Can I run a LED-Strip with 24 LED without an additional power source from a esp32-wroom board? The strip is an WS2812B 5V. It is working as intended so far but I realized the usb connector on the board gets hot to the touch when all LED are powered.
I’m appreciate any advice!
Not for long… 
What’s going to happen?
Do a calculation: according to datasheet each led can draw 60 mA when white is on (all 3 channels ON). If you have 24 of them it’s 24x60=1.4A.
So, first question: can your power source offer 1.4A? If you use usb port then answer is generally: NO (standard usb is 500mA), unless you use high-power usb, but in this case a cable must also be able to handle such currents.
Second: esp board is NOT designed to draw such high currents, so sooner or later something will end up in smoke.
Conclusion: get and external power supply. And ALWAYS do above calculations before connecting ANYTHING. It’s a good recipe against fire or smoke. It’s a simple math and datasheets are available.
We do not want that!
Thank you very much, this is a very helpful answer. What is max. current draw a esp board can handle? I feel I should be able to find this googling but I have not been successful so far.
GPIOs can only drain currents in mA amount.
If your esp does something to step the voltage down to 5V (for example from 9Vin) that is another bottleneck. Typical LDOs are often only capable providing 500mA and that includes the power for the esp/serial and what not…
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Well… if ESP board is powered from USB2.0 then 500mA is total limit, but you must take into account that esp32 consumption is included here, and it can draw up to 100mA with spikes well over that. Running device on (under)power limit tends to unwanted ESP reboots.
So, unless you have only a couple of led’s it’s better to use external 5V PSU with appropriate current, increased by, say 10-20% at least for reserve, since no device likes to run at max. In your case i’d take 5V/2A power supply. But, since you already noticed that usb connector gets hot, connect led’s separately, not through esp board.
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Thanks again. I even have a 5v 2a power supply sitting around 
The wiring seems straight forward, connect 5v and ground to the led strip and the board. But in this diagram there is an additional resistor between 5v and gnd (link to the whole article). Do I need that to avoid or is it just a part of the power supply?
That is a capacitor not a resistor. It is being used to “smooth” any fluctuations in voltage coming from the power supply.
When using a good quality power supply that is properly “sized” for your application, it is probably unnecessary. However, a capacitor is pretty cheap insurance against the frustration that can be caused by “dirty” power…
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