The Laying On Of Hands

[Jabulani Jonny]

Man what a sweet build. I too am a fan of the TDK MLCC's. I've used them in place of film caps for size restraints in the past but I've wondered if they have the same "performance" as films do. I read a couple articles that suggested that they may have varying capacitance under certain circumstances. Of course I also could be completely mistaken.



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[lincolnic]

This one is really gorgeous.

[juansolo]

Ridiculous and awesome as usual. 

[pickdropper]

Pick, your just determined to get your font size under 10 points with that laser aren't you? lol

Yeah, I think it was an 8 point font.  Definitely too small.

[pickdropper]

This is awesome Dave! Very clean and the black PCB looks killer. If only the 3pdt board were black! 

I agree, that would look much better.  Maybe I'll get some black switch boards in the future.

[pickdropper]

Man what a sweet build. I too am a fan of the TDK MLCC's. I've used them in place of film caps for size restraints in the past but I've wondered if they have the same "performance" as films do. I read a couple articles that suggested that they may have varying capacitance under certain circumstances. Of course I also could be completely mistaken.



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No, you are correct that some ceramic caps (not just MLCC) do vary with temperature and voltage, but there are some qualifiers.

1.) Dielectric type: C0G/NP0 are rock solid and basically don't vary with temperature or voltage.   Unfortunately, they are difficult to find in larger densities (and when you find them, they are usually pricier).  X7R/X5R are still usable caps provided you get them in a voltage level high enough above where you will use them.  As you get close to their rated voltage, their capacitance level drops.  Z5U and Y5V rated caps are basically rubbish and I don't use them anymore.

2.) Voltage rating: as mentioned above, you really want to give yourself some headroom if at all possible.  The other option is to put more capacitance in there and expect derating, but that gets a bit more complicated and predicting the level of derating might be tricky.

The whole conversation does bring up some important questions: If you look at a lot of vintage effects, many of them used cheap ceramic disc caps.  In addition to the changes with voltage and temperature, those types of caps were particularly sensitive to their capacitance drifting downward over time.  If tracing a build that sounds particularly good, you'd probably want to measure the actual components and not just read their value.

I've posted this before, but it's worth reading: it's a good article on MLCC construction from Johanson Delectrics.

http://www.johansondielectrics.com/technical-notes/product-training/basics-of-ceramic-chip-capacitors.html#.U0aTpVe9aKI

[pickdropper]

And thanks for the kind words, everybody.

[billstein]

Wow. Stellar as usual.

[peAk]

Oh my, Oh my.

Na-hice!