Tight Arse Stir Plate

[rich_lamb]

Has anyone made a heat function on one of theses?

I stick the whole thing in an esky with a heatpad connected to a timer switch - not accurate heat control but works fine for starters.

As my flask sticks out the top of the esky, I loosely cover it all with gladwrap to keep the heat in. Looks as ugly as crap, but works OK for the couple of days it's needed.

 

[Sammus]

Has anyone made a heat function on one of theses?

Not intentionally, but with mine turned all the way up if I'm stirring a lot (more than 2L) it warms up significantly. I can turn it down very slightly or put some thin insulating board between the stirrer and flask and it doesnt get much heat. Straight on the stirrer cranked right up and it seems to sit at a comfy 25-30C. I think ill add an exhause fan to my stirrer enclosure, shouldn't have to worry about overheating anything then.

 

[pdilley]

Would passive venting, drilled holes around top of enclosure work for you?

Im thinking of what to do with mine as Ive got a circular cutout on top to get the magnets up close to the jar as possible but plan to put a small plastic tub over and then the jar with stirbar to contain any spill overs so Ill be back to having to think about venting heat again.

I have not thought about heat as thats what Id worry about for mycelium but not yeast. Im thinking a small temperature controlled cabinet that the stir bar unit as a whole would fit inside while running. Or metal top and looking around pet shops for some electic heating item to mod into use for heating. eBay has temp probe / controllers for about $60 Aus and up that could be adapted but means probe in wort unless probe against glass and adjust for small temp
differential.

Cheers,
Brewer Pete

 

[Batz]

Would passive venting, drilled holes around top of enclosure work for you?


Cheers,
Brewer Pete

I did this soon after using mine, the heat build up was a bit concerning. It still gets warm with the vents,fans where not meant to be locked in boxes.It also necessary to drill a couple of holes in the bottom so the air can flow through the box of course.
It's something of a plus as the weather cools.

Batz

 

[Sammus]

Yeah I've got holes, they helped, but not enough The heat isn't really bad thing for propogation anyway I think.

 

[pdilley]

It would look quite the sight, but holes drilled and stuffed with drinking straws would vent the heat out far away from the immediate area around the stir plate unit and the jar

 

[LethalCorpse]

Now it's getting stupid. You've got an operable fan there. How had can it really be to use it to produce some airflow which passes over the heatsink on your regulator (or pot or whatever other thing you've got dropping your supply voltage)

 

[newguy]

Has anyone made a heat function on one of theses?

You could do a poor man's heater. All you need is some metal - standard kitchen grade tin/aluminum foil would do. Place a layer of tin foil directly under your starter flask. This method is based on electrical generators/motors whereby a changing magnetic field induces a voltage in a conductor, which in turn creates current in the conductor, which creates heat. You may have to experiment with the size of the foil sheet, or perhaps the shape - I'm thinking long narrow rectangle instead of a circle or square may be better. One thing you have to be aware of is that the foil will load the fan. Worst case is that it may not be able to start, go with a smaller size or different geometry if this is the case. Another issue is that you'll have to do some trial and error to find a right size/geometry to give you the heating result you want.

 

[pdilley]

Got a weekend night to myself away from SWMBO so started noodling around in the shed and by late evening got stuck into pulling the drill press out of storage and reassembling it.

Prototype 240Volt AC Stirplate.

Cooling holes on all sides, large venting holes below.

I have ditched the top for now as will use either clear acrylic top or simple idea of using a rubbermaid or tupperware style container, square in place of the lid. The Flask sits in the tupperware container which is a spill containment receptacle in case of excessive foaming.

I have to go look at plastic containers and see how much if at all they depress under different weights to build the magnetic disc height to get the magnets right up against the plastic container while not touching. This should get the magnets up close as possible to the flask while keeping them as far away from the fan as possible.

Full 240 Volt Shaded Pole Fan controlling Triac with 240Volt switch and noise suppression circuitry.

I have a conduit box I will cut down to make a sealed environment in which to do all the wiring. Thinking about a silicone seal around the Triac compression fittings.

As you can see this is a monster fan with enough guts to pull through some large batches. Not a bad eBay buy at $14 compared to Jar Car.

 

[MCT]

It may have been covered earlier but 27 is a lot of pages
How fast does the whirlpool have to be? I've just built my stir plate and have a 2 litre starter on it but I can't get much of a vortex/cyclone going without the bar shooting off, but it is still mixing everything around well. Is this all I really need to achieve? Am I just sposed to keep everything moving to stop the boor buggers from having a rest, or is the idea to keep introducing oxygen into the wort to keep them breeding?

 

[Sammus]

Now it's getting stupid. You've got an operable fan there. How had can it really be to use it to produce some airflow which passes over the heatsink on your regulator (or pot or whatever other thing you've got dropping your supply voltage)

I'm not sure it's the reg getting hot - I can't see how to heatsink it anyway, its about 1cm^2 and enlosed in the plastic behind the switch (it is a ceiling fan controller, all 240V here). I don't know/cant be bothered looking at what I might've claimed earlier, but I've recently realised it is only when its turned up that it heats up, and the heat is quite obviously coming from the fan itself - you can tell it is definitely straining under the load, lift the flask off and it nearly doubles in speed.

Have it a hair off full throttle and it doesnt heat up at all. Using a slightly smaller stir bar that I found, which actually stirs better, also reduces the load significantly and seems to reduce heating.

 

[pdilley]

You do not need a vortex going all the way down to the stirbar, or a violent vortex, just get one to form and be stable and you are set.

We just had a presentation on stir plates and preparing starters at the Canberra Brewers Club which was really good. What I came away with was with the number of steppings you need to do perform in order to prepare a starter for the correct number of yeast cells to do all the beer styles out there will require a 5 Litre flask. I was going to buy a 3 L but now I found out in time to get on the clubs next flask order for 5's.

The box is undergoing painting but should be ready to use in another week. I was predicting by christmas with SWMBO taking away all my mad scientist time but ive got a reprieve

A very boring lab grey colour for the choice in paint.

 

[MCT]

Look forward to seeing it Pete, thanks for the info. The vortex I get is probably only about 5mm deep, pathetic really, but the whole wort is moving fast enough to stop anything settling.
What is the main point of a stir plate? To keep yeast in suspension or to oxygenate via a vortex?

 

[pdilley]

Did I mention I like AC over DC

I saw a DC unit with 555 timer (better than the RC+pot+LM317 circuit) with the 5L flask but the flask was mostly empty so we could not see where the limits would be before the DC fan reached its torque limits regarding liquid volume in the flask.

The main purpose is oxygenating the wort so the yeast can all be shifted into respiratory metabolism and bud and reproduce like crazy.

Cheers,
Brewer Pete

PS 5mm sounds like you might be forming a dimple and not a true vortex. Picture would help.

 

[sanmerah]

Went to Jaycar to get all the bits for this project - thanks everyone for your input. Very valuable and interesting thread. Even after providing the exact part codes from this forum they managed to get the wrong

- potentiometer
- IC

I got a log pot and something that was in the wrong box. Luckily I checked in the shop and the assistant didn't apologise for the mistakes but blamed bad stocking procedure ... anyhow worth double checking ..

Plugged everything together and it is working a treat, just waiting for a new soldering iron (my old one needed upgrading it seems, thanks ebay) to arrive along with the stir rod and flasks (thanks Grain and Grape).

Happy stirring...

 

[LethalCorpse]

Yeah, Jaycar stores often have their passive components and semiconductors mixed up. I worked there for four years, three as manager, and the only time we had company wide stocktaking of those components was in my first year. I did my own stocktakes of those when we could, but the reasoning, from a business perspective, is actually fairly sound - it just isn't economically feasible to count all the thousands of little components and make sure they're in the right bins. Good staff will recognise that the bits are likely to be mixed up and check each part as they sell them to you, sorting bins or adjusting stock levels as necessary, but it is retail, and they can't all be good staff. It pays to check that the bits they give you are the bits you asked for.

BTW, to check pots, make sure the pot they give you is marked with a B before the resistor value (B1k or whatever it was I recommended way back when), not an A. A logarithmic pot will still work, but will be much more difficult to control.

 

[A3k]

Hi guys,
I've got all the component for a stir plate, but don't have a proper stir bar. I've got a ferite rod, but i think it's too chunky for this purpose and will rattle like crazy.

Does anyone know where abouts in adelaide (preferably just southish) i can get a stir plate.

Sorry if this has been covered in this thread, but i couldn't find it in the 14 or so pages. It's the only thing holding me back from being able to use the stir plate.

Cheers,
Al

 

[pdilley]

Look forward to seeing it Pete, thanks for the info.

The latest of the prototype AC StirPlate. -- what started off as a 12Volt Computer Fan project changed midway to AC design for more grunt.
-- Dedicated to finding my battery charger and getting the camera batteries charged again


The first shot shows the interior "Post" design of the box. By running nuts and washers to specific heights and then locking in place a platform is built for the AC fan to slide down to towards a predetermined depth.

I do not plan on having to adjust the fan past the experiementation phase, then simple drop of lock-tite will help keep the final locked in height from shifting.

Reverse washer and nut allows the fan to be clamped down firmly. Once in place, it will not be going anywhere.

Already bolted on is a cut down version of an AC power junction box. All AC wiring will be contained in this box, and the AC cord will be routed to this box. Keeps open wires away from inquiring fingers.



Now I've put in the fan, put some magnets on top, and just placed the AC Triac Fan Controller with RFI filters in the other side to get a general idea of what it will all look like. All edges will light up perfectly from top of box to Junction box to AC Fan Triac controller so a clear acrylic sheet, a rubbermaid tub, or with the giant size, a 5L flask could sit easily atop everything and have the magnets right up next to the glass and the stirbar.

12 Volt DC computer fan shown for scale comparison to the AC fan size.



Quick mockup of the front view showing Power ON/OFF control plus fan-speed control.

12 Volt DC computer fan shown for scale comparison.



Experimenting with venting holes on this box design. Will test out after stirring up a monster sized starter to see how much heat, if any is released from the AC gear.

EDIT: However with the directional air flow from the fan being downwards, I'm still planning on cutting out a large circular hole on the bottom to vent air which will be drawn in through the side air holes. That should eleviate any heat build-up worries.

Cheers,
Brewer Pete

 

[sanmerah]

Lethal, thanks for your input to this thread for your circuit that I used and thanks to all who contributed, I must have read all 27 pages a couple of times!!

Here is the finished product:

Magnets: Rare earth from Jaycar, 4 doubled up.

Circuit: Lethal Circuit, with 2 capacitors
Power: Nokia charger 3.7v output - still manages to drive the 12v fan perfectly
FAN: taken from a old computer case (includes coloured LEDs)
Case: slimline 2.5ltr freezer pantry plastic case from Foodland. Ideal size, and shape. Originally considered leftover 3kg Honey container, but converted it into a waterproof housing just in case.

Glass vessel: standard flat bottom flask (works a treat)

Glass vessel: works with 2ltr old sherry bottles with concave base

Note: the Magnetic Stir Rod has No ring, is silent in operation!

 

[LethalCorpse]

Happy to help, glad it worked out so well for you.

Must admit i'm a bit stunned you've got it working off a 3.7V supply. The LM317 has a 2V minimum dropout, which means less than 2V that's going to your load. a 12V fan shouldn't spin up at all with that supply, especially with such a heavy load.