Help for choosing the right module - pmw

Hi,

I want to control a 12V pc fan speed with my arduino yun.

I’m gonna plug the fans in a 24V DC power supply I’d like to variate the voltage (or pulse).

I need some help for choosing the right module. It won’t use more than 2 amps.

Thanks for helping

Here are some useful motor control modules. They take up to 3 amps and 5 to 35 volt separate power for your motor.

http://www.ebay.com/sch/i.html?_from=R40&_trksid=p2050601.m570.l1313.TR10.TRC1.A0.H0.Xh+bridge.TRS0&_nkw=h+bridge&_sacat=0