A Look Inside A Modern Mixed Signal Oscilloscope

High-speed bench equipment has become so much more affordable in the last decade that naturally one wonders what has made that possible. A great source of answers is a teardown by users like [kerry wong] who are kind enough to take apart their MSO2304X 300MHz osilloscope for our viewing pleasure.

The posted teardown video shows the guts of the scope without enclosure, heatsinks and shields that reveal a handful of boards that execute the functions nicely. The motherboard uses the Xilinx KINTEX-7 FPGA that is expected to run core processes such as signal processing as well as managing the sample storage on the paired DDR3 memory.

The analog front-end here is a bit of a surprise as it sports TI’s ADC08D1000 ADCs that are capable of 1.3 GSPS but the scope is advertised to be capable of more. The inferred design is that all four ADCs are being operated in an interleaved symphony to achieve 5 GSPS. Testing confirms that each input uses two ADCs at a time and when two or more channels are employed, the reconstruction quality drops.

Continue reading “A Look Inside A Modern Mixed Signal Oscilloscope”

Open Source Multimeter Raises The Bar For DIY Tools

Whether you only dabble in electronics as a hobby or it’s your full-time job, there are few tools as indispensable as the multimeter. In fact, we’d be willing to bet nearly everyone reading this site owns at least one of them. But as common and mindbogglingly useful as they may be, they aren’t perfect. Even the high-end models will invariably have some annoyance that only reveals itself once you become intimately acquainted with it.

Most people would just live with those quirks, especially when dealing with a cheaper model. But not [John Duffy]. Deciding nothing but perfection would do, he took every favorite feature he’d ever run into while using other multimeters and combined them into his scratch-built HydraMeter. In the process, he managed to come up with a few new ideas that push this device into a league of its own.

Some of the features of the HydraMeter will look familiar. You might even have them on your own personal meter, such as the wireless removable display module. Other features you’ll wish your meter had, such as the removable cartridge on the front of the device that lets you rapidly swap out a burned fuse. On the other side of the spectrum, there are some esoteric features that might leave you scratching your head. The ability to tell exactly how the meter is configured at a glance thanks to its exclusive use of toggle switches has a certain hacker appeal, but it’s a tricky user interface for most folks.

While the overall design of the HydraMeter may be divisive, one thing we can all agree on is that getting the project to this state took incredible determination. Over the years we’ve only seen a handful of individuals attempt to develop their own multimeters, and even then, none of them approached this level of fit and finish. The fact that [John] has turned all that effort over to the community by releasing his design under the CERN license is truly admirable.

[John] brought the HydraMeter out to Pasadena back in November for Supercon, and it got quite a reaction. And if you don’t like the user interface, it’s not hard to imagine how you could change it. This project has unquestionably pushed the state of the art for open source multimeters forward, and we’re eager to see where it goes from here.

Continue reading “Open Source Multimeter Raises The Bar For DIY Tools”

Korean Multifunction Counter Teardown

[Thomas Scherrer] likes to tear down old test equipment, and often, we remember the devices he opens up or — at least — we’ve heard of them. However, this time, he’s got a Hung Chang HC-F100 multifunction counter, which is a vintage 1986 instrument that can reach 100 MHz.

Inside, the product is clearly a child of its time period. There’s a transformer for the linear supply, through-hole components, and an Intersil frequency counter on a chip. Everything is easy to get to and large enough to see.

Continue reading “Korean Multifunction Counter Teardown”

Everyone Needs A 1950s Signal Generator In Their Life

At Hackaday, we comb the world of tech in search of good things to bring you. Today’s search brought up something very familiar, [Jazzy Jane] has an Advance E1 tube signal generator, the same model as the unit on the shelf above where this is being written. It’s new to her, so she’s giving it a teardown and fixing any safety issues before powering it on.

For a 70+ year old unit, the quality of these instruments was such that they remain useful and reliable to this day. Unsurprisingly a few things need looking at, such as an aged mains lead and a pair of filter caps in the power supply which haven’t aged well. These parts failed on the E1 here too, and while she’s taking the time to order appropriate replacements we have to admit to being cheapskates and robbing parts with an appropriate working voltage for ours from a nearby PC power supply.

Where this one becomes rather interesting is in an extra switch and socket. It’s a wafer switch with a load of capacitors, and the best guess is it provides some adjustability for the inbuilt audio oscillator which had a fixed frequency on stock models. This is part one of a series though, so we’re looking forward to finding out its purpose in the next installment. Take a look at the video below the break, and if that’s not enough, we seem to have had more than one piece of vintage British test equipment here of late.

Continue reading “Everyone Needs A 1950s Signal Generator In Their Life”

A Vintage AC Bridge Teardown

If you ever encounter a British engineer of a certain age, the chances are that even if they use a modern DMM they’ll have a big boxy multimeter in their possession. This is the famous Avo 8, in its day the analogue multimeter to have. Of course it wasn’t the only AVO product, and [Thomas Scherrer OZ2CPU] is here with another black box sporting an AVO logo. This one’s an AC bridge, one of a series of models manufactured from the 1930s through to the late 1940s, and he treats us to a teardown and restoration of it.

Most readers will probably be familiar with the operation of a DC Wheatstone Bridge in which two resistances can be compared, and an AC bridge is the same idea but using an AC source. A component under test is attached to one set of terminals while one with a known value is put on the other, and the device can then be adjusted for a minimum reading on its meter to achieve a state of balance. The amount by which it is adjusted can then be used as a measure of the difference between the two parts, and thus the value of an unknown part can be deduced.

In the case of this AVO the AC is the 50Hz (remembering that this is a British instrument) mains frequency, and the reading from the bridge is taken via a single tube amplifier to a rectifier circuit and the meter. Inside it’s a treasure trove of vintage parts with an electrolytic capacitor that looks as though it might not be original, with a selenium rectifier and a copper oxide signal diode in particular catching our eye. This last part is responsible for some reading anomalies, but after cleaning and lubricating all the switches and bringing up the voltage gently, he’s rewarded with a working bridge. You can see the whole story in the video below the break.

Test equipment from this era is huge, so perhaps not all of you have the space for something like this. Some of us have been known to own other AVO products though.

Continue reading “A Vintage AC Bridge Teardown”

TDS 744A Scope Teardown Fixes Dodgy Channel

There are a lot of oscilloscopes from around the 1990s which are still very much desirable today, such as the Tektronix TDS 744A which [DiodesGoneWild] got his grubby mitts on. This is a 500 MHz, 4-channel scope, with a capture rate of 500 MS/s (4 channels) to 2 GS/s (1 channel). It also has a color display and even comes with a high-density (1.44 MB) floppy drive. Unfortunately this particular unit was having trouble with its fourth channel, and its NuColor display had degraded, something that’s all too common with this type of hybrid CRT/LCD (LCCS) technology.

Starting with a teardown of the unit to inspect the guts, there was no obvious damage on the PCBs, nor on the acquisition board which would explain the weird DC offset on the fourth channel. After cleaning and inspecting the capture module and putting the unit back together, the bias seen on channel four seemed to disappear. A reminder that the best problems are the ones that solve themselves. As for the NuColor display, this uses a monochrome CRT (which works fine) and an LCD with color filters. It’s the latter which seems degraded on this unit, with a repair still being planned.

We covered NuColor-based devices before, which offer super-sharp details that are hard to capture even with modern-day LCDs, never mind the ones of the 90s. Fixing these NuColor displays can be easy-ish sometimes, as [JVG] found when tearing apart a very similar Tektronix TDX-524A which required a power supply fix and the removal of goopy gel between the CRT and LCD to restore it.

Continue reading “TDS 744A Scope Teardown Fixes Dodgy Channel”

Schematic of the Pi Pico wireup, showing the various outputs that the firmware will generate on the GPIOs

A Scope Test Tool You Can Build With Just A Pico

Ever wanted to see how well your oscilloscope adheres to its stated capabilities? What if you buy a new scope and need a quick way to test it lest one of its channels its broken, like [Paul Wasserman] had happen to him? Now you only need a Pi Pico and a few extra components to make a scope test board with a large variety of signals it can output, thanks to [Paul]’s Sig Gen Pi Pico firmware.

description of the signals generated by the software, that can be read in detail on the project websiteDespite the name it’s not a signal generator as we know it, as it’s not flexible in the signals it generates. Instead, it creates a dozen signals at more or less the same time — from square waves of various frequencies and duty cycles, to a PWM-driven DAC driving eight different waveforms, to Manchester-encoded data I2C/SPI/UART transfers for all your protocol decoder testing.

Everything is open source under the BSD 3-Clause license, and there’s even two PDFs with documentation and a user manual, not to mention the waveform screenshots for your own reference.

It’s seriously impressive how many features [Paul] has fit into a single firmware. Thanks to his work, whenever you have some test equipment in need of being tested, just grab your Pico and a few passive components.