Please help a complete idiot build his tonepad Ross Compressor!

[juncomatt]

Hi all.

This is my first post and I'm quite new to building pedals (although my first was a complete success!). I'm going to build the Tonepad Ross Compressor and have a question about which kinds of capacitors to get (electrolytic, poly film, ceramic, radial/axial etc...). The capacitors I need are the following:

5 - 0.01 uF
1 - 0.001 uF
1 - 0.05 uF
6- 1 uF
2 - 10 uF
1 - 220 pF

I'm just not sure which kind of capacitor to get for each value. I'm pretty sure small bear has all of these somewhere, but I don't want to get the wrong ones. I don't have any idea where to start, basically. If anyone can help, I would GREATLY GREATLY GREATLY appreciate it. Even a link to some document which explains the theory behind capacitors will help me. I know nothing. Thanks! love the forum...

-Matt

[calculating_infinity]

Hello and welcome.  First things first, familiarize yourself with the links up top DIY FAQ, GEO FAQ, Debugging Page, etc.  This one is from the wiki and the faq, http://www.diystompboxes.com/pedals/buy.html .  For stompboxes they say 16v+ should be higher.  Higher voltages usually mean larger sizes.  Check out this section of the FAQ http://www.diystompboxes.com/wiki/index.php?title=DIY_FAQ#CAPACITORS .  Theres a few links that will explain a lot!  Have Fun!

[mattpocket]

Right, look at your tonepad project file: http://www.tonepad.com/getFile.asp?id=9

Now look at the list of capacitors. Then look at the image of the PCB. You can see the caps are labeled with their values. The round ones with the + sign on one side (you may need to zoom in) are electrolytical capacitors and are available in radial, where both leads come out of the bottom of the cap and they look like this:



They are also available in axial form where a lead comes from each end of the capacitor, like this:



electrolytical capacitors are what we call polarised, meaning that they must be put in the correct way round. On radial caps there is normally one lead longer than the other, and a black stripe on the cap casing to tell you which lead is which. On axial caps there is normally a band at one end of the cap. For this layout you should try to use radial caps as they will be easier to fit, but you can just bend on of the legs of an axial cap to make it stand on end and use that. Some of the smallbear ones will be axial depending on their value. Electrolytic caps can also be of the tantalum variety, although this will be specified somewhere if tants are required. These are also polarised. They look like this:



Go and look at the PCB layout again, the oval/eliptical caps are probably ceramic or film caps. One of the two. It doesnt really matter which you use for these, as they are essentially the same, although some builders think that film caps offer an advantage, but really they are interchangable. They are cheap, so get both and experiment with them. They are NOT polarised and are almost always radial. I dont know if smallbear do ceramic caps, but they definately do film.

Also in the project file, beware that this layout is for the MXR dynacomp and the Ross Compressor, and there are sub-parts lists on the right hand side where parts differ for each project, make sure you dont forget this, otherwise you'll be short of parts when you come to build it. There is nothing more frustrating that realising you left something out of your order... Also a useful tip with tonepad projects is to read all the  build reports for this project: http://www.tonepad.com/project.asp?id=9# as some people may have found some parts to be better than others, and they normally list what they used instead in their build report. This is useful, I normally write down all the subs/mods and buy both the stock parts and the ones recommended by different builders and then try all possible combinations.

Also, note that smallbear have uF (micro farad) caps listed as mF... mF can also mean mega farad (i think) but on smallbears site it is micro, not mega.

edit: also the smallbear caps are all going to be ok for stompbox projects with regards to their voltage ratings, however note that larger voltage ratings will mean a physically larger cap, so beware when using larger voltages. I think most of the film/electro caps at smallbear are 16v or 25v and will be small enough for this layout, and any other voltage ratings are normally listed on the item description.

Hope that helps.

Matt

[juncomatt]

WOW. Exactly the info I needed! Thanks so much!

Cheers,
-Matt