Best source of an extra 5V (and a few MA) for a Raspberry Pi

I’m looking for a good source of a fractions of an amp along with 5V to power a raspberry pi, because my eventual plan is to use the pi (along with octopi) to control some relays to power on/off the CNC, as well as run the printing and toggle on and off various other things (lights, bigger relay for the router).

I’m trying to figure out the best way to get the little current required for the pi, I could add a voltage regulator to drop the 12 volts down right from the supply, and support the pi with that (Seems a little ugly with the small 12v/5A supply I got with the kit) but I’m thinking the ramps board must have a few outputs I could use, I’m using the 12v fan plug already, for a fan of course. Anyone have any suggestions for how I could do this, other then just running its own dedicated power, which might end up being the best course anyways because I’d like to be able to power down the 12v/5A power supply completely.

There is no spare power on the ramps, the 5v is far over taxed.

fair enough, that’s what I figured, after more thought it makes more sense for it to be completely separate power wise.

The pi isn’t a few mA either. 500mA at least. Pulling from the 12V supply or a separate supply are your options. Things like the heated bed draw current from the 12 V supply. Ramps just turns it on and off.

The ramps also can control a relay, if you have some spare pins.

take a look on amazon or banggood for the little 5v PSU’s we use on our quad copters. Most of those can take a 12V input and feed a very nice regulated 5V output… or maybe one of these



I made a quick voltage regulator (done it before for my robo3d, it only has 12v rails as well) and wired it into there seems stable enough but still debating on if I want the whole power supply to be controlled by an external relay.