Brand chuangzhuo Model RRD Quantity 1 Piece Color White Material CCL+PCB board Chipset PWM English Manual / Spec No Other Features If you build or upgrade your printer with/to DUAL-EXTRUSION (2 extruder) including a heated bed all the output ports (D8D9D10) will be used. In this case there is not 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 play 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 controllabe 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). Features: max 20V 2 (PWM controllable) channels (D6/D11) max 0.5A per channel (enough for a really big fan) flexible output voltage (you can connect the RRD-FAN-EXTENDER to 12V5V... in order to support the output voltage you need) each channel has a fly back diode easy setup (plug and play) already supported by Marlin firmware (choose "#define MOTHERBOARD 34") easy to adapapt to other firmware (e.g. Sprinter: just change "#define FAN_PIN 6" in "pins.h") TEST Test the Editing Reprap Ramps1.4 RRD Fan Extender Hardware required: -Ramps 1.4 -Mega2560 1.Upload Test for Editing Reprap Ramps1.4 RRD Fan Extender to your Mega. void setup() { pinMode(11 OUTPUT); pinMode(6 OUTPUT); } void loop() { digitalWrite(11 HIGH); digitalWrite(6 LOW); delay(5000); digitalWrite(11 LOW); digitalWrite(6 HIGH); delay(5000); } 2.Connecting 3. Power up two fans will take turns to rotate Packing List 1 x PCF8574 IO Expansion Board