A stir plate is a really useful tool to help make yeast starter, but they can be very costly. 
The aim of this post is to provide you with the a simple guide to to convert a USB desktop fan cooler into a stipulate, with minimal tools and materials.
Varying wildly in price the cheapest i’ve seen is this one for around £30 but they can go way higher than that, my stipulate came in at around £9.00 and works perfectly, there is integrated speed control and it plugs into a usb phone charger, which makes it ideal for all sizes of yeast starter mine can easily cope with 2l using a big bar.
Tools
- Small spanner
- Strong Glue
- Thermaltake A1888 – computer cooling components
- Strong magnets – these can be taken from an old HDD drive you may have around or purchased from Amazon
- A few smaller screws and nuts – you use these to reattach a guard that acts as a platform for your flask, you may need some small washers too to add more space between the base of the flask
and the magnet.
The instructions I followed are here over on Homebrew talk and they’re so easy to follow i won’t reinvent them but what you end up with is a very cheap stir plate that works really well ad only take a 5-10 mins to prepare.
There are of course other options too that would probably work too.
£5.99 option will require some imagination
Similar design but no speed control – might cause difficulty with the stir bar jumping off
