Isolated Oscilloscope Design Process Shows How It’s Done

[Bart Schroder] was busy designing high voltage variable speed motor drives and was lamenting the inability of a standard scope to visualise the waveforms around the switch transistors. This is due to the three phase nature of such motors being driven with three current waveforms, out of phase with each other by 120 degrees, where current flows between each pair of winding taps, without being referenced to a common notion of ground. The average scope on your bench however, definitely is ground-referenced, so visualising such waveforms is a bit of a faff. Then there’s the fact that the motors run at many hundreds of volts, and the prospect of probing that with your precious bench instrument is a little nerve-wracking to say the least. The solution to the issue was obvious, build your own isolated high voltage oscilloscope, and here is the Cleverscope CS448 development journey for your viewing pleasure.

The scope itself is specification-wise nothing too flash, it’s the isolated channels that make it special. It does however have some niceties such as an extra eight 100 Mbps digital inputs and a handy 65 MHz signal generator. Also, don’t reach for your wallets just yet, as this is a specialised instrument with an even smaller potential user base than a normal scope, so these units are rather pricey. That all said, it’s not the existence of the scope that is the focus here, it’s the journey from problem to solution that interests us the most. There is much to learn from [Bart’s] journey, for example, where to place the frontend ADC? Isolated side or not? The noise floor of the signal chain dictated the former.

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Wearable Scope Lets Your Fingers Do The Probing

For frantic hacking sessions where seconds count, this forearm mounted oscilloscope with fingertip probes built by [aniketdhole] might be just what you need. Well, maybe. It’s not immediately clear why you might want to wear an oscilloscope on your arm, and sticking your fingers inside of powered up electronic devices sounds specifically like something your mother probably told you not to do, but here it is anyway.

The scope consists of an nRF5340 evaluation board in a 3D printed mount, with an SPI-connected Adafruit 2.8″ TFT display on top. With a pair of wires run from the board’s ADC and ground pins, [aniketdhole] just needed a bit of code to glue it all together and show some basic signal visualizations on the display. It’s been tested against PWM signals generated by an Arduino and some potentiometer controlled voltages, but anything much wilder than that is probably a bit too much to ask for from this rig in its current configuration.

In the future, [aniketdhole] wants to add some step-down circuity so you can probe higher voltages than the nRF5340 can handle normally, as well as a shunt to allow current measurement. Once the hardware is in place, the next order of business will be an improved touch-capable user interface that lets the user adjust settings and switch between functions.

Even if you’re not sold on the idea of an arm-mounted oscilloscope, this is still an interesting platform for general wearable experimentation. Throw enough sensors into it, and we’re sure there’s more than a few hackers who wouldn’t mind strapping one of these on.

Gameduino + Mystorm = Oscilloscope!

There has to be more than one of us who over the years since the launch of systems like the original Game Boy have eyed up these handheld platforms and thought “You could make a really neat little oscilloscope with that!” But the commercial systems are closed-source, locked down, and proprietary, so in many cases there’s little easy prospect of such a device being created.

Fortunately though, there are now very accessible handheld gaming platforms, and [James Bowman], the creator of the Gameduino series of boards, writes in to tell us about an oscilloscope project for the Gameduino 3 created by [Lawrie Griffiths]. It uses a Mystorm FPGA board with an AN108 analogue board, and while the heavy lifting of acquisition is handled by the FPGA it is left to the Mystorm’s STM32 to talk to the Gameduino. There are a few teething troubles such as the Gameduino complaining when it is fed data too quickly, but the result is an effective 8 MHz bandwidth instrument with a touchscreen interface. He does however admit that the interface is a little fiddly at the moment. All the code is available via GitHub, so should you wish to pursue this particular avenue yourself, you can.

The Mystorm has made more than one appearance here over the years, and we’re sure we’ll see more. We saw it emulating a small OLED display to put Arduboy graphics on the big screen, for example, and implementing a complete Acorn BBC Micro home computer.

A DIY Nine Channel Digital Scope

Have you ever found yourself in the need of a nine channel scope, when all you had was an FPGA evaluation board? Do not despair, [Miguel Angel] has you covered. While trying to make sense of the inner workings of a RAM controller core, he realized that he needed to capture a lot of signals in parallel and whipped up this 9-channel digital oscilloscope.

The scope is remote-controlled via a JavaScript application, and over Ethernet. Graphical output is provided as a VGA signal at full HD, so it is easy to see what is going on. Downloading sampled data to the controlling computer for analysis is in the works. [Miguel] runs his implementation on an Arty A7 development board which is currently available for around a hundred dollars, but the design is transferable to other platforms. The code and some documentation is available on GitHub and there is a demo video after the break.

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Wireless Oscilloscope Review

[Martin Rowe] over at EDN recently put a $200 wireless oscilloscope to the test. The Aeroscope 100A is a single channel scope in a probe body that communicates back to an Apple smartphone or tablet via Bluetooth LE. You can see the video from the post, below.

The original prototype of the device had a high bandwidth, but the production model only manages to have a 20 MHz bandwidth at 100 megasamples per second: nothing earth-shattering.

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FPGA Rescues Scope From The Dumpster

I’m always on the lookout for a quality addition to my lab that would respect my strict budget. Recently, I’ve found myself pushing the Hertz barrier with every other project I do and hence desperately wanted a high bandwidth scope. Unfortunately, only recently have 70 MHz to 100 MHz become really affordable, whilst a new quad channel oscilloscope in the 500 MHz to 1 GHz range still costs a fortune to acquire. My only option was to find an absolute miracle in the form of an old high bandwidth scope.

It seemed the Gods of Hand Me Down electronics were smiling upon me when I found this dumpster destined HP 54542C. It appeared to be in fairy good shape and was the Top Dog in its day. But something had to be broken right? Sure enough, the screen was clearly faulty and illegible. Want to know how I fixed it? Four letters: FPGA.

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Keysight’s New 1000-X Scopes Get Double Hertz

It’s not every day that we have the pleasure of being excited about a new oscilloscope in the market; not only is it affordable but also produced by one of the industry’s big players. To top it all off,  all the marketing is carefully crafted towards students and hackers.

Keysight recently released a new line of oscilloscopes called the 1000X series that starts at $448. It’s an entry level, two-channel scope having (officially) 50 MHz, 70 MHz and 100 MHz versions to choose from. It hosts their standard technology such as Megazoom, but also some interesting, albeit optional extra quirks such as an in-built signal generator and a simple network analyser with gain and phase plot capability.

The release of this scope and the marketing strategy employed by Keysight feels like they’re late to this entry-level party but still want to get in on the fun. In the words of Keysight we should all immediately “Scrap the toys, get a real oscilloscope” . The persuasion has gone a step further; Keysight has kindly facilitated many giveaways and generated hype from our favorite EE YouTuber’sIf anything, this certainly heats up the entry level scope market, so we at Hackaday welcome it with open arms.

All this fuss about affordable yet capable entry level scopes started with Rigol. Here was a company that actually bothered to genuinely market a scope to the masses at a reasonable price. At the time, the norm for such scopes was to be marketed solely to schools and universities by large teams of suits. Winning the hearts (and money) of any hackers along the way was merely collateral damage.  The scope that considerably changed this was the Rigol DS1052e, the predecessor of the DS1054z which is now considered the benchmark for all entry level scopes. If Keysight is to entice us to scrap the toys, the 1000X series must spar with the community’s current sweetheart.

It is still early days for this scope, but [Dave Jones] already received one and successfully unlocked the shipped bandwidth lock. He has even unearthed an undocumented 200 MHz bandwidth mode by hacking the main processor board! Unsurprisingly, the analog front end is consistent across all the models with the sampling rate and bandwidth being set, rather old-fashionedly, by a few resistors on the main processor board.

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