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~More questions about CAPS~

Started by Haberdasher, April 21, 2010, 01:45:11 AM

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pigyboy

Quote from: Jamiroking on June 04, 2010, 07:45:58 PM
I'm a noob here. Just ordered my first PCBs and getting my stuff through mouser and am sort of going insane from their options on the caps (as for resistors, I was able to just get all metal film). I noticed you marked ceramic for pF, Electrolytic for uF and film caps for nF. Should I just choose my caps based on this breakdown? What is the actual type of film cap to use? Also, I notice a lot of people recommend the Vishay Dale resistors but is there anything wrong with just buying the cheap $.05 KOA speer ones? If it makes a difference, I'm going to be building the Zombii, the Krankosaurus, and a Ross/Dyna clone from Tonepad.

Sorry for all the questions but until I get the boards and get to start building, all I have is confusing choices to fill my time.

Thanks and love the site Brian!

Hi Jamiroking,
Welcome and good luck with your builds.  For the first ones you should use the exact components specified in the project pages for your first builds unless you feel real comfortable buying parts from a place like Mouser. Just keep in mind that you want the caps you buy to be the right physical size to fit on your board. It is easy to order the wrong stuff even when you know what you are looking for. I just bought $40 worth of surface-mount opamps from Mouser by accident.  
It does pay to use good caps in the right places. I have a booster design that uses a 2.2uf cap as the input cap. When I use a $3.50 vishay cap the difference over a 2.2uf electrolytic is unbelievable. The cap is in the audio path of the circuit so I can justify the cost. But if I needed a 2.2uf cap in the power section it would be foolish to use the vishay as it's placement has no effect on the tone.
Stick with the metal film resistors. I do not know why anyone would use carbon comp resistors for anything in a pedal. Some say they like the vintage tone but they are just noisy. If you want an old, noisy sounding pedal use them. If you want a sweet tone machine use the best parts you can.
Take a look over in the tech pages for the soldering tips thread I posted to give you some other things to get you started.
Pig



Jamiroking

Hi Pigyboy,
Thanks for the help and the soldering tips as well. I've built cables before but this is going to take a different level of soldering. As far as I can tell, the only info I can find on the project pages is the Farad level of the capacitors. The main issue I seem to be having is knowing which type of cap to get which I can't seem to find on the pages. I looked a little closer and noticed that the cap outlines are different sizes and shapes on the wiring diagram. Should I be able to tell the type of cap from this or should I wait until the PCBs arrive?

I'll be starting with the Zombii fuzz first since it seems to be the simplest of the pedals I'm building but I'd like to order all the components in one swoop to save on the shipping.

Haberdasher

It was recommended to me to use the polyester film box caps pretty much wherever possible because they are small, have a uniform shape (even for most of the larger values) and they fit on the board easily.  Those are usually the ones shown as rectangular caps on the diagram.  Just make sure you get the 5mm lead spacing (LS) for these so they will match the holes Brian has drilled.  A lot of people use the red ones made by WIMA. 63v is good but you could use higher if that's all they have in stock for a certain value.

For electrolytics (the rounds ones on the diagram), you will want radial caps for most builds (unless the graphic shows them laying down- in which case you would use axial leads), 16v minimum for a 9v pedal.  As you go up in voltage these increase in size pretty quick so try to stay kind of small here, maybe around 25v to 35v?  Try to find the mini caps because of their short size.  For non mini caps I usually leave about 3 mms of lead sticking up so I can partially "fold" the cap over if I need to when I'm finally ready to put the lid on.

Make sure you don't get anything that says SMD, which is surface mount.  Those are tiny.

I've only used metal film resistors so far and I have no idea who made them, but I doubt if it makes much difference.  I personally buy the cheaper ones.
The metal films are supposed to be quieter.  IMO quiet = good.

That's about all I've got for now.
BTW, I'm sort of newbish myself so everyone please feel free to correct me if I'm wrong about something!

Good luck
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Jamiroking

Thanks haberdasher, that helps a lot.