Hello. I have a nightlight that varies it's brightness depending on the ambient light. I want to make it less bright so I took it apart and traced the circuit and have a few questions.

1. It looks like it just uses two series resistors to drop the AC voltage to the rectifier. I this safe or a good practice, seems to me there should be better isolation.

2. If I am correct, the NPN in the circuit is simply a shunt that lifts the ground of the DC portion to decrease potential and dim the LEDs. This also seems bizarre to me. It seems like connecting the emitter to the ground side of the LED string and swapping the positions of the resistors in the voltage divider for the base of the NPN would be better, then the NPN would directly control current vs a shunt. What am I overlooking?

3. Am I correct in my interpretation of this circuit?

 

hi kief,
Are you able to read the transistor type number?
E

 

Hi,
You could see if "Big Clive on YouTube", has covered it. He normally produces a circuit, as well as describing how it works.

 

hi kief,
Are you able to read the transistor type number?
E
View attachment 342737

Hi Eric,

Yes, the etching reads "J3Y" which I believe is an S8050 NPN,

 

Hi,
You could see if "Big Clive on YouTube", has covered it. He normally produces a circuit, as well as describing how it works.

Good idea, I'll take a look. I'm a subscriber to his channel and was thinking about him when tracing the circuit. His voice is so soothing, haha.

 

Strange design, but no reason it can't work in theory.