Some basic questions

[sergio]

Hi! I'm new at trying to build pedals on my own. I recently bought some pcbs and have some questions:
Besides electrolytic capacitors what type of other capacitores is generaly used for the pedals?
When I have in the parts list GE diodes, is this germanium diodes of any type?

Thanks!

 

[zgrav]

similar questions have been discussed previously. you may be able to find some useful information by searching for germanium diodes in the forums.

spend some time going through the Basic Workflow Tips here: https://forum.pedalpcb.com/threads/basic-workflow-tips-for-building-a-pedalpcb.1165/

 

[bengarland]

I use WIMA brand of film capacitors and TDK MLCC ceramics. So far I've built a dozen pedals, no problems, everything sounds great. As a general rule of thumb, you want electrolytics for the "u" values, ceramics for the "p" values, and film for the "n" values (remember 1000p and .001u are really 1n). Don't be led astray by the graphics on some of the PCBs when it comes to film vs ceramic... it looks like only film are used (box graphic) but it really depends on the value. Some values you simply can't find as film caps or they are really expensive.

Other people will insist on tantalum caps for the audio pathway certain builds, but I've never found it necessary -- I'd only do it if the actual build guide specified it or I was trying to do an absolutely exact replica of an original vintage pedal.

As far as the GE diodes, yeah that's what I've been told... basically any GE diode is fine, they all affect the sound the same way. But when it comes to GE transistors, it's fun to try different ones and see how they affect the sound. Many people get transistors from either Ebay or Small Bear Electronics (which is closed right now due to the virus).

 

[MightySmallElectrons]

You’ll want to take care that the lead spacing of your capacitors is 5mm. Slightly smaller is sometimes okay but any bigger and you can run into trouble.
Also the higher wattage capacitors can get quite large. You won’t need anything more than 25v for pedal work.
It’s worth asking for help with a screen shot before ordering. I wasted a lot of time and money hoping I had the right components.

 

[bengarland]

Another tip: Wait until you have the board in front of you before you order. That way you can see how much space is on the board for each part. Get a nice stainless steel millimeter ruler (about 10cm long is a nice size), then make sure the components you're looking at on Mouser (etc) are the same size as the spot on the board. Generally for film caps, the spacing is 7mm across, 2mm thick, and 6mm tall. Occasionally there will be a bigger space on the board, indicating that the common size for that value is bigger (and that a film cap goes there, not MLCC because all MLCC are tiny). Otherwise, if the only film cap that you can find is too big for the space on the board, it might indicate that you should put a MLCC there instead.

Knowing the spacing also helps a lot for electrolytics, so you don't get one that's too fat to fit, especially when you've got tight spacing on the board.

 

[Barry]

It seems no matter how thoroughly I scan builds for odd parts, one oddity always pops up as I'm populating the boards

 

[Chuck D. Bones]

similar questions have been discussed previously. you may be able to find some useful information by searching for germanium diodes in the forums.

Indeed, search the forums for all of your questions. We're here to help, but answering the same questions over and over gets boring. Spend time perusing the Build Reports. You will find pix and discussions on the pedals you want to build. Start small. Tempting as it may be, don't make a Parenthesis or one of the Revv pedals your first build. Make sure you have the right tools.

 

[Barry]

Always, always search the build reports and read what others have experienced or changed, I do it before I order the board and again when I start the build!

 

[bengarland]

Pro tip for searching the forum:

Use google because the internal forum search limits you to words that are 4 characters or bigger.

So if you want to search for something like "LED not lighting up" you can't do it here.

But go to google and type exactly this:

site:forum.pedalpcb.com LED not lighting up

You'll get lots of relevant links.

 

[Robert]

Use google because the internal forum search limits you to words that are 4 characters or bigger.

Made it a little easier for you:

 

[sergio]

You’ll want to take care that the lead spacing of your capacitors is 5mm. Slightly smaller is sometimes okay but any bigger and you can run into trouble.
Also the higher wattage capacitors can get quite large. You won’t need anything more than 25v for pedal work.
It’s worth asking for help with a screen shot before ordering. I wasted a lot of time and money hoping I had the right components.

But the minimum voltage for caps needs to be like 10v right?

 

[sergio]

Thank you all for your comments! It became more clearer what I need to buy. I'm buying in europe and asia. Orders are very delayed at this point.
Some usa stores i can't go because it will be too expensive with customs fees

 

[MightySmallElectrons]

But the minimum voltage for caps needs to be like 10v right?

I don’t like to buy anything lower than 16v. 25v is even better. I

 

[Chuck D. Bones]

But the minimum voltage for caps needs to be like 10v right?

Generally speaking, yes. If you run the pedal on 9V and there are no charge pumps inside, then 10V is sufficient. I agree with MSE, 16V or higher is better because it's good to have some margin. The only upper bound for capacitor voltage (or resistor wattage) is physical size.

 

[MightySmallElectrons]

Anyone actually have one fail? I haven’t experienced that yet.

 

[Chuck D. Bones]

Me neither, and I don't intend to. Margin is there as cheap insurance against failure. Decent quality electrolytic capacitors (KEMET, AVX, Rubycon...) are sample tested by the manufacturer at rated voltage and 85C (or higher) for a few 1000 hours. Since we don't run our pedals at 85C, there is already some margin built-in.

 

[Ratimus]

Never had one fail from too much power, but I have had one explode on me when got the power backwards. This was some project I was building on perfboard back when I was in school. I was using ancient electrolytics I scrounged from a stereo because, hey, broke student. They were old enough to not have safety vents, and when I put 12 V but accidentally reversed polarity on the circuit, the shell blew off the cap about 18 inches in front of my face and embedded itself in the ceiling. My wife came out of the other room thinking maybe someone in the apartment below us had gotten shot or something, and I sheepishly said "uh, no, just science."

Lesson learned: MAKE SURE YOU GET YOUR POLARITY RIGHT!

 

[Chuck D. Bones]

Try plugging one into a switched wall socket with the switch off, then wait for someone to come home and turn the lights on. Not that I would ever do that...

 

[Ratimus]

Nor would I snap the clip on a clipboard behind my boss's back when he energized an unpotted 40 kV circuit sitting in a bath of dielectric fluid. And I certainly wouldn't do it more than once. ?

 

[Chuck D. Bones]

Nasty pranks!
I had a summer job at TRW when I was in college. I worked in a large lab where prototype were built and tested. Work benches were arranged in long rows, back to back. In those days, smoking in the buildings was allowed. One time I saw a tech feed some plastic tubing from the back of his bench into a unit under test on the bench behind his. Then he started blowing cigarette smoke thru tubing.