Stir Plate Help

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Alamo_Beer

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Hey guys,

I read the DIY Stirplate thread but I'm pretty electronicly retarted. I've got an old PC that I can steal the fan and magnets out of and a 5V cell phone charger but what else do I need besides a stir bar and a platform?

Do I really need a regulator and whatever to slow it down?

Thanks!
 
Yeah, sorry to say that regulating the speed of the fan is quite important. I have to start mine slow and increase the speed if needed. I never can run it full blast as it throws the stirbar.
 
If you're electronically retarded, you might want to rethink your strategy. You have to match the current sourcing of your power supply to the power requirement of your fan. And yes, you need to regulate the speed of your fan. There are several ways of doing it and some are far better than others. I prefer waveform 'chopping' over voltage regulation and would advise against voltage dropping over a resistor network.

Now, I'm speaking from the point of view of an electronics guy, not a stir plate owner/designer, so there may be some design parameters that allow voltage regulation without worrying about back EMF considerations. There was a DYI thread where a fellow successfully used a voltage regulator to control and just changed the bias to regulate the speed. He had success using that method but I'm wondering if he's limiting the life span of his fan by overheating it.

So, now that I've totally confused you, give me some faceplate details of your supply and your fan. I'll tell you if you can use them to do the job and you can see if it works without speed control.

*edit* Bender, you posted while I was typing. Was it your DYI thread that I saw? Does your fan heat at all with the lower voltage?
 
Fingers, most of us use a voltage regulator circuit of some sort in our DIY stir plates. I haven't noticed any heating problems with the ones I've made.

I agree that just dropping voltage via a series of resistors/pots is probably not the way to go.

To further expound on the "electronic retard" theme - if you don't know what you're doing, and you don't understand schematics, please don't mess with electricity. 5-12VDC at low current draws is relatively safe, but even very low power circuits can overheat components and create smoke and flames.
 
Cool, I'll break into the computer when I get home and let you know what I have.

I'm not opposed to a regulator or anything I'm just looking for an easy way to do it.

Is there anything else I could use from the computer?

Thanks guys
 
Yuri_Rage said:
Fingers, most of us use a voltage regulator circuit of some sort in our DIY stir plates. I haven't noticed any heating problems with the ones I've made.

Yeah, I thought that was the case and in all honesty I'm not familiar with computer fan design. I can tell you that you don't want to drop the voltage input to an ordinary AC motor. You'll let all the smoke out of it. You want to use a thyristor (such as an SCR) in those applications. It reduces the current and the voltage so that you don't turn your motor coil into a really hot piece of wire. :cross:

So I hope I didn't add to the confusion. In the immortal words of Gilda Radner, "Never mind...."
 
Fingers said:
I can tell you that you don't want to drop the voltage input to an ordinary AC motor.
Most computer fans are DC. All of the ones I've used have been 12VDC models. There are some 120VAC computer fans out there, but they're more expensive so I never bothered with them.

You confused me a little when you started talking about waveform clipping - didn't know how you could do that on a DC circuit. Guess we're all on the same page now!
 
Ok, so I've got an 8cmX8cm comp fan that is 12V 0.15A. It's currently mounted to a heat sink that came out of the comp...looks pretty neat. Especially if I can get a piece of plexiglass tomorrow for the top peice.

I've also got a Output: 12VDC 200mA power supply.

I ripped into an old harddrive as well and got out the magnet. Do I need 2 of these or will 1 do? I've got another HD if I need a 2nd but it was a bit of a PITA.

I hooked the power supply up to the fan and it spun fine... the reason for the speed controler is so the stir bar doesn't get thrown right?

Ok, so besides the obvious: stir bar, plexiglass, flask. What else do I need?

I'll check out newegg.com now...and try to get some pics of this hole thing when its done.

Any more info is apprechiated.

Thanks guys
 
Well, there you go, Yuri, I thought the fan was AC. We had some similar looking fans in our microwave radios but they were AC. Hence my confusion. Absolutely no point in using a rectifier on a flat waveform.

Greenhornet, your supply will be fine for that fan. You might want to build this to control your voltage:


7601-LM317.jpg


The output voltage is set by the ratio of the two resistors, R1 and R2, so your 12Volt input is fine. You can also use an LM317 instead of the LM117.
 
Well, if you want to take all the fun and adventure out of it, go ahead. :D

Anytime Yuri gives some advice, you can bet it's on the money.
 
I have this sitting around, and it just hit me:
8829-Hardcano9_1.jpg

8829-Hardcano9_2.jpg


with some extra thought going into this, I can get an adjustable fan speed, and the ability to even make a 'remote' stir plate and temp probe to go under the flask just for the hell of it.

What do you think Yuri? Obviously it would go into a housing of sorts! Or I can completely disassemble it into something cooler!
 
I just had a funny thought; why not use a cheap hard drive enclosure, and then power the fan through the 5V line on the USB cable? Could make an interesting geek project, and no power supply required! My computer's always on, at least.
 
orfy said:
If you get your self an external 5.25 inch drive housing then it'll be good to go.

http://www.area450.com/hardwaremods/harddrive18-externalhdpluscf.html

I have one, but it's a big metal POS. That will screw with the magnets right?

RadicalEd said:
I just had a funny thought; why not use a cheap hard drive enclosure, and then power the fan through the 5V line on the USB cable? Could make an interesting geek project, and no power supply required! My computer's always on, at least.


and you can gaze at it while you are on HBT!
 
This is what I was playing with last night. Using different fans, I found the bigger black one was better than my cool blue LED one :(

I was going for the BierMuncher theme with it being ugly, but working, but I think I have an idea for a nice enclosure. I am also thinking about making a jack on the side where I can plug in another 'fan' for a second stir plate off the same power supply and fan controller. I need to dig up some switches. I'm not investing any money but stir rods for this project, I know I have all of this crap around the house. Here is what I have so far

8829-Homebrew060.jpg

8829-Homebrew057.jpg


Since this pic I have taken one of the fan controllers out of the Thermaltake Hardcano 9 and I've chosen the black fan over the blue LED one. Next up is an enclosure, and switch.
 
HMMMM.....I wonder about that Thermaltake Hardcano 9. That might make a nice controller for a fermentation cabinet with multiple fans and thermal chambers.....think it's possible/practical?
 
Hawkie333 said:
HMMMM.....I wonder about that Thermaltake Hardcano 9. That might make a nice controller for a fermentation cabinet with multiple fans and thermal chambers.....think it's possible/practical?

yes sir! I may dig up another one for that project :D
 
How would you get that controller to kick specific fans on at specific temps? It doesn't seem to have that function; only the ability to alarm when critical temps are reached.....
 
Hawkie333 said:
How would you get that controller to kick specific fans on at specific temps? It doesn't seem to have that function; only the ability to alarm when critical temps are reached.....


yes, you are correct. I dunno if TT makes one that does that.....but google knows!
 
ok. so i had never heard of a stir plate untill yesterday. after looking at a few different tutorials on how to build one, and the advantages of it for building yeast cell counts in starters, i get it, and want to make one, and it looks easy enough.

HOWEVER, how in the hell do they actually work? it freaking baffles me. i had NO idea that two little magnets could somehow produce a magnetic field with the strength to cyclone liquid sitting on top of them. that's freaking bill nye science **** in action yo!
 
the magnets spin a stir rod that is in the flask, pushing the yeast to the sides of the flask, and creating that wicked cool vortex :D
 
98EXL said:
the magnets spin a stir rod that is in the flask, pushing the yeast to the sides of the flask, and creating that wicked cool vortex :D


ooooh. duh. :cross:

i totally missed the fact that there was something inside the flask. i thought it was just a plain flask, and i could not figure out how it made the liquid stir just by magnets alone.

so how does the stir plate stay affixed to the flask? is it inside it, outside of it glued to the bottom or what?
 
Maybe I'm jacking this thread, maybe I'm not, but that hardcano would make one smooth interface on a cabinet if we could figure out how to respond to temps....a third fan could run an integrated stirplate chamber. There. I didn't jack the thread!
 
brian williams said:
so how does the stir plate stay affixed to the flask? is it inside it, outside of it glued to the bottom or what?

The flask is heavy, and it's full of liquid that's heavy as well. Heavy as compared to the weight of the stir bar that's being moved by the magnet. So gravity is the only attachment mechanism.
 
Hawkie333 said:
Maybe I'm jacking this thread, maybe I'm not, but that hardcano would make one smooth interface on a cabinet if we could figure out how to respond to temps....a third fan could run an integrated stirplate chamber. There. I didn't jack the thread!

yes, you are jacking (I think :D )

But I know I can use my liquid cooled controller to do that, but I'm not spending $150+ to make a ferment closet
 
Just thought I would chime in as the odd guy that successfully uses a very simple stir plate without a voltage reg of any kind. A 6.25VDC 350mA phone charger powering a 120mm 12VDC 350mA computer fan. The key to the design is that the fan is large enough to double as the base, and it also spools up slower so it doesn't throw the bar. 6.25VDC pulls an adequate vortex with a 1 qt. starter and produces adequate movement for a 2 qt. starter, which is what that is in the pic below, in a 1 gallon growler.

medium.jpg


medium.jpg


Even if you want variable speed but are "electrically retarded" you could do this same design but buy one of those Radioshack universal AC/DC adapters.
 
MrFebtober, that is a nice and simple design. Thanks for the inspiration. I built my stirplate along the lines of yours, but used a variable voltage adapter (3V-12V, although it won't turn the fan below 6V), which is a great way to control fan speed to a certain extent, all the control I'll need for 1L or 2L starters.

Simple, cheap, effective.

Cheers
 
I have a fan hooked up to a rheostat and a 6.0VDC power supply and can get a nice little whirlpool going in a 1L flask. If I hook the fan up to a 12VDC power supply, the fan spins so fast it throws the rod and the rheostat doesn't slow the fan down enough to correct this. If I add another rheostat (so that its power supply--->rheostat--->rheostat--->fan) will i be able to use my twelve volt power supply and get a more controllable vortex which will enable me to do larger starters?
 
Hmmm, I don't know too much about rheostats, so I can't help you there. If a double rheo was to work, a better idea would be to put a voltage regulator in front of one rheo, which should use less electricity (and cost less).

A better idea may be to design a simple voltage regulator circuit. If you can get your hands on some resistors, a potentiometer, and an operational amplifier (aka op amp), I'd be glad to post up a simple circuit diagram for you. :D
 
RadicalEd said:
Hmmm, I don't know too much about rheostats, so I can't help you there. If a double rheo was to work, a better idea would be to put a voltage regulator in front of one rheo, which should use less electricity (and cost less).

A better idea may be to design a simple voltage regulator circuit. If you can get your hands on some resistors, a potentiometer, and an operational amplifier (aka op amp), I'd be glad to post up a simple circuit diagram for you. :D

Thank you for the offer but I've recently discovered that me and anything involving a soldering iron is a painfully bad idea. I can get a second rheostat for about $2.00 so I might just try it for SAG.
 
eddie said:
I have a fan hooked up to a rheostat and a 6.0VDC power supply and can get a nice little whirlpool going in a 1L flask. ...

I'm piling on, but whatever:D , I did the same on a stirplate from HERE and HERE
I liked the simplicity of the first link and the tangible parts I could find with second.

Results, I stacked two rare earth magnets on fan in the center of fan similar to
medium.jpg
Works well with a 2 liter erlehnmeyer flask with wort and 1.5 in. stir bar.


What I'm wondering is if magnets were stacked like this in opposition,
3040-stir3.jpg
would this be more effective to get a strong magnetic pull then the "stacked, single magnet setup" in the first picture?

Anybody out there have experience with the difference in strength of magnetic pull on stir bar in these situations?
 
How about just using one of the selectable power supplies? I built the stir plate and it didn't work for some reason. So I just wired up an adjustable power supply through a switch and put it in a project box. It looks like it should work. I need to glue the magnets on the fan and get a stir bar. Quick question, do you glue 2 magnets on, one upside down?

Thanks
 
I couldn't get mine to work very well at all with multiple magnets at opposite sides of the fan. The stir bar keeps latching onto one of the two magnets and swinging around like a lasso, which makes it very easy to get thrown. I think if I were to build it over again, I would do the single strong magnet in the middle.
 
Thalon said:
I couldn't get mine to work very well at all with multiple magnets at opposite sides of the fan. The stir bar keeps latching onto one of the two magnets and swinging around like a lasso, which makes it very easy to get thrown. I think if I were to build it over again, I would do the single strong magnet in the middle.

thanks, thats my next step. I'll try the one strong magnet first. Maybe I could hot glue it in order to test it and epoxy the final magnet/s on depending what works the best.
 
for whatever reason, mine has been throwing the stir rod around and not actually working....it's been pissing me off
 
98EXL said:
for whatever reason, mine has been throwing the stir rod around and not actually working....it's been pissing me off

I believe that if the fan is moving too fast or if the stirbar is too small, it will be thrown. I've also learned that the fan must be still when you drop in the stirbar or it will be thrown.
 
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