what kind of caps/inductors?

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chico1st

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Joined 2010
Hi there what kind of caps/inductors should I be aiming to use on a given build?

I will probably be pursuing this build, and I am limited by what is available at some reasonable price (you can buy 400$ tantalum caps which is crazy) on digikey.

There are many kinds of caps for instance, tantalum, film, ceramic etc.
there is Low ESR, Low ESL, low tolerance etc
Same goes for inductors.

I attached the schematic.
 

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theAnonymous1

theAnonymous1

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Joined 2004
Like Simon says, you want low ESR X7R ceramics wherever possible. That means pretty much every cap except the input caps, the >10uF decoupling cap on AVCC, and the >470uF PVCC caps. The AVCC cap should be either low ESR tantalum or low ESR electrolytic, bypassed with 100nF ceramic.

Cap tolerance isn't very important in this application (IMO).

Inductor cores should be Micrometals type 2, or you can try shielded ferrite bobbin cores like I used.
 
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chico1st

Member
Joined 2010
Do you recommend X7R because that is the lowest Letter than comes in low ESR? (as opposed to X7D)
On these non-input caps how much margin do i need in voltage? I have always doubled the needed voltage on inputs but is it the same for audio?

Anonymus you had inductors on your build? for a cut-off?
I can seem to find any "Micrometals type 2" on digikey... are these just fixed inductors?
EDIT: the speaker output is 12V to my understanding so i would go with a 25V cap.
 
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nigelwright7557

nigelwright7557

Member
Joined 2008
murtonpikesystems.co.uk
chico1st said:
do you need to make your own inductors? does it make a big difference?
I would prefer to be lazy and just something off digikey, unless its like night and day.
Click to expand...

I couldnt find one online, all I could find was very small class d inductors or power indcutors which got red hot 120 degrees c !

Its not difficult to wind your own, just keep the winding as tight as you can.
1.5 meters is enough wire. Takes me 5 minutes to wind one. Its much cheaper as well to wind your own.
 
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chico1st

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Joined 2010
what really, what causes the heat? You can get them with very low DC resistance (<50mohm) if thats what causes the heat but i guess its all the switching.

These are under 2$ and are at least rated for 3 amps.

Regarding the caps, you say that the capacitor tolerance doesnt matter so then why does it matter if they are X7R?
 
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