I have a led strip running with wled (5m, 300 lights), I also have a power adapter (5V 10A). But it looks like it can not provide stable energy, flickering, restart of led strip, even with brightness limiter.
So I am looking for recommendations for a good power supply available in Germany would be great.
Thx
Without knowing which strip you are using, any advice will be a shot in the dark (pun intended)
Right now we dont even know if you are using a resitor for the data?
How were you able to put wled on that strip? Are specially tools needed? 
Jokes a site if you look here:
You probably will find out that your 50W PSU simply isn’t powerful enough to run your strip at full brightness and all leds turned on. 
Also with 300 leds you should inject power not only at the start but also at the end of the strip 
In any case you may just also try (together with the power injection at the end) limit the maximum power output in software 
Depends on the type of LED strip you’re using. Different LEDs have a different power consumption, eg. the WS2812B have around 60mA per LED.
Just calculate it yourself:
300 lights x 60mA = 18000mA = 18A => your power unit does only half what you need even if running with full power…
As you said you’re located in Germany ( 
) , here is a german guide on how to calculate the needed power.
If I may make a suggestion: after calculating which size you want, take a look around for MeanWell power units. They are affordable, have a CE and VDE sign, so you’re safe for the case that something happens. I had the experience, that these are almost identical in cost, if you buy from Amazon, Berrybase or Conrad. Conrad, as usual, is the most expenisve. Like this one:
And dont forget to take into account, that LED strips are very fragile. Most of the times it is needed, that after around 3m you have to give it a second power entry. That can easily be from the same power unit, but you have to lower the power that runs through your LED strip!
Let me say one thing at last: this is SERIOUS stuff, calculate and check not only once or twice, better five or six times. You should have already known, that 10A are way to low for such a strip, and it is not only your life that depends on this! PLEASE check everything that you build against the most common electronical laws like the above! Really, this is not meant offensive, but in the end it’s you, maybe your family or partner, that will have injuries or die an agonising death, so take care!
Wled is not on the Strip, I use athom as controller with ws2812b strip. I know that a led need around 60ma so 300 need around 12A 5v. But I found only power supply’s with 10a. I tought the brightness limiter will handle that.
Or would 12v work better?
If you don’t want to inject power 12V for a 5m of 300 leds strip for sure is the better choice then…
Math is not your strongest talent, isn’t it? 
300 LEDs x 60mA = 18000mA = 18A - this is not 12A, it is 18A. This is not negotiable, it’s a physical law…
I’m out, before I get angry.
Am I mis-reading something or are you suggesting using a 12v PS for the current LED strip that is now running on 5v?
If That is what you are saying then you have a fundamental misunderstanding of electricity.
You CAN NOT use 5v or 12v interchangeably. The LED’s are either rated for 12v or 5v.
Putting 5v on LED’s rated for 12v won’t have enough current to run them. It likely won’t harm it but it just likely won’t run.
putting 12v on LED’s rated for 5v will let the magic electrical smoke out. DON’T do it.
Note that this is a theoretical maximum with LED’s at white and full brightness.
Typical colored usage uses much less than the max.
Even with a 10A supply, e.g., a full red at half brightness should provide a stable color output.
OP, do you see that? Note that for long strips, you want to inject power at both ends of the strip.
Do you use a level shifter?
Well it won’t have enough voltage actually 
As the quinled site says 24v is better than 12v is better than 5v. But of course you have to make that choice before purchase.
The main (only?) advantage of 5V is to be able to run your strip from an ESP without any additional hardware.
I have a couple of ~100 leds strips working superbly that way
When it comes to electrical power, there is no “theoretical” maximum. Because of some error on the ESP (let’s say the default is accidentally all white, full power), it starts itself when nobody is home. After a few hours the strip gets on fire… Sure, there is nobody at home, but maybe some neighbours?
If you have lost someone to a fire in a flat, you have zero to none understanding for people, who aren’t willing to at least acknowledge they are to **** to figure out physical and/or mathematical laws. I don’t know many things in life, that are so simple to understand: with electrical power you don’t do games - you either know what you’re doing or you leave it alone. If you have to ask, then the least thing to do is to listen to people with a bit more understanding. 
But as I said, I’m out, I can literally feel my blood pressure boil…
@koying not targeted against you, really!
Yep, otherwise you need to step down the voltage with a regulator from the 12v power supply. It’s pretty easy to do and the hardware (on amazon) costs $2. I just built one 2 days ago with the following diagram:
For the calc, I found out how much each “LED” was drawing by looking at the spec sheet. They typically list how many watts each led draws. You then just multiply. No need to perform any other calc. For safe measures, I always get a power supply that has wiggle room. I had to power 2 strips, with about ~240 watts. So I bought a 12v 320watt power supply. The cost is negligible when dealing with more watts typically.
EDIT: The biggest concern I found with LED strips like this is that you need a common ground for the strip and the ESP32.
Before I added the voltage regulator, I powered the ESP32 with a 5v 2a usb power supply and the LEDs with the 12v 320watt power supply. It flickered like crazy. I implemented the diagram above and flickering went away.
OFC you don’t want to play that game
Just pointing out, as a debug path, that if red @ 50% produces the same effect, it’s not related to the power supply (that obviously will need to be changed anyway, but that will not necessarily fix the issue).
And empathy is not your strength it looks like. 
Yes you are right 300x60ma is 18a, not sure why I wrote 12. I have a power supply with 10a so not sure where the 12 came from. And I know 10a is not enough but I tought the brightness limiter would handle that not more power is used.
If you get angry that fast if someone makes a mistake better you not try to help someone. 
About 12v on the led I was not sure so I asked here for support. Now I know the athom can handle 12v but the led strip would be a problem.
You have some serious lightning going on! How many (kilo?)meters of led strip do ~2800W (12V*240A) equal?
ugh, morning coffee didn’t kick in
it’s the current that actually does the work in the electrical circuit.
The voltage just provides the “push” required to drive adequate current against the circuit impedance to allow the current to do it’s job. Kind of like a pump in a plumbing system.
I can put all the voltage I want onto a circuit but if I don’t give that voltage a path to allow current to flow nothing happens at all. Just like a closed valve in that plumbing system.
Well, until you put enough voltage on the circuit that the voltage eventually makes IT’S OWN path back to itself. Usually with horrible consequences. 
(burst pipes!)
Too much voltage = too much current = too much heat == BAD!
Sorry to drag up an old thread but would this work for multiple strings in a row on the end of your strip or does voltage drop on the data channel become an issue?
Got an athom wled controller and it’s relay is only rated for 16A. Need 18A for each strip but also like the idea of one controller multiple strips (albeit with power injection along the way).
I haven’t had any issues but I believe you can get a pixel node to boost the signal between chained strjngs
