I am building a digital music box as a gift for someone very special to me
The project will be most likely composed of an Arduino Uno controlling an Adafruit Wavshield, 8-ohm 1W speaker, BYJ-48 Stepper Motor and driver, Tower mini servo motor, hall sensor, and a few other switches and inputs. These, powered by a rechargeable battery bank, are to be contained in a portable ornate wooden box. Now, I've heard nearly every youtuber, forum-poster, and EE-blogger say that you need to isolate your microcontroller from your higher current peripherals like motors due to signal noise, but the common suggestion seems to be to run the controller and peripherals with different power sources that have completely separate grounds (like usb power to the arduino and benchtop psu for the motor). Without a significant redesign this would an unacceptable solution for my project, as I'd prefer it to have a single battery bank, rechargeable via a single usb input. I know Opto-isolators can be used to seperate high and low power circuits but they can't share a ground.
So:
Is what I'm trying to accomplish even possible? I would assume so as plenty of battery-powered consumer electronics run low-power chips alongside higher power motors or amplifiers.
Is there a common component that's used to isolate ground signal noise in this case?
Is the easiest answer really to run them on seperate psu's (batteries)? And if so, which components need to be isolated from each other?
Open to redesign, just need to know what I don't know, ya know?
With careful power supply decoupling design, there is usually no need for complete electrical isolation of the Arduino and other powered components.
Every competent electronics engineer has to thoroughly understand the subject matter, in order to design robust toys and consumer equipment.
Most hobbyists have encountered the problem, but don't understand it and have not researched the solutions, which goes a long way to explain the popular (but incorrect) mythology.
Power supply decoupling is discussed in EE textbooks and no doubt, in tutorials on line. Dave Jones' EEVblog videos might be helpful.
Power supply decoupling... got it. Thank you, that's definitely what I needed to know to research more. Dave Jones' videos have been instrumental in empowering me to take on more complex projects like this one.
What you need to do it join the grounds but in such a way as to keep the ground current flowing from one power supply to its load separate from the current flowing from another power supply to its load. The simplest way is to wire each power supply to its respective load separately, then join the grounds, and only the grounds, at a single point. This is called a star connection, because if there are several grounds all joined together it looks like a star.
I suggest you "prototype" the thing to see what happens.
With a common power supply the circuits can't be completely isolated.
Digital electronics are relatively immune to noise. All you have to do is reliably distinguish between a "1" and a "0", and that tends to work very well! But, stepper motors & drivers CAN be VERY noisy and they can put "glitches" on the power supply lines, or you can get noise when a DC motor stops & starts (especially when it stops).
If there's a problem, it will probably be with the analog audio amplifier.
Voltage regulators tend to be good "filters" so if you use separate regulators for the Arduino, audio amplifier, and motor (if the motor has a regulator), I would expect good results.
The Arduino has a built-in regulator and the motor might not need one, so you might get-by with adding one for the audio, and you may not need that one.
But, the Arduino's regulator is not rated for 48V so you may need at least two power supplies (or a supply with multiple outputs) anyway.
Are you sure you want to use a stepper motor? They also tend to be mechanically noisy.
About 25 years ago, I was working on a 500,000 square foot television facility - remember composite video typically tuns at 1V p-p...
A very humid tropical climate with 'dubious electrics' at every turn. And satellite uplinks to add to the mix!
We actually flew-in overseas power / grounding specialists to measure and ensure the whole system was within a fraction of an ohm to ground across the whole facility!
THat system was local star-groundingm while the building had a 'mat' made with a 3-inch wwide copper mesh tape across the whole facility.
