I'm new to the Arduino community but already love the endless possibilities and nice projects I've encountered so far. After walking through many tutorials, I'm currently planning my first own project where I could need some advice/guidance. I do have experience in programming, however, the whole hardware part is rather new to me.
The Project
There is this app that controls an 11x18 LED matrix attached to a board (see attachment). Since the original hardware isn’t available all over Europe, I want to build it myself since I also consider it as a very nice beginner project for me. The main output is this LED matrix with 188 pixels with 20cm distance between each pixel. So overall, the LED strip will be ~40m long. The app sends a message via Bluetooth defining what pixels should be ON/OFF. Usually, there are not more than 20 pixels ON at the same time.
My setup
I have an Arduino UNO with an Adafruit Bluefruit LE UART Friend to receive the message. As an LED strip, I’m considering using a WS2801 (or something similar – see questions below). I’ve read many posts already and the setup attached seems to be best practice (BT module missing of course). Some people also add a 1000uF capacitor. I'll add 20cm connecters between each LED (see attachment).
Power station
I think I need a 5V / 15-20A power supply to operate all LED at full brightness. The LED matrix will be installed in a barn that is off the grid. However, I have a GoalZero YETI400 power station that should serve as a power source. The YETI has the following outputs:
USB port (output): 5V, up to 2.4A (12W max), regulated
6mm port (output, 6mm): 12V, up to 10A (120W max)
12V car port (output): 12V, up to 10A (120W max)
AC inverter (output, pure sine wave): 120VAC 60Hz, 2.5A (300W continuous, 1200W surge max)
My biggest concern is damaging the YETI400 power station! Most 5V power supplies I find online are 100-240V AC-> 5V DC. It somehow feels stupid to use the AC inverter of the YETI to convert DC -> AC -> DC. Therefore, I’d prefer to use the 12V car port or 6mm port instead. Is there any problem/risk involved? Are 10A sufficient for my project (considering it will only light up max 20 LEDs)? Any other suggestions?
Another concern I have is the voltage drop since I have so many LEDs and such a long distance. Is 5V a good idea at all or should I run it on 12V instead and add a conversion to 5V to power the UNO? This would also simplify my first question I guess?
I still don’t understand whether I need a clock line for the LED strip. Most people use WS2812B for their project and I never read any problems.
I’m really excited continuing my project! Looking forward hearing your advice/feedback.
Question 1: Sum up the amps possibly used by the load.
Question 2: Measure the voltage drop and take appropriate action.
Question 3: Check what wiring "most people" have used.
I would suggest using a SEPIC (Buck would also work) converter on the 12V generating the 5V for your LEDs. They can be gotten very inexpensively and many will give you over 3 Amps and even more. 2.Putting the converter at the end of line near the LEDs would resolve that problem. I would suggest using the 12V for the UNO, the UNO has filtering etc that will help. 3. Since you have 5 volts at the LEDs why not use a CAN driver as a receiver for your clock signal. Leave it enabled all the time as receive. On the Arduino do the same thing but leave it in Transmit. This will give you a clean signal. I hope this works great for you.
I would suggest using a SEPIC (Buck would also work) converter on the 12V generating the 5V for your LEDs. They can be gottes very inexpensively and many will give you over 3 Amps and even more.
To be honest, I'm a bit afraid of building/solding my own power supply because I don't want to damage the power station. That's why I was looking for ready-to-use power supplies.
gilshultz:
2.Putting the converter at the end of line near the LEDs would resolve that problem. I would suggest using the 12V for the UNO, the UNO has filtering etc that will help.
If using 12V for the Arduino, wouldn't it be a good idea then to also operate the LED on 12V, e.g. using WS2811 or WS2815? Any pros/cons using 5V?
elgarnelo:
To be honest, I'm a bit afraid of building/soldering my own power supply because I don't want to damage the power station. That's why I was looking for ready-to-use power supplies.
What is suggested is using a ready-to-use "buck" converter. Choose one rated well beyond the calculated requirement of the LEDs. You do not "build" power supplies in this context. Choosing the correct components will not "damage" your "power station".
Please explain clearly exactly which LEDs you propose to use in this array so we can figure just how much current it will require. You seem to have mentioned quite a number of different options. The last picture shows a 12 V RGB strip where all LEDs are the same colour.
elgarnelo:
If using 12V for the Arduino, wouldn't it be a good idea then to also operate the LED on 12V, e.g. using WS2811 or WS2815? Any pros/cons using 5V?
12 V addressable strips will either have each set of three LEDs having the same colour, or be extremely inefficient if each LED is individually addressed, as they draw the same current at 12 V as a 5 V strip would. A switchmode "buck" converter draws only about 40% of the current at 12 V as it provides to the 5 V output.
Paul__B:
12 V addressable strips will either have each set of three LEDs having the same colour, or be extremely inefficient if each LED is individually addressed, as they draw the same current at 12 V as a 5 V strip would. A switchmode "buck" converter draws only about 40% of the current at 12 V as it provides to the 5 V output.
Thanks for your input!
As mentioned in the original description, the LEDs need to be 20cm apart from each other. I just found this DC5V 12mm WS2811 led smart pixel node on AliExpress (50 pcs, 25cm wire spacing): https://www.aliexpress.com/item/1005001861198844.html
Since this would perfectly fit my wooden frame, I'm think about putting four of them in a row. I've also ordered a "buck" converter now as suggested (DC12V -> DC5V). So both, Arduino and LED will run on 5V. Anything else I should consider?
Well now, these chains which presumably incorporate WS2811 chips (separate from the LEDs visible in the encapsulation) will each draw a minimum of 50 mA when dark and about 2.8 Amps at full white brightness. Four of them, about 11 Amps maximum. What is the rating of your "buck" converter?
You need to connect 5 V power to both ends of each chain to avoid significant voltage drop along the chain (at high brightness). "Connecting power" of course always means both 5 V and ground.
And indeed, you connect that 5 V power to the "5V" pin on your Arduino. A Nano is far more practical than a UNO (and generally cheaper) - reliably connecting to the socket headers of a UNO is difficult - you would really need to insert pin header strips and solder to those headers.
