ZAPOOS
RAMPS 1.4 RRD Fan Extender for Dual-Extrusion, 3D Printer, Reprap
Module Max 20V Max 0.5A per channel (enough for a really big fan) Flexible output voltage (you can connect the RRD-FAN-EXTENDER to 12V,5V,... in order to support The output voltage you need) Each channel has a fly back diode Easy to adapapt to other firmware (e.g. Sprinter: just change "#define FAN_...
$5.49