12v for a fan on extruder?

Is there anywhere on the rambo board that I can bleed off 12v for a fan, or an easy way we know of to get to 12v? I’m upgrading my extruders to the E3D Titan and v6 nozzles, and the fans they supply are 12v. I’d prefer not to have to fork out more $$$ for 24v 30mm fans for the heat sinks. I’m comfortable with soldering, electronics etc, so I can pull the 12v from somewhere on the board. Worst case I’ll have to get a voltage stepper or something and install that.

The RAMBo has 24 volts supplied to it, so it has 5 volts for the digital logic on board and then 24 volts(supplied external voltage) for the steppers and fans. No 12 volts! That is only a missed point that many other printers that use the same RAMBo control board use 12 volt supplies instead of the 24 volts ones used by AO.

Thanks for the info.

For anyone who may search the forums later looking for the same answer, what I did was, since I do not use a 2nd extruder (and likely won’t), I hijacked the Extruder 1 Fan output, ran a wire down to the extruder, and tweaked the firmware to accept the P option on the M106/107 fan Gcode. By capping the fan ‘speed’ to 120, it outputs 12v to the fan. PWM for the win.

You can also use a 12v Zener Diode to bring the voltage down from 24 to 12v.
Mirage335 explained it here -
https://forum.lulzbot.com/t/a-suitable-40mm-24v-fan/3046/1
He suggested using 2x6v Zenners in series. I found some 12v Zeners of a similar amperage rating.
This would, I think, preclude the need to Limit the fans in firmware.


Best regards,
PCH