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 Post subject: non-magnetic smt caps
PostPosted: Fri Aug 26, 2011 1:13 am 
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God

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New parts. Front page of the data sheet.


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PostPosted: Wed Jan 18, 2012 5:11 am 
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Thanks, Mike! These look nice.


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PostPosted: Thu Jan 19, 2012 3:45 pm 
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Cow
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Thank you Mike.

And good to see you back in this forum, Charles. Hope you are well!


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PostPosted: Thu Jan 19, 2012 5:54 pm 
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God

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I think I need to design something new so I can try them.


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PostPosted: Tue Jan 19, 2016 3:29 am 
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Sheep

Joined: Thu Dec 06, 2007 9:07 am
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I just found this which offer different non-magnetic termination of smd ceramic caps.

http://www.jilicom.com/product/Syfer/Non-magnetic.pdf

2 = Sintered silver base with copper barrier (100% matte tin plating). RoHS compliant. (available on C0G/NP0 & High Q only).
3 = FlexiCap™ base with copper barrier (100% matte tin plating). RoHS compliant.
4 = Sintered silver base with copper barrier (tin/lead plating). Non RoHS compliant. (available on C0G/NP0 & High Q only).
5 = FlexiCap™ base with copper barrier (tin/lead plating). Non RoHS compliant.


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PostPosted: Fri May 27, 2016 11:25 pm 
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Cow
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Off topic, but seeing this is active at the moment, can someone say what a smd X7R type cap of around 10uf does (electrically/sound wise) when solder across pins 4 and 7 (+ & - pins) to say OPA627 opamp?

Cheers George

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PostPosted: Mon May 30, 2016 2:49 am 
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Cow
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Nobody keen to have a go?? Must be voodoo?

Cheers George


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PostPosted: Tue May 31, 2016 2:59 pm 
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God

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i do this a lot but with electrolytic caps. Never tried it with a ceramic.


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PostPosted: Tue May 31, 2016 6:08 pm 
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Sheep

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With split rails I do the full 'delta' - one each rail to 0v, and a third across the pins.
Since this is the tightest loop I usualy use a rather smaller cap for it - tens of nF works for me; push that SRF up as far as possible.

I'd also observe what you propose is all that happens when using any opamp in a single-supply condition. It works.

NB three caps can get interesting if you are also trying to use high performance/discrete/roll-your-own high feedback regulators on the split rails owing to the cross-coupling by the cap between rails. In which case I deliberately introduce some small defined ESR ( a discrete resistor, smt) into the rail-to-0v decoupling. Or compensate my regs better. Use of 'scope and test signals is mandatory!


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PostPosted: Wed Jun 01, 2016 8:30 am 
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Muriel
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Hi,

georgehifi wrote:
Nobody keen to have a go?? Must be voodoo?


I think it is because you are asking many question in one (possibly without recognising), mixing subjectivity and objectivity from an apparent position if ignorance and no-one cares to take on such a task.

To break it down...

The reason why one may wish in Op-Amp decoupling to tie the positive rail and negative rail together through a cap are down to several issues.

Op-Amp's have of course a "ground pin" (and yes, most of them have ONE ground pin - it is the one with less PSRR) and stability often improves if we link the Supply pin to the ground pin through the shortest possible loop. One may then take extra measures to minimise the loop impedance between the Op-Amp ground pin and the actual ground.

What sort of capacitor we use there would of course depends strictly on the actual application and the Op-Amp used.

As for X7R, they have very low ESR and their ELS is pretty much down to the physical length, sadly their capacitance is very much modulated by voltage (and to a lesser degree current) and so they may be okay for low end products or where we deliberately want to add some H2 dominant distortion at low frequencies (I have used them like this explicitly to achieve this).

What will be the subjective effect - again there is simple quick answer, again it depends on the specifics. Adding some H2 dominant, low order HD at low frequencies often "warms up" the sound.

As said, way too many questions in all of this including some where the answer highly depends on context.

Ciao T

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PostPosted: Wed Jun 01, 2016 9:31 pm 
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Cow
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So T if I break down what you've said.
With an opamp which has the usual normal rail decoupling to ground. Adding this 10uf XR7 across the voltage rails of can introduce a certain amount of 2HD nothing else?

Cheers George

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PostPosted: Sat Jun 04, 2016 5:47 pm 
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Muriel
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Hi,

georgehifi wrote:
So T if I break down what you've said.
With an opamp which has the usual normal rail decoupling to ground. Adding this 10uf XR7 across the voltage rails of can introduce a certain amount of 2HD nothing else?


That is nothing like what I said.

But why don't you run with, seeing you cannot understand what is really going on?

Ciao T

PS, note that H2 would only appear at very low frequencies. And only if the standard decoupling allowed the X7R capacitor to see significant AC voltage and thus to distort. As I said, you asked an incredibly complex question and expect a simple answer - the world does not work like that.

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