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Ferrite or Iron Powder toroid core for a low pass filter

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xzswq21:
Hello
I have designed a 10KHz low pass filter so I need to build a 680uH Toroidal inductor, but I'm skeptical to use Ferrite core or Iron Powder core,
the input and output impedance of the system is 50 Ohm and the signal level is only 1Vpeak but the Q should be higher than 20 and DCR should be lower than 2 Ohm.
could you please help me to choose a suitable Material and core type?

This is the response of my 10KHz LPF with Q=20 and DCR=2 Ohm in simulation, the response is good enough for my application:


I usually use "mini ring calculator" to design Toroidal inductors.

coppercone2:
i recommend you buy both and have a few rings on hand to get a good feeling of how they work along with how the windings effect them. It's really gonna cut down on the bullshit you have to deal with if you get a few spools of wire and a few rings, it won't be more then like $40 and your gonna know a whole bunch of shit people don't touch ever. I made a inductor box and a magnet wire box that has a bunch of different gauges of magnet wire and cuttings of other wire in there so I can rapidly make a whole bunch of things. I also keep some tape in there.

how do you want to build your filter? CLC?

Seriously, getting your mind over inductor calculations is like hard and confusing. If you get a few materials that you actually know you will learn ALOT.

T3sl4co1l:
What's wrong with buying one, probably of ferrite bobbin/spool type?

What about distortion, is this something that needs to be really clean, or does it not matter much?

The Q more or less rules out the lossiest powdered iron (#26, #52) but the rest are fine.  Something #8 or #18 or any of the brand names (Kool-Mu, Sendust, MPP, etc.) will do.  Gapped ferrite of pretty much any sort will do.

Tim

xzswq21:

--- Quote from: coppercone2 on April 26, 2021, 05:38:28 am ---how do you want to build your filter? CLC?

--- End quote ---

Yes, it is a 7th order CLC filter


--- Quote from: T3sl4co1l on April 26, 2021, 06:16:26 am ---
What about distortion, is this something that needs to be really clean, or does it not matter much?

The Q more or less rules out the lossiest powdered iron (#26, #52) but the rest are fine.  Something #8 or #18 or any of the brand names (Kool-Mu, Sendust, MPP, etc.) will do.  Gapped ferrite of pretty much any sort will do.

Tim

--- End quote ---

Actually I want to attach the filter at the output of a signal generator to clean the signal and then apply this clean signal to a sensor, finally I will check the output distortion by using a Spectrum Analyzer :) in fact I want to report the linearity of some new designed sensors.
the signal generator's distortion is -50dBc@10KHz but I need -90dBc@10KHz! so I need to build a 10KHz Low pass filter to reduce the distortions

coppercone2:
i think a 7th order filter will be difficult to get nice response.


what you want to do, since its a low frequency signal, is to buy a low distortion oscillator.

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