Pocket CO2 Sensor Doubles As SMD Proving Ground

October 10, 2023 by Tom Nardi 4 Comments

While for some of us it’s a distant memory, every serious electronics hobbyist must at some point make the leap from working with through-hole components to Surface Mount Devices (SMD). At first glance, the diminutive components can be quite intimidating — how can you possibly work with parts that are literally smaller than a grain of rice? But of course, like anything else, with practice comes proficiency.

It’s at this silicon precipice that [Larry Bank] recently found himself. While better known on these pages for his software exploits, he recently decided to add SMD electronics to his repertoire by designing and assembling a pocket-sized CO2 monitor. While the monitor itself is a neat gadget that would be worthy of these pages on its own, what’s really compelling about this write-up is how it documents the journey from SMD skeptic to convert in a very personal way.

A fine-tipped applicator will get the solder paste where it needs to go.

At first, [Larry] admits to being put off by projects using SMD parts, assuming (not unreasonably) that it would require a significant investment in time and money. But eventually he realized that he could start small and work his way up; for less than $100 USD he was able to pick up both a hot air rework station and a hotplate, which is more than enough to get started with a wide range of SMD components. He experimented with using solder stencils, but even there, ultimately found them to be an unnecessary expense for many projects.

While the bulk of the page details the process of assembling the board, [Larry] does provide some technical details on the device itself. It’s powered by the incredibly cheap CH32V003 microcontroller — they cost him less than twenty cents each for fifty of the things — paired with the ubiquitous 128×64 SSD1306 OLED, TP4057 charge controller, and a SCD40 CO2 sensor.

Whether you want to build your own portable CO2 sensor (which judging from the video below, is quite nice), or you’re just looking for some tips on how to leave those through-hole parts in the past, [Larry] has you covered. We’re particularly eager to see more of his work with the CH32V003, which is quickly becoming a must-have in the modern hardware hacker’s arsenal.

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An SMD Capacitor Guide

October 5, 2023 by Al Williams 5 Comments

For electronics, your knowledge probably follows a bit of a bell curve over time. When you start out, you know nothing. But you eventually learn a lot. Then you learn enough to be comfortable, and most of us don’t learn as much about new things unless we just happen to need it. Take SMD components. If you are just starting out, you might not know how to find the positive lead of an SMD capacitor. However, if you’ve been doing electronics for a long time, you might not have learned all the nuances of SMD. [Mr SolderFix] has been addressing this with a series of videos covering the basics of different SMD components, and this installment covers capacitors.

If you are dyed-in-the-wool with SMD, you might not get a lot out of the video, but we picked up a few tips, like using a zip tie for applying flux. The video starts with an examination of the different packages and markings. Then it moves on to soldering the components down.

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RPDot: The RP2040 Dev Board Barely Bigger Than The Chip

August 25, 2023 by Dan Maloney 33 Comments

Is [William Herr]’s RPDot actually the world’s smallest RP2040 dev board? We can’t say for sure, but at 10 mm on a side, we’d say it has a pretty good shot at the record.

Not that it really matters, mind you — the technical feat of building a fully functional dev board that’s only 3 mm longer on each side than the main chip is the kind of stuff we love to see. [William] says he took inspiration from the [SolderParty] RP2040 Stamp, which at one inch (25.4 mm) on a side is gigantic compared to the RPDot. Getting the RP2040 and all the support components, which include an 8MB QSPI Flash chip, a 3V3 LDO, a handful of 0201 passives, and even a pair of pushbuttons, required quite a lot of design tweaking. He started his PCB design as a four-layer board; while six layers would have made things easier, the budget wouldn’t allow such extravagance for a prototype. Still, he somehow managed to stuff everything in the allotted space and send the designs off — only to get back defective boards.

After reordering from a different vendor, the real fun began. Most of the components went on the front side of the board and were reflowed using a hot plate. The RP2040 itself needed to go on the back side, which required gentle hot air reflow so as not to disrupt the other side of the board. The results look pretty good, although those castellated edges look a little worse for the wear. Still, for someone who only ever worked with 0402 components before, it’s pretty impressive.

[William] says he’s going to open-source the designs as well as make some available for sale. We’ll be looking out for those and other developments, but for now, it’s just pretty cool to see such SMD heroics.

Pixel Pump, The Open Source Vacuum Pickup Tool Is Now Shipping

August 1, 2023 by Donald Papp 9 Comments

The Pixel Pump is an open source manual pick & place assist tool by [Robin Reiter], and after a long road to completion, it’s ready to ship. We first saw the Pixel Pump project as an entry to the 2021 Hackaday Prize and liked the clean design and the concept of a completely open architecture for a tool that is so valuable to desktop assembly. It’s not easy getting hardware off the ground, but it’s now over the finish line and nearly everything — from assembly to packaging — has been done in-house.

Pixel Pump with SMD-Magazines, also using foot pedal to control an interactive bill of materials (BoM) plugin.

Because having parts organized and available is every bit as important as the tool itself, a useful-looking companion item for the Pixel Pump is the SMD-Magazine. This is a container for parts that come on SMD tape rolls. These hold components at an optimal angle for use with the pickup tool, and can be fixed together on a rail to create project-specific part groups.

A tool being open source means giving folks a way to modify or add features for better workflows, and an example of this is [Robin]’s suggestion of using a foot pedal for hands-free control of the interactive BoM plugin. With it, one can simply use a foot pedal to step through a highlighted list of every part for a design, an invaluable visual aid when doing hand assembly.

The Pixel Pump looks great, but if you’d prefer to go the DIY route for vacuum pickup tools you would certainly be in good company. We’ve seen economical systems built for under $100, and systems built around leveraging bead-handling tools intended for hobbyists. On the extreme end there’s the minimalist approach of building a tool directly around a small electric vacuum pump.

LED Matrix Displays Get New Look Thanks To SMD Stencils

April 28, 2023 by Dan Maloney 26 Comments

Even if surface-mount skills aren’t in your repertoire, chances are pretty good that most of us are at least familiar with SMD stencils. These paper-thin laser-cut steel sheets are a handy way to apply a schmear of solder paste to the pads of a PCB before component placement and reflowing. But are stencils good for anything else?

It turns out they are, if you’ve got some plain old 8×8 LED matrix displays you want to jazz up a bit. In this case, [upir]’s displays were of the square pixel type, but this trick would work just as well for a matrix with circular elements. Most of the video below is a master class in Adobe Illustrator, which [upir] used to generate the artwork for his stencils. There are a lot of great tips here that make creating one simple shape and copying it over the whole array with the proper spacing a lot easier. He also details panelizing multiple stencils, as well as the workflow from Illustrator to manufacturing.

When lined up properly over the face of the LED matrix, the stencils have quite an effect. We really liked the narrow vertical bars, which make the LED display look a bit like a VFD. And just because [upir] chose to use the same simple shape over all the LEDs in a matrix doesn’t mean that there aren’t other options. We can see how you might use the same technique to create different icons or even alphanumeric characters to create custom LED displays. The possibilities are pretty much limited to your imagination.

This isn’t the first time we’ve seen [upir] teaching old displays new tricks.

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3D Printed Tool Lets You Measure Component Reels Easily

April 15, 2023 by Lewin Day 5 Comments

Component reels are a highly-0ptimized packaging format. They deliver components to pick and place machines for effective high-speed assembly. As more of us get into working with SMD components, we’re exposed to them as well. [MG] wanted a way to easily measure tape from component reels, which is difficult because they’re often curled up. Thus, they whipped up a nifty little tool for the job.

The device consists of a 3D printed bracket which is designed to fit on a cheap electronic tape measure from Amazon. The bracket holds an 8mm wide component tape against the measuring wheel. As the component tape is fed through the device, it turns the wheel, and the measurement appears on the screen. No more must you try and flatten out a tape and measure it section by section. Instead, you just feed it in, yank it through, and you’re done!

[MG] notes that the tape measure itself runs on an STM32 microcontroller. As an extra-credit assignment, they suggest that the device could be reprogrammed to display component count instead of distance if that’s more suitable for your application. If you happen to make that mod, be sure to notify us on the tipline!

Binary Watch Rocks A Bare PCB With Pride

January 26, 2023 by Lewin Day 18 Comments

Most of us learn to read digital clocks first, which display the time in obvious numbers. Analog clocks are often learned later, with the hands taking our young brains a little longer to figure out. Once you’ve grown into a 1337h4XX0r, though, you’re ready to learn how to read a binary watch. Then you can build your own, just like [taifur] did.

The watch rocks a simplistic, bare bones design with the PCB acting as the body of the device itself. It’s not great for water resistance, or even incidental contact, but it’s a sharp look with the golden traces on display. The heart of the operation is a ATmega328P, as seen in the popular Arduino Uno, and it’s paired with a DS3231M real-time clock module to keep accurate time. 13 SMD LEDs are charged with displaying the time in binary format, with [taifur] choosing to spec a classic red color for the build. The watch is powered via a CR2032 coin cell, which you’re best advised not to swallow. So far, [taifur] has found the watch will last for over a month before the battery is tapped out.

It’s a fun build, and one that looks good when paired with a classic NATO watch strap in green. If, however, you desire a watch that definitely won’t last a month on a single coin cell, you can always build a Nixie watch instead. Video after the break.

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