Fatpants capacitor question

[CK1]

Hi all,

REALLY feeling like a n00b at the moment, but I searched the forum and couldn't find this answer anywhere:

The only place I could find 220pF (.00022uF) electrolytic caps was Mouser and they don't keep it in stock.  Where do you guys find these?  Is there an acceptable substitute (I'm assuming there is not)?  Thanks in advance for any info.

[maysink]

You want a ceramic cap for C1. Generally speaking, u only want an electro cap for larger values (10uf, 47uf, 100uf, etc.). All the standard parts suppliers will have 220pf ceramic caps.

[CK1]

Ahh, OK.  The V2 pdf specifically listed electrolytics, but nothing else, so I figured I was to look for those for all the caps.  Thanks for clearing that up!

[jkokura]

You can also get 220pF in film as well. I have film caps for everything 100pF and above. It's not a necessity, but I will say that Ceramic is not the only option for the 220pF value. Smallbear and Mouser both stock film caps in that value.

One thing to note, it is much easier to get the right parts from Smallbear Electronics. If you get your parts from Mouser, especially if you're new at this, try posting the part #'s and links to the parts you're planning on getting. Sometimes it's very easy to get the WRONG part even though it looks right. There are lots of differences between parts, and size can sometimes be deceiving.

On a general level, getting 1/4W resistors is pretty easy to keep straight, but getting the proper caps can be like sorting through a cupboard full of mugs looking for one mug in particular.

Jacob

[CK1]

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I think this is everything (not including the switch, jacks, etc.).  I put double what I need in the cart, just in case, plus I added a higher value cap as recommended in the v2 pdf.  Did I miss anything?

[maysink]

A lot of the ceramic caps you have listed can be (metal film) box caps. Looking at the project docs, whenever you see a cap that is a circle with a '+' sign to one side it is a polarized aluminum electrolytic capacitor. Whenever you see a rectangle it is an unpolarized box cap. The elongated ovals are unpolarized ceramic caps. (Complicating matters, there are also polarized tantalum caps available)

So, quick look at the fatpants pcb diagram:

C1 = ceramic cap
C2 - C4 = box cap
C5 - C7 = electro cap (longer lead is the positive lead)

However, as mentioned above, you can get box caps in a typically-ceramic cap value and ceramics in typically box cap values and that will all work. Some people claim one type of cap vs. another yields a different sonic outcome but that's another matter.

[CK1]

Thanks for clearing that up!  I know that in non-audio circuits, as long as the specs are within tolerance, you can use different types of caps/resistors/etc., and I've heard similar things on audio forums (depends who you ask, though, as you mentioned).  The reason I used ceramic was that was the main option I had from Futurlec for those ratings.  They don't seem to stock box caps (at least I couldn't find them if they do), so the ceramics were my only choice.  I obviously don't NEED to order from Futurlec, but their prices seemed very good and they supplied a few other things I wanted, so it saves me from too many orders for one project.  Still, if you recommend going with the specified cap types, I'll just order from somewhere else this time.  Man, getting this first project off the ground is harder than I thought!  

[jkokura]

I dont know what futurlec does or doesn't have cause I haven't looked, but what you need is a FILM cap, which doesn't always mean a box cap. Check and see if they have other caps with the specs you need.

[madbean]

I'm pretty sure all box caps are metalized film types, but I can't say definitively. Anyway, I don't have much to add to what's already been posted, other than my personal preference is:

under 1n: ceramic, film or silver mica (usually ceramic)
1n - 2.2uF: box type or poly film
1uF and greater electrolytic: Xicon high temp or miniature caps (mostly the miniature).

Most ceramic caps are at least 50v, and up. Box caps generally run 50, 63, or 100v. Film caps are 16v (Panasonics, at least), and all my electros are 25v.

Another overseas supplier you can try is Tayda electronics. They don't have everything, but the prices are cheap and I have used them once. The service was great, and the best packing I've ever seen.

[CK1]

I appreciate the listing of personal preferences by you or anyone else, for that matter.  It's nice to know what you've come to trust or prefer so I can use that as a starting point.  Thanks again for getting me up and running, and I promise to answer my share of n00b questions once I know better what I'm talking about!