Current Measurement With Oscilloscopes

What do a Rogowski coil, a magnetic core, and a hall effect sensor have in common? They are all ways you can make oscilloscope probes that measure current. If you think of a scope as a voltage measurement device, you ought to watch the recent video from Keysight Technology (see below). It is true that Keysight would love to sell you a probe, but the video is not a sales pitch, just general technical information about making current measurements with an oscilloscope.

Of course, you can always measure the voltage across a shunt resistor — either one that is naturally in the circuit or one you’ve put inline just for measuring purposes. But if you add a resistor it will change the circuit subtly and it may have to handle a lot of power.

The Keysight video points out that there are different probes for different current measurement regimes. High current, medium current, and low current all use different probes with different technologies. The video is only about 6 minutes long and if you’ve never thought about measuring current with a scope, it is worth watching.

The video shares some high-level details of how the current probes work — that’s where the Rogowski coil comes in, for example. Of course, you can’t expect a vendor to tell you how to build your own current probes. That’s OK, though, because we will. Current probes are often expensive, but you can sometimes pick up a deal on a used one.

Continue reading “Current Measurement With Oscilloscopes”

Scope Review: Keysight 1000 X-Series

A few weeks ago we published an article on the newly released Keysight 1000X, an oscilloscope that marks Keysight’s late but welcome entry into the hacker-centric entry-level market. Understandably, this scope is causing a lot of excitement as it promises to bring some of the high-end pedigree of the well-known 2000X and 3000X models down to a much affordable price. Now couple that with the possibility of hacking its bandwidth lock and all this fuss is well justified.

[Dave Jones] from the EEVblog got his hands on one, and while conducting a UART dump saw the scope report 200 MHz bandwidth despite being labelled as a 100 MHz model. He then proceeded to actually hack the main board to unlock an undocumented 200 MHz bandwidth mode. This created a lot of confusion: some said [Dave] got a “pre-hacked” version, others assumed all 100 MHz versions actually have a stock bandwidth of 200 MHz.

Alongside the question of bandwidth, many wondered how this would fare against the present entry-level standard, the Rigol 1054Z. Is the additional cost and fewer channels worth the Keysight badge?

Keysight’s response to our queries and confusion was the promise to send us a review unit. Well, after receiving it and playing around with it, clearly a lot of Keysight’s high-end excellence has trickled down to this lower end version. However, this machine was not without some silly firmware issues and damning system crashes! Read on the full review below. Continue reading “Scope Review: Keysight 1000 X-Series”

Friday Hack Chat: Audio Amplifier Design

Join [Jørgen Kragh Jakobsen], Analog/digital Design Engineer at Merus-Audio, for this week’s Hack Chat.

Every week, we find a few interesting people making the things that make the things that make all the things, sit them down in front of a computer, and get them to spill the beans on how modern manufacturing and technology actually happens. This is the Hack Chat, and it’s happening this Friday, March 31, at noon PDT (20:00 UTC).

Jørgen’s company has developed a line of multi level Class D amplifiers that focus on power reduction to save battery life in mobile application without losing audio quality.

There are a lot of tricks to bring down power consumption, some on core technologies on transistor switching, others based on input level where modulation type and frequency is dynamically changed to fit everything from background audio level to party mode.

Here’s How To Take Part:

join-hack-chatOur Hack Chats are live community events on the Hackaday.io Hack Chat group messaging.

Log into Hackaday.io, visit that page, and look for the ‘Join this Project’ Button. Once you’re part of the project, the button will change to ‘Team Messaging’, which takes you directly to the Hack Chat.

You don’t have to wait until Friday; join whenever you want and you can see what the community is talking about.

Upcoming Hack Chats

We’ve got a lot on the table when it comes to our Hack Chats. On April 7th, our host will be [Samy Kamkar], hacker extraordinaire, to talk reverse engineering.

Friday Hack Chat: ASIC Design

Join [Matt Martin], ASIC designer at Keysight, for this week’s Hack Chat.

Every week, we find a few interesting people making the things that make the things that make all the things, sit them down in front of a computer, and get them to spill the beans on how modern manufacturing and technology actually happens. This is the Hack Chat, and it’s happening this Friday, March 17, at noon PDT (20:00 UTC).

[Matt] has been working at Agilent / Keysight since 2007 as an ASIC designer. The work starts with code that is synthesized into logic gates. After that, [Matt] takes those gates and puts them into silicon. He’s worked with processes from 0.13um to 28nm. Turning code into silicon is still a dark art around here, and if you’ve ever wanted to know how all of this works, this is your chance to find out.

Here’s How To Take Part:

join-hack-chatOur Hack Chats are live community events on the Hackaday.io Hack Chat group messaging.

Log into Hackaday.io, visit that page, and look for the ‘Join this Project’ Button. Once you’re part of the project, the button will change to ‘Team Messaging’, which takes you directly to the Hack Chat.

You don’t have to wait until Friday; join whenever you want and you can see what the community is talking about.

Upcoming Hack Chats

We’ve got a lot on the table when it comes to our Hack Chats. On March 24th, we’re going to argue the merits of tube amplifiers in audio applications. In April, we have [Samy Kamkar], hacker extraordinaire, to talk reverse engineering.

Because I’ve never had the opportunity to do so, and because these Hack Chat announcement posts never get many comments anyway, I’m going to throw this one out there. What would it take to build out a silicon fabrication plant based on technology from 1972? I’m talking about a 10-micrometer process here, something that might be able to clone a 6502. Technology is on our side — a laser printer is cheaper than a few square feet of rubylith — and quartz tube heaters and wire bonding machines can be found on the surplus market. Is it possible to build a silicon fab in your garage without going broke? Leave your thoughts in the comments, and then bring them with you to the Hack Chat this Friday.

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.

Continue reading “Keysight’s New 1000-X Scopes Get Double Hertz”

Oscillator Design By Simulation

[Craig] wanted to build a 19.2 MHz crystal oscillator. He knew he wanted a Pierce oscillator, but he also knew that getting a good design is often a matter of trial and error. He used a 30-day trial of a professional simulation package, Genesys from Keysight, to look at the oscillator’s performance without having to build anything. He not only did a nice write up about his experience, but he also did a great video walkthrough (see below).

The tool generates a sample schematic, although [Craig] deleted it and put his own design into the simulator. By running simulations, he was able to look at the oscillator’s performance. His first cut showed that the circuit didn’t meet the Barkhausen criteria and shouldn’t oscillate. Unfortunately, his prototype did, in fact, oscillate.

Continue reading “Oscillator Design By Simulation”

Hackaday Links: December 13, 2015

So you’ve been rocking a tin foil hat for years now, and people have finally gotten used to your attire and claims that fluoridated water is a government mind control experiment. This holiday, how about something a little more stylish? Yes, it’s a Kickstarter for the World’s First Signal Proof Headwear. This fashionable beanie or cap protects you from harmful electromagnetic rays. Next time you shoot an eighteen minute long YouTube video of a wheezing rant about chemtrails, look fashionable with Shield – the world’s first stylish signal proof hat.

That last tip came to us from a Crowdfunding marketing agency. That means money was exchanged for the purposes of marketing a modern tin foil hat.

[Mike] has an old IBM 5155, the ‘luggable’ computer with design cues taken from the first Compaq. With an Ethernet adapter and a little inspiration, He was able to get this old computer to load the Hackaday retro edition.

[gyrovague] has a Chromecast that’s a bit janky. When it comes to electronics, strangeness means heat. The solution? A heat sink for the Chromecast. You don’t even need a proper heat sink for this one – just epoxy a big ‘ol transformer to the aluminum plate in the Chromecast.

This year, Keysight gave away a pile of test and measurement gear to the i3Detroit hackerspace. Keysight is doing it again, with a grand prize of around $60,000. Entries close on the 15th. Protip: you, personally, don’t want to win this for tax reasons. A non-profit does.

The Internet recently caught wind of a satellite modem being sold by Sparkfun. It’s $250 for the module, with a $12/month line rental, and each 340 byte message costs $0.18 to receive. Yes, it’s cool, and yes, it’s expensive. If you ever need to send a message from the north pole, there you go.

Need to remove the waterproof coating from LED strips? Don’t use a knife, use a Dremel and a wire brush.