General advice on power requirements and building them?

I was just wondering how people tackle some of their power requirements, simple circuits powered from 5v yeah no problem. But what do you do if you need two separate sources maybe one at a higher amperage. Or two at different voltages. Do you use two plugs or build a board to do both?

At the minute im needing two 5v sources, one for the Arduino and one to power servos at a 5A. Happy to use a 2 plugs one with a small transformer, but two plugs take up space, look messy etc etc. Also not sure if i'll get to the point where im good enough to build a circuit to do this.

What do you guys do, software to generate boards like these? build them with skill and knowlege, or just use two plugs :grinning:

For experimentation, who cares? Just be sure to connect the grounds.

For a commercial product in a nice box, hire a seasoned EE to design the power circuitry. It is not at all trivial to properly isolate high current (servo or motor) and Arduino power, derived from a single source.

If you don't, motor generated electrical noise creates havoc with the Arduino -> dud product.

You're right it doesn't really matter, but my OCD side looks at something that's complete and i think... How can I improve it, i'm a bxxxx (edit) for it. :smiley:

A simple example.

Notice the common ground.

One simple approach is to use the mains PSU to derive the largest voltage you need, and then
use DC-DC buck converters to derive lower voltages (and maybe linear regulators too if sensitive
analog signals are involved). If lots of power is involved for something, that thing might benefit
from its own tailored supply (big motors, bit batch of servos, that kind of thing).

Thus you might have 24V 2A supply, an LM2596 buck converter dropping that to 12V for a small motor,
and another buck converter generating 7.5V that you feed into the Arduino’s barrel jack so its on-board
regulator produces nice clean 5V for your analog sensors. LM2596 buck converters are cheap and seem to
be pretty reliable in my experience. They come with a ten-turn pot to set the output voltage accurately
and its worth buying them in batches of 5 or 10 they are so cheap.

Smaller buck converters are also available, using other chips with higher switching speeds, I believe Polulo
have a range of these.

If you are battery powered you can use boost and buck converters as necessary.