About
100nF is written by byscg, an embedded and hardware engineer working on firmware, board bring-up, and the awkward space between the two where most of the interesting bugs live.
Why 100nF
It is the most-placed part in electronics and the least-discussed. It does one job, close to the pin, and the board does not work properly without it. That seemed like a reasonable thing to name a site after.
It is also a good example of the thing this site is about. Almost everyone places 100 nF because everyone else does. Far fewer could say what its self-resonant frequency is in the package they just used, or why the via stitching next to it matters more than the value printed on it.
What is here
Write-ups of measurements and mistakes, and 96 calculators. The tools exist because the same equations kept needing re-deriving, and because most of the ones already on the web will not say where their numbers come from.
How the calculators are checked
Every tool names the standard it implements and lists the assumptions that come with it, because an uncited calculator is just a number generator. Under that:
- The maths lives in plain modules with no UI attached, and each one is unit-tested against worked examples taken from the published reference — the table in IPC-2221, the example in an application note — rather than against whatever the code happened to return first.
- Outbound citations are link-checked on every build. When a vendor deletes an application note, the replacement is a document that has actually been opened and confirmed to contain the thing being cited.
- Where a closed-form approximation stops being trustworthy, the page says so and points at what to use instead. IPC-2141 microstrip is a good example: past a certain geometry you want a field solver, not this.
How the site is built
Static pages, with fonts, styles and the site's own scripts served from this origin. Traffic is measured with Google Analytics and by reading the web server's own logs, which are written with the client address already masked. Beyond that measurement, calculators are the only pages that ship JavaScript.
Contact
Corrections are welcome, particularly on the maths: if a tool disagrees with your bench, that is worth hearing about. Contact is via GitHub, or the address in security.txt for anything security-related.