Were can I connect a cooling fan on Ramps 1.4 for Polulu

My Y axis driver is overheating and shutting down.

I have a small 12v 40mm fan I would like to use to cool them down but im not sure were to connect it.
I dont want to connect it to the voltage output for extruder 2 or the heat bed because I need those.

Can I simply connect the fan in parallel with the 12v input comming from the Power supply to the ramps?

More specificaly the 12-35 VDC in on this schematic: [reprap.org]
Should I hook it up in parallel to the 5a or 11a input?

Or is there a better way to do this?

I could drive a new wire all the way from the psu but id rather not do that, I want to keep things clean.

Thanks for your help.

I run a 80mm fan on my Ramps board, and power it directly off 12V from the PSU, which would be identical to powering in in parallel from the 12 V to the board as you suggest.

Ditto on my "always-on" fan that I have pointed at my extruder thermal break. I just tapped it off of the power connector that goes into the RAMPS board. Which one doesn't matter since it is before the breakers. I just have to consider the overall capacity of my PSU (which is 30 amps).

Thanks to you both for confirming this.

With electricity and electronics i prefer to double check everything.

Thanks again and happy new year to everyone!

theCrazy,

Another way to do this would be to tap into your Aux pins on your ramps board. Cool thing about this is you can set up G-code then to turn the fan on/off as well as control the speed of the fan. This is what I do for both my extruder motor fan, and my driver board fan.


Example: under Aux-2 (note I do this using an Azteeg X3, this should work the same but before wiring stuff up try running the code and testing the output with a multi meter)

Hook the negative of your fan the ground and positive to D44 (arduino PWM digital pin). If you want to turn on your fan you can send G-code like so

M42 P44 S255 = M42 (command to talk to specific pins) P44 (the pin you are talking to) S255 (% of voltage to be supplied 0=none 255 = full).
So at the start of your g-code you could put M42 P44 S255 to turn on the fan, then M42 P44 S0 to turn off the fan when print is complete.

It's not a good idea to connect a motor directly to the arduino. The arduino has limited current capacity, plus the possible current induced by the motor when it starts up or shuts off can damage the arduino. A simple circuit based on a single transistor is a much safer way to go.