The (RF) Sniff Test

Sometimes the old tricks are the best. [Kevin] learned an old trick about using a ‘scope to sniff RF noise and pays it forward by sharing it in a recent video. He uses an oscilloscope. But does he need some special probe setup? Nope. He quickly makes a little RF pickup probe, and if you have a ‘scope, we’re pretty sure you can make one in a few seconds, too.

Of course, you can get probes made for that, and there are advantages to using them. But the quick trick of quickly and non-destructively modifying the existing probe to pick up RF means you always have a way to make these measurements.

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The Oscilloscope From 1943

[Thomas] comes up with some unusual gear. In his latest teardown and repair video, he has a vintage 1943 Danish oscilloscope,  a Radiometer OSG32 on the bench. It isn’t lightweight, and it certainly looks its age with a vintage cracked finish on the case. You can check out the tubes and high-voltage circuitry in the video below.

If you’ve only seen the inside of a modern scope, you’ll want to check this out with giant condensers (capacitors) and a slew of tubes. We love seeing the workmanship on these old chassis.

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DHO800 function generator

Budget Brilliance: DHO800 Function Generator

The Rigol oscilloscopes have a long history of modifications and hacks, and this latest from [Matthias] is an impressive addition; he’s been working on adding a function generator to the DHO800 line of scopes.

The DHO800 series offers many great features: it’s highly portable with a large 7-inch touchscreen, powered by USB-C, and includes plenty of other goodies. However, there’s room for enhancements. [Matthias] realized that while software mods exist to increase bandwidth or unlock logic analyzer functions, the hardware needed to implement the function generator—available in the more expensive DHO900 series—was missing.

To address this, he designed a daughterboard to serve as the function generator hardware, enabling features that software tweaks can unlock. His goal was to create an affordable, easy-to-produce, and easy-to-assemble interface board that fits in the space reserved for the official daughterboard in higher-end scopes.

Once the board is installed and the software is updated, the new functionality becomes available. [Matthias] clearly explains some limitations of his implementation. However, these shortcomings are outweighed by the tremendous value this mod provides. A 4-channel, 200 MHz oscilloscope with function generator capabilities for under $500 is a significant achievement. We love seeing these Rigol mods enhance tool functionality. Thanks, [Matthias], for sharing this project—great job bringing even more features to this popular scope.

Tektronix TDS8000 banner

Repairing An Old Tektronix TDS8000 Scope

Over on his YouTube channel our hacker [CircuitValley] repairs an old TDS8000 scope.

The TDS8000 was manufactured by Tektronix circa 2001 and was also marketed as the CSA8000 Communications Signal Analyzer as well as the TDS8000 Digital Sampling Oscilloscope. Tektronix is no longer manufacturing and selling these scopes but the documentation is still available from their website, including the User Manual (268 page PDF), the Service Manual (198 page PDF), and some basic specs (in HTML).

You can do a lot of things with a TDS8000 scope but particularly its use case was Time-Domain Reflectometry (TDR). A TDR scope is the time-domain equivalent of a Vector Network Analyzer (VNA) which operates in the frequency-domain.

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Capturing Screenshots Using A Fake Printer

If you have very old pieces of analogue test equipment with CRTs on your bench, the chances are they will all have surprisingly similar surrounds to their screens. Back when they were made it was common to record oscilloscope screens with a Polaroid camera, that would have a front fitting for just this purpose.

More recent instruments are computerized so taking a screen shot should be easier, but that’s still not easy if the machine can’t save to a handy disk. Along comes [Tom] with a solution, to hook up a fake printer, and grab the screen from a print.

Old instruments come with a variety of ports, serial, IEE-488, or parallel, but they should usually have the ability to print a screen. Then capturing that is a case of capturing an interpreting the print data, be it ESC/P, PCL5, Postscript, or whatever. The linked page takes us through a variety of techniques, and should be of help to anyone who’s picked up a bargain in the flea market.

This isn’t the only time we’ve touched on the subject of bringing older computerized equipment into the present, we’ve also shown you a disk drive emulator.

Thanks [JohnU] for the tip.

Two Bits, Four Bits, A Twelve-bit Oscilloscope

Until recently, hobby-grade digital oscilloscopes were mostly, at most, 8-bit sampling. However, newer devices offer 12-bit conversion. Does it matter? Depends. [Kiss Analog] shows where a 12-bit scope may outperform an 8-bit one.

It may seem obvious, of course. When you store data in 8-bit resolution and zoom in on it, you simply have less resolution. However, seeing the difference on real data is enlightening.

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A Vintage ‘Scope Comes Back To Life

We’re suckers for a vintage electronic teardown here at Hackaday, and thus it’s pleasing to see [Thomas Scherrer OZ2CPU] with a 1962 AEG oscilloscope on his bench. It’s definitely seen better days, and is a single-trace 10 MHz unit of the type you might have seen in a typical general purpose electronics lab back in the day.

Pulling the cover off, and as expected there’s a row of tubes each side of the centrally mounted CRT. No printed circuits in sight, and no transistors either, though the rectifiers are selenium parts. After a clean-up it’s time to look at the tubes, and they show the metallic deposits characteristic of long operation. We’re more used to that from older televisions than test equipment,

Gently bringing the power up it looks promising, but there’s a purple glow from one of the PCL82 triode-pentodes. Replacing that and a double-triode results in a ‘scope that surprisingly, is working. It was evidently a high quality device in the first place, with components capable of lasting for over six decades.

We’ve seen more from his bench involving tubes, including this device using a magic-eye tube as the heavy lifter.

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