Description If you build or upgrade your printer with to DUAL EXTRUSION 2 extruders including a heated bed all the output ports D8 D9 D10 will be used In this case there is no option to connect a firmware controlled FAN to RAMPS board directly However in Sprinter Marlin firmware there is an option already Marlin BOARD 34 which redirects the FAN to RAMPS output D4 But this solution needs a buffer driver in order to work The RRD FAN EXTENDER is exactly what you need in this case It is a plug and plays solution to mount the FAN for DUAL EXTRUSION setups with RAMPS1 4 But instead of adding only one additional output port the RRD FAN EXTENDER is equipped with 2 PWM controllable channels D6 D11 The second channel can be used for another fan e g to cool the stepper driver or for adding light control e g add dimmable LED light to your machine Specifications Support Max 20V 2 PWM controllable channels D6 D11 Easy to install Plug and Play Support per channel Max 0 5A enough for a big fan Flexible output voltage you can connect the RRD FAN EXTENDER to 12V 5V in order to support the output voltage you need Already supported by Marlin firmware choose define MOTHERBOARD 34 Easy to adapt to other firmware e g Sprinter just change define FAN PIN 6 in pins h Features 1 You need Marlin firmware v3 or newer If you are using the older firmware you must re flash your board 2 Power up two connecting fans will take turns to rotate 3 Can