isn't going to burn down my house once it's used for real!!

thanks gents for all the help. much appreciated!!!!

so here's a few pics... one with the wiring so y'all can see if i've got something wired up wrong.

Apoxbrew said:

so here's a few pics... one with the wiring so y'all can see if i've got something wired up wrong.

Click to expand...

That's a nice box!! I like that you cut the top for less resistance (I'm assuming), but it gives the opportunity for stuff to get in should your starter explode.
I've got mine wired a bit different. The hot from the fan is on the right terminal, the hot from the plug is on the center, and the two negative are connected.
Beautiful box! Were the cigars good?

Apoxbrew said:

so here's a few pics... one with the wiring so y'all can see if i've got something wired up wrong.

Click to expand...

Yeah, there is a problem there. Basically the rheostat is not doing anything, if you pulled the connectors off the rheostat, you still have a circuit right? If you really want speed control wire it like Chefencore describes.

Edit: If you look at the pics in the very first post you will notice that only two wires connect tothe rheostat, not four as in your pic.

thanks chef and cam!!!

okay... got the wiring fixed. the rheostat now doesn't turn the fan all the way off... but it does adjust the speed a bit (though not as much as i expected).

regardless... it's not smoking anymore so that's awesome, and it's working great!!

so what's the ideal speed. do you want the vortex to come all the way down and hit the stirbar or not so much?

should i cover the hole with some thin plastic or something to protect against liquid in the event of an explosive starter?

I usually shoot for an inch or half an inch, really just need to keep it stirring.

I would cover the hole with a thin piece of clear plastic.

Like I said, mine won't pull a vortex down with 1L in a 2L flask. But it works. It's a stirplate, not a tornado-maker.

To preserve the beauty of your stirplate, maybe you could find the thinnest piece of plexiglas to put over the top. Or if you are handy enough, place an insert just in the place you cut out.

hmm... is there a way to slow down the fan even more then? i've already dropped to the DC 9v, 100mA power supply and still, with both a 1L and 2L starter on the slowest speed, i'm pulling the votext all the way down to the stirbar. not consistantly, but it'll move up and down and occasionally touch the stirbar.

i'd rather not have to find another power supply. can i place a resistor inline on the hot side of the PS or something to drop the current (or voltage or whatever) more and slow the fan down a bit?

i know very little about electronic wiring so if there's a way to do this, would love your input.

otherwise though, i'm quite happy with things! going to find a nice piece of clear plastic to put over the hole. thanks for the tip!

Just wanted to thank the OP. This was a great $ saver project. I probably would never had a stirplate without this cheap build. I did just like the OP except I mounted mine to the top. Cost me about $20. Just finished and dialed it in. No big vortexes but it works great. Thanks

Glad to hear Stevo. Thanks to everyone that has been providing support for this thread. I never thought it would grow so large...

I have no idea whats going on with my setup, but I went through 3 fans, and finally found one that isn't crapping out on me. problem is it only works with a 18V power supply, my 12,9,6 volt supplies don't even tickle the fan to move. I have a starter working now and while its not crazy fast, I feel it is still to fast for my liking.

anyone else have problems matching fans and power supplies?

-=Jason=-

I ended up wiring up a 9v and a 12v that I split and wired to the fan. Depending on my starter size, I plug in whichever I need.

Flomaster said:

I have no idea whats going on with my setup, but I went through 3 fans, and finally found one that isn't crapping out on me. problem is it only works with a 18V power supply, my 12,9,6 volt supplies don't even tickle the fan to move. I have a starter working now and while its not crazy fast, I feel it is still to fast for my liking.

anyone else have problems matching fans and power supplies?

-=Jason=-

Click to expand...

Get one of those laptop power supplies, that's what I use. Just make sure it can be set to 12V. One of those can power a dozen fans if need be...

emjay said:

Get one of those laptop power supplies, that's what I use. Just make sure it can be set to 12V. One of those can power a dozen fans if need be...

Click to expand...

I am going to get one of these instead

https://www.homebrewtalk.com/f11/building-stir-plate-check-out-usb-adjustable-computer-fan-253254/

amazon.com sells this adjustable USB fan to which I can just use one of my many usb wallworts

-=Jason=-

thanks for the walkthrough

Thanks for the guide! This was my first time ever wiring anything and I was pleasantly surprised with how easy this worked. After a little fidgeting with the height of the fan I got a nice consistent vortex to form!

I'd only change the potentiometer I used. I don't know if there is a better one for the job, but using my 9V adapter, I can't get the power down real low. I either have a medium sized vortex or a deep vortex.

I just finished building one! It's silently stirring nearly a half-gallon of water in a clear growler right next to me now. It's awesome. I'm not the greatest DIY'er but had little trouble with the instructions; just be sure to read them all the way through after you acquire all your parts (INCLUDING THE SPACERS!!) before you begin.

All the parts numbers from the Shack were correct. This was a great project and very rewarding. Thank you so very much Mr. Lopez!! I can't to get a flask (I think the convex bottom on the growler-style jug isn't the best for the mangets' connectivity) and start making starters!!

awesome thread! here's some pics of my stir plate. i got all the info from here!
thanks






the box cost me nothing because the NES was broken before i gutted it. beats paying $8 at radio shack

i ran an unused 12v plugin out of my living room pc so right now my stir plate is computer controlled. heh i'll probably change that once i find the right standalone power cord.


edit: 7/27/11

just got my first stirbar and tested this guy out. here's how it works. i may need to find either a different jar or a more powerful cord. its now being run off a 12vdc 200ma cord from an rc car. link below for video

http://s63.photobucket.com/albums/h149/Allaxul666/?action=view&current=Pic2016.mp4

edit: 7/27/11

i swapped out the power cord for a 12vdc 1.7amp cord. it definately spins faster now. video below

http://s63.photobucket.com/albums/h149/Allaxul666/?action=view&current=Pic2017.mp4

El^Diablo said:

awesome thread! here's some pics of my stir plate. i got all the info from here!
thanks

the box cost me nothing because the NES was broken before i gutted it. beats paying $8 at radio shack

i ran an unused 12v plugin out of my living room pc so right now my stir plate is computer controlled. heh i'll probably change that once i find the right standalone power cord.

Click to expand...

That is THE COOLEST BOX EVER!!!

ZOMG... so after spending HOURS trying to get mine working and was never really happy with my results. I ended up buying this $11 plug in play solution....
https://www.homebrewtalk.com/f11/building-stir-plate-check-out-usb-adjustable-computer-fan-253254/

I am using my same wooden box I used for my stirplate and the power supply, but this time I have control of my speed. and I can slow my fan to a crawl or get the vortex touching the bottom of a one gallon pickle jar.

-=Jason=-

looks pretty straightforward. cant wait to build this soon

I got swindled out of my old built one and have to build another. On the plus side I've got a stronger fan and at worst I might have to buy another Potentiometer if the one I scrounged is weak.

That said, I was toying with the fan I had sourced for it (140mm ancient beast) with a good incredibly stout motor on it. Only problem is I don't seem to get a lot of effect with varying the voltage like I did on my previous one. Has anyone experienced something of this sort? It kicks on at around 5V or so and this RPM stays approximately the same all the way through 12V (it's max rating).

Additionally I've discovered I'm out of old SCSI drive magnets (which are absolute kings for this btw with either 1 or 2" stir bars easily up to nearly an inch away and I don't remember them ever getting thrown) so I was going to use a few of the crappier hard drive magnets. How much added magnetism are you getting stacking these because while a nightmare to pull apart they don't seem to be that much of an improvement in field strength but maybe it's just my imagination. Any particular brands work better than others per chance? I have literally hundreds of em. (Have to dismantle and hardcore destroy every platter on a drive that fails here so might as well salvage the magnets $.

Lastly, on my previous build I put a couple resistors on either side of the ends of the Pot to ensure a minimal divide of my power source (I've got numerous 24V with great power out) to split it from the getgo and then I use the Potentiometer simply as a voltage divider. My electronics theory is getting a bit fuzzy/rusty from lack of use but is there any reason they can't simply be used as a voltage divider? That would shut off the fan at the low segments and negate the need for a switch anyway. The only thing I can think of that might cause problems is at the lower end of the pot the current would spike on the smaller divide but it seems like the reduced voltage would prevent this from being an issue anyway. Was thinking about going this route this time anyway til I found out my stupid fan doesn't wanna cooperate. May just say screw it and just try to source out an AC door cooling fan.

Turns out that fan was only variable of a few percent adjustment at best. I used two different fan controls (commercial) that had the same result but adjusted a couple 80s with same pin out just fine. Even broke outre the bench ps with the same results. I wonder if that'd the source of some of the reported issues with the rheostat setup...

That said came out well although I still have some concern about violent agitation. Will drag a 3/4 inch whirlpool to the bottom with heavy bubbles at 1L, ~1/4 inch with intermittent bubbles at 2L, 3/4 to bottom in 2L plastic pitcher (w/0.25 elevated lip), and 1/3 to bottom in gallon jug. Still don't like the lack of control but looks ok in computer speaker box I guess.

Thank you so much for the info on how to build the stir plate. Here is my build.
I cut the fan blades off to keep the 'drag' down for the fan. I was worried that the fan would be out of balance, but spun just fine with my cut off blades. I used 6 'super magnets' from Ace (3 per side). Those magnets are very strong and I could have gone with less but I was using 1/2" spacers for the fan and 3 magnets fit perfectly. I was using a 9v power supply and switched it out for a 12v. I would highly recommend the 12v. It spins the 2" bar faster.


I also only had 1 1/2" #6 screws and they wouldn't go through the fan and 1/2" spacers so I ended up cutting a part of the fan mount away to fit the nut. It worked perfectly.


Finished product:


In action:

I just built mine, and I love it. The first thing I did was to start experimenting with stir-bars. . . they have one inch, one and a half inch, two inch. . .

It just occurred to me yesterday that, instead of hunting all over creation to find magnets - or prying them off a hard drive - I could have just used a three inch stir-bar glued to the fan.

Just figured I'd pass along my revelation.

Maybe this has been brought up already but when I get the connector end off of my power supply I noticed that all I have is two black wires. On one side there is grey shading on the outside of the wire and then the other just has some gray printed words that show 80c 300v etc.....Which is the ground?

There is no ground

Ground doesn't really have anything to do with your ps (presumably wall wort?). One is positive, the other negative assuming the output is dc. Ground is really only for safety reasons and frequently isn't what most people think it is in most cases.

Thanks for the quick reply! How do I know which is positive and which is negative?