oscilloscope

184 Articles

Repairing And Upgrading A HP 16533A Scope Card

May 10, 2019 by 17 Comments

In the world of oscilloscopes, as in the rest of the test equipment world, there’s always some trickery afoot. Companies will often offer different models to the market at different price points, in an effort to gain the widest possible customer base while also making the most profit. Cheaper, less capable models are often largely identical to more expensive hardware, save for some software or a couple jumpers that disable functionality. [Alexandre] found just this when working to repair his HP 16533A scope card.

Work began when [Alexandre] received his HP 16533A in the mail after a long wait, only to find the trigger functionality was inoperable. This is crucial on a digital scope, so this simply wouldn’t do. After some research online, a post was found discussing which signals to probe to troubleshoot the issue. It noted that corrosion is a common problem on these units, and that occasionally, a certain resistor goes open circuit and causes problems. Initial measurement showed there was still resistance there, but reading closer, [Alexandre] noted this fateful line:

You might not be able to measure it accurately in circuit. 

Removing the 100K resistor from the board, the part was indeed open circuit. After replacement with a new component, the trigger circuit was again fully operational. With the scope still open, it was then a simple job to execute a further resistor swap which gives the 16533A the functionality and range of the higher-spec 16534A model.

It’s very common for oscilloscopes and other test hardware to be configured this way from the factory. Rigol scopes are particularly popular with hackers for this very reason.

[Thanks to jafinch78 for the tip!]

Power Measurement Oscilloscope Style

April 24, 2019 by 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 33 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 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 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 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 56 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.

Continue reading “Sharpest Color CRT Display Is Monochrome Plus A Trick” →