Chinese mushroom night light teardown.04:33

I bought a cheap Chinese plug-in night light based on weird mushrooms because it looked kinda cool. It’s just as cool as it looks on ebay and has some neat design features. For a start, the LEDs plug into small sockets, so they can be changed if desired. Note that this should be done with the power off and polarity must be observed as the high open circuit voltage could nuke wrongly inserted LEDs.
The circuitry is a simple capacitive dropper with a 220nF cap limiting the current. The light sensor circuit is just an NPN transistor, a resistor and an LDR (Light Dependent Resistor) that effectively shorts out the LEDs during the hours of daylight. There’s a strange extra resistor just placed across the LEDs. I’m not sure if this is just to limit the open circuit voltage if the LED circuit goes open circuit. By my rough calculations the voltage would still be around 70V which would still greatly exceed the voltage rating of the small electrolytic used to smooth the LED supply slightly.
At the end of the video I chop the transistor out so that the lights will stay on 24/7. The power consumption is the same anyway.
Another interesting point to note is that the mains plug connections are just pressed against solder pads on the back of the PCB and not soldered. I guess that with a single screw holding the PCB in it will effectively triangulate on the two power pins.
I actually like this light a lot. I’ve just ordered another two and a different style to make one really big one.
You can find these on ebay if you do a search for – led mushroom night light.
Although designed for 220V they should be fine on anything from 90V upwards.