Sunset type lamps

Other Types of Lights LED Spotlights
1

I bought a few of these things. They’re lensed with a thick round lens with a colour filter and led sat on a star shaped board behind. Runs off a USB plug, not much to go wrong.

https://www.amazon.co.uk/Jooayou-Projection-Rotation-Romantic-Birthday/dp/B0928434NH

I left one of the rainbow ones on overnight and it didn’t seem as bright the next day. I switched it off to cool down and turned it back on, it definitely wasn’t running as bright so I sent it back.

As an experiment I left on of the sunset colours on and one off for 24 hrs. This is what happened. Anyone know why this is happening? It’s a simple circuit, running low wattage and voltage. I’m powering them through a couple of old iPhone USB chargers.

2

Insufficient heatsinking combined with a poor quality LED. It’s roasting itself to a slow death. Most aliexpress USB and other low voltage power LED gadgets I’ve seen don’t bother much with current regulation and cooling. Try adding a power resistor inline to get the heat and current into a more manageable state.