Capacitor question...

[asm]

100nf=.1uF right?

im getting some parts on a BOM right now, and none of the ceramic caps have Voltage requirements. do i just get whatever is close?
i see most of the electrolyitcs do.

thanks.

 

[alk509]

[quote author="asm"]100nf=.1uF right?[/quote]

Yes. Check this out:

http://sst-web.tees.ac.uk/external/U0000504/Notes/labwork/LabManual/Units.html

Scroll down to Table 3.

Peace,
Al.

 

[alk509]

[quote author="asm"]im getting some parts on a BOM right now, and none of the ceramic caps have Voltage requirements. do i just get whatever is close?[/quote]

Close to what? It would really help if we knew what the project is. Having said that, ceramics usually come in some pretty high voltage ratings, so you're probably safe no matter what you get.

Peace,
Al.

 

[Family Hoof]

100nF leads me to believe it is a ceramic or metalized film. These types of caps (electrostatic, nonpolarized) aren't usually available in voltage ratings less than 50VDC, and that's probably sufficent for for most projects. I do tend to use 100V rated in power supplies for durability.

 

[asm]

thanks guys.
this is for the SSL9K pre.

neeno made a list of materials, but theres not one with part numbers, ect.

im doing the ceramic caps right now, and a few are only available as metallized film or disc or chip.
does any of this matter per se?

only 2 of the ceramic caps have V specs on the list they are 2.2uF/63v. the rest are just 470nF, 3.3pF, ect. no more description.

so if one is in 50v and another in 100v i should go with a higher voltage?

thanks.
taylor

 

[cannikin]

I use this often

http://recording.org/users/kev/capacitor_values_chart.htm

 

[bcarso]

asm, is there a schematic you could post or point me to? The effect of caps is highly variable depending on their function in the circuit, so one really wants to see how these values are being used.

Ceramic is not horrible in the audio path if it is NP0/C0G, but that dielectric is not volumetrically efficient and gets quite pricey above a few nanofarads. For budget work X7R is passable (barely). The higher dielectric constant materials are quite piezoelectric, injecting signals due to vibration and singing like crazy under a.c. excitation.

Probably that 2.2uF is meant to be a film cap.

 

[asm]

http://ebay.thegeorgiaproject.com/ws6/SSL.pdf

i couldnt find the post that had it, so i threw it on my server.
theres really not alot of info on what brand/type/spec for each cap, which is weird. the pcb overlay diagram shows if its elec or ceramic but thats about it

thanks for the help man.

taylor

 

[bcarso]

You may want to look at the packages' dimensions for the higher film values before you order some of these, because the footprints on the PCB look a little small for some of them.

But, basically, all the values below and including 470pF can be NP0 ceramic, 50V or greater.

The remaining non-electrolytics can be film. Mylar is cheap and certainly good enough for the d.c. servo caps, which are the 470nF values. 50V or 63V is standard.

The 100nF can also be mylar---it's a power supply bypass---50V or 63V or higher.

The purists will want the signal coupling caps, the 2.2uF ones, to be polypropylene, or one of the other polys, but these are likely to be too big to fit on the board. Mylar is good enough imo for gummint work... A 50V rating would be fine I think.

Brad

 

[asm]

and the lower tolerence the better right? 5% vs 10% ?

 

[bcarso]

Tolerance---well, none of the electrolytics are critical, which is a good thing because you couldn't get them in a tight tolerance anyway, and they have a large temperature coefficient.

The absolute value of the 470nF parts looks not too critical, but I would check to see that none are way different than the others.

The circuit has a certain symmetry, and where there are corresponding components it's nice to have them match each other for good common-mode rejection. But I don't see anything really supercritical. 5% if you can manage, 10% if not. The really small value ceramics may be specified as +/- a delta C rather than as a percent.

 

[asm]

thanks.

trying to convert these f**** cap values is pissing me off to no extent. im searching for an online convertor calculator right now.

 

[asm]

is 3300 pf the same thing as 3.3pf?
wtf

 

[Kev]

[quote author="cannikin"]I use this often
http://recording.org/users/kev/capacitor_values_chart.htm[/quote]

wow ... :shock:
did I do that ??

I must remember to move that one to the new place, since at least one person found it useful.

 

[asm]

[quote author="bcarso"]The purists will want the signal coupling caps, the 2.2uF ones, to be polypropylene, or one of the other polys, but these are likely to be too big to fit on the board. Mylar is good enough imo for gummint work... A 50V rating would be fine I think.

Brad[/quote]

which 2.2uF ones? the 63v or the unmarked?
i'm having problems finding a "tube" with leads on both ends style poly cap in 2.2, there are 2uf , and one 2.2uf for 80$ EACH.

?

thanks for the help so far

 

[bcarso]

On the schematic all of the 2.2uF caps are marked 63V. As remarked earlier 50V rated devices should also work fine. You won't find anything lower in film with leads anyway.

Polypropylene is going to be too large to fit I believe. Mylar aka ~polyester is your best bet for this board.

You don't need a " 'tube' with leads on both ends" (so-called axial lead). A radial lead (leads emerging from the bottom) is fine, and has become the de facto standard these days. Typically the radial will fit into a smaller footprint too.

Don't pay 80 bucks for anybody's small-signal cap unless an audiophile is paying for it and insisting on it ;-). You shouldn't have to pay more than 2-3 bucks in small quantities.

 

[asm]

where at? neeno's pdf i printed out (the one i linked) had c69/c55 as just 2.2uF, and c68/c84 as 2.2uF/63V

:?

 

[bcarso]

I'm talking about the SCHEMATIC, page 2 of 7, not the parts list.

 

[asm]

damn, your right, they all are 63v. thanks for pointing that out.

one question.. what does 3.3pF equal? same as 3300 pF?

stupid questions amok

 

[bcarso]

3.3pF is three point three picofarads. 3300 pF is thirty-three hundred picofarads, 1000 times more. It could also be written as 3.3 nF.

milli means 10^-3
micro means 10^-6
nano means 10^-9
pico means 10^-12