$1 fan controller for stir plate

[alien]

http://ptarmiganlabs.wordpress.com/2013/08/22/one-dollar-variable-fan-controller/

 

[FuzzeWuzze]

Nice except for the need for a heatsink to dissipate all the extra heat.

Not like people have spare heatsinks laying around.

 

[alien]

Easily found in junked appliances if you don't want to spend $0.24. This thing is dissipating 6V @ 0.5A = 3W max. Plus the fan itself helps circulate cold air.