# Beginner questions (choice of components)



## Red.Beard (Jan 30, 2021)

Hello,

I looked at several BOM for pedals I would like to build and as it will be my first try, I am wondering about the components to order :

1) 1uF capacitor : is it better to take a film capacitor (Wima MKS2 for example) or an electrolytic capacitor (Nichikon FW) ? I read somewhere that film capacitors are privileged for filtering.
For example, both are used in this BOM (parenthese fuzz) : https://musikding.de/docs/pedalpcb/parentheses_BOM_en.pdf

2) similar question : is it better to take a film capacitor for capacitors < 1nF (when it exists) rather than ceramik ones ? For example, I found film capacitors Wima FKP2 for 100, 150, 220, 330, 470 and 680 pF.

3) there is always bumpers in BOM from "musikding.de" : 1 bumper transparent and 12,7mm Bumpers. For example here : https://musikding.de/docs/pedalpcb/softii_BOM_en.pdf
I guess 12,7mm bumpers are for potentiometers (from what is written) but potentiometers are 16mm wide... So I'm lost. And I don't know what the transparent bumper is for.

Your help will be greatly appreciated 😁.


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## TGP39 (Jan 30, 2021)

A general rule for capacitor Shopping is:
1. 1pf - 999pf = ceramic caps or mlcc or silver mica. 
2. 1nf - 1uf = Film capacitor (box caps or other types) 
3. >1uf = electrolytic capacitors (aluminum or tantalum)

Please note that you could buy a film cap > 1uf or buy a silver mica cap > 999pf, or an electrolytic cap < 1uf, etc.  it’s just an easy guideline to get you started.  
My best advice is to always look at the picture of the board before you buy components.  PedalPCB more than anyone else gives you a wealth of information.  
Let’s look at the SOFTii overdrive board:
Do you see how some capacitors on the board are round and some are rectangular? the rectangular ones with a capacitance value of 1nf - 999nf are meant for film caps.   The spacing on these rectangular caps are 5mm.  Watch for that when picking out caps.  A 27mm spacing cap is not going to fit. trust me 🤣. 
See the rectangular spacing for the 150pf cap?  This tells you that you can use the usual ceramic, MLCC or silver mica cap OR you can use a film cap so long as the capacitance is 150pf and the spacing is 5mm.  
The round cap space is for electrolytic caps.  Aluminum electrolytics are the most common.  These have a lead spacing of 2.5mm on this board.  Electrolytic caps are polarized so make sure the positive lead corresponds to the + symbol on the board.  The film caps and ceramic caps are non-polarized so orientation isn’t crucial.  
There’s so much more info about capacitors out there and I suggest you read all about them. This is just a beginner’s guide to getting started. Good luck and have fun. This community is always here to answer questions that will arise.


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## TGP39 (Jan 30, 2021)

PS. The 4 12.7 mm bumpers are indeed the dust covers for the 16mm pot.  I honestly don’t know what the 1 transparent bumper is for.


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## Red.Beard (Jan 30, 2021)

Thank you for taking time to answer me. You are right ; I forgot spacing... I will review it all carefully.

For the example you take (150pf cap, C3 on Softii board), I think a ceramik cap are not ideal since it's 2,5mm while it seems to be a 5mm slot.

When spacing is respected, is there a better option between film, ceramic or silver mica ? I mean for audio quality.


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## TGP39 (Jan 30, 2021)

Red.Beard said:


> Thank you for taking time to answer me. You are right ; I forgot spacing... I will review it all carefully.
> 
> For the example you take (150pf cap, C3 on Softii board), I think a ceramik cap are not ideal since it's 2,5mm while it seems to be a 5mm slot.
> 
> When spacing is respected, is there a better option between film, ceramic or silver mica ? I mean for audio quality.


They do make ceramic caps that have 5mm lead spacing, you just have to search for them.  

I have a preference for film caps in the audio section of any build. Remember that not all caps on the pcb are in the audio section.  Some are strictly for power filtering or other functions.  Many people love the silver mica caps, but they can be downright expensive.  

Coda Effects has several great tutorials and info for pedal beginners.  Take a look.








						Coda Effects: Best capacitors for guitar pedals: which one to choose?
					

Learn more about electric guitar related electronics: DIY guitar pedals, from fuzz faces to delays and reverb, cables and circuits theory




					www.coda-effects.com


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