Production PCB And Pogo Pins Produce A Clever Test Jig

January 7, 2022 by Dave Rowntree 13 Comments

[Hans Summers] runs a site qrp-labs.com, selling self-assembly kits mostly for radio gear and GPS applications, and had some production problems with his QCX-mini QRP transceiver kit. They were using an assembly house that had some problems with a sub-contractor going under during the pandemic, and the replacement service was somewhat below the expected level of quality, resulting in a significant number of SMT populated boards coming out non-functional. Obviously, not wanting to pass these on to customers as a debug problem, they set to work on an in-house QA test jig, to give them the confidence to ship kits again. The resulting functional test jig, (video, embedded below) takes a fairly interesting approach. Skip the video to 9:00 for the description of the test jig and detailed test descriptions.

By taking an existing known-good PCB, stripping off all the SMT parts, and moving the through hole components to the rear PCB side, pogo pins could be soldered to strategic locations. Building the assembly into a rudimentary enclosure made from sawn-up raw copper clad board, with the pogos facing upwards, and a simple clamp on top, allowed the PCB-under-test (let’s call it the UUT from hereon) to be located and clamped in place. This compressed the pogos in order to make a firm electrical contact. A piece of MDF that had been attacked with a dremel did duty as a pressure plate, with cutouts around the SMT component areas to achieve the required uniform board pressure and keeping the force away from the delicate soldered parts. All this means that with an UUT connected via pogo pins to a through-hole only test PCB, the full circuit would be completed, if and only if the UUT was completely functional, and that means defect-free soldering and defect-free components.

Next the firmware was rewritten to do duty as the test controller, which when powered up would step through a sequence of test scenarios and measurements, logging the results to an OLED display and a serial interface. This rig survived 1,000 SMT tests without failing, giving [Hans] the confidence to ship out new kits and providing a database of datalog results as a backup should a customer have an issue during final assembly. All-in-all a smart idea to solve a difficult problem, with nary a custom test jig PCB in sight!

These pages have been graced with many a pogo-based test rig over the years. Here’s one to start, and if you’ve got a handy laser cutter and some scrap wood, making an accurate test rig is no bother either.

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Segments light up as a person's step goal is achieved.

Slither: A Visual Pedometer That Sheds Light

January 7, 2022 by Kristina Panos No comments

Have you already broken that New Year’s resolution to get more exercise? Yeah, us too. Maybe the problem is simply that we didn’t gamify the goal. A simple visual aid that shows your progress can help make a goal more achievable and easier to stick to, day after January day. That’s the idea behind [skhackett]’s Slither, the visual pedometer.

Although Slither uses the Fit Bit app, no actual Fit Bit is required — great news for those of us who don’t like to wear accessories. But you will have to carry your phone everywhere if you want your steps to count. By tracking the steps taken each day, the sum of Slither’s segments signifies a weekly total goal of 50,000 steps.

Around back is a Feather Huzzah that receives step data from the phone and drives a strand of side-lit LED strips. There’s a Hall effect sensor in the tail, and Slither is powered on and off with a small, separate piece of wood and acrylic with a magnet embedded inside. Isn’t that a classy way to switch a snake?

We really like the look of the plywood here, though [skhackett] recommends using MDF instead because they experienced a fair amount of chipping. If you just want to watch the snake light up, it shouldn’t be too hard to cheat the pedometer.

Tiger Boy Advance Is A 90s Kid Dream Come True

January 7, 2022 by Tom Nardi 6 Comments

From the release of the DMG-01 in 1989 until the final Micro variant hit store shelves in 2005, the Nintendo Game Boy line represented the epitome of handheld gaming for hundreds of millions of players. But that’s not to say there weren’t a wide array of other handheld systems that aimed to chip away at the Japanese gaming giant’s monopoly. SEGA and Sony released high-tech systems that brought impressive technical innovations, while Tiger Electronics famously took the opposite approach with ultra-cheap handhelds that leveraged simplistic games based on popular children’s franchises.

[Chris Downing] had to make do with these budget Tiger games as a child, and now as an adult, he’s determined to made things right with the Tiger Boy Advance. As the name implies, this retro hybrid combines the look and feel of a branded Tiger game with the power and software compatibility of a legitimate Nintendo Game Boy Advance (GBA) circa 2001. It even sprinkles in some modern niceties, like USB-C charging and a backlit display. While most of its charm is probably lost on anyone who didn’t grow up within a fairly narrow range of years, the video below seems to prove that even modern kids can appreciate this one-of-a-kind creation.

From an electronics standpoint, the system is essentially just a gutted GBA crammed into a 3D printed approximation of an old Tiger game from around the mid 1990s. But what makes this project special is the nostalgia-fueled attention to detail that [Chris] brings to the table.

Take for example the custom manufactured faceplate that combines artwork from some of the era’s best known games. Getting the image printed on the back of the CNC-cut piece of clear acrylic proved to be quite a challenge, but the final result looks incredibly professional. Instead of using the GBA’s stock buttons and directional pad, [Chris] decided to 3D print replacements that mimic the look of the original Tiger controls. It all culminates in a device that perfectly recreates the unique look of the original Tiger games.

Some will argue that he’d have done better to equip the system with a Raspberry Pi Zero 2 and the latest build of RetroPie, and frankly, it’s easy to see the appeal of going that route. But [Chris] didn’t make this for us, he built it to encapsulate a very specific time from his own childhood. We’re just glad that the technology now available to the individual maker allowed him to turn this particular dream into reality.

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A Savage Discussion Of Measurement And Accuracy

January 7, 2022 by Ryan Flowers 69 Comments

It’s commonly said that the great thing about standards is that there are so many of them. Of course, that’s talking about competing standards. But there’s another kind of standard that you want a lot of: Measurements. Without standard measurements, the Industrial Revolution wouldn’t have been facilitated to the extent it was. The illustrious [Adam Savage] takes a deep dive into the art of measurement in the video below the break, and if you have 45 minutes to spare, you will not be disappointed.

We don’t want to give away any big spoilers, but [Adam] starts out with things we can all relate to if we’ve done any kind of measuring for accuracy: measuring between the given lines on a standard tape measure. From there he goes into calipers and other tools for measurement.

Then, out come the Big Guns. The ceramic blocks so flat that… well you’ll just have to watch it. But the discussion goes deep into nanometers, microns, and jeweled movements.

Whether you’re a machinist or a garage hacker with nothing more than a stick welder and an angle grinder at your disposal, or anywhere in between in any segment of being a maker, this video is for you. [Adam]’s enthusiasm is off the charts in this diatribe, and we have to admit- it’s contagious! We’ve never been so excited about measuring things.

Of course, if you need to measurement tool, you can just build a measurement tool. It’s all subjective, after all.

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Books You Should Read: The Perfectionists

January 7, 2022 by Sonya Vasquez 28 Comments

After pulling late hours in my school machine shop for a few years, I couldn’t help but wonder, who measures the measurement tools? How did they come to be? I’d heard anecdotes from other students and engineers while they inspected my freshly machined parts, but these stories were one-offs. What I wanted was a tale of industrial precision from start to finish. Years later, I found it.

The story of precision, as told by Simon Winchester, is captured in The Perfectionists: How Precision Engineers Created the Modern World. Published in 2018, Winchester’s overview stretches as far back to the Antikythera mechanism and brings us to present day silicon wafer manufacturing. Of course, this isn’t a chronology of all-things made precisely. Instead, it’s a romp through engineering highlights that hallmark either a certain level of precision manufacturing or a particular way of thinking with repercussions for the future. Continue reading “Books You Should Read: The Perfectionists” →

Hackaday Podcast 150: Blackberry Runs Out Of Juice, NODE Has Your Pinouts, Rats Learn DOOM, And 2021 Is Done

January 7, 2022 by Tom Nardi 4 Comments

Join Hackaday Editor-in-Chief Elliot Williams and Managing Editor Tom Nardi as they ring in the New Year with the first podcast episode of 2022. We get the bad news out early for those still thumbing away at their Blackberries, then pivot into some of the highlights from over the holidays such as the release of NODE’s The Pinouts Book and the discovery of a few expectation-defying OpenSCAD libraries. We’ll look at modifying a water cooler with Ghidra, and the incredible technology that let’s historians uncover the hidden history of paintings. Oh, and we’ll also talk about all the best and most important stories of the last 12 months. There’s a lot of ground to cover, so get comfortable.

Take a look at the links below if you want to follow along, and as always, tell us what you think about this episode in the comments!

Direct download (70 MB)

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How Many Wires Do You Need To Measure A Resistor?

January 7, 2022 by Al Williams 13 Comments

Measuring resistance doesn’t seem to be a big deal. Put your meter leads across two wires or terminals and read the value, right? Most of the time that is good enough, but sometimes you need better methods and for those, you need more wires, as [FesZ] explains in his recent video that you can see below.

In the usual case, the meter applies a known voltage and measures the current which, by Ohm’s law, gives you the resistance. It is also possible to control the current and measure the voltage — doesn’t matter. [FesZ] shows how many meters measure voltage across a known resistor and the unknown so that a precision voltage or current source isn’t necessary.

But there are a number of problems with this simple method. For one thing, the test leads have resistance as well. So some voltage will drop across them, contributing to measurement error. Sure, that extra 0.5 ohms won’t matter if you are looking at a 100K resistor, but if you are trying to measure, say, the heated bed of a 3D printer, that extra 0.5 ohms is a large percentage of the total measurement.

Bench meters for lab use often support 4-wire measurements. As [FesZ] shows, this method measures three different voltages to try to negate some of the measurement errors. We liked that he used three different meters to show how it works and the difference between a 2-wire and 4-wire measurement on a small resistor.

There’s an even stranger method using 3 wires to save on wiring for, say, a sensor a long distance away. There are actually at least two ways to use 3 wires, and the video covers both of them.

For measuring resistors in a circuit, though, you need a whopping six wires. This technique uses the two extra wires to control a balance voltage that keeps the current between the unknown resistor and the rest of the circuit at zero. This prevents current flowing except for the measurement current. You’ll see a simulation of how this works in the video.

We’ve looked at 4-wire measurements before if you want some practice simulations to try. Probes for this measurement are a popular project, too.

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