powering LED strips - Page 1
Forum section: electronics / projects

author: Fluxia
author_rank: Contributor
timestamp: April 08, 2025, 10:54:21 am
content: Hi, I have made a lamp using led strips ws2812b, the microcrontoller is an ESP-01S with an ESP01 LED Adapter. I am using the WLED firmware on the board.I need to decide how to power it. 3AMP PSU would be enough (only 48 leds)I have a 5v 5A PSu like the one on pic uploaded (not exactly that, just looks like that) which would be ok. Only I need to enclose it in a box and it will be quite big and ugly....I am considering just getting a USB charger but I am unsure about a few things..1 - it will be quite far away from the lamp (probably a 2 or even meters cable needed) but I thought to get an 18 AWG wire to wire it to reduce the voltage drop.2 - I have seen videos about the safety of USB chargers, so I wander if buying them from aliexpress is something I should avoid ?3 - is there any other safety iussue that I need to be aware of? for example if I use the big PSU and enclose it in a box, will I need to drill some holes in the box for ventilation? where in the circuit is best to place a fuse? Should I also puse a fuse if I opt for usb charge power supply (ie. inside the lamp)?

author: Zero999
author_rank: Super Contributor
timestamp: April 08, 2025, 11:01:35 am
content: Why WS2812B? It's about the most inefficient way of doing this. It mandates a low voltage of 5V and considerable power is wasted in the internal current limiting resistors. They're fine for small numbers of LEDs, but not good for that many.Put the PSU as near as the LED strips and use as shorter cables as possible. You might need to power the strip from both ends and have additional power feeds in the middle.

author: Fluxia
author_rank: Contributor
timestamp: April 08, 2025, 12:01:16 pm
content: QuoteI bought them sometime ago together with a ws2811 12v stirp and a ws2815 12 v one. I knew nothing about LEDs strip and wanted to starting building a few lamps. When I research on line the ws2812b was the most recommended for arduino projects...Quotethe closest I can put the 5A PSU is 1 metre but more if I use a USB charger/psu (as I would plug it straight in the electric socket)QuoteI have power injection at the end of the strip

author: Zero999
author_rank: Super Contributor
timestamp: April 08, 2025, 12:31:19 pm
content: I didn't know that 12V WS2812B strip existed. All the questions relating to it I've seen here are about the 5V type. Good, 12V is much better than 5V. It needs less current and it should consist of strings of three LEDs in series, so less power is wasted in the current limiting resistors.1 metre isn't far. A single feed of 18AWG or 0.75mm2should be fine. Wikipedia states the resistance is 21mΩ/m, giving a total resistance of 42mΩ (1m for the positive and 1m to the negative connections. If the current is 5A, the voltage drop is 5*42m = 210mV, which is under 2% of the supply voltage.

author: Fluxia
author_rank: Contributor
timestamp: April 08, 2025, 01:21:04 pm
content: Quoteit doesn't... the one I mentioned is the ws2811, but it is not the one I am using for this project. I just mentioned that I bought three different LED strip for my first diy project a few month ago..in this project I am using the 5 v ws2812b. is it really so bad in term of effciency?

author: Zero999
author_rank: Super Contributor
timestamp: April 08, 2025, 01:51:21 pm
content: Quote from: Fluxia on April 08, 2025, 01:21:04 pm12V LED strip consists of numerous strings of 3 LEDs connected in series with a current limiting resistor. Each LED drops around 3V*, so 9V in total, with 3V (25% of the total power) being wasted by the current limiting resistor.5V LED strip has a resistor for each LED, so the resistor drops 2V, so 40% of the total power is being wasted by the resistor.5V LED strip requires three times the current of 12V strip, for the same amount of light, which means the cables will need to be three times thicker.*3V is the forward voltage drop of the green and blue LEDs, the red ones only drop 2V, but this detail was omitted, for the sake of simplicity.

author: Fluxia
author_rank: Contributor
timestamp: April 08, 2025, 02:05:00 pm
content: thanks a lot! Do you have any recommendation on the best power supply to use with the ws2812b? It will probably never run above 2 amps

author: Zero999
author_rank: Super Contributor
timestamp: April 08, 2025, 02:13:33 pm
content: Quote from: Fluxia on April 08, 2025, 02:05:00 pmAny decent quality 5V 2A power supply will do.

author: themadhippy
author_rank: Super Contributor
timestamp: April 08, 2025, 03:02:33 pm
content: QuoteOn a bog standard RGB string id agree, but aint all that dealt with chip doing the decoding and spiting out the 3 channels of pwm for the leds on the ws2812 stuff? And to be honest dealing with a bit of inefficiency is more than made up by much simpler wiring compared to trying to knit 40 rgb leds together so they all work individually.

author: brucehoult
author_rank: Super Contributor
timestamp: April 08, 2025, 03:18:52 pm
content: Quote from: Fluxia on April 08, 2025, 01:21:04 pmws2812b is great for pretty colours that you can change when you want, at a very high speed, with a different colour for every LED (if you want). You can update up to about 1000 ws2812b LEDs in a single chain at 30 FPS so you could even play badapple or whatever if it's a rectangular grid.But if you just want a fixed colour, or at least all the LEDs the same colour at any given time, and you're using it for actual room lighting rather than decoration, then other types of LED string are probably better.