Testing A Battery-Powered Mini Spot Welder

Did you ever see a thin metal tab bonded to a battery terminal with little pock marks? That’s the work of a spot welder. Spot welding is one of those processes that doesn’t offer much in the way of alternatives; either one uses a spot welder to do the job right, or one simply does without. That need is what led [Erwin Ried] to purchase a small, battery-powered spot welder from a maker in Korea and test it out on nickel strips.

The spot welder [Erwin] used is the work of a user by the name of [aulakiria] (link is Korean, machine translation here) and is designed to be portable and powered by batteries commonly used for RC. [Erwin] is delighted with the results, and demonstrates the device in the video embedded below.

Spot welder projects see a lot of DIY, some of which are successful while others are less so. Our own [Sean Boyce] even gave making a solar-powered spot welder a shot, the results of which he described as “nearly practical!”

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Take a Mini Lathe for a Spin

[This Old Tony] is no stranger to quality tools, but he started on a mini lathe. Nostalgia does not stop him from broadcasting his usual brand of snark (actually, it is doubtful that anything short of YouTube going offline will stop that). He rates the lathe’s ability to machine different materials and lets you decide if this is an investment, or a money pit.

Lathe parts range from a chintzy start/stop button assembly that looks like it would be at home on a Power Wheels restoration project to a convenient cam locking mechanism on the tail stock which is an improvement on the lathe with which our narrator learned. We see the speed tested and promptly disproved as marketing hoopla unless you allow for a 40% margin of error. It uses a 500 watt DC motor, so don’t try correcting for mains power frequency differences. The verdict on the lead screw and thread dial is that you get what you pay for and this is demonstrated by painstakingly cutting threads into aluminum. Finally, we see torture tests on cold rolled steel.

Maybe someone from the mini lathe community will stop by with their two-cents. If you appreciate this introduction to lathes, consider [This Old Tony]’s guide to CNC machines or injection molding. But for us, [Quinn Dunki’s] series of machine tools has been a real treat this year.

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Review: CXG E90W Temperature-Controlled Soldering Iron

It’s an entertaining pastime when browsing the array of wonders available from the other side of the world at the click of the mouse, to scour the listings of the unusual, the interesting, or the inexpensive. Sometimes when you find something unexpected you are rewarded with a diamond in the rough, while at other moments your bargain basement purchase is revealed as a hilariously useless paperweight. This is a game in which the stake is relatively low and the reward can be significant, so rarely does an order for some parts or sundries go by without a speculative purchase.

The latest to arrive is a soldering iron. The CXG E90W is a 90W mains-powered temperature controlled iron with its control electronics built into its handle. Such irons are by no means unusual, what makes this one different is that it has a low price tag.

The Miniware TS100, an iron I quite like and the current darling of the pack, is priced at nearly £50 ($71). Just how can this iron priced at just under £15 ($21) be any good? I placed one on the order, and waited for delivery.

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Twitter Celebration of Scientist Hacks For Lab And Field

If you like reading about scientists creatively using household objects for their work, you will enjoy browsing Twitter hashtag #reviewforscience where scientists are sharing stories of repurposing everyday things for their lab and field.

Research papers focus on the scientific hypothesis and the results of testing it. It is very common for such papers to leave out details of tools and techniques as irrelevant. (A solid scientific conclusion should be reproducible no matter what tools and techniques are used.) This sadly meant much of scientists’ ingenuity never see light.

We can thank Amazon user [John Birch] for this event. His son wished to study how ants from different colonies interact. In order to observe how these groups of ants react to each other while still keeping the populations separate, he wanted to keep one group of ants inside a tea strainer. He posted this technique as a review on the tea strainer’s Amazon product page, where it caught the attention of @RobynJWomack and started spreading, taking off when @DaniRabaiotti suggested the tag #reviewforscience.

Sadly, it appears our original scientist (who posted under his dad’s Amazon account) did not succeed with the tea strainer technique. But he has succeeded in drawing attention to creativity in science worldwide, as well as making his dad internet famous.

We love lab hacks here. For scientists who wish there was a place to document their creative lab hacks, might we suggest Hackaday.io?

[via Washington Post]

How Cheap Can A 3D Printer Get? The Anet A8

The short answer: something like $200, if your time is worth $0/hour. How is this possible? Cheap kit printers, with laser-cut acrylic frames, but otherwise reasonably solid components. In particular, for this review, an Anet A8. If you’re willing to add a little sweat equity and fix up some of the bugs, an A8 can be turned into a good 3D printer on a shoestring budget.

That said, the A8 is a printer kit, not a printer. You’re going to be responsible for assembly of every last M3 screw, and there are many. Building the thing took me eight or ten hours over three evenings. It’s not rocket surgery, though. There are very accessible videos available online, and a community of people dedicated to turning this box of parts into a great machine. You can do it if you want to.

This article is half how-to guide and half review, and while the fun of a how-to is in the details, the review part is easy enough to sum up: if you want the experience of building a 3D printer, and don’t mind tweaking to get things just right, you should absolutely look into the A8. If you want a backup printer that can print well enough right after assembly, the A8 is a good deal as well; most of the work I’ve put into mine is in chasing perfection. But there are a couple reasons that I’d hesitate to recommend it to a rank beginner, and one of them is fire.

Still, I’ve put 1,615 m (1.0035 miles) of filament through my A8 over 330 hours of run-time spread across the last three months — it’s been actively running for 15% of its lifetime! Some parts have broken, and some have “needed” improving, but basically, it’s been a very functional machine with only three or four hours of unintentional downtime. My expectations going in were naturally fairly low, but the A8 has turned out to be not just a workhorse but also a decent performer, with a little TLC. In short, it’s a hacker’s printer, and I love it.

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Review: JYE Tech DSO150 Oscilloscope Kit

When men were men, and oscilloscopes were oscillographs.
When men were men, and oscilloscopes were oscillographs.

Do you remember your first oscilloscope? Maybe we have entered the era in which younger readers think of a sleek model with an LCD screen, but for the slightly older among us the image that will come to mind is likely to be a CRT-based behemoth. Mine was a 2MHz bandwidth Cossor from the 1950s, wildly outdated by the 1980s, but it came to me at no cost. It proudly proclaims itself as a “Portable Oscillograph”, but requires its owner to be a weightlifter to move it. I still have it, as a relic and curio.

For most of us a new ‘scope is still a significant investment. Even affordable current models such as the extremely popular Rigol instruments are likely to cost several hundred dollars, but offer measurement functions undreamed of by those 1950s engineers who would have looked on the Cossor as an object of desire.

Oscilloscope buyers on a budget may not have the cash for a Rigol, a Hantek, or any of the other affordable ‘scopes. Someone starting on the road of electronic engineering can scout around for a cheap or free second-hand CRT model, but thanks to the ever advancing march of technology they also have another option. Modern microprocessors and microcontrollers have analogue-to-digital converters and processor cores that are fast enough to provide the functions of a simple oscilloscope, and to that end a variety of very cheap ‘scopes and ‘scope kits have come on the market. These invariably have a rather small LCD screen and a relatively low bandwidth, but since they can be had for almost pocket-money prices their shortcomings can be overlooked in the name of value. It’s been a matter of curiosity for some time then: are these instruments any good? For around £16 ($21) and the minor effort of an online order from China, we decided to find out.

If you look at most stockists of electronic kits these days, you are likely to find an oscilloscope kit in their range. These are volume produced in China, and the same design trends appear across different models. You can buy surface mount or through-hole, and most of them feature a bare board with maybe a piece of laser-cut Perspex standing in for a case. There are one or two models appearing that come with a case though, and it was one of these that we ordered. The JYE Tech DSO150 is a single-channel ‘scope with a 2.4″ 320×240 pixel colour LCD screen and a 200kHz bandwidth. Its specification is typical of the crop of similar kits, though its smart case sets it apart and made it an easy choice.

In the Box

We ordered one, and when it arrived, it was packed in a small cardboard carton that had suffered some crushing in transit, but had protected the internal contents well enough that no harm had been done. A layer of foam protected the LCD, and the case parts appeared rigid enough to protect the rest of the components. There was a bag of discretes, the case parts, two PCBs, a test lead with crocodile clips, and two pages of instructions.

When looking at a kit, it’s best to start with the instructions, because no matter the quality of the kit itself it is the quality of the instructions that make or break a kit. If you can’t build it then it doesn’t matter how good it might be, it’s effectively junk.

The DSO150 instructions are two sheets of high quality double-sided colour print, with the emphasis on pictures rather than words, The front page introduces the kit and gives a quick soldering guide, then the next two pages step through each stage of construction. The final page has basic instructions for use, specification, and a troubleshooting guide. Our kit had all surface-mount parts already fitted, if we’d known the kit could also be had with SMD parts to fit we’d have bought that version instead.

Inside the DSO100.
Inside the DSO100.

The instruction steps are long on images and short on text, but there are sometimes few cues as to where the component in question lies on the board. Sometimes some careful examination of board and picture is necessary to ensure correct placement. The first step though doesn’t involve any soldering, wire the main board up to a 9V supply, and watch the LCD boot into the oscilloscope software. There is support via a forum on the JYE Tech website, we presume you’d go there if it failed to boot out of the box. A 9V PSU isn’t included, you’ll need to find one with a 2.1mm centre positive plug. Fortunately a suitable candidate was in the box of wall warts here, formerly being used by a router.

The main board assembly is straightforward enough, being the assembly of larger through-hole parts such as switches and connectors. The analogue board has a brace of small through-hole resistors and ceramic capacitors to fit, of these the resistors were of the tiny variety which made distinguishing between some of their colour stripes a little difficult. Bring your multimeter to check. There is a BNC connector that requires significant heat on there too, so make sure you have a suitably beefy iron to hand. Finally there is a small board for the rotary encoder, then the front of the case can be assembled to the main board, the analogue board attached, and the ‘scope set up. Verify on-board voltages, attach the test clip to the calibration output and adjust the compensation capacitors for a square wave, and the rest of the case can be added to complete the unit.


The DSO150 showing the upper end of its bandwidth.
The DSO150 showing the upper end of its bandwidth.

In use, the DSO150 makes a simple and straightforward enough oscilloscope. The usual volts/division and timebase selection is easy enough, and the various trigger modes can quickly be selected. If you’ve used an oscilloscope before then you will have no problems getting started with it. But of course, the DSO150 isn’t just a simple oscilloscope, it’s a digital storage ‘scope. And with 1024 sampling points it can do the usual storage ‘scope thing of allowing the user to examine a stored waveform in great detail, scrolling back and forth through the stored points. Here the instruction sheet falls short, not mentioning that a double tap on the V/div or Sec/div buttons allows you to scroll.

Connecting the signal generator to our DSO150 allowed the exploration of its bandwidth. The claimed 200kHz is pretty spot-on, winding the signal generator far beyond that point showed a tail-off in displayed amplitude. Also the minimum 10µS per division limits the usefulness of a waveform display at these frequencies.

The DSO150 is supplied with a short test lead terminated in a pair of crocodile clips. This is somewhat less useful than the oscilloscope probes we’re used to, though happily it can also be used with a standard 1x/10x probe. Looking at the square wave on the test terminal through a standard probe reveals a sharp corner on the waveform, so there seems not to be any problems between the compensation on-board and that in the probe. It’s likely that either the DSO150 here will be used with a standard probe, or that the crocodile clip will swiftly be replaced with a probe of some kind.

Closing Thoughts

So then, the JYE Tech DSO150 oscilloscope kit. A nice little ‘scope within the limitations of the STM32F103C8 microcontroller that drives it. If you can put up with a 200kHz bandwidth and a 50V peak input voltage then it’s a useful pocket instrument. Its calibration will depend on the STM’s crystal and voltage reference, but as with the rest of its specification, when you consider its pocket-money price those become minor considerations. Add in that its software is open-source, and you have a very nice platform indeed. If we wanted to nitpick we’d ask for a battery compartment and a proper probe, but since both of those would put up the price we wouldn’t make too much noise about it. If you need a pocket ‘scope to supplement your bench scope when working on lower frequencies, or if you have a youngster in the family looking for their first ‘scope, buy one! Our review unit will definitely see some use rather than gathering dust.

Why You Shouldn’t Quite Forget The Moving Coil Multimeter

Did any of you have an AWS multimeter? Was it the best? Radio-electronics magazine, August 1981.
Did any of you have an AWS multimeter? Was it the best? Radio-Electronics magazine, August 1981.

If you were to ask a random Hackaday reader what their most fundamental piece of electronic test equipment was, it’s likely that they would respond with “multimeter”. If you asked them to produce it, out would come a familiar item, a handheld brick with a 7-segment LCD at the top, a chunky rotary selector switch, and a pair of test probes. They can be had with varying quality and features for anything from a few dollars to a few hundred dollars, though they will nearly all share the same basic set of capabilities. Voltage in both AC and DC, DC current, resistance from ohms to mega ohms, and maybe a continuity tester. More expensive models have more features, may be autoranging, and will certainly have better electrical safety than the cheaper ones, but by and large they are a pretty standard item.

If Hackaday had been around forty years ago and you’d asked the same question, you’d have had a completely different set of multimeters pulled out for your inspection. Probably still a handheld brick with the big selector switch, but instead of that LCD you’d have seen a large moving-coil meter with a selection of scales for the different ranges. It would have done substantially the same job as the digital equivalent from today, but in those intervening decades it’s a piece of equipment that’s largely gone. So today I’m going to investigate moving coil multimeters, why you see them a lot less these days than you used to, and why you should still consider having one in your armoury. Continue reading “Why You Shouldn’t Quite Forget The Moving Coil Multimeter”