Home Made Stir Plate

[spook123_uk]

Now I'm really getting into this brewing malarky, I've turned my attention to yeast starters ready for my next brew. Whilst in the shed the other day, I noticed I had a spare project box and an old gutted computer. so I decided to make a stir plate.
I used a 92mm case fan and the control board with knob from the old case. I fitted couple of switches, one to turn on and off and another with a resistor wired across it to halve the voltage (and speed) of the fan for when a more gentle spin is required.
The magnet glued to the top of the fan is a really strong rare earth magnet (neodymium) which I liberated from the inside of an old hard drive.
I got a cheap 2L conical flask made from Borosilicate glass and a cheap magnetic stir bar to complete it.

Job done. If I was buying the kit, it would have been around £15 - £20 on the parts for the stir plate.

Flask was £17 delivered and the stir bar was £3. I'd need the flask even if I was making a starter without the plate I reckon.

 

[TheRedDarren]

Super!
That's a cracking effort mate.
I'll be making one myself soon, god help me!
Is it 12v?

 

[spook123_uk]

It is 12V. I found an old mains adaptor and used that.

 

[mereside]

that is a super job I have just made mine yesterday and the stir bar arrived this morning so will have to post up,

 

[brumbrew]

I've got one to, buts it's in a wooden box, Probs not best for higiene though.

I'll take some pics when I get home unless I have some on my phone.

Great effort, looks better than mine. I only make starters here and there, should do it more really since I have the kit.

I find the trick is getting it level and centered to make the proper vortex.

 

[ManseMasher]

Mine is housed in a cigar box! What I did find initially was the stir bar kept getting thrown off. I found by increasing the distance between the magnet and the bottom of the flask this stopped happening. So now the flask sits on a couple of washers.

 

[johnnyboy1965]

Good job, I built one about two years ago (everyone should build one) if I can do it with very limited knowledge of tech/engineering, so can you.
OP make sure the magnet is strong enough. Atrial with water is great, but when the yeast starts to multiply the starter gets thicker and thicker and might "throw" the stir bar.

 

[johnnyboy1965]

I've got one to, buts it's in a wooden box, Probs not best for higiene though.

I'll take some pics when I get home unless I have some on my phone.

Great effort, looks better than mine. I only make starters here and there, should do it more really since I have the kit.

I find the trick is getting it level and centered to make the proper vortex.

Absoltley no probs with hygiene....its the inside of the flask that matters

 

[mereside]

Here's my effort from gear I had from other projects,

 

[GHW]

Anyone want to make me one?! My diy skills were stretched by my wort chiller (as its appearance bears testament to).

If so, let me know your price! I'll pay postage too obvs.

 

[DethApostle]

It is 12V. I found an old mains adaptor and used that.

What size is the project box you used Spook123?
I built mine but the box is only just big enough for a 1l flask nevermind a 2l one! I'm doing a re-build to add a power jack socket so will move to a bigger box at the same time!
Also, is that the potentiometer taken out of a cheap ebay dimmer switch?

Cheers
DA

 

[spook123_uk]

It's roughly 22cm x 15cm x 6cm. Pretty sure it came from maplin

 

[DethApostle]

Nice one, thanks Spook.
DA

 

[spook123_uk]

sorry. completely missed the bit about the pot. It's taken off an old fan control panel from a PC.
You can do the same thing with a pot and voltage regulator I think... or even just a pot.

 

[DethApostle]

Yeah. The pot I use doesn't dial the speed down to nil for some reason so my stirplate is starts at Medium and goes to Very Fast! Still works on Medium but it's not ideal!
Is this because of the amount of voltage being supplied? (I also have the same issue with my 'Solar pump in a box' build so would be useful to nail this issue!)

DA

 

[spook123_uk]

It is. You could add another resistor to bring it down more. I think there should really be a voltage regulator on it but I didn't bother with mine. You can google reducing fan speeds with resistors and there are calculators out there.. Basically the lower the voltage, the slower the speed.
Something you could try... Plug in a 9v psu instead of a 12v one. Max speed will be slower and also the slowest speed would be slower.
I'm no electronics expert.. I just google stuff and know what tends to work!

 

[DethApostle]

Me neither! I'll see if I can track down a lower voltage PSU at home to experiment!

DA