For an art installation project in a gallery, I need to make a WS2811 Led Strip (12V) blink like a "morse code" using a basic Arduino nano, running all day for several months. I am not sure yet about the length of the Led strip that I would need, but let's say I will need a full 5m length with 60 Led/m. The strip that I will use specifies that each Led is drawing 0.3W, so in total 0.3W * 60 * 5m = 90W. The stip is powered by a 12V power supply, so I checked that I will need at least a 90W/12V = 7,5A power supply (I will use a 10A).
Also, I was planning on using that same power supply to power the Arduino.
I was planning on wiring things like this :
Since there is quite a lot of current that needs to be turned on and off very quickly (blinking like a morse code) and that needs to last for several months, I was wondering if there was any way to protect the circuit so that it can last this long ?
Since the Arduino is powerred with the same power supply as the Led strip, is there any chance that the Arduino will sometimes be accidentally turned off because of the quick changes of current draw ? In that case, is it better to add a seperate power supply for the Arduino ?
I was also maybe planning on adding a little potentiometer between the power supply and the strip to adjust the overall brightness (voltage divider), but for this to be working I will need 2 separate power sources (one for the strip with the potentiometer, and another stable one for the arduino) or am I wrong ?
A good quality power supply of an appropriate size (wattage) will survive just fine.
A good quality power supply will have ample buffer capacity on its output. You can add another buffer capacitor on the input of the Arduino; e.g. 1000uF will be fine.
This will not work. You should dim the LEDs in your code by displaying a less bright color/value instead. Alternatively, mount a filtering material like semi-opaque/milky plexiglass over the LEDs to reduce light output, although this will also diffuse the light somewhat. The software dimming option is the best approach from a technical viewpoint.
Make sure that you connect the power supply in several places along the strip so that the entire current doesn't have to run down the length of the strip. The traces on the LED strip are quite thin and not really fit to carry several amps. Connect the power supply at e.g. every meter.
You cannot run 7.5A through any practical available potentiometer, aside from the fact that it is not in the least necessary with the addressable LEDs. Instead, you should vary the data being sent to the LEDs from the Arduino, likely most effectively through the use of increase/decrease buttons, or mode switches, read by the Arduino using the unused pins in your diagram.
Agreed, the amount of power involved means you really should run a parallel heavy-gauge wire pair for the 12V, and periodically feed the strip from that. How frequently will depend on your physical arrangements, but I would recommend every 2-3 meters. This will improve intensity uniformity and contribute to a better effect.
Thank you all for your quick answer, helps a lot !
The buffer capacitor on the input of the Arduino is a good idea, and of course I should have guessed that running that much current throught a potentiometer was not a good idea...! I will probably use a potentiometer with the analog input to control the overall brightness via software dimming.
Thank you for the advice of periodically feed the strip for the intensity uniformity !
The strip will be attached around the borders of an enclosure (around 80cm x 50cm), so eventually I will only need around 2m of strip, so there were will probably be around maximum 3 to 4 A of intensity running trough the strip if I set the brightness at full intensity (which probably won't be the case), so I was not that much concerned by the heat in the end. But thank you for the reminder, I will pay attention nevertheless !
I had a 300 x WS2811 (IP67 = encased in a silicone rubber tube), 12vdc power supply with pattern changes at half-bright (127 max) without flickering, sag or the need for power injection running for a couple years without issue. I calculated the power supply for these LEDs at FULL bright as 3 LED (r+g+b) x 300 pix * 20ma/LED = 18000ma = 18A, and used a 470 Ohm resistor on the data pin and a 1kuF electrolytic capacitor across power/gnd.