Hackaday Links: June 24, 2018

What do you do if you’re laying out a PCB, and you need to jump over a trace, but don’t want to use a via? The usual trick is using a zero Ohm resistor to make a bridge over a PCB trace. Zero Ohm resistors — otherwise known as ‘wire’ — are a handy tool for PCB designers who have backed themselves into a corner and don’t mind putting another reel on the pick and place machine. Here’s a new product from Keystone that is basically wire on a tape and reel. It’s designed to jump traces on a PCB where SMD zero ohm resistors and through-hole jumpers aren’t possible. I suppose you could also use it as a test point. They’re designed for high current applications, but before we get to that, let’s consider how much power is dissipated into a zero ohm resistor.

By the way, as of this writing, Mouser is showing 1,595 for Keystone’s 5100TR PCB jumpers in stock. They come on a reel of 1,000, and a full reel will cost you $280. This is significantly more expensive than any SMD zero ohm resistor, and it means someone bought four hundred of them. The electronic components industry is weird and you will never understand it.

There’s a new product from ODROID, and you want it. The ODROID-GO is a Game Boy and Sega Master System emulator running on an ESP-32, has a fantastic injection molded case, and looks phenomenal.  You can buy it now for $32. Does this sound familiar? Yes, a few months ago, the PocketSprite was released. The PocketSprite is the tiniest Game Boy ever, and a project [Sprite_TM] introduced to the world at the 2016 Hackaday Superconference.

This week, the speaker schedules for two awesome cons were announced. The first is HOPE, at the Hotel Penn on July 20th. Highlights of this year? [Mitch Altman] is talking about DSP, [Chelsea Manning] will be on stage, someone is talking about HAARP (have fun with the conspiracy theorists), and someone is presenting an argument that [Snowden] is an ideological turd. The speaker schedule for DEF CON was also announced. The main takeaway: god bless the CFP board for reigning in all the blockchain talks, the Nintendo Switch was broken wide open this year, but there’s only a talk on the 3DS, and there’s more than enough talks on election hacking, even though that was a success of propaganda instead of balaclava-wearing hackers.

The C.H.I.P. is no more, or at least that’s the rumor we’re running with until we get some official confirmation. When it was introduced, the C.H.I.P. was a Linux system on a chip with complete register documentation. It appears the end of C.H.I.P. is upon us, but have no fear: there’s a community building the PocketC.H.I.P., or the C.H.I.PBeagle. It’s a single board computer based around the OSD3358 from Octavo, the same system found in the PocketBeagle. Source in KiCAD, and people are working on it. Thanks [smerrett79] for the tip.

The Zero Ohm Resistor

What’s your favorite value of resistor? 1K? 10K? They’re all fine, but when you need nearly no resistance at all, nothing beats the good old zero-ohm resistor.

Wait a minute! Resistors are supposed to resist current. What the heck does a zero-ohm resistor do? Well, the short story (tee-hee!) is that it’s like a jumper for single-sided surface-mount boards. In the bad old days, companies used to save money by running single-sided boards, and you could buy wire jumpers to help make the layout that much easier.

Fast forward to the modern era, where there’s not a through-hole component to be seen. What’s the resistance (ideally) of a wire? Zero ohms. And thus the zero-ohm resistor was born. We have a whole spool of them in our closet in 1206, the largest SMD size that we use, in order to be able to sneak two or three tracks underneath, even on a home-etched board. They’re great.

Anyway, what set us off rhapsodizing about the lowest value resistor was this article on the peculiarities of the zero ohm resistor. Of course, nothing has zero resistance, and the article walks you through some of their real-world properties. Enjoy!