Home made magnetic stirrer

[Vaping Daz]

Evening all.

There is a thread on here somewhere about how best to mix the contents of your homebrew juices, and it got me thinking, a bit! I've just started mixing my own, and already the frequent shaking is getting tedious.
After a little research, and some replies about taping your bottles to drills, reciprocating saws and other fairly dangerous processes etc, I found some very expensive laboratory magnetic stirrers. Some are heated, and although this is still doable, it isn't really in the scope of most people seeing as you're messing with 240 AC volts.
So, I decided to see just how easy it will be to make my own much safer non heated 12 volt DC variable speed magnetic stirrer, for an absolute minimal cost.
Now you could make it even cheaper with bits that you will probably have around your home right now, and save a few bob. I'm not talking about the few necessary electronic components that are needed, because unless you know what is on a scrap PCB, I'd suggest don't bother as these parts are dirt cheaper (pennies), but by using the 12v CPU fan from an old PC, and a tupperware style lunch box for the enclosure.

I've ordered the electronic components, of which cost about £4, and ordered my mixing glass beakers, and some magnetic PTFE stirrer bars. The beakers (2 x 100ml) and 5 x PTFE stir bars cost around £10 from a laboratory supplier. I'd rather buy from a lab supplier as I know that they're going to be clean and unused. Ebay sell them, but they are dearer and I don't know their history.

I have an old 12v PC CPU fan that I stripped out of an old computer which is about 4" wide, and I have a plastic project box. You'll need some rare earth magnets (pennies to buy), a resistor, a capacitor, a potentiometer, an LM317 linear voltage regulator, a 12v power supply like the type that plugs into the wall to power small electrical items (becareful if using a PC power supply as these can be anything from 12v upto 20v, although the LM317 linear voltage regulator should handle the power, it will get hot and you may need to use a heatsink to dissipate the heat from the LM317 chip. Best be safe, and stay with a 12v supply.

The rare earth magnet can also be found in the CD drive of the PC, but it will involve breaking that down to remove it. It's probably easier just to buy some small 3 - 5mm round ones.

Once you've gathered your supplies, the actual build should take no more than an hour or so.

Once I've got all my bits I will do a photo guide on how to build your own. You could save a great deal by building your own, and it will be fun to build.

Anyone interested in this?

Cheers

Daz

 

[daz_app]

Top tinkering right there. I think I'll stick to my £1 coffee frother, but fair play to you chap. I'd be interested to see the results.

 

[NINman]

Dremel with a cotton bud chopped at each end
splice the cotton bud at one end to act as a mixer

 

[EmbraSewerRat]

Couple of bent bits of 316 steel wire put into drill, select slow speed......[emoji106]

 

[Vaping Daz]

But this is fun! I'll be making 50ml's at a time, and I can leave this going without being present if necessary. So while I'll cleaning up and putting my ingredients away, this can be left going without having to hold anything or worry about it falling over.
I enjoy messing with electronics and tinkering as my name sake above says I built the programmable electronic mapping control unit for my kit-car's ignition a few years back, and a bunch of portable power stations for camping/hiking/fishing etc. although I do not have an electronics background, my 2 brothers do, but I'll find a schematic diagram and build from there, or just try things and see if they work.
If this works, which it will, I'll post the details of the components used, part numbers etc. They are all available from Maplins or similar electronics supplier., and are dirt cheap. Some as cheap as 9p. Probably the most expensive part is the project box, but this could be something as simple as a 1 ltr ice cream tub!
Watch this space.

 

[Loco]

I'm interested to see how this comes out. Id planned on making one and have done some research. The main problem have noticed, is that some builds struggle with high vg (worse in this weather). If you have some success I will be copying you quickly! Good luck

 

[Loco]

Any clue on what impacts the strength of the spin...Thinking about it, could it just be down to magnet strength?

 

[davroz]

Any clue on what impacts the strength of the spin...Thinking about it, could it just be down to magnet strength?

Magnet strength and keeping the magnets as close as possible together. See http://www.thingiverse.com/thing:1663540/#files

 

[Vaping Daz]

Magnet strength and keeping the magnets as close as possible together. See http://www.thingiverse.com/thing:1663540/#files

The one in the above post is very primitive, and you're stuck with whatever speed each voltage allows. The one I'm building (95% built now) has a variable speed controller controlled by an IC chip, so it is a protected circuit as it has a thermal cut-out if things get too hot. On the chip I've mounted a heatsink which sits under the fan, so it has cooling as well.
It has a 1A surge fuse on the power in as well. All I've got left to do is mount the fan and drill in some ventilation holes.

I'm very happy with it. Just waiting for my beakers and stir bars to arrive, but I've been messing with around with a home made stir bar made from a magnet and 2 small screws, and a Pyrex jug of water. Lol it mixes nice drinks

In regards to the high VG mixes, I reckon a bigger stir bar should be ok and a high RPM. I prefer 40% VG so it shouldn't matter much to me, but no doubt I'll try 50ml's of pure VG just to see how it copes.

Stay tuned folks!

 

[Vaping Daz]

Magnetic Stirrer Build part 1.

Well, here it is folks. Before we get onto the video, I like to apologise for the many "Umms" and "Ers", but I'm on meds that affect my cognitive function, and memory loss and forgetfulness is part of the side effects unfortunately.
Everything I used was from Maplin. I will list the parts and their values if you wish to do the same build, however please note that the parts I used were found on somebody else's build, and it is your choice to either go with me or research your own build. Either way I will not be held liable if you injury yourself or burn your house down! It is your decision to build it. I am not making you build it, ok?

So here's the video:



So parts used:

Plastic project box. This only needs to be as bigger (or a little bigger than the fan you use. Tupperware tub or similar will also work.
12v PC fan. Mine is 94mm wide and removed from an old desktop PC.
2.5mm jack plug and socket.
20mm in-line PCB fuse holder(or board mount as they are also called), and a 1A quick blow glass fuse.
12v (or higher) LED rocker switch. Doesn't have to be an LED type, a normal rocker, push or toggle will do.
1x 1k ohm linear single gang potentiometer.
An LM317T 1.5A 3 terminal adjustable voltage regulator, TO220 style case.
0.1µF 36v 330 ohm Tantulam bead capacitor
1µF 100v 85°C Electrolytic capacitor.
Rare earth magnets. I used 2 x 3mm x 2mm magnets.
PTFE stir bars.
Some wire! I used 24 gauge 6 amp wire as that's all I had, but that is a bit heavy for this work, hence why I used a 1 amp quick blow fuse.

12v power adaptor. You may have a few of these laying around. (see below)
Resistor/s. See below also.

Ok, the power adaptor will tell you the output in Volts and mah (milliamps) . Look for one with 12volts and enough milliamps to power the fan. The fan "hopefully" will tell you also what volts (usually 12v, and also what milliamps it needs. My power adaptor says 500 milliamps (or 0.5 amps), and my fan needs 550 milliamps, however it is sufficient to power the fan,. So long as the difference is within 100 milliamp it should be fine.

Ok, You're saying, "Well, all that's good, but how do I hook it all up?" Here is where I got into a bit of trouble. I followed one schematic diagram, but it was wrong, and it didn't work, so after some head scratching I found that the diagram was wrong, and after a short time of de-soldering and starting again, it worked!

Resistors:

Now, following the original diagram, I used a 330 ohm resistor, however this restricts the voltage out of the LM317T regulator on my set up using the values of the components shown above. The output voltage is around 5.1v. Now in all truth, this is absolutely fine from what I can tell using the mixing jug in the video, but once the ingredients are in place instead of the water, I may need a higher voltage. We'll wait and see. I may buy a few of each resistor around the range of 12 - 150 ohms, just in case. Furthermore, making the fan spin faster (more volts) may cause a need for stronger, bigger rare earth magnets. I have some spare bigger ones so can always swap them over.

Here is a grid showing values of R1 (the resistor) and R2 (the potentiometer), and the maximum average voltage that will flow from the LM317T to the fan.

R1 vs R2 Grid
R1 150 180 220 240 270 330 370 390 470

R2
68 1.82 1.72 1.64 1.60 1.56 1.51 1.48 1.47 1.43
82 1.93 1.82 1.72 1.68 1.63 1.56 1.53 1.51 1.47
100 2.08 1.94 1.82 1.77 1.71 1.63 1.59 1.57 1.52
120 2.25 2.08 1.93 1.88 1.81 1.70 1.66 1.63 1.57
150 2.50 2.29 2.10 2.03 1.94 1.82 1.76 1.73 1.65
180 2.75 2.50 2.27 2.19 2.08 1.93 1.86 1.83 1.73
220 3.08 2.78 2.50 2.40 2.27 2.08 1.99 1.96 1.84
240 3.25 2.92 2.61 2.50 2.36 2.16 2.06 2.02 1.89
270 3.50 3.13 2.78 2.66 2.50 2.27 2.16 2.12 1.97
330 4.00 3.54 3.13 2.97 2.78 2.50 2.36 2.31 2.13
370 4.33 3.82 3.35 3.18 2.96 2.65 2.50 2.44 2.23
390 4.50 3.96 3.47 3.28 3.06 2.73 2.57 2.50 2.29
470 5.17 4.51 3.92 3.70 3.43 3.03 2.84 2.76 2.50
560 5.92 5.14 4.43 4.17 3.84 3.37 3.14 3.04 2.74
680 6.92 5.97 5.11 4.79 4.40 3.83 3.55 3.43 3.06
820 8.08 6.94 5.91 5.52 5.05 4.36 4.02 3.88 3.43
1000 9.58 8.19 6.93 6.46 5.88 5.04 4.63 4.46 3.91
1200 11.25 9.58 8.07 7.50 6.81 5.80 5.30 5.10 4.44
1500 13.75 11.67 9.77 9.06 8.19 6.93 6.32 6.06 5.24
1800 16.25 13.75 11.48 10.63 9.58 8.07 7.33 7.02 6.04
2200 19.58 16.53 13.75 12.71 11.44 9.58 8.68 8.30 7.10
2700 23.75 20.00 16.59 15.31 13.75 11.48 10.37 9.90 8.43
3300 28.75 24.17 20.00 18.44 16.53 13.75 12.40 11.83 10.03

here is a schematic diagram of the circuit:

Capacitors:

Now technically these aren't strictly necessary, but they do help smooth out the wavelength of the DC current from the power adaptor to the LM317T chip. The diagram above only shows one capacitor, the part that shows 0.1uF. I fitted one x 1.0uF immediately before the fan, across the "vOUT" line (top line) and the GROUND line (that's the bottom line in the diagram). A capacitor stores and releases power very quickly and it helps smooth out the pulses found in DC current, to keep the current as constant as is possible.
Hopefully I have explained as best as I could, and although I have no electronics background, I have gleaned some knowledge from reading stuff on the net over the years, oh, and some trial and error lol. However, the above components I have posted do all work together, but as stated I may swap out the 330 ohm resistor for a smaller value one.

Well, that's all for tonight, it is 2am after all. I'll post some photos of the build, and I'll do a line drawing as this schematic may confuse you somewhat if you're not used to them.

Cheers, and stay tuned for Part 2