Ever wondered why 100nF is a go-to value for decoupling capacitors? This number has pervaded in datasheets and electronics advice going back to the 1980s, and is still widely present in the datasheets of modern components. Folks are out there sprinkling 100nF capacitors on their boards like seasoning, and when they decide 100nF isn’t enough, they inevitably recommend the big/little practice, e.g. 1uF + 100nF in parallel.
Unfortunately, 100nF kinda sucks, and this common decoupling practice is incredibly...
Back in August I did a stream on Twitch where I dug through the OCP Grand Teton server chassis design. The Open Compute Project (OCP) is an organisation that works to design and publish open server standards. Their projects cover all sorts of datacenter tech, including entire server platforms. Many of their projects are published with collateral, i.e. the design files for the platform, including entire sets of schematics, PCB designs, documentation, mechanical drawings, etc.
OCP Grand Teton is a...
The SPICE models released by vendors are often really bad, producing results that do not anywhere near match the behaviour described in the datasheet. A recent example I ran into was for the CREE XLamp XP-E2 series LEDs, where the provided models underestimated the forward diode current by a factor of 6 compared to the datasheet and real-world measurements. Some vendors also don’t bother to release SPICE models at all, making it difficult to simulate the parts in LTspice.
Luckily, it is possible to turn...
This blog post is a companion piece to my LED PWM Calculator web tool.
Your eyes are part of an evolutionary pathway that started more than half a billion years ago. Vision capable of accurately identifying objects and movements in the dark has proven to be a key asset when it comes to the chances of surviving the night in an environment filled with predators. This blog post is about LEDs, which are not generally considered to be predators. However, this millennia-long evolutionary process of biological...
This is part two of my “convert a bunch of notes I made about capacitors into a blog post” series. If you missed part one, which covered ceramics and MLCCs, you may wish to read it first.
Again, this article is mostly going to be useful to you if you already know a bunch about capacitors and want a big infodump to pick up some new facts from, and it comes with a caveat that I am not a capacitor expert.
I’m primarily going to talk about wet aluminium electrolytic capacitors in this post, since they’re...
I’ve been reading about capacitors a lot lately. Not just their high-level circuit behaviours, but also their materials and physical properties. I put together a heap of notes on the topic. Knowing me, these notes will languish in my documents folder and I’ll never look at them again. And that’s ok, because that’s just how my brain works, but it occurs to me that someone else might find these notes useful.
As such, I’ve transformed them into something more readable, and that’s what this blog post is. I’ve...
Memory DIMMs have a small flash memory chip (EEPROM) on them, containing an important descriptor table called the Serial Presence Detect (SPD). This data tells the system the size, speed, timings, operating voltage, manufacturer, part number, overclocking profiles, and all sorts of other information about each DIMM. The SPD chip is accessed using the SMBus protocol, which is based on I2C.
Tools such as CPU-Z, RAMMon, and RW Everything can be used to read the SPD data by talking to the flash chip over a...