Capacitors types and voltages?

[pappasmurfsharem]

I was looking into buying some of the PCBs from here, but the instructions don't say what caps to use. Aluminum electrolytic... Polyester film, ceramic disc, tantalum...

how do I know what type to buy, and what about voltages. I see ranges from 25v, 50v, 63v, 100v etc

[Ang3lus]

25V is enough for everything pedal related.

Ceramic are the lowest values, 1pf - 1000pf.
the next range of values is 1n-1uf, and here you got many choices.

you got the Mylar Greenies, which are polyester.
you got Wima and Panasonic ECQ, which are polypropelene.

the next set of values is 1uf - whateverUF (in pedals, usually 1uf-2200uf).

these are electrolytics, and they range in being Tantalum and Aluminum.

Tantalum is more "mojo" but more prone to die before the aluminum.
aluminum is better, and you can also get a bipolar version.

in electrolytics, the orientation is very important.

Tantalum will explode in your face if you get them wrong.
Aluminum will get mad/burn, and bipolar is the best choice if you are a beginner I reckon, since you never get the orientation wrong.

with ceramics, you usually get a 50v rating.

with polyester/poly, you can get anything from 50v-630v, YOU MUST CHECK THE PHYSICAL SIZE OF THE CAPACITOR TO KNOW IT FITS (usually 5mm lead spacing).

with electrolytics, usually 16v is enough for most applications (unless it's a 18v pedal), i'd get 25v just to have the "security".

just note that sometimes the 25v can be physically too big.

you will get some stuff wrong at first, but life is all about learning. you will evantually know this stuff by heart.

this here is a very handy chart for value conversion.

http://www.justradios.com/uFnFpF.html

so to sum up

1pf - 1000pf (1n) - ceramic
1n - 1000n (1uf) - polyester/polypropelene
1uf-2200uf - electorlyic family - tantalum and aluminum

[night-B]

Most of pedals run between 9v and 18v (9v is the most frequent). Don't go higher than 25v if you don't want to get huge caps that don't fit on the PCB.
Usually ceramic discs are fine for pf values, box film caps for nf values and use axial polarized caps when you can see the polarisation on the schematic or on the PCB silkscreen, they are in the uf values.

Hope that helps! Feel to ask if you need more help, I'll send some links to the caps you need  

Edit : angelus was faster than me...

[jubal81]

I'll add that you'll want to generally aim for the lowest voltage caps you can to keep the size down. 25V for electrolytics and 63V for the others are common for pedals. Also, you want to get 5mm lead spacing.

[icecycle66]

This is good stuff, I'm still learning all this too.

I look at the guts in peoples build reports, and their capacitors usually don't look anything like mine.

A lot of the guides have stuff written in "n", such as 100n.  I have to convert that into PF or UF because I can hardly find anywhere that sell "n". 

[stecykmi]

the "n" prefix just means 1 x 10^-9, so a 100nF cap is the same as .1uF. you just have to move the decimal to the left by three digits. it's really just a matter of preference, brian uses nF notation a lot in his documentation, i happen to prefer uF.

be careful if you order from smallbear since he uses "mf" instead of "uf" for some reason. smallbear rocks, but that makes no sense to me since the "m" prefix means "milli" (10^-3) not "micro" (10^-6).

also, when ordering electrolytic caps, i would just go with the polarized kind. most of the time it'll be pretty obvious what orientation you need. polarized caps are cheap, reliable and far easier to source.

[jubal81]

My trick for remembering how to convert: Schoolhouse Rock. "3 is the magic number"

That's how many places you move the decimal place. For uF to nF, move 3 places to the right. For nF to pF, move 3 more places to the right. Just reverse to go the other way.

So, for 4n7 (4.7 nF)
.0047 uF = 4.7 nF = 4700 pF

[murdog47]

http://www.madbeanpedals.com/forum/index.php?topic=2970.0

Here is a thread with good info for you. I prefer to order from mouser.

[pappasmurfsharem]

I unfortunately bought 3 polyester 1uF film caps instead of Aluminum Electrolytic. So that is a bummer.

I need to order some knobs anyway so no big deal I guess.

On that note, I have to highly recommend mammothelectronics.com as a parts source.

They have great customer service.

On my first order a 3.5mm headphone jack was missing the locking ring, so they 2nd day aired me a replacement and also gave me 3 sets of patch cables free.

On my 2nd order I forgot to order an LED, 4 DIP8 sockets, and a 22k resistor. I e-mailed them if there was a way to pay for them and get them shipped with the same order and they gave to them me for free.

[Vallhagen]

I unfortunately bought 3 polyester 1uF film caps instead of Aluminum Electrolytic. So that is a bummer.

For that specific value - 1uF - you will need BOTH polyester/box and polarized electrolytics, if you build a few boxes from madbean. So its no bummer, you will need them:)

As an example; on Low Rider, C13 is polarized and C18 is not. Both 1uF. And, this is NOT obvious if you just look at the BOM. You have to look at the schematic as well.

So, from my point of view, its a good idea to have a few of both types at hand.

Cheers