[applegd]

Quote:

Originally Posted by n_maher /img/forum/go_quote.gif You are spending way more time worrying about this than it merits. And honestly, with some of those configurations you're asking for problems. Your PPA does not need or want 8000uF of power rail capacitance.

Thanks! I saw someone use 8000uF for PPAv2 power rail without any problem with his power supply, but I think that is too much capacitance. I will control mine below 4400uF. If I end up can get 8 Cerafine 220uF/35V, it will be around 2000uF.

 

[AudioCats]

I guess at the PPA level all you need is 2000uF. The speed of is alot more important than the capacity. There should never be a large but slow cap in the power supply system, you can not speed it up by // 'ing a smaller fast cap.
How much faster is the Cerafine comparing to the FM? The FM's are good caps, but they are not even the low ESR type.....

Anybody have the ESR specs of Cerafines?

 

[Seaside]

Panasonic FM datasheet does not say anything about Low ESR, but it stated "Low Impediance (40 to 70% less than FC series)" in it. Isn't that enough for power supply section of PPA?

In fact, no pana electolytic cap is specifed as Low ESR, but a lot of them is specifed as Low Impediance. In case of SMT and polymer caps, panasonic did specified it as Low ESR.

I checked nichicon PW series datasheet, and it did not say anything about low ESR, but it did say about low impediance.

It's bit odd, but I know both caps are descent, so I wouldn't worry too much about low ESR thingy.

I think arround 2000uF is enough for PPA, no need to go higher like 8000uF.

 

[AudioCats]

per the specs, the FM have lower ESR than the generic stuff, but still not to the point to be called "low ESR".
I think ESR rating is more important than the impediance rating, when used in DC power supply circuit.

Still I wonder if the cerafine's are as fast as the "extra-low-ESR" switching caps. Couldn't find the specs on Cerafines though.

 

[hellomai]

Quote:

Originally Posted by applegd /img/forum/go_quote.gif It is funny to see myself that I want to build a PPAv2 to play with so later after I know what is in HR '06 Max module. So I am looking for Cerafine 220uF/35V caps these days. I tried digikey(not in stock), mouser(NONE),newark(None). If you know where to buy it in US, I will appreciate your help. Anyway, I am still searching now......

here

it's ELNA RFS, Silmic II, better than Cerafine (ROA).

 

[applegd]

Quote:

Originally Posted by hellomai /img/forum/go_quote.gif here it's ELNA RFS, Silmic II, better than Cerafine (ROA).

Thanks very much!!

When I placed digikey order couple days ago, it was not there, now I have to deal with the handling fee and shipping fee....

 

[hellomai]

Quote:

Originally Posted by applegd /img/forum/go_quote.gif Thanks very much!! When I placed digikey order couple days ago, it was not there, now I have to deal with the handling fee and shipping fee....

also stock some other values like 4.7uF/35V, once over $25, no handling fee.

 

[applegd]

Quote:

Originally Posted by hellomai /img/forum/go_quote.gif also stock some other values like 4.7uF/35V, once over $25, no handling fee.

Thanks! Hellomai

Now the cap for C1 position for PPAv2 is selected. I will buy 220uF/35V Silmic from digikey.

The other headache is C4 position(local bulk capacitance for op-amp, d<=10mm, PCM=5mm) in PPAv2. I checked some data sheet, it looks like Silmic 220uF/16V is the best choice, the second option is Silmic 100uF/25V or Nichicon Muse 100uF/25V, the third one is Cerafine 220uF/16V. The headache is I can not find anywhere sells Silmic 220uF/16V, not at digikey, not handme, not Welborne, not mouser/newark. So it looks like I have two choice so far, either buy 100uF/25V Silmic/Muse from Hndme or buy 220uF/16V Cerafine from Welborne. This makes me wondering whether 100uF is large enough for C4 position, do I have to have 220uF?

 

[hellomai]

Quote:

Originally Posted by applegd /img/forum/go_quote.gif Thanks! Hellomai Now the cap for C1 position for PPAv2 is selected. I will buy 220uF/35V Silmic from digikey. The other headache is C4 position(local bulk capacitance for op-amp, d<=10mm, PCM=5mm) in PPAv2. I checked some data sheet, it looks like Silmic 220uF/16V is the best choice, the second option is Silmic 100uF/25V or Nichicon Muse 100uF/25V, the third one is Cerafine 220uF/16V. The headache is I can not find anywhere sells Silmic 220uF/16V, not at digikey, not handme, not Welborne, not mouser/newark. So it looks like I have two choice so far, either buy 100uF/25V Silmic/Muse from Hndme or buy 220uF/16V Cerafine from Welborne. This makes me wondering whether 100uF is large enough for C4 position, do I have to have 220uF?

I would go for 100uF/25V for the following reasons:

1. assuming you are using 24V, quote from tangent's website "However, it's safer to use caps with a voltage tolerance at least as high as the voltage the op-amp sees."

2. the isolation JFET will provide constant and stable current, the opamp will draw almost constant current (because the opamp load is quite large), there is not much gain putting a big cap there.

hope this will help.

 

[twc5964]

15 days have passed now since my order at Welbourne and nothing.Took them 6 days just to charge my credit card and that's after I sent them an e-mail.*SIGH* Hope I get my order.I've never had a problem in the past with them.Now I'm a little worried

 

[jbloudg20]

I have had over half of my order to welbourne go bad. Took 4 months to get 4 capacitors. They sent them in two shipments (getting charged for shipping twice). And another part of that order, I still ahve not recieved, its been over a year now. I will never order from them again.

 

[Paperweight]

I just received an order from Welborne today the 16th. The order was placed on the 4th. I order lots of parts online. 12 days is a slightly long wait. That's not the kicker though. I live in Lexington, NC and that's what the order conformation e-mail said too. I got the box and guess what it said? Lexington, KY. Someone with more sense at the post office marked out the KY and scribbled in NC. I bet it sat a few days in KY untill someone figured out the zip code was for NC.

HeadRoom had a package delivered to 278 not 287. I had to go commando and storm up the neighbor's front steps to retrieve it. Same thing with them. Apparently it's hard to type in a customer's address this time of year.