stirring plate

[Cellar_Rat]

I want to set up a yeast propagator, and continual steering induces more air, and will increase the cell count by 50%

I have seen stirrers on eBay for 60 quid and upwards.

Has anybody made one out of the computer fan lying on its back, with two magnets glued to 2 opposing blades (for balance) with the rest removed?

[Delmonteman]

No but lots of people have if you google around. I have seen plenty of pics of homemade ones which people use for stepping up starters etc.

[Rich]

Yup, very successfully too.

8cm computer fan, large steel washer glued onto it centrally onto it Magnets attached to the washer. Fan wires lead out to the side of the box and are terminated in a socket. Box is a small square plastic jobby, fan held in some long M4 (?) screws and held in place by nuts. This is fed by an adjustable (universal) power supply so you can adjust the voltage to adjust the fan speed.

It powers my conical flask collection from 50ml upto 3000ml.

Get the right sort of stir bars to make it work properly. I got some with a central ring that they should spin on. These are crap, so I carefully removed the ring and they work a lot better. Also got one from Koomber that works a treat in my 1 litre flask.

[Cellar_Rat]

Hadn't thought about the universal power supply. Good call thanks.

[Cellar_Rat]

Are the stir bars available on eBay - could you point me in the directions of the right ones please?

[lockwood1956]

here you go

http://www.ebay.co.uk/itm/Set-4-magnetic-stirrer-bar-stir-mixer-mix-spin-bars-PTFE-TEFLON-coated-New-/260995781298?pt=LH_DefaultDomain_0&hash=item3cc48f92b2