Power Measurement Oscilloscope Style

April 24, 2019 by Al Williams 7 Comments

If you want to measure voltage you reach for a voltmeter. Current? An ammeter. Resistance? An ohmmeter. But what about measuring AC power? A watt meter? Usually. But if you know what to do, you could also reach for your oscilloscope. If you don’t know what to do, [Jim Pytel] has the video answers for you. Truth is, an oscilloscope can measure almost anything if you know how. [Jim] shows how to measure the voltage and current in a circuit and then it is simply a matter of doing a little math, something modern scopes can do very easily.

We like that [Jim] shows a circuit and how the math works before he verifies the math with the scope. Of course, theory doesn’t always match practice. The method uses a small current-sensing resistor that throws readings off a bit. The scope and signal generator are not perfect, either. However, the results match up pretty nicely with the computed results.

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Grab An Image From Your O-scope The Easy Way

March 30, 2019 by Brian Benchoff 34 Comments

The Rigol DS1054Zed is the oscilloscope you want. If you don’t have an oscilloscope, this is the scope that has the power and features you need, it’s cheap, and the people who do hardware hacks already have one. That means there’s a wealth of hardware hacks for this oscilloscope. One small problem with the ‘Zed is the fact that capturing an image from the screen is overly complicated, and the official documentation requires dedicated software and a lot of rigolmarole. Now there’s a simple python script that grabs a screen cap from a Rigol scope.

The usage of this python script is as simple as plugging the DS1054Z into your USB port and running the script. A PNG of whatever is on the screen then appears on your drive. Testing has been done on OS X, and it probably works on Linux and Windows. It’s a simple tool that does one job, glory and hallelujah, people are still designing tools this way.

This work was inspired by the efforts of [cibomahto], who spent some time controlling the Rigol with Linux and Python. This work will plot whatever is being captured by the scope in a window, in Linux, but sometimes you just need a screencap of whatever is on the scope; that’s why there were weird Polaroid adapters for HP scopes in the day.

Yes, it’s a simple tool that does one job, but if you need that tool, you really need that tool. [rdpoor] is looking for a few people to test it out, and of course pull requests are accepted.

Talk To Your ‘Scope, And It Will Obey

March 3, 2019 by Jenny List 3 Comments

An oscilloscope is a device that many of us use, and which we often have to use while our hands are occupied with test probes or other tools. [James Wilson] has solved the problem of how to control his ‘scope no-handed, by connecting it to a Raspberry Pi 3 running the snips.ai voice assistant. This is an interesting piece of software that runs natively upon the device in contrast to the cloud service provided by the likes of Alexa or Google Assistant.

The ‘scope in question is a Keysight 1000-X that can be seen in the video below the break, but looking at the Python code we could imagine the same technique being brought to other instruments such as the Rigol 1054z we looked at controlling via USB a year or two ago. The use of the snips.ai software provides a pointer to how voice-controlled projects in our community might evolve beyond the cloud services, interestingly though they do not make a big thing of it their software appears to be open-source.

Oscilloscopes do not have to be remotely controlled by voice alone. It seems to be a common desire to take measurements no-handed — one project we’ve featured in the past did the job with a foot switch.

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A Science Lab In Your Pocket?

January 31, 2019 by Al Williams 13 Comments

Since even the cheapest phone or computer now has plenty of horsepower, there’s been a move to create instruments that can do everything, using a reasonably simple front end and crunching data back on the host device. This is one of those tasks that seems easy, but doing it well turns out to be a lot of effort. One we recently noticed was Pocket Science Lab — a board that connects to your PC or Android phone and provides an oscilloscope, a logic analyzer, a wave generator, a power supply, a multimeter, and a few odd items such as an accelerometer, barometer, compass, and lux meter. The cost is about $65, so it isn’t a big investment. But what can it do? Read on, or you can watch the video below from Geekcamp Singapore.

The datasheet shows a reasonable device, although nothing amazing. The oscilloscope has 4 channels but only does 2 MSPS, so assuming the front end can handle it, you might visualize 1 MHz sine waves. There’s also a 12-bit voltmeter, three 12-bit power supplies with different ranges, a 4 MHz 4 channel logic analyzer, two sine or triangle wave generators, 4 PWM outputs, and the ability to measure capacitance. Finally, there’s a frequency counter that’s good to 16 MHz.

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Break Your Scope’s Bandwidth Barrier

January 24, 2019 by Al Williams 12 Comments

Oscilloscope bandwidth is a tricky thing. A 100 MHz scope will have a defined attenuation (70%) of a 100 MHz sine wave. That’s not really the whole picture, though, because we aren’t always measuring sine waves. A 100 MHz square wave, for example, will have sine wave components at 100 MHz, 300 MHz, and the other odd harmonics. However, it isn’t that a 100 MHz scope won’t show you something at a higher frequency — it just doesn’t get the y-axis right. [Daniel Bogdanoff] from Keysight decided to think outside of the box and made a video about using scopes beyond their bandwidth specification. You can see that video, below.

[Daniel] calls this a “spec hacks” but they aren’t really hacks to the scope. They are just methods that don’t care about the scope’s rated bandwidth. In this particular spec hack, he shows how the frequency counter using a 70 MHz scope’s trigger circuit can actually read up to 410 MHz. A 100 MHz scope was able to read almost 530 MHz.

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Sharpest Color CRT Display Is Monochrome Plus A Trick

January 17, 2019 by Ted Yapo 68 Comments

I recently came across the most peculiar way to make a color CRT monitor. More than a few oscilloscopes have found their way on to my bench over the years, but I was particularly struck with a find from eBay. A quick look at the display reveals something a little alien. The sharpness is fantastic: each pixel is a perfect, uniform-colored little dot, a feat unequaled even by today’s best LCDs. The designers seem to have chosen a somewhat odd set of pastels for the UI though, and if you move your head just right, you can catch flashes of pure red, green, and blue. It turns out, this Tektronix TDS-754D sports a very peculiar display technology called NuColor — an evolutionary dead-end that was once touted as a superior alternative to traditional color CRTs.

Join me for a look inside to figure out what’s different from those old, heavy TVs that have gone the way of the dodo.

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Delicious Vector Game Console Runs Pac-Man, Tetris, And Mario

December 26, 2018 by Dan Maloney 20 Comments

The only question we have about [mitxela]’s DIY vector graphics game console is: Why did he wait five years to tell the world about it?

Judging by the projects we’ve seen before, from his tiny LED earrings to cramming a MIDI synthesizer into both a DIN plug and later a USB plug, [mitxela] likes a challenge. And while those projects were underway, the game console you’ll see in the video below was sitting on the shelf, hidden away from the world. That’s a shame, because this is quite a build.

Using a CRT oscilloscope in X-Y mode as a vector display, the console faithfully reproduces some classic games, most of which, curiously enough, were not originally vector games. There are implementations of the Anaconda, RetroRacer, and AstroLander minigames from Timesplitter 2. There are also versions of Pac-Man, Tetris, and even Super Mario Brothers. Most of the games were prototyped in JavaScript before being translated into assembly and placed onto EEPROM external cartridges, to be read by the ATMega128 inside the console. Sound and music are generated using the ATMega’s hardware timers, with a little help from a reverse-biased transistor for white noise and a few op-amps.

From someone who claims to have known little about electronics at the beginning of the project, this is pretty impressive stuff. Our only quibbles are the delay in telling us about it, and the lack of an Asteroids implementation. The former is forgivable, though, because the documentation is so thorough and the project is so cool. The latter? Well, one can hope.

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