oscilloscope

274 Articles

Double Your Analog Oscilloscope Fun With This Retro Beam Splitter

November 24, 2024 by 18 Comments

These days, oscilloscope hacking is all about enabling features that the manufacturer baked into the hardware but locked out in the firmware. Those hacks are cool, of course, but back in the days of analog scopes, unlocking new features required a decidedly more hardware-based approach.

For an example of this, take a look at this oscilloscope beam splitter by [Lockdown Electronics]. It’s a simple way to turn a single-channel scope into a dual-channel scope using what amounts to time-division multiplexing. A 555 timer is set up as an astable oscillator generating a 2.5-kHz square wave. That’s fed into the bases of a pair of transistors, one NPN and the other PNP. The collectors of each transistor are connected to the two input signals, each biased to either the positive or negative rail of the power supply. As the 555 swings back and forth it alternately applies each input signal to the output of the beam splitter, which goes to the scope. The result is two independent traces on the analog scope, like magic.

More after the break…

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Close Shave For An Old Oscilloscope Saved With A Sticky Note

November 23, 2024 by 12 Comments

When you tear into an old piece of test equipment, you’re probably going to come up against some surprises. That’s especially true of high-precision gear like oscilloscopes from the time before ASICs and ADCs, which had to accomplish so much with discrete components and a lot of engineering ingenuity.

Unfortunately, though, those clever hacks that made everything work sometimes come back to bite you, as [Void Electronics] learned while bringing this classic Tektronix 466 scope back to life. A previous video revealed that the “Works fine, powers up” eBay listing for this scope wasn’t entirely accurate, as it was DOA. That ended up being a bad op-amp in the power supply, which was easily fixed. Once powered up, though, another, more insidious problem cropped up with the vertical attenuator, which failed with any setting divisible by two.

With this curious symptom in mind, [Void] got to work on the scope. Old analog Tek scopes like this use a bank of attenuator modules switched in and out of the signal path by a complex mechanical system of cams. It seemed like one of the modules, specifically the 4x attenuator, was the culprit. [Void] did the obvious first test and compared the module against the known good 4x module in the other channel of the dual-channel scope, but surprisingly, the module worked fine. That meant the problem had to be on the PCB that the module lives on. Close examination with the help of some magnification revealed the culprit — tin whiskers had formed, stretching out from a pad to chassis ground. The tiny metal threads were shorting the signal to ground whenever the 4x module was switched into the signal path. The solution? A quick flick with a sticky note to remove the whiskers!

This was a great fix and a fantastic lesson in looking past the obvious and being observant. It puts us in the mood for breaking out our old Tek scope and seeing what wonders — and challenges — it holds.

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Retrogadgets: Oscilloscope Cameras

November 11, 2024 by 23 Comments

Today, if you want to get a picture from your oscilloscope — maybe to send to a collaborator or to stick in a document or blog post — it is super easy. You can push an image to a USB stick or sometimes even just use the scope’s PC or web interface to save the picture directly to your computer. Of course, if it is on the computer, you could use normal screen capture software. But that hasn’t always been the case. Back in the days when scopes were heavy and expensive, if you wanted to capture an image from the tube, you took a picture. While you might be able to hold up your camera to the screen, they made specific cameras just for this purpose.

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Component Tester Teardown

November 10, 2024 by 9 Comments

In the modern age, when you hear “component tester” you probably think of one of those cheap microcontroller-based devices that can identify components and provide basic measurements on an LCD screen. However, in the past, these were usually simple circuits that generated an XY scope plot. The trace would allow an experienced operator to identify components and read a few key parameters. [Thomas] tears down an old Hameg device that uses this principle in the video below.

The unit is in a nice enclosure and has a feature that controls the amount of current the unit uses in the excitation signal. It plugs into the wall, and you can connect the component under test with either test leads or a socket. The output, of course, is a pair of BNCs for the scope’s X and Y inputs.

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Don’t Forget Your Curve Tracer

November 2, 2024 by 4 Comments

As cheap microcontrollers have given us an impressive range of test equipment trinkets to play with, it’s easy to forget some of the old standabys. A curve tracer for example, the relatively simple circuit allowing the plotting of electronic component response curves on an oscilloscope. Lest we forget this useful device, here’s [Gary LaRocco] with a video describing one that’s so easy to build, anyone could do it.

It’s a simple enough premise, a low AC voltage comes from a mains transformer and is dropped down to the device under test through a resistor. The X and Y inputs of the ‘scope are configured to show the current and the voltage respectively, and the result is a perfect plot of the device’s IV curve. The best part is that it’s designed for in-circuit measurement, allowing it to be used for fault-finding. There’s a demonstration at the end with a variety of different parts, lest we needed any reminder as to how useful these devices can be.

The cost of one of these circuits is minimal, given that the transformer is likely to come from an old piece of consumer electronics. It’s not the first simple curve tracer we’ve seen, but we hope it will give you ideas. The video is below the break.

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Signal Processing Shenanigans: The Createc SC 01 Pocket Oscilloscope

October 23, 2024 by 4 Comments

If you’re passionate about signal processing and retro tech, you’ll want to check out the Createc SC 01, a quirky handheld oscilloscope that recently caught the eye of [Thomas Scherrer] from OZ2CPU Teardown. This device, cheekily dubbed a “signal computer,” promises to be both intriguing and, perhaps, frustrating. You can view [Thomas]’ original teardown video here.

This device is packed with buttons and a surprisingly retro aesthetic that can make even the most seasoned hacker feel nostalgic. With a sample rate of 20 MHz and a bandwidth of up to 10 MHz, it’s a digital oscilloscope with a twist. Users may find its setup challenging, thanks to a somewhat convoluted manual that boasts numerous errors. However, beneath the confusion lies the potential for creative exploration: this signal computer can analyse analog signals, perform calculations, and even store data.

Despite its quirks, the SC 01 is sure the experience. Imagine troubleshooting a circuit while grappling with its unpredictable user interface—an adventure in itself for those who like a techy challenge.

The Createc SC 01 is not just another tool; it’s an invitation to embrace the imperfections of vintage tech. If you enjoy the hands-on learning process and don’t shy away from a few hiccups, this device might be something you’ll enjoy. Hackaday featured an article on similar devices last year.

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Classic Heathkit OL-1 Scope Gets Some TLC

October 23, 2024 by 9 Comments

These days, not only are oscilloscopes very common, but even a cheap instrument today would have been the envy of the world’s greatest labs not that long ago. But back in the day, the home experimenter basically had two choices: buy a surplus scope that a big company was getting rid of or build a Heathkit. [Radiotvphononut] bought an old Heathkit OL-1 scope at an estate sale and set about putting it back in service.

If you are used to a modern scope, you’ll be amazed at how simple a scope like this can be. A handful of tubes and a CRT is the bulk of it. Of course, the OL-1 is an analog scope with a 400 kHz bandwidth. It did, however, have two channels, which was a rarity at the time.

The OL-1 was sold for a few years up to 1956 and cost about $30 as a kit. There was a version with a larger screen (five whole inches) that cost an extra $40, so you can bet there were more OL-1s sold since $40 was a big ask in 1956. While they don’t seem like much today, you were probably the envy of the ham club in 1956 when you lugged this in for show and tell.

This is a long video, but it pays off at the end. Overall, this was a more capable scope than the $66 scope from 10 years earlier we looked at. Did you ever wonder how people visualized signals before the CRT? Funny, we did too.

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