Best power configuration for reliability

Projects General Guidance
1

Hey all,
I've been working with Arduino kit for a while, but am only starting to move to 12v set-ups from 5v.
I've got a project consisting of a 90-LED 5v WS2812b strip, an Uno with Ethernet Shield, a 5A-rated adjustable step-down Buck Converter, and a 12v/20A regulated power source. I need this to be as reliable as possible, so as to minimize maintenance issues in the medium-long term (I'm handing it off to some other people who aren't at all tech-savvy). So, which configuration is more reliable -

  1. 12v into the Uno barrel jack and the Buck Converter (12v->5v), buck converter powers the strip, shared ground and DIN to Arduino via a resistor.
  2. 12v into the Buck Converter (12v->5v), powers the Arduino and strip, strip DIN to arduino via a resistor.
  3. Swapping out the LED strip for a 12v strip.
  4. Some other configuration, possibly involving more components.

Thanks for the advice!

2

Welcome!

Posting an annotated schematic would help us help you resolve your problems. That schematic should show all connections and the exact parts you are using. For example, I currently have about eight different devices on my bench that are all simply called “buck converters,” but they are not the same. Please also post links to technical information for each hardware item.

For grins, I looked up your LEDs and found that there are quite a few versions of a 5 V WS2812B strip, even before considering different manufacturers. One major difference is LED density. Common strips are available in several densities, such as 30, 60, 74, 96, 100, 120, and 144 LEDs per meter.

So when you say “90-LED 5 V WS2812B strip,” I would want to know whether that means 90 LEDs total on the strip or 90 LEDs per meter. “90 LEDs/m” is not one of the more common densities; 96 LEDs/m is more common.

There are also variations in strip width, waterproofing, PCB color, length, connector arrangement, and the particular WS2812B revision or manufacturer.

In summary, the statement “90-LED 5 V WS2812B strip” is not enough information to positively identify the hardware. A link to the actual strip or its technical specifications would still be appropriate.

3

Is asking for trouble.
At that voltage you can't draw much (if any) current from the Arduino. You certainly can't power an ethernet shield from the Uno that way.
The 5volt regulator has to drop12 -5 = 7volt, and would be using more power (hotter) than the Uno and shield itself, resulting in shutdowns or a failing regulator.

4

Note that a 12V strip works by controlling three LEDs at the same time.
You can't have individual LED control.
That might not be a problem for your project.
The advantage is 1/3th of the current draw, so better suited for very long edge lighting.

I would just use a 5volt cellphone charger with USB socket to power the Uno R3.
Just plug your USB lead into that.
Then power the 12V strip separately.

5

So why you want to use 12V supply in the first place? Just get sufficient 5V power supply to power all your setup.

6

It's a puzzle for an escape room. The whole thing is powered through 12v as most of the other elements use that.

7

This means you want the fewest number of devices. Use one 5vdc power supply. Discard the step-down converter. Power Arduino doectly from power supply. Power 5VDV WS2812B directly from power supply.

8

This is useful to know. Oddly, this project will be mostly powering the LEDs in sets of 3, but under the current configuration with the 5v strip I'm able to skip past individual LEDs that arent needed without cutting the strip (its a fake digital clock tied to an escape room game clock, and each segment of each digit contains 3 LEDs). I could cut it to just jump over these gaps.
Annoyingly, the device will be some distance away from mains power (its in an escape room on the wall away from mains sockets), and wired through the walls about 3-5m - so running it off a USB charger plug will be difficult.

9

Unfortunately due to the set-up changing the power supply is not on the cards.

10

Rather than p-laying a buck/boost game you may want to consider just buying an ATX PSU. That gives you 3.3 volts, 5.0 volts and 12 volts. Then for a pinout in the interest of simple and neat I would use an atx power supply break out board or similar.

Ron

11

This is all old kit so I don't have specific links to where or when I got hold of them.
Buck Converter - XL4015A 5A. Probably this one.
LED Strip - 60LEDs/m, 90 LEDs total. IP30, black. That's all I've got - I've got a ton of these in the workshop with no record of specific suppliers.
Power Supply - https://www.ebay.co.uk/itm/406775361236

12

Unfortunately the power supply is locked in (its supplying most of the other elements in the escape room its based in). An alternative power supply just for this project would need to fit inside a stud wall, which is a fire safety no-no.

13

Long strips may suffer from voltage drop in the internal supply lines. It is possible to feed multiple strips from one source. The data may be may still be continuous, but may also be independent.

LedStripsDigits
LedStripsDigits1092×600 2.69 KB

14

Then get good quality 5V buck, for example from here:

15

Why is it a fire safety no-no?

Stud walls carry a lot of wiring and appliances.
Normal stud walls are drywall i.e. plasterboard and timber or metal studwork, CLS timber and optional fire resistant rockwool/glass fibre.

The main power wiring, twin and earth in the UK, is derated according to the amount of insulation compared to free air.

Wiring junction boxes can be the no maintenance types (e.g. Wago).

A lot of power outlets and light switches aren't simple switches screwed into back boxes, but can be sophisticated dimmer switches and power outlets can have USB chargers built in.

All it takes is some ingenuity to make it all fire resistant. Why can't your power supply be surface mounted?

Just curious, what is your escape room all about? A safe refuge or a calming down room?

16

The main issue is that the power supply unit just wont fit, and wont be able to ventilate anywhere as it will be above a door and can't be visible from either side (not my call).

The room is meant to be a venue backstage green room of a small music venue circa 1999 - a wall clock in that setting would be battery powered, so the boss doesn't want visible wiring going to it.

17

I have the 5V buck - the question is literally about where I place it in the circuit.

18

I you want reliable then throw that one away.
Don't use any buck/boost that is adjustable

19

That buck module can't handle 90 LEDs at full brightness. Maybe half.

20

For a long-term reliable setup, I would avoid powering the Arduino through the barrel jack while also running the LEDs from a separate buck converter. The barrel jack regulator can generate extra heat and may become a weak point over extended use.

Option 2 is generally the cleaner approach: use the regulated 5V output from the buck converter to power both the Uno and the WS2812B strip, with a common ground. Make sure the buck converter is properly sized, add a large capacitor near the LED strip power input, and include the recommended resistor on the data line.

For 90 WS2812B LEDs, also consider the current requirements. At full brightness white, the strip can draw a significant amount of current, so leave enough power headroom and avoid running the converter close to its limit.

A 12V LED strip can simplify power distribution, but if you need addressable LEDs, the 5V WS2812B setup with proper power management should work well.

Adding basic protection like a fuse, good connectors, and strain relief will also improve reliability for a handoff project.
For a long-term reliable setup, I would avoid powering the Arduino through the barrel jack while also running the LEDs from a separate buck converter. The barrel jack regulator can generate extra heat and may become a weak point over extended use.

Option 2 is generally the cleaner approach: use the regulated 5V output from the buck converter to power both the Uno and the WS2812B strip, with a common ground. Make sure the buck converter is properly sized, add a large capacitor near the LED strip power input, and include the recommended resistor on the data line.

For 90 WS2812B LEDs, also consider the current requirements. At full brightness white, the strip can draw a significant amount of current, so leave enough power headroom and avoid running the converter close to its limit.

A 12V LED strip can simplify power distribution, but if you need addressable LEDs, the 5V WS2812B setup with proper power management should work well.

Adding basic protection like a fuse, good connectors, and strain relief will also improve reliability for a handoff project.