Digital Oscilloscope Does Its Best Analog Impression

September 10, 2019 by Tom Nardi 48 Comments

Do you ever find yourself yearning for the days before digital storage oscilloscopes (DSOs)? Where even the basic scopes commanded four figures, and came in a bench-dominating form factor? No, of course you don’t. The DSO is a wonder of modern technology: for a couple hundred bucks you can have capabilities that previously would have been outside the reach of hobbyists, all in a package that’s small enough to fit on even the most cramped workbenches.

Which is why the good folks of the EEVblog forums are so confused about the OWON AS101, a modern digital oscilloscope that’s designed to look and operate like the analog CRT monsters of old. Despite the 3.7 inch LCD, users are treated to the classic analog scope look, and the switches and knobs on the front should trigger a wave of nostalgia for hackers of a certain age.

But this isn’t just some “retro” look-alike, OWON is committed to delivering on that analog experience by taking away all those modern digital features we’ve become so dependant on. This single-channel scope can’t save data to USB, doesn’t have any sort of protocol decoding capabilities, and forget about automatic…well, anything. It’s even limited to 20 MHz, just like the old-school CRT scopes that you pick up for a song at any swap meet. All for the low, low, price of $150 USD from the usual importers.

In the EEVblog thread, the best idea anyone can come up with is that the OWON AS101 is designed for educational markets in developing countries, where outdated equipment is so common that there may actually be a need for faux-analog oscilloscopes to match what’s already in use. These new-manufactured “analog” trainers can be used to get students ready for a professional life of using antiquated technology. It’s hard to believe, but sometimes we can forget how fortunate many of us are to have easy access to cheap tools and equipment.

Even still, when you can get a pocket-sized 10 MHz DSO for around $50, it’s difficult to imagine how this analog-digital hybrid could possibly attract any takers at 3x times the price. If any of our readers would care to shed some light on this unusual piece of gear, we’d love to hear it.

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Sprucing Up A Bell & Howell Model 34 Oscilloscope

July 4, 2019 by Tom Nardi 20 Comments

We’ll admit it, in an era when you can get a four channel digital storage oscilloscope with protocol decoding for a few hundred bucks, it can be hard not to see the appeal of analog CRT scopes from decades past. Sure they’re heavy, harder to use, and less capable, but they just look so cool. Who could say no to having one of these classic pieces of gear on their bench?

[Cody Nybo] certainly couldn’t. Despite the fact that he already has a digital scope, he couldn’t pass up the chance to add a Bell & Howell Schools Model 34 from circa 1973 to his collection. It needed a bit of TLC before it could be brought back into service, but now it’s all fixed up and ready to put in some work. Not bad for a piece of gear with nearly a half-century on the clock.

The restoration of the Model 34 was aided by the fact that [Cody] got the original manual and schematics for the scope in the deal, which he was kind enough to scan and upload for the rest of the class to enjoy. Those of you who have worked on older electronics can already guess where the scope needed the most love: all the capacitors needed to be swapped out for fresh ones. He also found a few resistors that were out of spec, and the occasional bad solder joint here and there.

Even if you’re not looking to repair your own middle-aged oscilloscope, his pictures of the inside of Model 34 are fascinating. The scope was sold as a kit, so the construction is surprisingly simple and almost entirely point-to-point. Of course, there’s something of a trade-off at work: [Cody] says it won’t display much more than 2.5 MHz before things start getting wonky. But then again, that’s a more than reasonable frequency ceiling for audio work and most hobbyist projects.

Oscilloscopes have come a long way since the days when they had to draw out their readings on a piece of paper. While newer devices have all but buried the classic analog scope, a beauty like this would still have a place of honor in our lab.

You’ve Never See A Solid-State Oscilloscope Like This One

August 25, 2018 by Jenny List 44 Comments

Remember a the time before oscilloscopes had a brain? It’s easy to forget as we’ve become accustomed to a class of simple solid state oscilloscope using a microcontroller as signal processor and a small LCD display to show the resulting waveforms. They are commonly available as inexpensive kits, and while their bandwidth is not huge they give a good account of themselves in low frequency applications. But of course, originally the signal processing was handled in a much simpler way.

[SimpleTronic] reminds us that a small solid state oscilloscope does not need a microcontroller, with a ‘scope on a breadboard that displays waveforms on an LED matrix in a much more traditional manner. This is very much an analogue oscilloscope, in which the X deflection circuitry of the CRT is replaced by a decade counter stepping through the columns of LEDs on the display, and the Y deflection circuitry by some analogue signal conditioning followed by an LM3914 bar graph display chip driving the display rows. There are a few refinements such as a trigger circuit, but it remains a very understandable and surprisingly simple device.

It has a claimed bandwidth of 40 kHz defined by its sweep ranges rather than its analogue bandwidth, and an input voltage range from 50 mVpp to 50 Vpp. It’s hardly a useful instrument due to its low bandwidth, but its strength lies in novelty and in understanding a traditional oscilloscope rather than in its utility. You can see it in action in the video we’ve placed below the break.

‘Scopes of limited use appear from time to time on these pages. A favourite of ours is this soldering iron.

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