Oscilloclock.com

Handcrafted Scope Clocks with circle graphics

Tag: 時計

  • Right on Time…

    Oscilloclocks keep time indefinitely, without needing any adjustment…

    Such unique time displays… and they’re accurate!

    How?

    By automatically synchronising time against a reliable external time source, at regular intervals.

    The current standard synchronisation sources are GPS satellites (via either onboard or external receivers), or NTP servers (via WiFi).

    GPS receivers – both external and on-board options
    The Oscilloclock Wave – a WiFi dongle to pull time (and other things) from the Internet

    And for the most decadant timepiece, there is an even cooler option: a rubidium time source. You can gain/lose at most 2 milliseconds per year!

    Even an Atomic Oscilloclock is an option.
    Because We Can.

    But let’s take a more in-depth look at the two standard options:

    GPS – stand-alone & reliable

    Yes, that’s right – you can get extremely accurate time from GPS satellites!

    The long-standing favourite amongst Oscilloclock aficionados is the External GPS (Garmin ‘puck’) option. Features include:

    • a long cable that allows positioning for best sensitivity
    • an inbuilt magnet for attaching to metal beams
    • a gorgeous connection system – satisfying haptics and robust locking
    Toshiba ST-1248D Oscilloclock - GPS connector

    Of course, we also have the internal GPS option, where the GPS receiver is mounted on the Control Board itself. This is super nifty, if there is no concern about satellite signal strength where the clock is placed. (This is very rarely an issue. These receivers are extremely sensitive!)

    Can you spot the onboard GPS module in this gorgeous OscilloBlock?

    Geolocation

    The GPS option allows the Oscilloclock to obtain not just time, but also geolocation information from satellites.

    Okay, it’s true that Oscilloclocks are generally placed in a fixed location, so showing the clock’s location on a map might not be very useful…

    Think again!

    How about an OscilloGlobe, to warm up your long-distance relationship? Plot you and your friend’s Oscilloclocks on a spinning globe, and count down the hours til you meet again…

    A delightful Heathkit SB-610 shows another Oscilloclock, live and ticking elsewhere in the world!
    (Want a closeup of this demo feature? See this video)

    Or perhaps you fancy an OscilloWear? A wearable Oscilloclock, sporting a miniature CRT and it’s-only-possible-in-Japan miniaturised circuitry! Complete with GPS.

    An OscilloWatch capable of recording your sporting activities? With OscilloMaps that guide you to the nearest Oscilloclock retailer? And of course: the OscilloPhone, or oPhone for short?

    Ahh, we could have so much fun making devices that use location data…!

    Want even more info on the GPS hardware option? We have a nice support page here: Garmin 18x GPS Puck.

    NTP – low-cost & extensible

    The Oscilloclock Wave is the glorious device that allows your Oscilloclock to connect to a Wi-Fi router and pull in time from NTP (Network Time Protocol) servers.

    It comes in different forms, both external and internal:

    Wave
    Wave Onboard
    Wave Core

    The Oscilloclock Wave requires a WiFi connection (and Internet), and some initial configuration – it doesn’t just work straight out of the box, in a standalone way like the GPS option.

    However, the Wave has a distinct advantage: it can access various APIs (think: providers of data over the Internet) to pull in and display all kinds of information!

    Want to display the current weather on Mars? The latest news? Stock prices ticking madly? All this is technically possible… and can be implemented upon request.

    To date, we’ve used this capability in several themed Oscilloclocks: the Astro Clock (pulling in sidereal time from an API) and the AfterShock Clock (pulling in earthquake data).

    Sidereal time, for all the astronomers out there!
    Earthquakes are disasters – no joke. But a semi-live visualization in Lissajous figures? Too cool..

    Not saturated yet? For more on Wifi based synchronisation and various configuration options, see the support page: Oscilloclock Wave.

    The No Synchronization option!

    Do you want to take your Oscilloclock off-grid? We’ll craft you a unique clock powered by wind, solar, USB-C power bank, or even a hamster wheel. (We can even procure extremely low-power CRTs!) But to go fully off-grid, you won’t want to use GPS or WiFi.

    A (more likely!) scenario is simply that signal strength is just too poor. Maybe your clock sits in a basement 3 stories below ground…

    For such cases, you can set the time manually in the Time Setting screen. Once set, an on-board quartz oscillator then maintains reasonably good time (in the order of seconds per month). You’ll want to adjust it occasionally!

    Manual time configuration screen on the Tek 520 VectorClock

    Decisions, decisions…

    Must it be one OR the other? Can’t a gadget lover have their Oscilloclock source data of different types from both GPS and public APIs over the Internet?

    Sadly, no – not in the current Control Board revision. This supports only a single interface, which is occupied by either the GPS or the Wave module. (We have multiple input capability on the long to-do list!)

    Oscilloclocks are beautiful and entertaining. There’s that warmth of the CRT filament and the brilliance of coloured phosphor excitation, combined with all the features of our digital era.

    But above all – they are clocks! Hope you enjoyed this treatise on how time is managed.

    If you’re up for the craziness of an Atomic Oscilloclock, or if you want a custom theme using specific API data, let me know! Otherwise, stay tuned!

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  • Made in Japan. Then. Now.

    Made in Japan. Then. Now.

    Here at the Oscilloclock Lab, we see a lot of vintage Japanese oscilloscopes made in the 50’s to 70’s. Most were purely utilitarian and austere, with little aesthetic appeal.

    But this Toshiba ST-1612B is different. It’s cute, compact, and culture-rich. Just when we thought Toshiba had exhausted its artistic reserves with their stunning ST-1248D, they managed to come up with THIS. Wow…

    Oscilloclock’ed!

    We discovered our protagonist some years back – dirty, dusty, and destined for the trash heap. For aeons, it sat in stock, patiently waiting its turn.

    “Oh, when can I transcend test equipment mundaneness, and reach nirvana like my brethren?” screamed our protagonist.

    During our COVID-era hiatus, this unit’s pitiful wail fell on deaf ears. But with a strong recent recovery in parts availability, shipping routes, and other stabilizing factors, the Oscilloclock Lab has begun to thaw. Spring has arrived!

    And what better way to mark the occasion than to grant our Toshiba its wish?

    Done.

    And yes – it was made in Japan. Again.

    Exquisite exterior

    The case and knobs were in reasonably good condition and polished up very nicely…

    One knob is NOT original. Can you pick it?
    Class and style – even down to the model number plate at rear!

    Sadly, the leather carrying strap had seen better days. Yes, you read that correctly! This was designated as a portable oscilloscope, although it weighed in at more than 10kg, and had no battery supply!

    Nice leather. But was it really… portable?

    We love this adorable hatch compartment and secret patch panel. So utilitarian! Whole tribes of radio servicemen must have stashed their valuables here for safe keeping, before going away on holiday. Sadly, there was no jewellery or secret documents to be found in our unit…

    Take a look at this CRT hood. The phosphor screens in cathode-ray tubes are sensitive to external light, so many ‘scopes employed hoods or shades to keep ambient light out. This improves screen contrast for the lucky operator. Kudos to you if you can recognise the material used our Toshiba’s hood:

    Yes, it’s rubber. Solid rubber, with no metal tube inside. And while it’s a little banged up on the surface, it’s not disintegrating or brittle! It’s firm, yet still sufficiently flexible to support the CRT. And a little plastic polish did wonders. Good for another 60 years!

    Incredible internals

    Unlike many other scopes of the era, opening the case is easy. Just turn the latches with a coin, a single revolution. Voila!

    A nice complement of 12 tubes. Toshiba made them accessible for easy replacement

    As with its Toshiba brother and several other units crafted to date, we carefully installed amber LED lighting to simulate the original warm, gentle glow of electron tubes. This generates a beautiful, peaceful ambience.

    XY Input inspires!

    Avid readers may recall the XY Input feature first introduced in the Metropolis Clock, and included in several models since.

    This ST-1612B unit features a neat set of banana jacks in the rear hatch compartment, where the oscilloscope probes used to plug in. We repurposed them as X and Y channel signal input connectors.

    Driven by function generators, preamps, or even a mobile phone, we can explore an entirely different level of visual imagery!

    A function generator app
    A scene from “Planets” by Jerobeam Fenderson, played on the Toshiba

    A just-fit retrofit

    The ST-1612B was an engineering marvel. They packed an amazing amount of circuitry into a very limited space.

    But we needed to find space for two 100 x 80mm Oscilloclock boards. With legroom to isolate high voltage and provide circulation. And where controls can be reached. Not easy!

    Well, removing just a few bits and pieces* revealed two nice big cavities. And the best part? There were already access panels, complete with ventilation holes! What foresight those Toshiba designers had!

    A perfect fit! * Which bits were removed? Subscribe and await the “Making of…” post!
    In situ adjustments, made easy

    Control Freak

    You can’t beat vintage test equipment if you like controls: toggle switches, slide switches, rotary switches, potentiometers, trimpots – these guys have it all!

    But at Oscilloclock.com we target simplicity. There is only one control you need to turn the clock on and off, change faces, change settings, and generally play with your precious. Here, the focus control (焦点) gives you this authority. Who would ever guess?

    And for that most discerning owner, keen to install her beloved Toshiba ST-1612B in a moody environment such as a bar counter, living room, or bedroom: the intensity control (輝度) dictates the velocity of the electrons, as they smash haplessly into the phosphor. Okay, okay – it’s just a brightness control!

    Finally: we’ve wired up the frequency range switch (周波数範囲) to switch something on and off. We haven’t decided what. Let the Toshiba’s future owner decide its fate!

    What does this DO? You decide!

    Circle Graphics – with a caveat

    Oscilloclocks employ Lissajous figures to generate smooth, curvy artwork and characters on the screen. No pixelated, chunky graphics! But fastidious followers may spot that on the Toshiba ST-1612B’s screen, circles are not as perfect as advertised in our Circle Graphics post. And there are some jagged edges on the segments.

    This is because we’ve installed some prototype boards. These are early revisions of the yet-to-be-announced New Design, and the circle generator and deflection amplifier circuits aren’t quite right. But they’re too good to waste.

    Earlier prototypes of the New Design. – not quite right, but not wrong either!

    But we think it’s just fine! Tube amplifier enthusiasts understand: vinyl records and tube amplifiers actually sound better than digital devices, for some music. And our Toshiba here is 50 to 60 years old. A few kinky curves only add to its grace.

    The Toshiba ST-1612B Oscilloclock is in stock and ready to perform. Want to customize the screens? Decide on the secret switch’s secret? Work up some crazy XY effects? Check our Availability page!

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  • Building the Astro Clock

    Building the Astro Clock

    In the last post, we took a look at a funky new sidereal clock from the Oscilloclock Lab. Now let’s take a look at what fanciness went into it!

    The Hardware

    [Alan], our astronomer protagonist, wanted to install all the electronics inside his Tektronix 620 X-Y Monitor. He didn’t need a nice fancy case.

    Demonstration of a Lissajous circle
    No pixels here! Circle Graphics

    No problem! We supplied the Oscilloclock Bare – our stand-alone controller board that generates images and text rendered in smooth and silky Lissajous figures.

    The board ships on a cast acrylic mount to make it easy to test externally, prior to installation into the host piece of equipment.

    Next, we added the Oscilloclock Wave. This is a Wi-Fi adapter that allows an Oscilloclock to pull (Solar) time from NTP servers over the internet, keeping accurate time indefinitely.

    Bare-bones Wave Core module

    For [Alan], we left the cabling and aesthetics options open, and shipped the basic Wave Core module instead of the stand-alone type pictured above.

    Finally, we included a decent quality power pack, to allow running the assembly prior to installation.

    This would eventually be eliminated by powering the unit from the Tek 620’s internal supply itself.

    The software – Sidereal time enhancements

    To transform the Oscilloclock Bare into the astronomically great Astro Clock that it is today, we needed sidereal time.

    Querying the sidereal API. Easy as pie!

    Easy! The US Naval Observatory Astronomical Applications Department provides a publicly available API for querying sidereal time, given a location.

    The Oscilloclock Wave already had features to pull earthquake data from a similar API and push it to the Oscilloclock for display. Extending this for another API wasn’t astronomically difficult.

    The Wave sports a bunch of advanced settings for particularly tweak-loving oscillofans out there. We just needed to add a few more! These are to enable querying and sending sidereal time to the Oscilloclock, and to set the location.

    Setting up for sidereal time

    But why not just calculate sidereal time?

    Some readers may have guessed that formulae and code libraries for calculating sidereal time are readily available. Why didn’t we just implement the calculation in code, and avoid depending on an external API?

    Our minimalist PIC 18F2680 even had a terrible bug at one point…

    Well, I’ve mentioned before that the current revision Oscilloclock Control Board uses a minimal-specification microcontroller with very limited capabilities, and is heavily optimized by coding in assembly language.

    Sadly, this chip was already jam-packed to the hilt, and there simply wasn’t any more space left for the code and run-time memory needed to calculate sidereal time internally.

    And writing the necessary floating-point calculations in assembly would be no mean feat!

    Why Assembly Code?

    Because We Can.

    But, it sure ain’t easy…

    So NO – we couldn’t easily calculate sidereal time, and it was API Option full steam ahead!

    Astro Screens!

    Even with its minimalist microcontroller chip, we’ve managed to squeeze some amazing stuff into the Oscilloclock Control Board firmware.

    For more of the weird and wacky, see Screens & Things!

    For this build, we needed yet more screens.

    First, we used our trusty Figure Creator software to render a rudimentary telescope into Circle Graphics sprite code.

    From a sketch … to … assembly code! Voila!
    Astro Clock splash screen

    We then crafted a simple Astro Clock splash screen, by adding some random circles for stars and laying out basic text around the telescope.

    Finally, we added some basic digital and analog clock screens, using the same telescope figure as a centrepiece. This was mostly straightforward, but the existing clock hand drawing code did need some tweaking, to reference either solar time or sidereal time depending on the active screen.

    Done!

    Invoiced. Paid. Shipped. Received. Treasured forever. Right?

    Wrong!

    Sidereal really sidelined…

    A year after [Alan] received his lovely Astro Clock, the unhappenable happened. The Astronomical Applications API was taken down!

    “undergoing modernization”… a harbinger of API death! Jan 2020 snap courtesy archive.org

    The site was taken offline for a planned six months, for “modernization”. [Alan]’s sidereal clock was relegated to a normal solar Oscilloclock, albeit temporarily.

    Astro Clock features relegated. Utter sidereal sadness

    But as lovers of electron beams striking phosphor, we always look at the bright side! Six months is still relatively short in astronomical terms! We resignedly marked “X” on the calendar, and bided our time.

    But then… the unfathomable fathomed. The COVID-19 pandemic struck. The USNO site modernisation was completely halted – very likely deprioritised in the midst of indiscriminate illness, clinical chaos, and staff shortages.

    Halted… 2 years later, still no luck… Mar 2022 snap courtesy archive.org

    We waited, and waited, and waited. There were no fingernails remaining to chew when, after two and a half years, a revised API was finally made available at the end of 2022. Hooray! Thank the stars!

    API resurrected

    Fresh API documentation in hand, we set about modifying the Wave to use the fresh fruits of the USNO modernisation machine.

    Fortunately, there were only minor changes to the API – a few more mandatory data fields, a change in date format and such. These required a relatively small amount of rework in the Wave’s firmware.

    And … we were back in the amateur astronomy business.

    Almost like a big Christmas present from Santa!

    Was this [Alan]’s Christmas present? – Santa in your Clock

    Do we regret taking the API approach?

    It’s a good question. API death could happen at any time – possibly rendering the Astro Clock lifeless, listless, or lethargic yet again.

    But, no. The decision not to calculate internally was valid, based on the known constraints. And we did our veritable utmost to revive poor [Alan]’s Astro Clock as soon as possible.

    By the way, we at the Oscilloclock Lab certainly can’t complain about USNO’s API shutdown. We, too, have been heavily impacted by pandemic and other worldly events. As of this posting, our formal activities, too, remain on pause…

    … for now!

    Curious about other Oscilloclocks that use APIs? Check out the AfterShock Clock, which taps into an earthquake API to display earthquakes in (almost) real-time on a lissajous-rendered map!

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  • Astro Clock

    Astro Clock

    “Metropolis Time“

    A few years ago, we introduced Metropolis Time, a time system based on the 20-hour, two-shift days featured in Fritz Lang’s iconic movie Metropolis.

    Since then, we’ve received a few requests to craft clocks that display some other calendar and time systems – from the ancient and archaic, to the religious, to the scientific.

    That’s Astronomical!

    Today’s exciting story began with a request from [Alan], a prominent amateur astronomer. He happened to have a lovely Tektronix 620 X-Y Monitor lying around, and wanted to turn it into a clock.

    Well, that would be easy – the Oscilloclock Bare is a bare-bones controller assembly that can be used to drive an oscilloscope or XY monitor that meets certain requirements (for the techies: a DC coupled Z-axis amplifier). And the Tek 620 is perfect – wonderfully performant, and perfectly compatible. Job done! Right?

    Oscilloclock Bare + Tek 620 + scientific passion = Astro Clock!

    No way! [Alan] didn’t want just any old clock. The custom splash screen above was pretty cool, but could his clock display something called “sidereal time“?

    Yes! Anything is possible, and here’s what we ended up delivering: several custom clock faces showing sidereal time (in both analog and digital formats), in addition to all the standard screens that are based on solar time.

    The shipped Astro Clock assembly!

    But what is sidereal time?

    A Solar day

    Well, most normal human beings and their clocks like to measure a 24 hour day by using the Sun as a reference point. One solar day is the time it takes for the Earth to spin on its axis enough and see the Sun at the same height in the sky as the previous day.

    For example, let’s say it’s 1 May 2023. It’s lovely weather out, and you happen to notice that the Sun reached its highest point in the sky at 12:30 pm. The next day, 2 May, you would find the Sun at its highest point at — you guessed it! — 12:30 pm. And if you ignore man-made tweaks such as daylight savings, you find the Sun is always at its highest point at 12:30 pm*, year-round, looking from the same location.

    *This is not quite true – because every day is slightly shorter or longer. But it averages out over the year.

    A sidereal day

    Sidereal time, on the other hand, uses the distant stars as a reference point to measure 24 hours. One sidereal day is the time it takes for the Earth to spin on its axis enough to see the same distant star at the same height in the sky as the previous day.

    Because the Sun is so close, and a distant star is so (relatively) far, there is a difference in the length of a sidereal day compared to a solar day. A sidereal day turns out to be approximately 23 hours, 56 minutes, and 4.0905 seconds.

    Confused? I don’t blame you. This video should help:

    History and Sidereal clocks

    According to this brilliant post, the concept and utility of sidereal time has been around a very long time. The length of a sidereal day was even calculated to a surprisingly high level of accuracy some 1,500 years ago!

    Here are two surviving sidereal clocks that were made “recently” – just a few centuries ago.

    But who on Earth would use sidereal time?

    Astronomers would.

    Most people don’t look at the boring old Sun all the time. We look out to the stars and galaxies far, far beyond our solar system. If an astronomer wants to track the position of Betelgeuse day after day, she can record the sidereal time that she saw it, and know that it’ll be at the same ascension at the same sidereal time the following day. Brilliant!

    Mariners and Astronauts would.

    They can fix their location even when the Sun is not visible, by observing the position of the stars and calculating their position back from the current sidereal time. Life-saving!

    Oscilloclock Labs would.

    Because we can.

    In the next post, we’ll take a look at the build. What hardware went into this Astro Clock? How on earth does it tick? Can you figure it out?

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  • Oscilloclock Bare(ly) makes it to Brazil

    Oscilloclock Bare(ly) makes it to Brazil

    Whether directly or indirectly, the pandemic seems to have slowed everything down: chip production; the global economy; and even Oscilloclock blog post publishing!

    But perhaps most impacted of all is transport logistics. [Dante] in Brazil discovered this to his dismay in July 2020, when he purchased an Oscilloclock Bare unit. The P.O. had stopped all air service to Brazil just 3 weeks earlier – well after our discussions had started. Oh no!

    [Dante]’s crisp new Oscilloclock Bare, ready to go, but unable to ship!

    [Dante] waited patiently for 6 months for the post office to resume accepting airmail service to Brazil. But they never did. And FedEx and DHL came at too hefty a price. In desperation, he authorized shipment by sea – and at last, in December 2020, his package was off! 

    Absence (of air mail service) makes the heart grow fonder...

    After an agonizingly long wait, [Dante] finally received his unit 6 months later – in July 2021. He then spent the next 5 months completing his dream project!

    [Dante]’s Dream: A Hewlett Packard retrofit

    The Oscilloclock Bare is designed to be a no-frills controller assembly that highly knowledgeable folks can install into their own displays. [Dante]’s dream was to use this to convert his beloved HP 182T / HP 8755C unit into a living, breathing scope clock.

    And convert he did!

    Question: How do you add ambience to a home?
    Answer: Instill new life into a device from yesteryear!

    Clearly, [Dante]’s 18 month end-to-end was worth the wait.

    The Build

    [Dante] was kind enough to supply a write-up of his project, including some clever solutions for pitfalls along the way. Let’s hear from him in (mostly) his own words!

    Motivation

    The model HP 182T is an oscilloscope featuring a large CRT with a graticule of 8 x 10 major divisions and a display area of 133 cm2, coated with a P39 aluminized phosphor for high brightness and long persistence.

    The HP 182T works as a display mainframe supporting other HP plug-in test equipment, such as the HP 8755C, a swept amplitude analyzer.

    Both items are nowadays considered “vintage” test equipment. But with the Oscilloclock board installed, they have been transformed into a unique appliance with a natural appeal for practical use. Far better than the regular surplus market destinations, or — even worse — destructive disposal!

    HP 182T + HP 8755C. Can you spot the Oscilloclock control board?
    Control board installed!

    HP 8755C in short

    This plug-in unit works primarily as a signal conditioner and a multiplexer for “almost dc levels” from three RF detector probes attached to three input independent channels. There are front panel adjustments for the scaling, gain and multiplexing controls that provide the appropriate Y-Axis composite signal for displaying by the HP 182T mainframe.

    The Oscilloclock control board was elected to be installed inside this plug-in unit.

    HP 182T in short

    This oscilloscope is built around the CRT with its high voltage power supply.

    The X-Axis signal from the Oscilloclock board is fed to the HP 182T’s chain of the horizontal pre-amp plus output amplifier, which drives the CRT horizontal deflection plates.

    The internal wiring of the HP 182T connects the CRT’s vertical deflection plates directly to the plug-in cabinet of the display mainframe, so the Y-Axis signal from the Oscilloclock board is routed inside the HP 8755C itself.

    The Z-Axis signal from the Oscilloclock board is fed to the HP 182T’s gate amplifier.

    Wires, wires…. What goes where?

    Drawbacks

    Contrary to any standard X-Y scope where the two input channels are always supposed to have electrically similar (if not identical) characteristics, the correct operation of the Oscilloclock board for the application here was shown to be not as seamless as first imagined. You have to face some details of these integrated “host” equipment (HP 182T + HP 8755C) to see why…

    As described, there are distinct amplification chains accepting the Oscilloclock output signals. This presents specific challenges regarding (a) the differential gain for the X and Y signals, and (b) the differential time delay between any combination of the three X, Y, and Z signal outputs of the Oscilloclock board.

    First Approach

    Before having the board at hand and expecting to make it work as soon it arrived (the shipping took longer than expected due to COVID restrictions), I first planned the signal flow and did the wiring. I had one eye on achieving a ‘clean packaging’ of the board inside the HP 8755C, and the other on ensuring compatibility between the Oscilloclock’s X-Y-Z output signals and their respective chains planned in the host equipment, considering signal amplitude and required frequency response.

    The adaptations made at this time considered a minimally-invasive approach, where the criteria was to “make it simple”. This was limited to just opening or re-using connections and keeping the existing routing, in order to use the Oscilloclock’s X-Y-Z output signals in the most simplistic way possible.

    Another necessary one-time adaptation was for the board’s power supply, and integration of its PSON output signal with the equipment’s hardware. This part of the design was successfully kept to the end of the project without any further modification.

    First time installation of the oscilloclock board

    Upon arrival and a bench test of the Oscilloclock board with a scope, I immediately figured out that the amplitude levels for the X and Y output signals were lower than expected (maybe due to my misinterpretation of the specs). I did the gain compensation corrections again and went thru the complete installation of the board inside the host equipment, anxious to see it working.

    What a disappointment when instead, up came a completely distorted and elliptically shaped image, blurred with noise, and what looked like un-blanked retrace lines. Worse yet, mainly when alphabetic characters were displayed on the screen, none of the shapes were correctly formed.

    Of course, that was time for a break — and a complete review of the job and the work done so far!

    Chasing the problems

    The Lissajous figures generated by the Oscilloclock board use an approximately 40 KHz  sinusoidal signal, so I started to play with an external generator at the same frequency and amplitude for the X and Y signals (at about 1 Vpp) and trace it inside the HP 8755C and HP 182T.

    At this time, I’d already exercised the Z-axis waveform from the Oscilloclock board and the expected processing through the HP 182T. There was no evidence of problems with this Z-axis signal chain, and I achieved a measured propagation delay of around 50 nS.

    The minimalist approach mentioned earlier showed its consequences, when a propagation delay of an impressive 8 uS was measured at the vertical deflection plates, and  around 1.5 uS at the horizontal deflection plates! It was time again for another break, to elaborate a new routing scheme for the X and Y signals.

    Final Approach

    From the previous analysis, I ended up with two different and both very large propagation delays for each of the X and Y signals (as compared with the measured 50 nS for the Z-axis). How to solve this? It did not seem to be only a routing problem.

    I decided to investigate X-Y-Z signal propagation delays in the two units separately. After a thorough measurement of propagation delays inside the HP 182T itself, comparing with the HP 8755C plug-in itself (where the Oscilloclock board was installed), I concluded on two countermeasures:

    1. The complete removal of the Processor board XA-6 from the HP 8755C. (This is where the Y-axis signal from the Oscilloclock board had initially been connected.) Instead, this routing was transferred directly into the Normalizer Interface board XA-11 (which interfaces with the HP 182T).

    2. Also at the Normalizer Interface board XA-11 inside the HP 8755C, the substitution of two original op amps U9A and U9B (HP #1826-0092) by TL072 op amps, which are faster and have a higher slew rate.

    These solutions were enough to align the signal propagation and complete my project!

    Dante JS Conti, 8 November 2021

    Like what you see?

    We do! We love to hear back from Oscilloclock owners, to hear their stories.

    Check out our previous posts and the Gallery for info on other unique creations!

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