can anyone suggest what exactly this circuit does.....rfi/emi filter.......

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jit_singh_tara

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Hello friends ,

PLease help me understand how this pcb circuit is helpful in reducing noise...

I have an application where ac motor noise creates problem in the load cell data reading....
what can be done to reduce it....:

will this kind of ckt help reduce the noise coming from ac motor to ac mains from entering my unit.......


I am also attaching a video to demonstrate whats happening:
 

Hi ,
did you use a opamp buffer before the ADC input of the micro if not there is a chance of wrong reading
use .1 and .01 mf capacitors on your DC line of the MC, How much more that much good

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Hi ,
did you use a opamp buffer before the ADC input of the micro if not there is a chance of wrong reading
use .1 and .01 mf capacitors on your DC line of the MC, How much more that much good
 

I think the schematic printed on the PCB shows two inductors on one toroid core; the sense of both windings is opposite. Therefore such "transformer" cancels all high-frequency current components, acting as a EMI filter.
The other EMI-filtering components are the red capacitors connected across, and voltage-spike limiters are blue.
 
The leads to the motor must be screened and the motor casing must be earthed, this will stop it transmitting its noise effectively. A filter such as you showed could be fitted at the motor end of the leads. This would only stop the noise that the motor was originating. the other problem is to filter/screen the incoming supply lines so noise from elsewhere will not be radiated in your location. As a general comment I am not surprised that your layout is picking up noise. Are your low level signal leads screened?
Frank
 
I forgot to tell you The photo shown is of a surge protector with L N and Earth as inputs and L and N outputs
which if connected to your circuit is of no use for the above problem
 
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