Installing the power supply

The headbed and the extruder hotend both need a lot of power. A cheap solution is a normal PC power supply. Besides the standard 12V it supplies 5V and 3.3V, which can be used for powering LEDS and other stuff.

I used a Thermaltake Munich 430W ATX 2.3. The cooling fan is silent, and it doesn’t need the 5V resistor as base load.


The ATX pinout of the power supply is as below. In order to switch on the power supply you have to short wire pin 14 (PS_on) with ground (GND).


To make thinks easier I connected an ATX Female pin adapter to the standard ATX male adapter of the power supply.


Then I cut the two wires on pin 13 and 14, and stripped them.


The next step was soldering them to a switch.


To feed the RAMPS, the headbed and the etruder hotend, you need the AMP ATX 12v Power Connector, that is, the wires connected to it. There are four wires on that connector; two yellow and two black.


Cut the wires from the connector and strip the wires


Connect the four wires to the green 12V power connectors of the RAMPS board


Tie-wrap the rest of the cables nicely together.


You can cut all the wires you don’t need, but I chose to bind them together and stack them away under the power supply, for possibly later use.


Take a tiny sheet of plywood, measure and saw.


Drill and countersink the screw holes


Stack the wires under the power supply unit and mount the plywood plank.


An extra LED

You won’t need it, but I thought it would be nice to have some sort of indication my 3D printer was turned on. So I attached a LED to the power supply. A standard LED needs to have a resistor to work with 5V. I used to calculate the resistance of this resistor.

A typical red LED has the following characteristics:

  • voltage drop across LED: 2V
  • Desired LED Current: 20mA
  • Supply voltage: depends, I chose 5V

The resistor then needs to be 180 ohm.



Plaatje van led met weerstand aan pootje


Plaatjes van 5 en 12 volt verdeler.


Now proceed to chapter 09: Installing the End Stops