Hacker Tactic: Building Blocks

The software and hardware worlds have overlaps, and it’s worth looking over the fence to see if there’s anything you missed. You might’ve already noticed that we hackers use PCB modules and devboards in the same way that programmers might use libraries and frameworks. You’ll find way more parallels if you think about it.

Building blocks are about belonging to a community, being able to draw from it. Sometimes it’s a community of one, but you might just find that building blocks help you reach other people easily, touching upon common elements between projects that both you and some other hacker might be planning out. With every building block, you make your or someone else’s next project quicker, and maybe you make it possible.

Sometimes, however, building blocks are about being lazy.

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Hacker Tactic: Multi-Design Panels

Last time, we talked about single-PCB-design panels, all the cool aspects of it, including some cost savings and handling convenience. Naturally, you might wonder, and many did – can you put multiple different PCBs on a single panel? The answer is “yes, without a doubt!” The tool we used last time, KiKit, will not be as helpful here, so we’ll be looking elsewhere.

Making multi-PCB panels can help you save money, naturally, but it can also make your assembly a whole lot easier, and it can bring you hacking to a whole new level. It sure helped with mine! You might have already learned that some fabs scoff at multi-design panels and add surcharges. Well, you’ll be delighted to learn that there are more hacker-friendly fabs out there, too.

Developing PCBs In Bulk

So far, I’ve worked on about 300 different PCB designs, with half of them available in my monorepo. I’ve assembled and tested just about half of these. You might guess that this would cost a lot of money, and that assembly would take a fair bit of time, but I have some tricks up my sleeve. For a start, you can easily order PCBs 10-12 times more cheaply if you do multi-panel.

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PCB Design Review: HAB Tracker With ATMega328P

Welcome to the Design Review Central! [VE3SVF] sends us their board, and it’s a HAB (High Altitude Balloon) tracker board. It’s got the venerable ATMega28P on it, a LoRa modem and a GPS module, and it can be powered from a LiIon battery. Stick this board with its battery onto a high-altitude balloon, have it wake up and transmit your coordinates every once in a while, and eventually you’ll find it in a field – if you’re lucky. Oherwise, it will get stuck hanging on a tree branch, and you will have to use a quadcopter to try and get it down, and then, in all likelihood, a second quadcopter so that you can free the first one. Or go get a long ladder.

The ATMega328P is tried and true, and while it’s been rising in price, it’s still available – with even an updated version that sports a few more peripherals; most importantly, you’re sure to find a 328P in your drawer, if not multiple. Apart from that, the board uses two modules from a Chinese manufacturer, G-Nice, for both GPS and Lora. Both of these modules are cheap, making this tracker all that more accessible; I could easily see this project being sold as a “build your own beacon” kit!

Let’s make it maybe a little nicer, maybe a little cheaper, and maybe decrease the power consumption a tad along the way. We’ll use some of the old tricks, a few new ones, and talk about project-specific aspects that might be easy to miss.

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Too Much Over-optimization Is Never Enough!

A discussion came up on the Hackaday Discord PCB design channel about resistor networks, and it got me thinking about whether we (the hacker community) use them in designs or not. These handy devices often take the shape of an IC, SMD or otherwise, but between the pins are a bunch of resistors instead of active silicon. They come in all sorts of configurations and tolerances, but the point is usually the same: When you need a bunch of similar resistors, it’s cheaper to go with a network package.

But how much cheaper? I did a quick search for 1 kΩ resistors and the corresponding network, and came up with similar prices for the resistors and networks – but the network has eight resistors in it! That’s an eightfold savings! Which, at a price of roughly one cent per piece, is less than a dime. While it’s certainly true that if you’re making a million widgets, saving a penny per widget matters. But do you spend the time to optimize your projects down to such margins? I want to say “of course not!” but maybe you do?

For me, worrying about seven cents in a PCB design that I may make ten of is foolishness. But still, I’ve used resistor networks for their other side effects: the resistors in a common package tend to be very tightly matched, even if their overall tolerance isn’t. If you’re making something like an R-2R DAC, that’s a definite advantage. Or if you’re space constrained, or just hate placing lots of tiny resistors, the networks shine.

I often forget about resistor networks, and when I do think of them, I think of them in terms of cost savings in industrial applications. But maybe that’s not fair – maybe they do have their hacker uses as well. Are there other parts like this that we should all know about?

Check Your Board: Call For Submissions

As both beginning hackers and Silicon Valley investors alike keep discovering, there are a lot of differences between hardware and software. One important difference is cost of iterating over a design. In software, you can comfortably rerun your build process and push updates out near instantly to tons of users. In hardware, all of that costs money, and I do mean, it costs way more money than you’d want to spend.

When I see people order boards that could never work because of some fundamental design assertions, with mistakes entirely preventable, it hurts. Not in an “embarrassment” way – it’s knowing that, if they asked someone to take a look at the design, they could’ve received crucial feedback, pulled the traces on the board differently or added some components, and avoided spending a significant chunk of money and time expecting and assembling a board that has a fundamental mishap.

Every thing like this might set a beginner back on their hacker journeys, or just have them spend some of their valuable time, and we can do a ton to prevent that by simply having someone experienced take a look.

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Vectorscope KiCad Redrawing Project

When I saw this year’s Supercon Vectorscope badge, I decided that I had to build one for myself. Since I couldn’t attend in-person, I immediately got the PCBs and parts on order. Noting that the GitHub repository only had the KiCad PCB file and not the associated schematics and project file, I assumed this was because everyone was in a rush during the days leading up to Supercon weekend. I later learned, however, that there really wasn’t a KiCad project — the original design was done in Circuit Maker and the PCB was converted into KiCad. I thought, “how hard can this be?” and decided to try my hand at completing the KiCad project.

Fortunately I didn’t have to start from scratch. The PCB schematics were provided, although only as image files. They are nicely laid out and fortunately don’t suffer the scourge of many schematics these days — “visual net lists” that are neither good schematics nor useful net lists. To the contrary, these schematics, while having a slightly unorthodox top to bottom flow, are an example of good schematic design. Continue reading “Vectorscope KiCad Redrawing Project”

Try It Out

It’s like Star Wars versus Star Trek at a SciFi convention, or asking creamy or chunky at the National Peanut Butter Appreciation Festival. (OK, we made that one up.) When Jenny reviewed the 1.0 version of LibrePCB, it opened the floodgates. Only on Hackaday!

Of course it makes sense that in a community of hardware hackers, folks who are not unfamiliar with the fine art and engineering of designing their own PCBs, have their favorite tools. Let’s face it, all PCB design software is idiosyncratic, and takes some learning. But the more fluent you are with your tool of choice, the more effort you have invested in mastering it, leading to something like the sunk-cost phenomenon: because you’ve put so much into it, you can’t think of leaving it.

The beauty of open-source software tools is that there’s almost nothing, aside from your own psychology, stopping you from picking up another PCB program, kicking the proverbial tires with a simple design, and seeing how it works for you. That’s what Jenny did here, and what she’s encouraged me to do. Whether it’s beginner-friendly Fritzing (also recently in version 1.0), upstarts LibrePCB or Horizon EDA, heavyweight champion KiCAD, or the loose-knit conglomeration of tools in coralEDA, you have enough choices that something is going to fit your PCB hand like a glove.

I certainly wouldn’t risk a swap up to a new tool on something super complicated, or something with a tight deadline, but why not start up a fun project to test it out? Maybe follow Tom Nardi’s lead and make a Simple Add-on, for a badge or just as a blinky to put on your desk? Don’t be afraid to try something new!