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Filtering switch mode power supply

Posted: Mon Feb 22, 2021 10:35 pm
by mpx
Hello necks

Is it possible to filter a switch mode power supply output? One I have is causing havoc with pilot tones, ringing noise. God only knows what spurs it might be generating. Wondered if I can cure it with some filtering caps or something.

Cheers

Re: Filtering switch mode power supply

Posted: Tue Feb 23, 2021 7:05 am
by radium98
try some ferrites or beads coils with decoup caps

Re: Filtering switch mode power supply

Posted: Tue Feb 23, 2021 7:38 am
by mpx
Decoupling 0.1uF?

Re: Filtering switch mode power supply

Posted: Tue Feb 23, 2021 12:05 pm
by radium98
have to try many values 100 , 10 and 1 nf with some vk200 to remove thoses EMI

Re: Filtering switch mode power supply

Posted: Tue Feb 23, 2021 1:05 pm
by mpx
LC in series (psu-L-C-out)?
Which type of vk200? Or can I use a few turns through a regular ferrite tube?

I read it is quite difficult to clean up smpsu outputs completely

Thanks

Re: Filtering switch mode power supply

Posted: Wed Feb 24, 2021 9:08 am
by nrgkits.nz
Use Meanwell power supplies, I’ve never had any problems with them.

Re: Filtering switch mode power supply

Posted: Wed Feb 24, 2021 10:27 am
by teckniqs
Yeah I think it would be much easier to just replace the PSU. I've tried using microwave link box from laptop charger and it made a high pitched whining noise over the audio but with another laptop charger it was fine (all I had at the time).

Re: Filtering switch mode power supply

Posted: Wed Feb 24, 2021 4:11 pm
by mpx
I might replace it with a linear psu.

Do the Meanwell ones need anything on the output?

Re: Filtering switch mode power supply

Posted: Wed Feb 24, 2021 10:29 pm
by LeeCavanagh
mpx wrote: Wed Feb 24, 2021 4:11 pm Do the Meanwell ones need anything on the output?
No they dont, but they are also not the only brand that dont need extra filtering, you could find others cheaper, but mean well do have the best rep dont they.

Re: Filtering switch mode power supply

Posted: Wed Feb 24, 2021 10:35 pm
by mpx
Thanks :tup