Mains Filter

[vik1501]

Hi friend,

Can u guide me as to how to make microprocessor based circuits immune to mains transients and noise.

Vikas

 

[kinjalgp]

Some of the steps to be followed.
1) Use EMI/RFI Line Filter before the transformer in your power supply.
2) Use 0.1uF decoupling capacitors near power pins of each IC in your circuit.
3) Use PCB with ground plane.
4) Use Reset controller chip for uC/uP instead of conventional R-C circuit.
5) Use ferrite bead inductor on Vcc rail near power pins of all ICs.
6) Avoid ground loops on the PCB. Avoid long tracks.
7) House the PCB in a metal cabinet but "do not" ground the cabinet with your circuit ground.

 

[vik1501]

thanx kinjalgp !

1. What make of EMI/RFI line filter ? or what specifications ?

2. Yeah , I follow this.

3. But what about pth board ? we can only increase the ground plane tracks.

4. Yeah I follow this. U mean watch dogs.

5. What value of inductor ? I believe one uses even choke filters. Isn't it ?

6. & 7. I follow this always.

 

[kinjalgp]

You can use Filter of any make. I use "Elcom" make which is easily avaiable in India (BTW: where are you from?). These are available in may shapes and sizes and current capacity. Choose the one which best suits your requirement.

On PTH board, increase the ground plane. If possible route the ground tracks only on one side of the board and use "Copper Pour" to make the enitre one side a ground plane. Some tracks intersecting this ground plane are allowed.

I use 6-hole ferrite bead with 2.5 turns wire wound in it. You can also use ready made choke filters.

 

[vik1501]

Kinjalgp,

Thanks again. Pleasant surprise to know that we hail from same country !! ( I am from Pune, Maharashtra)

I'll definitely contact ELCOM rep.

Anybody from India who deals in choke filters ? I have seen some reputed makes of power supplies using common mode filters (I was two in combination in one power supply). What's the significance ? How do u design such ?

But what's this 6 hole ferrite stuff ? Can u post picture ? How did u design this ?

Bye !

 

[kinjalgp]

Hi,
I am from Mumbai.

I don't know any choke manufacturers over here.

6-Hole ferrite is a small cylindrical bead about 7.5mm in diameter and 10mm in height. It has 6 holes drilled longitudinally around its periphery.
I don't have a digital camera so can't post the picture.