Fan extension board for ramps 1.4

If you decide to upgrade your 3d printer with a double extruder and a heat bed, all output ports (D8, D9, D10) will be used. In this case, there are no more possibilities to connect a fan controlled by your RAMPS 1.4 firmware. However, in Sprinter / Marlin there is an option (Marlin: BOARD = 34) which redirects the fans to the D4 output. But this solution needs a driver to work.

The RRD-FAN-EXTENDER is exactly what you need in this case. It is the plug and play solution for assembling and powering your fans for configurations with double extruders and RAMPS 1.4. The RRD-FAN-EXTENDER is equipped with 2 controllable PWM channels (D6 / D11). The second channel can be used for another fan (for example to cool the pilot step by step or your room if you print in PLA).

The RRD FAN EXTENDER is compatible with the BL Touch. This still requires additional modifications (see below)
Features of the RRD Fan Extender:

• Number of controllable channels (PWM): 2 (D6 / D11)

• Max intensity per channel: 0.5A

• Input voltage: 12V or 5 V

• Compatible: Ramps 1.4 with Marlin (MOTHERBOARD 34), Sprinter (#define FAN_PIN 4 'in' pins.h '). For other versions, internet research will be necessary to validate compatibility.


BLTouch: Automatic heating bed leveling sensor for 3D printers.

RAMPS1.4 + RRD Fan Extender

You will find in the images of this article the wiring diagram.

It will be necessary to modify the value of the RRD Fan Extender as below.

D11 -> D5
D6 -> D4