Smartify garden fence posts with WLED

Hardware
1

First of all, I’m sorry to have posted this in Discord a few days ago. I’ve completly missed that there is a forum.

The following situation; I would like to “smarten” my garden fence with some rgbw leds. The initial idea was to use some random solar leds and replace the circuit, but that turned out to be unpractical (at least for my knowledge level / budget). The picture below shows the commercial non-rgb solar solution I’ve bought as a template for the housing. It seems a bit too small to fit everything inside and one of those cost about 20 €.

1024×1024 101 KB

I’ve made a sketch that shows the setup of “one” fence post. I’m not yet sure whether to split the electronics up in two parts later. One in the led housing and the other part in the distribution box.

Sketch
Sketch1333×678 11.4 KB

As far as I understand (beginner here), due to the resitance in the wire, I have a voltage drop and therefore cannot feed 5v into a cable that is 20m long before reaching the first fence post, right? First things first then would be to get mains (220-ishV AC) to a distribution box in the garden house (with all the protection circuit needed - will be done by a professional) and from there, feed 12 V or 24V into a, what is it called five strand / core wire? that goes to the first fence post. By the way, I’ve got the 5V version of a SK6812 strip.

While my first choice would have been to use some sort of Dig-Uno board as an all-in-one solution, sadly ordering 1, 2 of those from allnetchina would cost me between $40 to $80, which is why I hope to be able to build everything “manually”. I already have “all” the components shown in the picture at hand.

Since it seems overkill(?) to put that circuit in each and every one of my 18 fence posts, I was hoping to have one ESP32 controlling between 12 to 16 rgbw leds per post. I would then bridge the 12V/24V from one post to the next having only a buck converter in the posts distribution box and maybe a signal booster. Does that make sense?

The only thing I can’t figure out is how to include a relay to switch off not only the power to the first led strip in the first post, but to cut the power to all posts.

Edit: There seem to be a usermod that supports multiple relays. If I were to put a second relay in the distrbution box of the first post that brdiges the 24V or 12V to the next post before it is stepped down … would that work? Also, I missed to include the data line to the relay in my sketch.

Am I missing something? Your feedback is highly appreciated.

P.S: Does anyone of you have or know of an alternative 3D design that could be used as an enclosure?

2

I’ve done something similar in my back patio area using 3 SK6812WW LEDs in each “lantern”.
For my approach, I use an 18V “power bus” that goes to all the lights and 1 wire handles data in and out.
At each light I include a 5V buck converter that brings power from 18V down to 5V for the lights.
The lights are “daisy chained” with power common to all and data out from one light feeding data in of the next.
The only thing to watch for is the distance from the ESP32 to the 1st LED and then the gaps between each light. If any of those distances get “too long”, you’ll get flicker, loss of control, wierdness (perhaps 5m???). In that case you’ll end up adding differential TxRx pairs at each light to handle the longer runs.

For my setup, I was able to get by with a simple 22/4 cable that gave me 2 wires for power and another pair that could be either a single data line or a pair for TxRx as needed.

If you look at this previous thread: Backyard thoughts

You may get some ideas.

3

Hey @divsys,

thank you for your reply and sorry for my late feedback (busy with work, family and actually building the fence).

I noticed the thread you mentioned and have read it a few times now. But am not quite sure if I have understood the power bus part correctly.

In the meantime, I’ve assembled the electronics for a prototype based on some Wemos D1 mini + Shields.

prototype
prototype1920×1080 288 KB

The footprint is quite large compared to a QuinLED Dig Uno I guess and alhtough my first attempt includes a level shifter and a relay, it lacks a fuse and all the other fancy stuff.

While the angel on one shoulder tells me to stop throwing money at a problem, the devil on the other side already ordered two Dig Uno boards … good to have options, you know.

For now, I’ll keep working on the fence before I worry too much about the electronic side of things.

4

The power issues are all about making sure there’s sufficient voltage at each fence post to drive the LEDs reliably. For small lights like you’re describing, there isn’t a whole lot of power required for each one so it should be fairly easy. The hitch comes in when you have a total length of 20m +18*2.5m=65m total length.

That much wire acts like a resistor in series with your power supply. The famous Ohm’s law says:
V=IR, or V (Voltage drop) equals I (the current you need for all your LEDs) times R (the resistance of your wire).

When you choose a higher supply voltage (12V, 18V, 24V) plus a buck converter to drop things down to what you need, the net effect is the I value on your power supply wire becomes much lower than what you need if you try and just send 5V. That means the drop that each buck converter sees (and the last one in your chain will be the worst) is much less than what the 5V line would see. Additionally, your buck converter doesn’t really care if it converts from 18V to 5V or 14v to 5V. So if your “bus” drops 4V from start to end (18V to 14V), that’s a 22% drop, which would be horrible on a 5V supply line. But with converters each LED sees a clean 5V from its “local” buck converter.

Keep going the way you’re working and you should be fine.

1 Like