Digitize An Analogue Oscilloscope

May 31, 2020 by Jenny List 13 Comments

Many of us will possess digital oscilloscopes which offer at an affordable price an array of features once unimaginable on the analogue CRT ‘scopes of yesteryear. But those old analogue beasts were fine pieces of equipment when they were made and remain so today. So how can they find a place in the digital age?

Perhaps [Joseph Eoff] has the answer, because he’s fitted his trusty Telequipment D43 with a camera in a 3D-printed attachment, paired with a piece of cross-platform Python/Qt custom software using OpenCV to identify, digitize, and quantify the traces. The software allows viewing the either the digitized trace or the real trace, and derives measurements of voltage and frequency from them. One limitation is that despite the ‘scope being a dual-trace model, the software only has a single set of cursors to measure one trace at a time. All the code can be had from the GitHub repository, should you wish to experiment with it or extend it.

It’s worth thinking for a minute at what price point a remotely decent digital ‘scope starts, then considering the ease with which surprisingly good older analogue instruments can be found on the second-hand market for not a lot. An approach such as this one makes them an even more attractive proposition.

If you’re looking further into enhancements for an analogue ‘scope, how about a logic analyser?

What Rhymes With Spice And Simulates Huge Circuits?

May 28, 2020 by Al Williams 9 Comments

Most of us have computers on our desk that would have been considered supercomputers not long ago. We always wonder how many of them get any actual workout other than decoding video. If you want to simulate circuits you may very well start chewing up significant CPU time, so you might consider Xyce, an open source high-performance analog circuit simulator from Sandia National Labs. As you’d expect from a giant government lab it is able to support large scale parallel computing, but will also work on common desktop systems. On Linux, it will do what they call “small-scale parallelism.” In addition, it can deal with simulations of things as diverse as neural networks and power grids.

The code is open source, but oddly you do have to register to download it. Xyce has been around for a bit, but version 7.0 just arrived in April. Many of the changes are to improve compatibility with other Spice programs, notably HSpice.

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A DIY Electronics Lab You Can Show Off With Pride

May 25, 2020 by Tom Nardi 27 Comments

It’s hardly a secret that getting into a serious electronics habit can be detrimental to your bank account. A professional grade lab is simply unobtainable for many a tinkerer, and even mid-range hardware can set you back considerably. Which is why many folks just starting out will attempt to salvage or build as much of their equipment as possible. It might not always be pretty, but it’ll get the job done.

But this project by [Chrismettal] could end up completely reinventing the home electronic workspace. Using 3D printed frames, low-cost components, and a sprinkling of custom PCBs, this modular electronics workbench has all the bells and whistles an aspiring hardware hacker could need. As an added bonus, it looks like something that came off the International Space Station.

Inside the resistor substitution module.

This is one of those projects that simply can’t be done justice in a few paragraphs. If you’ve ever wanted to put together a dedicated electronics workbench but were put off by the cost of individual components, read though the fantastic documentation [Chrismettal] has prepared for the EleLab_v2. Is it all top-of-the-line hardware? No, of course not. But it’s more than suitable for the kind of work people in this community usually find themselves involved in on a weekend.

So what’s included? Naturally [Chrismettal] has created a power supply module, in both variable and fixed flavors. But there’s also a module for a resistor substitution, a component tester, and even a digital storage oscilloscope. You can mix and match the modules suit your needs, and if you want to create entirely new ones, the FreeCAD sources are available to get you started.

We’ve seen low-cost power supply modules before, and naturally we’re no strangers to cheap DSO kits. But this project wraps those devices and gadgets up into a form factor that anyone would be happy to have on their bench. We’re exceptionally interested in seeing new modules developed for the EleLab_v2, and doubt this is the last time you’ll see this impressive project grace these pages.

[Thanks to BrunoC for the tip.]

Ironclad Tips For Copper-Clad Prototyping

May 24, 2020 by Kristina Panos 25 Comments

The idea of trying to prototype with SMD parts on the fly sounds like insanity, right? But then we watched [Leo Fernekes] walk calmly and carefully through his process (video, embedded below). Suddenly, SMD prototyping jumped onto our list of things to try soon.

[Leo] speaks from a lot of experience and tight client timelines, so this video is a fourteen-minute masterclass in using copper-clad board as a Manhattan-style scratch pad. He starts by making a renewable tool for scraping away copper by grinding down and shaping an old X-Acto blade into a kind of sharpened Swiss Army knife bottle opener shape. That alone is mind-blowing, but [Leo] keeps on going.

In these prototypes, he uses the through-hole version of whatever microcontroller is in the design. For everything else, he uses the exact SMT part that will end up on the PCB that someone else is busy designing in the meantime.

After laying the board out on paper, [Leo] carves out the islands of conductivity, beep-checks them for shorts, shines the whole thing with steel wool, and goes to town.

The tips and tricks keep coming as he makes jumps and joins ground planes with bare copper wire insulated with heat-proof Teflon tubing, and lays out the benefits of building up a stash of connectors and shelling out the money for a good crimp tool.

And why do you need a good crimp tool? Because when they’re done properly, crimped connections are stronger and more reliable than solder. There’s a lot more to them than you might think.

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Finding RF Cable Impedance

May 24, 2020 by Al Williams 25 Comments

At DC and low frequency, we can pretend wires are perfect conductors. At radio frequencies, though, there are many effects that you need to take into account for wires and cables. One of these is characteristic impedance. If you have a marked cable, you can look it up on the Internet, of course. But what if you don’t know what kind of wire it is? With help from [The Offset Volt], you can measure it as he shows in the video below.

This is one of those things that used to take exotic test equipment like an LCR bridge, but these days meters that measure inductance and capacitance are commonplace. The trick is simple: measure the capacitance and then short one end of the cable and measure the inductance.

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Resistors Sorter Measures Values

May 23, 2020 by Al Williams 22 Comments

We’ve all been there. A big bag of resistors all mixed up. Maybe you bought them cheap. Maybe your neatly organized drawers spilled. Of course, you can excruciatingly read the color codes one by one. Or use a meter. But either way, it is a tedious job. [Ishann’s] solution was to build an automatic sorter that directly measures the value using a voltage divider, rather than rely on machine vision as is often the case in these projects. That means it could be modified to do matching for precise circuits (e.g., sort out resistors all marked 1K that are more than a half-percent away from one nominal value).

There is a funnel that admits one resistor at a time into a test area where it is measured. A plate at the bottom rotates depending on the measured value. In the current implementation, the resistor either falls to the left or the right. It wouldn’t be hard to make a rotating tray with compartments for different values of resistance. It looks like you have to feed the machine one resistor at a time, and automating that sounds like a trick considering how jumbled loose axial components can be. Still, its a fun project that you probably have all the parts to make.

An Arduino powers the thing. An LCD screen and display control the action. If you want some practice handling material robotically, this is a great use of servos and gravity and it does serve a practical purpose.

We have seen many variations on this, including ones that read the color code. If you ever wanted to know where the color code for resistors came from, we took a trip to the past to find out earlier this year.

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Old School Rotary Tools That Weren’t Made By Dremel

May 18, 2020 by Al Williams 58 Comments

Albert Dremel developed the now famous rotary tool and started the company in 1932 to make blade sharpeners. It would be 1935 before the company produced the Moto-Tool which is mostly recognizable as an ancestor of the modern Dremel.

Dremel achieved such dominance that today the name is synonymous with rotary tools in the same way Xerox means photocopy and Crock-Pot is any slow cooker. Sure, there are knock offs you can get from the usual cheap tool outlets, but generally, people reach for a Dremel even when it isn’t really one. Today that tool might really be a Black and Decker or a Dewalt or even a cheap brand like Wen or Chicago Electric. But in the first half of the 20th century, you might have reached for a Handee.

A Whole Shop Full of Tools

The Handee was a product of the Chicago Wheel and Manufacturing Company who, in 1937, billed it as “a whole shop full of tools in one,” as you can see in this ad. While $10.75 might sound like a price for a Harbor Freight cheapie tool, adjusted for inflation that’s around $200 in 2020 money. At least for that price you got three free accessories out of the over 200 available.

I didn’t remember the Handee and I wanted to see if I could figure out what happened to it and the company who made it. After all, with the Internet at your disposal, how hard could it be? Turns out, I did learn a lot, but in the end, tracing down a company like this from the old days isn’t always as easy as you might think.

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