Powering things using the printrboard

[__Vinz__]

Hi everyone,

I am setting up an Octoprint server for my Play which I want to run on an Intel Edison using the mini breakout board (see "Powering the Mini-breakout Board" section of for more information on that board, full HW guide is ). I plan on using the J21 7-15V jumper to feed it power as it is needed to enable USB host (for Octoprint). 1A should be enough to power it, from what I read.

Is there a way to use a 12V rail of the Printrboard to power it instead of a separate power supply? I am looking at the but don't know which connection to pick. This would use the stock laptop power brick coming with the printer, I am not running a heated bed.

I have found similar posts on the forum (like ) but this is to power a Raspberry Pi off the 5V rail, which is not what I want (I expect this to be doable using one of the 12V rails since those provide more power than the 5v ones).

Bonus points for the same question, this time for powering an LED to light up the print area.

Thanks for your help,

Vincent

[RetireeJay]

If you are not using a heated bed, then the one side of the connector for the heated bed gives you a steady +12V. So then you need to find ground. Are you willing to hack the Printrboard a little? The heated bed normally has one lead switched to ground via the power MOSFET transistor that's adjacent to the heated bed connector. If you removed the transistor, you could put in a jumper to permanently connect that node to ground, and you'd have a complete 12V supply coming out of the heated bed connector. There are a few other places on the Printrboard where you can pick up ground, but if you are going to be drawing 1 Amp (and possibly a "noisy" draw at that, considering the digital load) then going to those other pins is a bit risky. AFIK only the heated bed connector has high-current traces on the printed circuit board feeding it.

[Mooselake]

Can you splice into the wiring harness to the 6 pin connector?

Switching buck converters are all over eBay and other electronics gadgetry sites, with or without LCD, led, or graphics displays, and pretty cheap. They're an efficient way to convert 12V to 5 (adjustable over a wide range), plus many have current limiting if they accidentally are shorted. Get one bigger than you need, marketing claims being what they are.

I have one with a graphics display for current and voltage, in a little laser cut acrylic case, as a trickle charger for my ham station battery. It cost under $5.

Kirk

[__Vinz__]

Hi Kirk, RJ,

Thanks much for your replies, this is exactly what I was looking for. I think I might go with the lesser mod of the two (splicing the power cable) but I like the heated bed one too! I am currently busy with the SW side of things and will get back to you with more info once I start the HW part of the project.

Thanks again!

PS: looking at the EdisoN power info, it actually draws around 500-650mW when wifi is on (cf ), so 1A@12V was definitely exaggerated I think.

[Mooselake]

Forget to mention the obvious answer. If this is a repurposed PC ATX supply you already have 5V available directly from it. If it's one of those 12V laptop or other 12V only supplies then you'll need some kind of step-down converter.

Kirk

[__Vinz__]

Hi Kirk,

Thanks again. Just for the record, this is a 12V line that I need, not a 5V one (the Edison input needs to be 7-12V on that specific jumper).