DIY Soldering Tweezers, Extra Thrifty

It started when [Mitxela] was faced with about a hundred incorrectly-placed 0603 parts. Given that he already owned two TS101 soldering irons, a 3D printer, and knows how to use FreeCAD (he had just finished designing a custom TS101 holder) it didn’t take long to create cost-effective DIY soldering tweezers.

Two screws allow adjusting the irons to ensure the tips line up perfectly.

The result works great! The TS101 irons are a friction-fit and the hinge (designed using the that-looks-about-right method) worked out just fine on the first try. Considering two TS101 irons are still cheaper than any soldering tweezer he could find, and one can simply undock the TS101s as needed, we call this a solid win.

One feature we really like is being able to precisely adjust the depth of each iron relative to each other, so that the tips can be made to line up perfectly. A small screw and nut at the bottom end of each holder takes care of that. It’s a small but very thoughtful design feature.

Want to give it a try? The FreeCAD design file (and .stl model) is available from [Mitxela]’s project page. Just head to the bottom to find the links.

We’ve seen DIY soldering tweezers using USB soldering irons from eBay but the TS101 has a form factor that seems like a particularly good fit.

Buyer Beware: Cheap Power Strips Hold Hidden Horrors

We’ve got a love-hate relationship with discount tool outlet Harbor Freight: we hate that we love it so much. Apparently, [James Clough] is of much the same opinion, at least now that he’s looked into the quality of their outlet strips and found it somewhat wanting.

The outlet strips in question are Harbor Freight’s four-foot-long, twelve-outlet strips, three of which are visible from where this is being written. [James] has a bunch of them too, but when he noticed an intermittent ground connection while using an outlet tester, he channeled his inner [Big Clive] and tore one of the $20 strips to bits. The problem appears to be poor quality of the contacts within each outlet, which don’t have enough spring pre-load to maintain connection with the ground pin on the plug when it’s wiggled around. Actually, the contacts for the hot and neutral don’t look all that trustworthy either, and the wiring between the outlets is pretty sketchy too. The video below shows the horrors within.

What’s to be done about this state of affairs? That’s up to you, of course. We performed the same test on all our outlets and the ground connections all seemed solid. So maybe [James] just got a bad batch, but he’s still in the market for better-quality strips. That’s going to cost him, though, since similar strips with better outlets are about four times the price of the Harbor Freight units. We did find a similar strip at Home Depot for about twice the price of the HF units, but we can’t vouch for the quality. As always, caveat emptor.

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Fiber Laser Gives DIY PCBs A Professional Finish

While low-cost professional PCB fabrication has largely supplanted making circuit boards at home, there’s still something to be said for being able to go from design to prototype in an afternoon. Luckily we aren’t limited to the old toner transfer trick for DIY boards these days, as CNC routers and powerful lasers can be used to etch boards quickly and accurately.

But there’s still a problem — those methods leave you with a board that has exposed traces. That might work in a pinch for a one-off, but such boards are prone to shorts, and frankly just don’t look very good. Which is why [Mikey Sklar] has been experimenting with applying both a soldermask and silkscreen to his homemade boards.

The process he describes starts after the board has already been etched. First he rolls on the soldermask, and then sandwiches the board between layers of transparency film and clear acrylic before curing it under a UV light. After two coats of the soldermask, the board goes into a fiber laser and the silkscreen and mask layers are loaded into the software and the machine is set to a relatively low power (here, 40%). The trick is that the mask layer is set to run four times versus the single run of the silkscreen, which ensures that the copper is fully exposed.

Since the board doesn’t need to be moved between operations, you don’t have to worry about the registration being off. The end result really does look quite nice, with the silkscreen especially popping visually a lot more than we would have assumed.

We’ve previously covered how [Mikey] uses his CNC router and fiber laser to cut out and etch the boards, so this latest installment brings the whole thing full circle. The equipment you’ll need to follow along at home isn’t cheap, but we can’t argue with the final results.

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Pluto’s Not A Planet, But It Is A Spectrum Analyzer

The RTL-SDR dongles get most of the love from people interested in software-defined radio, but the Pluto is also a great option, too. [FromConceptToCircuit] shares code to turn one of these radios into a spectrum analyzer that sweeps up to 6 GHz and down to 100 MHz. You can see a video of how it works below.

While it may seem that 100 MHz is a bit limiting, there’s plenty of activity in that range, including WiFi, Bluetooth, radio systems, both commercial and amateur, and even cell phones.

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A Portable Electronics Workstation

You don’t see them as often as you used to, but it used to be common to see “electronics trainers” which were usually a collection of components and simple equipment combined with a breadboard, often in a little suitcase. We think [Pro Maker_101’s] portable electronics workstation is in the same kind of spirit, and it looks pretty nice.

The device uses a 3D printed case and a custom PC board. There are a number of components, although no breadboard. There is a breakout board for Raspberry Pi GPIO, though. So you could use the screw terminals to connect to an external breadboard. We were thinking you could almost mount one as a sort of lid so it would open up like a book with the breadboard on one side and the electronics on the other. Maybe version two?

One thing we never saw on the old units? An HDMI flat-screen display! We doubt you’d make one exactly like this, of course, but that’s part of the charm. You can mix and match exactly what you want and make the prototyping station of your dreams. Throw in a small portable soldering iron, a handheld scopemeter, and you can hack anywhere.

We’d love to see something like this that was modular. Beats what you could build in 1974.

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Handheld 18650 Analyzer Scopes Out Salvaged Cells

You can salvage lithium 18650 cells from all sorts of modern gadgets, from disposable vapes to cordless power tools. The tricky part, other than physically liberating them from whatever they are installed in, is figuring out if they’re worth keeping or not. Just because an 18650 cell takes a charge doesn’t necessarily mean it’s any good — it could have vastly reduced capacity, or fail under heavy load.

If you’re going to take salvaging these cells seriously, you should really invest in a charger that is capable of running some capacity tests against the cell. Or if you’re a bit more adventurous, you can build this “Battery Health Monitor” designed by [DIY GUY Chris]. Although the fact that it can only accept a single cell at a time is certainly a limitation if you’ve got a lot of batteries to go though, the fact that it’s portable and only needs a USB-C connection for power means you can take it with you on your salvaging adventures.

The key to this project is a pair of chips from Texas Instruments. The BQ27441 is a “Fuel Gauge” IC, and is able to determine an 18650’s current capacity, which can be compared to the cell’s original design capacity to come up with an estimate of its overall health. The other chip, the BQ24075, keeps an eye on all the charging parameters to make sure the cell is being topped up safely and efficiently.

With these two purpose-built chips doing a lot of the heavy lifting, it only takes a relatively simple microcontroller to tie them together and provide user feedback. In this case [DIY GUY Chris] has gone with the ATmega328P, with a pair of addressable WS2812B LED bars to show the battery’s health and charge levels. As an added bonus, if you plug the device into your computer, it will output charging statistics over the serial port.

The whole project is released under the MIT license, and everything from the STL files for the 3D printed enclosure to the MCU’s Arduino-flavored firmware is provided. If you’re looking to build one yourself, you can either follow along with the step-by-step assembly instructions, or watch the build video below. Or really treat yourself and do both — you deserve it.

If your battery salvaging operation is too large for a single-cell tester, perhaps it’s time to upgrade to this 40-slot wall mounted unit.

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Software Hacks Unlock Cheap Spectrometer

A spectrometer is one of those tools that many of us would love to have, but just can’t justify the price of. Sure there are some DIY options out there, but few of them have the convenience or capability of what’s on the commercial market. [Chris] from Zoid Technology recently found a portable spectrometer complete with Android application for just $150 USD on AliExpress which looked very promising…at least at first.

The problem is that the manufacturer, Torch Bearer, offers more expensive models of this spectrometer. In an effort to push users into those higher-priced models, arbitrary features such as data export are blocked in the software. [Chris] first thought he could get around this by reverse engineering the serial data coming from the device (interestingly, the spectrometer ships with a USB-to-serial adapter), but while he got some promising early results, he found that the actual spectrometer data was obfuscated — a graph of the results looked like stacks of LEGOs.

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