Alpenglow Industries' Carrie Sundra has launched a pair of PCB rulers designed to help those working with small-outline transistor (SOT) and diode (SOD) components by providing a handy physical footprint reference.
"Who the heck can keep transistor package names straight? Sure the SOT names make a little bit of sense," Sundra bemoans, "but who can keep track of the difference between an SC-88 and an SC-88A? And wait is one of those also an SC-70-6? And what the heck are the TO sizes all about? I've been designing PCBs for almost 20 years and it's infuriating! Instead of shaking your fists and screaming "WHAT THE SOOOOOOOT???!?!?", grab this handy PCB ruler. Easily see at a glance alternate names for each package, and how big each footprint is in real life."
The What the SOT?! PCB Ruler includes metric and inch measurements, including fractions and tenths, plus transistor footprints ranging from "a big honkin D3Pak" to the "insanity-sized SOT-883," along with all name variants - making it easy to see when a particular component is referred to by multiple names. "Other PCB rulers have a few transistor patterns with maybe one or two common names," Sundra explains, "but this has every single darned one I could dig up."
What the SOT?! has a companion in For the Love of SOD!, a similar ruler design focused on small-outline diodes. "OK, so you have the What the SOT?! PCB ruler and can now keep your transistors straight, but now you've got to place some diodes," Sundra writes. "Sure the SOD names make a little bit of sense, but who can keep track of the difference between a DO-215AA and a DO-215BA? And where the heck do the MELFs fit in? Is a Micro-MELF more like an 0805 or an 0603?"
Both designs are available now, with For the Love of SOD! costing $6 and What the SOT?! costing $8, from the Alpenglow Industries Tindie store.