A magnetic stirrer is simply a box with a rotating magnet. Homebrewers use magnetic stirrers to start yeast colonies but the community is generally unwilling to pay the exorbitant prices charged by scientific suppliers for these relatively simple devices. Some homebrewers decided to build their own stirrers by glueing powerful magnets to old PC fans mounted in tupperware containers. For an upcoming field experiment, I'll need two battery-powered stirrers. Unfortunately, Cole Parmer is charging $437 for one of these units. In this guide, I'll build two battery-powered stirrers using techniques developed by the homebrewing community. The goal of this project is to save the lab ~$700. I modified this build from a post on the Red Kettle Brew Blog.
Laboratory grade peristaltic pumps are unbelievably expensive. A variable speed pump drive from Masterflex (Cole Parmer) will cost $1000-$5000. Don't forget to add another $200-$1500 for the pump head. Watson Marlow and Thermo Scientific sell similar products but they are just as expensive. Fortunately, there is an alternative.
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R. Di Rocco |