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How 12V is generated from Neutral Line

vrmidhun12

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Hi fiends,

I was working checking a circuit. In that circuit there is an AC DC converter section. The 12DC is generated from the neutral
line not the mains line. I was wondering how it works. This circuit is a part of a trailing edge dimmer circuit.
Please see the images attached. In the AC-DC circuit N is neutral.

AC DC.png
Dimmer.png


The IC used in the AC DC is BPA8504D from BPS. Please help me to understand the circuit, especially the AC-DC section.

Regards,
Midhun V R
 
A low voltage supply is derived from the voltage between L and N, not from a single terminal. You should supplement the schematic with L connection to the switch transistors to better understand how the supply works. Apparently it's using the center of the transistor series circuit as common node (supply ground). Notice that in the negative L half wave, the DC/DC input capacitor is charged to the mains peak voltage.
 
Hi

"From neutral not mains"
Any voltage needs two nodes!
Every current needs a loop.

Mains is not a signal. Neutral and live, both belong to mains.

Klaus
 
That BPAXXX is like an LNK302, a high voltage buck.
With you, they do half wave rect of the mains.
It just gives 12v output.

Half wave is often used when neutral is wanted to be passed contiguously right through the supply......ie, in your case, your 12v gnd is neutral.
 
A low voltage supply is derived from the voltage between L and N, not from a single terminal. You should supplement the schematic with L connection to the switch transistors to better understand how the supply works. Apparently it's using the center of the transistor series circuit as common node (supply ground). Notice that in the negative L half wave, the DC/DC input capacitor is charged to the mains peak voltage.
Hi,

Thanks for the quick replay.
Here D+ is the line and D- is the point where the load is connected.

Thanks,
Midhun V R

Hi,

Please see the attached image of Load connection to the neutral

Regards,
Midhun V R
Dimmer.png

Hi,

Thanks for the quick replay.
Here D+ is the line and D- is the point where the load is connected.

Thanks,
Midhun V R
 

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