I'm a long-term software developer who hasn't touched a soldering iron since Uni. I've been mulling an idea for a hardware project for some time, and have cajoled a raspberry pi into managing the following devices:
- Touch screen
- e-Ink Display
- 2 x Stepper Motors [Very infrequent use - <5 mins/day]
- Thermal receipt printer [20cm print ~hourly]
- GPS/LTE module [On for extended periods (hours)]
- Arduino Zero [Not actually connected yet, but will be "always on"]
I have a bare-bones implementation running, and -now I know it's possible- I'm turning my attention to packaging it all up.
At present, I've got half a dozen DC power supplies connected to the various components.
I've started to put together a rough layout (for scale, the box is 28x18x13cm internally)
Some of the devices offer power saving modes which I intend to use when possible, but it'd be nice to be able to use it all simultaneously if required.
The pi 3 B+ itself requires 5V and up to ~2.5A. That's powering the touch screen, e-ink display and stepper motor driver board.
The motors themselves require a 12V supply (350mA/ea)
The thermal receipt printer requires 5-9V at 1.5A.
The GPS/4G module requires 3.3V/1A.
- 12v/700mA [Motors]
- 5V/2.5A [Pi/Screens/Motor Driver/a few sensors]
- 5V/1.5A [Printer]
- 3.3V/1A [Comms]
- 3.3V/1A [Arduino]
I know some of those are max draw (eg the Pi) but I'm actually quite close in that case (largely thanks to the touch screen). Eg if try to run the comms board from the Pi's 3.3v rail, it's enough to trip the pi's power.
So, my primary question is... How can I (cleanly) run all of this from a single wall socket? Due to my lack of experience, I've got a preference for keeping everything in the case low voltage (or at least keeping mains voltage fully enclosed/isolated).
Ease of integration is a consideration considering my soldering "skills" and scarcity of equipment.
I'm hoping that the subsequent step will be to use a large power pack, and have found this https://www.amazon.com/NOVOO-22500mAh-Universal-Compatible-Smartphones/dp/B07JKP3PWY but haven't really had time to look into it yet (presumably converting up to 240v and back is wasteful). I mention it in case the idea of a power pack changes the answer significantly.