How to build a stir plate for less than ten quid

[Drunkula]

have now thrown the little magnetic spinner into the wort on TWO occasions!

Niiiice. You running that off a car battery or something?

I might put warning labels on mine, too - it's just a fan that sits under a beer kit lid but I've bought a pwm so might jazz it up soon by putting it in a food tub.

I sometimes use a litre cafetiere and had a starter that a fly got in so I decided to sling it by throwing it in the garden. Then realised the stir bar was in it... Urghhhhh. I made temporary stir bar by encasing a nail in hot glue inside a straw and heat sealing it while china-post did its thing.

 

[Dutto]

I love "botch jobs" like the one you describe!:clap:

I run my Stir Plate off a couple of 12v Mobility Scooter batteries that my Mum had as spares. They each last for over 48 hours so I tend to use them one at a time and then recharge both together using the "double battery charger" that I also inherited.

Knowing my own clumsiness I just daren't invest in a borosilicate flask so I use a one litre glass jug that has so far survived at least two drops onto the floor. After looking for ages to find one with a flat bottom on the inside I finally found one in my local Poundland!

It works a treat.

 

[strange-steve]

@Dutto
Rather than putting the telescopic magnet into the brew, could you use a magnet on the outside of the FV and drag the stirbar up and out?

 

[Sheepish]

If batteries are a bit of a bind, and you don’t have a 12v charger, these fans will also run off a 9v charger...

 

[Dutto]

@Dutto
Rather than putting the telescopic magnet into the brew, could you use a magnet on the outside of the FV and drag the stirbar up and out?

In theory "Yes." but finding a small magnet through a translucent material inside a vessel that weighs over 23 kilos and is about 40cm diameter just isn't that easy!

 

[Drunkula]

If batteries are a bit of a bind, and you don’t have a 12v charger, these fans will also run off a 9v charger...

I've got 3 different switchable power supplies and 3 stir plates (I move about, ok!) and all of them will run on 4.5v plus. Messing about with the pwm voltage regulator with my bar and 6v in gives full range use, at 7.5v the bar goes a bit crackers and jittery top end like when your swmbo has just done all the washing up and mopped the floor and then you decide it's time for a a quick ole' stovetop brew.

Minimum and max speed will vary on the length of the bar and the magnetic coupling you get from your magnets. I'm a hard driver on all three. Two just have one banana shaped one mounted in the middle, another has two either side of a lolly stick. I really recommend doing what they do here and getting separate ones if you can. I just decided I needed to make a stirrer RIGHT NOW while pissed up every time I've made mine - didn't even have any beer to make.

 

[Saisonator]

In theory "Yes." but finding a small magnet through a translucent material inside a vessel that weighs over 23 kilos and is about 40cm diameter just isn't that easy!

Dutto, do you have some form of OCD?
I have noticed you can't leave a post without a

 

[Dutto]

It just gives me a moment to correct grammar and spelling mistakes.

 

[Schtoops]

Hi folks,

I'm having a bit of trouble working the electronics out...

I had a 12v AC/DC adapter lying around, and I've bought an 80mm PWM computer fan, and a PWM controller as per the first page on this thread.

Notice the next image shows that the PWM fan has 4 wires. Yet the PWM speed controller only has two inputs for the motor (+ and -).

I understand that the fan wires have the following configuration:

1. Black = GND
2. Yellow = Live
3. Green = Sense (tach.)
4. Blue = Control (PWM)

First of all, is that correct?

Secondly, which wires do I connect to the PWM speed controller? Just black and yellow and ignore the other two?

 

[Dutto]

I feel your pain because I had the same dilemma, but apart from nipping out to the garage and dismantling the Stir Plate I can't help you.

Don't worry, an electrician will be along in a moment.

 

[Drunkula]

Either snip n strip the black and yellow wires on the fan or get a little screwdriver and push on the little tab on the other side of the black connector and pull on them and you can pull them out with the metal bit on them.

If you've got a multimeter now put the
yellow into Motor+
black into Motor-
If you don't, leave them out for now.

Snip the end off that adapter then strip a little bit off each of the wires and twist them so they're not spreading and fraying. Plug the adapter in and turn it on, just make sure the exposed wires aren't touching.

Now you've got to find which is the +ve wire on the adapter wire.

If you've got a multimeter put it into DC voltage mode - anything above 12v and put the multimeter red probe onto one of the wires, just hold them together between your fingers and then do the same with the other. If the reading on the meter is positive you've got the positive wire on the red probe, if it's negative the positive wire is on the black probe. Screw the +ve into the Power+ on the pwm, and guess what you do with the other?

If you haven't got a multimeter you've got to have to do what I call 'titting about'.

Get the fan and hold together one of the wires against the yellow wire, then against the black wire just dab and release instantly the other adapter wire - if you see the fan start to spin then try again and hold it a bit longer just to see if it spins all nice**. Then you'll know you've got the +ve adapter wire on the yellow - if not swap the wires over and do the dabbing again.

**If it ever looks like it's doing nothing when you're doing a hold longer than half a second then STOP and try the wires the other way, start with the little dabs.

The dabbing is so that if you've got it wrong the magic blue smoke fairy doesn't appear, which it does if you tickle her up the wrong way too long.

Turn the adapter off, put the +ve adapter wire into the pwm power+ and I don't think you need to be told the rest.

NOTE: Using a PWM controller to control a fan doesn't mean you need to have a PWM fan, just any bog standard fan will do. PWM fans have their own controller circuitry and the PC motherboard just lets it know how fast it should go via the pwm wire - if you don't supply the wire anything it'll just spin full speed. It's done that way so that if the PC's signal goes belly up it won't stop. That's why you can ignore the pwm wire built into the fan.

 

[Schtoops]

Thank you for your reply, Drunkula.

So basically, I only need the yellow and black fan wires, yeah? But the PWM speed controller will still control the speed, using just those two wires?

Earlier on in this thread there seemed to be some chat about if you use a 2-wire fan (non-pwm), it's kind of a toss-up as to whether the fan will actually work because the PWM speed controller does something weird to the frequencies or something. The suggested solution was to use a PWM fan with the PWM speed controller. That's why I went for a PWM fan. However, it seems like this Chinese PWM speed controller I've bought doesn't accommodate a PWM fan's 4 wires. Seems a bit odd. Surely you must be able to buy 4-wire PWM speed controllers? Or is the 4-wire thing just for computer motherboards?

 

[Drunkula]

Thank you for your reply, Drunkula.

So basically, I only need the yellow and black fan wires, yeah? But the PWM speed controller will still control the speed, using just those two wires?

Earlier on in this thread there seemed to be some chat about if you use a 2-wire fan (non-pwm), it's kind of a toss-up as to whether the fan will actually work because the PWM speed controller does something weird to the frequencies or something. The suggested solution was to use a PWM fan with the PWM speed controller. That's why I went for a PWM fan. However, it seems like this Chinese PWM speed controller I've bought doesn't accommodate a PWM fan's 4 wires. Seems a bit odd. Surely you must be able to buy 4-wire PWM speed controllers? Or is the 4-wire thing just for computer motherboards?

Yeah, the 4 wires is for motherboards.

The PWM controller we've all bought works with just the two wires and is just a very fast on/off switch so in reality it doesn't do any voltage dropping in the traditional transformer sense, it's just like... ummm... a normal transformer if you gave it a pie would cut it in half and give you half a pie a day. Half way on the pwm dial would give you a whole pie every other day, which works out kinda the same, but not quite.

I've just had a pie.

So using the fan you've bought without feeding anything to the actual pwm wire on it means it'll just set itself to full speed, then the pwm controller we've bought will do the actual pulsing of the voltage, so it's acting just like the normal dumb fans which is absolutely fine.

 

[Schtoops]

Ginsters or Greggs?

Edit - Oh wait that's pasties, nevermind.

 

[Old_P]

Okay, so a few weeks ago I built my stir plate and tested it out last week and was super happy with how it worked.

 

[Drunkula]

Your flask got to play Joseph in the nativity!! Grrrr, my flask was promised it.

Great - and I've just found out my bench capper won't be playing Gabriel.

 

[Bigcol49]

Hi @Old_P
Do all things for God's glory.
That'd better be a good beer!
PS What on earth are you toasting?

 

[Old_P]

I was thinking it looked less nativity and more sheik or do I mean chic

Well I'm hoping it will turn out okay, it's my first attempt at a Bohemian Pilsner. I had to wait for our caller to get cold enough, since I don't have a fermentation fridge as yet.
I wanted to increase the yeast count, so I added one pack of Wyeast 2124 Bohemian Lager to a litre of 1,040 wort and had it on the stir plater for a good 48hrs. I now have 21.5L fermenting away at 12c.

 

[KLucky_13]

I ordered my stirplate from this place: www.magneticstirplate.com

They also sell DIY kits but I just went for the easy route and bought the single pre-assembled version :-)

 

[svenito]

I've just replaced the fan on my DIY stirplate but now I've got the whole "centering an odd shaped magnet" issue. Any tips on how to center a hard drive magnet (like a flat kidney bean) so the fan doesn't vibrate so much?