Review on JMEXSUSS 33ft 100 LED Warm White Christmas Lights - Indoor/Outdoor Waterproof Twinkle 🎄 Fairy String Lights for Christmas Wedding Party Decoration - Clear Wire Plug-in Tree Lights by Inyong Dow

As I suspected, those Christmas lights flicker terribly. A cheap Chinese power supply doesn't convert electricity from 60Hz to 120Hz, the light spins through a flickering 30Hz, they switch + and - very quickly, when the switching stops only half of the LED is lit. You may not notice it, but the effect will be - you will not be able to stay in a room where this light is on, you will see a flicker in the corners of your eyes and you will get a headache. Of all the modes only the 3rd mode where it flashes from one LED to the next doesn't flicker, but the on and off cycle can be annoying for some but is much less annoying than the flickering. Capacitor, that might not work either. If this light were designed properly it would have a power supply that doubles the frequency from 60 to 120Hz and then splits it to either side at 60Hz on each cycle, but the Chinese save money by giving you a headache. Check out my slow motion video to see this flickering. It's real, even if it's invisible to some people, it will definitely give you a headache or throw you out of the room. The second way to fix this is to need 50 LEDs, which would be a huge task.