[Kerry Wong] Is Really Into Scope Meters

If a combination multimeter and oscilloscope is on your holiday shopping list this year, you might want to have a look at some of [Kerry Wong’s] recent videos on the subject. Over several videos he looks at — inside and out — an OWON HDS272S and a Hantek 2D72, both reasonably inexpensive entries in the field. Both instruments are similar and have a few variants depending on the frequency capability and the addition of a waveform generator.

There are several videos on the Hantek device that are a few months old, then some recent videos — like the one below — on the OWON device along with some comparison videos.

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Differential Probe Clocks At 100MHz And $200

[Voltlog] often looks at interesting test equipment and in the video below he reviews something that isn’t very common in hobby labs: a differential oscilloscope probe. These are usually pretty expensive, but the Micsig probe in the video costs under $200. The question, of course, is what do you need with a differential probe?

A typical scope probe has a ground lead that connects directly to the actual grounding point. This can cause a problem if you try to measure across some component that has more voltage than you want to short to ground. It might hurt your device under test, your scope, or both.

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Multimeters Go Big Screen

We’ve noticed lately that some cheap meters have gone to having big colorful screens. The screens aren’t dot matrix, but still have lots of graphics that could be useful or could be distracting eye candy, depending. The really cheap ones seem more like a gimmick, but [OM0ET] took a look at one that looked like a fair midrange instrument with some useful display features, the GVDA GD128.

A lot of the display shows the current function of the meter. No need for an expensive multiposition switch or rows of interlocking pushbuttons. Many of these new meters also have non-contact voltage sensors, which is handy. Otherwise, it looks like a pretty conventional cheap meter. Continue reading “Multimeters Go Big Screen”

Schematic-o-matic

Tricked-Out Breadboard Automatically Draws Schematics Of Whatever You Build

When it comes to electronic design, breadboarding a circuit is the fun part — the creative juices flow, parts come and go, jumpers build into a tangled mess, but it’s all worth it when the circuit finally comes to life. Then comes the “What have I done?” phase, where you’ve got to backtrack through the circuit to document exactly how you built it. If only there was a better way.

Thanks to [Nick Bild], there is, in the form of the “Schematic-o-matic”, which aims to automate the breadboard documentation process. The trick is using a breadboard where each bus bar is connected to an IO pin on an Arduino Due. A program runs through each point on the breadboard, running a continuity test to see if there’s a jumper connecting them. A Python program then uses the connection list, along with some basic information about where components are plugged into the board, to generate a KiCad schematic.

[Nick] admits the schematics are crude at this point, and that it’s a bit inconvenient to remove some components, like ICs, from the breadboard first to prevent false readings. But this seems like one of those things where getting 80% of the work done automatically and worrying about the rest later is a big win. Plus, we can see a path forward to automatic IC probing, and even measurement of passive components too. But even as it is, it’s a great tool.

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Keep The Sparks Away With A Plasma Cutting Table

For one-off projects or prototypes it’s not uncommon for us to make do with whatever workspace we have on hand. Using a deck railing as an impromptu sawhorse, for example, is one that might be familiar to anyone who owns a circular saw, but [Daniel] has a slightly different situation. He had been setting up metal workpieces on random chunks of brick in order to use his plasma cutter, but just like the home handyman who gets tired of nicking their deck with a saw, he decided to come up with a more permanent solution and built a custom plasma cutting table.

Plasma cutting has a tendency to throw up a lot of sparks, so most commercial offerings for plasma cutting tables include a water bath to catch all of the debris from the cutting process. [Daniel] builds his table over a metal tub to hold some water for this purpose. The table itself is built out of aluminum and designed to be built without welding even though most people with plasma cutters probably have welders as well. The frame is designed to be exceptionally strong and includes curved slats which add to the strength of the table. The table is also designed to be portable, so the curved slats stay in place when the table is moved.

While this might seem like an average metal table at first glance, the table is actually being designed with a homemade CNC machine in mind which [Daniel] is working on. The CNC plasma cutter needs a sturdy, flat surface and can’t be set up on bricks in the driveway, so this table suits both [Daniel]’s immediate needs to not shower himself in sparks every time he cuts something and also his future CNC machine’s need for a sturdy, flat workspace. We look forward to seeing that build being completed but in the meantime take a look at this motorized plasma cutter which has the beginnings of a CNC machine if in one direction only.

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Shady Air Umbrella Given New Lease On Life

Many infamous Kickstarter projects have ultimately flopped or failed, leaving backers frustrated and angry. Often pitched with a splashy convincing video that happens to have critical components conveniently offscreen. [Allen Pan] was reminiscing about one such project, the air umbrella, and decide to redeem the project by making his own.

The basic idea of the air umbrella was a device that could create a cone of fast-moving air over your head to deflect air. Going off of the specs listed on the original Kickstarter page, [Allen] made a simple prototype that did nothing. Suspicions confirmed, he decided to keep going by buying a powerful electric leaf blower. A nozzle was 3d printed that could direct the air into the needed disc. Early testing with the mist function on a garden hose seemed promising, and they worked their way up to progressively larger raindrops.

Finally, the clouds of California smiled upon them, and it rained. [Allen] was ecstatic that his umbrella worked. He couldn’t hear much out of one ear as he was holding a leaf blower next to it for a few minutes, but it’s a small price to pay to stay dry with the Air Umbrella.

If you’re curious about more false Kickstarter claims, why not read up on this tiny Arduino compatible board making some dubious claims.

[Header image courtesy of Air Umbrella Kickstarter page]

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An array of 3D-printed parts for old sewing machines.

Printed Sewing Machine Parts Extend Singer’s Range

[Grow Your Own Clothes] had finally found their ideal sewing machine for doing zig-zag stitches (/\/\/\) and converting to a treadle drive (mechanically foot-fed) — a Singer 411G. This is a well-respected workhorse of a machine, and if you see one in a secondhand store, you might want to grab it. The only problem is that its multi-step zig-zag stitch is a 4-stepper and not a 3-step, which is what [GYOC] prefers. Having heard it was possible to hack them into doing a 3-step, [GYOC] set out to learn Tinkercad and grow their own sewing machine parts.

A 3D-printed cam lets this machine do the zig-zag in three steps instead of four.
The new zig-zag top hat cam in place.

So once upon a time, sewing machines didn’t just do a bunch of things out of the box. They needed an array of plastic cams to do different stitches, kind of like trading out the element or disk in a typewriter to print in italics. While most machines still have exchangeable feet for different needs and special parts for sewing things like buttonholes, most domestics now have decorative stitches and their cams built in.

The 3-step zig-zag cam was just the beginning. [GYOC] decided to make a few more parts before their Tinkercad knowledge faded: a needle adapter with an improved design, some tension stud sprockets for a different machine, and a couple of buttonhole templates for making different sizes with a buttonholer. Although they aren’t giving away the files for free, all of these parts are available quite cheaply in their Shapeways store.

Got an old machine you don’t know what to do with? Try converting it to a computerized embroidery machine.

Thanks for the tip, [Raphael]!