Stir Plate

[Keifer]

Hey, i was bored yesterday and couldn't do much coz my back was killing me, so i made a stirplate. I used an old 0.12A pc fan and a 0.3A 12V power pack. I tested it with a stainless steel tablespoon (just snapped the spoon part of and used that) and it does whip up a small whirlpool.

So, would using a 0.5A power pack spin it faster? or is the fan going as fast as it will with the 0.3A power pack?
i.e. would i need a stronger fan to get it to spin faster?

Will the fan last while its getting double the current it wants? how far can you push it, like will 1A kill it?

 

[Jye]

Hey Keifer,

You can not make the fan draw more current without upping the voltage and this isnt recommended since the fan is rated for 12V. The stir plate doesnt need to produce a huge whirlpool and only needs to be going fast enough to keep the yeast is suspension, my stir plate does this on less than half power.

Congrats on the stir plate and it sounds like it working great, how about some pics?

Cheers
Jye

 

[Keifer]

Cool thanks for the help, heres some pics, remember i said small whirlpool

 

[Hogan]

Cool thanks for the help, heres some pics, remember i said small whirlpool

That looks the goods Keifer. As Jye says you don't need a vortex that would suck down the Titanic. The purpose of the stir plate is to exchange gases with the liquid. Yours is doing more than enough for this purpose.


Cheers, Hoges.

 

[Keifer]

Cool, now i just want to add a speed dial.

 

[PostModern]

Cool, now i just want to add a speed dial.

Google rheostat.

 

[simpletotoro]

hi
i wish to have a crack at making something like this ...is pic to follow for my questions ...

also to add a variable speed switch do you just buy a dial or something from dick smiths and wire it into the circuit?pic might explain it a little more...



i'm not much chop at things electical so sorry if question seem to be the work of a simpleton
cheers simpletotoro

 

[Jye]

simpletotoro,

That is pretty much it, check out the Tight Arse Stir Plate thread which has heaps of examples and info.

 

[Keifer]

Cool, will look up the stat thingy

Thats just a pc fan with some steel 'liqued nailed' onto it with 2 strong magnets from a busted up 20gig harddrive. The steel is there so i can play with the magnets and also it stops the fan from getting the strong magnetic field.

I moved the fan and magnets up as close as i can to the base and the whirlpool doubled in size

Lastly i ordered a stir magnet and flask from G&G so it should be even better then. Does anyone here use a stirbar from them? I read they withstand high temps so am thinking i can just boil everything in the flask?

 

[Jagungal]

Hey, i was bored yesterday and couldn't do much coz my back was killing me, so i made a stirplate.

How did you go gluing the magnets on ? and how did you go balancing it ? - are you seeing any vibration ?

 

[Keifer]

It took me a couple of goes coz i couldnt wait long enough before playing with it and the glue just came off. Coz i glued the metal to the fan, the magnets can be taken off and re-arranged. I tried all sorts of configurations with 1 and 2 magnets and found in the centre with both magnets as close to the flask went best. Not much vibration when centered

 

[shonky]

I used blu-tak on mine which worked quite well as the magnets were sort of pulled into position naturally when spun. Been running for 18mths and hasn't missed a beat.

One thing to watch Keifer is a bit of spillage. In case you get a lively yeast that overspills your flask you might want to seal the base so that the fan doesn't get gunked - just a thought, as this happened to me last week!

 

[SpillsMostOfIt]

I'm very happy with mine - to the extent that I've published a short blurb on it here:

http://sillybeertricks.blogspot.com/2007/0...stir-plate.html

The relevant bits to this discussion are the use of veroboard and a little jig to place your magnets.

 

[Keifer]

Nice whirlpool Nice tidy unit too, well done.

 

[Keifer]

How much resistance does the Potentiometer have to have?

Here's what im looking at:
http://www.dse.com.au/cgi-bin/dse.fileread...logs/CTG0001111

EDIT:Looks like 500ohm is the go, gonna go have a look at dick smiths