Correct way of using an NPN transistor

[PerryBebbington]

@jasper1234567890 ,

You asked why each LED should have its own resistor, this topic:

Camera IR LEDs fault

Hi. This is nothing to do with Arduino, but there are awesome electronic people who maybe can help On my Wi-Fi Dahua HDBW1320EP-W stopped working IR lights. 24 LEDs version, but only 3 of them working. I saw some videos which told that all that's LEDs (in other cameras) are connected in series (if 1 goes-all goes). So, how can be possible that 3 working and others not? I saw some methods of testing, checking LEDs by amps, or one led disconnect and give 3v separately for each on…

Is an example of what happens when 2 or more LEDs wired in parallel share one resistor.