LC filter (Capasitor)

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#1
Which 0.47 uF 100 Volt capacitor would you choose for the LC filter at a kl. D amplifier?
Can an ordinary Wima capacitor as in the picture be used there?
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Thanks
 
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#2
Yes that capacitor will do but it is large for the purpose. Often SMD ceramic caps are used at that spot but film caps are preferred by many (sound wise). MKP and PPS are a tad better. Smallest size and higher voltage rating than strictly necessary is better. If going for film caps then 5 mm pitch is probably advisable just as good PCB design.
 
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#3
Here we have high frequency components, so the cap needs to have low inductance. SMD MLCC C0G are probably best, and you will need several in parallel b/c they come in small values. There are stacked film SMD which are probably just as good as C0G ceramics. If you cannot go SMD, the one in your picture will do, relatively small. You want the leads as close as possible for minimal loop. Large 'hifi' film caps are the worst for this application.
 
#6
Nothing a datasheet and a ruler wouldn't solve (beforehand). So get used to measure parts/PCBs and read datasheets.

It is good practice to measure the distance between the holes in the PCB pads and that is called pitch. It is expressed in millimeters. Then one tries to find an alternative in the same pitch. That small cap looks like a 5 mm pitch capacitor and you thus need a 5 mm alternative.

* Now we learn and agree at once that any contraption with extension wires, tie-wraps, melt glue, outboard caps etc. is only allowed in the tube section. In practically all other electronic devices we try to place fitting parts and keep wires as short as possible. We even cut the wires. Wires can behave like antennas and we don't want parts to behave like antennas certainly in circuits where the other parts are perfectly able to amplify HF/RF.

MKS4:

https://www.wima.de/de/produkte/metallisierte-kondensatoren-im-rm-7-5-52-5-mm/mks-4/

You would have needed MKS2 as those can be had in 5 mm pitch:

https://www.wima.de/de/produkte/metallisierte-kondensatoren-im-rm-7-5-52-5-mm/mks-2/
Since Wima is German the pitch is called Rastermass or RM. Thankfully Germany is metric so everything is in (milli)meters.
 
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#7
jean-paul said:
Nothing a datasheet and a ruler wouldn't solve (beforehand). So get used to measure parts/PCBs and read datasheets.

It is good practice to measure the distance between the holes in the PCB pads and that is called pitch. It is expressed in millimeters. Then one tries to find an alternative in the same pitch. That small cap looks like a 5 mm pitch capacitor and you thus need a 5 mm alternative.
Click to expand...
There is room for it but the smaller the capacitor the better it should be
 
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#8
Now I speak a few languages but that one is not my forte. It is Danish I think? Since this is an anglosaxon forum it is even forbidden to use any language other than English.

Edit: I would have sworn that I read Danish a few minutes ago... Anyway, yes that is right. Preferably with short lead wires as usual in quality/modern/fast electronics. Also pay attention to the length/height and width of the capacitor. This counts especially with electrolytic caps where often various sizes of the same value exist within one and the same series. So 10.000 µF 25V exists in thick + short but also in thin + tall.

Never assume, just measure. Simple and adequate, saves money and time.
 
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