Oscilloclock.com

Handcrafted Scope Clocks with circle graphics

Tag: CRT

  • Heavenly Harnesses

    Heavenly Harnesses

    A modern military-spec connector from France meets an ancient Bakelite connector from Japan. It’s love at first sight! The two are joined together in eternal conductivity. Not by a priest, but by eleven 3kV silicon wires surrounded in a lustrous braided sheath…

    … Or so goes the story. There are other accounts, but we like this one best!

    Diversity and distinction

    Serious readers will have recognized the above harness, as it was used in Exo series Oscilloclocks such as the recently featured Exo 3KP1.

    The Exo series. CRT and Control Unit must mate!
    … and this is how it’s done.

    The Gold standard

    We’ve crafted all kinds of harnesses for other Oscilloclock models. This one below takes the cake! Check out the chrome connectors, gold-plated pins, IP68 compliant clamps, and fray-resistant sheathing.

    Model 1-S ultimately extravagant cable
    The ultimate in extravagant cabling! Why not?
    As used in the stunning Model 1-S

    Simple and functional

    Coming back down to earth, we have a less extravagant, highly functional connectivity solution for the Model 1 series:

    No gold or chrome. But still military-spec and very solid. A joy to plug and unplug!
    … As used in this Model 1 130BXB31

    Crazy cabling

    NO single Oscilloclock used more cabling than the infamous AfterShock Clock! This consisted of two complete Oscilloclock Core sets integrated together to drive a dual-gun CRT.

    The AfterShock Clock in its initial form. Have you ever seen so many cables?

    The harnesses supplied in this first delivery were… raw, to say the least.

    Later, as [Atif] worked on his AfterShock Clock’s case, he ordered a set of production quality cabling: two CRT harnesses, and one custom interconnect cable to join the two control units together. Beautiful!

    Fixated on the affixed

    At another point on the spectrum of craziness are harnesses that are not fully removable. Below we have the incredible OscilloBlock Summer Dusk Edition, where the cabling enters the Lego-built Control Unit via a grommet:

    There are more designs to show. But let’s move on to an important topic!

    A safety consideration

    Some Oscilloclocks, especially those in the Exo series, are designed to physically expose the CRT as much as possible to the happy owner and his/her entourage of vintage electronic aficionados. They can touch. Feel. And even listen. (Yes! Some CRT electrodes can even emanate sound!)

    An Exo 3KP1 needs 2.2kV to draw this!

    But many readers may also know that cathode ray tubes operate at high voltages. In fact, in the baseline Exo 3KP1, some pins of the CRT are supplied with roughly 2,200 volts compared to other pins.

    Now, clever readers may have noticed in photos of the assembled Exo 3KP1 that there is a slight gap between the socket and the base of the CRT. The metal pins are slightly exposed. If someone or something somehow bridged that gap – with prying fingers, paws, coffee, or dust – the results could be serious.

    Never fear! There is an insulating o-ring (gasket) that was not installed at the time the Exo photos were taken. It’s a very basic but effective solution. See these instructions from the Operating Manual:

    Installing the ubiquitous o-ring

    We don’t have enough hours in the day to talk through all the safety considerations. But they include:

    • usage of high voltage tolerant silicon-sheathed wires
    • selection of military-spec connectors rated for high-voltage use\
    • a clever pin layout that minimizes the voltage difference between any given pin and its neighbors

    We’re proud of our harnesses. And you can be too.

    And that’s a wrap!

    Are YOU haplessly hooked on harnesses? Does capably-crafted cabling captivate you? Stay tuned! Next time we craft up a CRT harness, we’ll snap a few photos along the way. It’s a surprisingly deep topic!

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  • Exo 3KP1

    Exo 3KP1

    Huh? R2D2’s cousin? C3PO’s sister?

    No! We’re not here to talk about a new Star Wars character! The 3KP1 is a type of cathode-ray tube that was used in many low-cost 1960s-1970s Japanese oscilloscopes.

    And the Exo is a series in our Oscilloclock range that fully exposes the CRT both visually and physically, much to the delight of the owner and visitors – while of course protecting high voltage areas from dust and prying fingers.

    The Exo 3KP1!

    First crafted for [Jerry] back in 2019, the Oscilloclock Exo 3KP1 is the default character in the Exo series, alongside the arguably oddball Oscilloblock – Summer Dusk Edition and the slightly more exotic OscilloTerm Exo B7S4.

    OscilloBlock “Summer Dusk”
    OscilloTerm Exo B7S4

    There’s nothing more soothing than the green glow of flourescent phosphor backed by the amber ambience of the CRT heater. Ahhh, that’s nice.

    This Exo shipped with all the “standard” screens, like the analog clock face below. But why stop there? We’ve done custom logos, movie themed features, oddball time systems, and so much more!

    From the top, [Jerry] and his dinner guests can readily inspect every square centimeter of the CRT and its exquisite innards. Cooool.

    Inside the unit, neatly tied cabling lends an air of gentle sophistication, while the green of the circuit boards harmonizes well with the phosphor.

    Even as a baseline model in the series, the Exo 3KP1 is distinctly attractive.

    [Jerry] did make some choices along the way, including which CRT to use. Let’s explore his CRT options in more detail!

    Round vs. flat

    The flat-faced 3KP1(F) version

    As shown in the photos, the CRT that [Jerry] selected has a slightly convex face. This was the standard shape of the original 3KP1 type CRT, and is a perfect choice for the Exo case style, as it visually softens the glass edge exposed in front of the acrylic ring supports.

    The round-faced 3KP1 was superseded after some years on the market, by a flat-faced version: the 3KP1(F). This version is rather more commonly found and they are delightful to use. We used a 3KP1(F) in the Exo series Oscilloblock, as shown at right.

    Which would YOU prefer – round or flat?

    Phosphors and flavours

    [Jerry] had another choice to make: the phosphor! While the standard phosphor of most CRTs of the day was green, other colours were available such as amber, blue, white, purple. Such CRTs are more rare, but we have some… and so could Jerry!

    Phosphor diversity. What would [Jerry] go for?
    The “trailing effect” on a long-persistence CRT

    There were also varieties of CRT with different persistences; i.e., how long the trace would continue to show on the screen! We love this shot of the moving second hand on a blue, long-persistence CRT:

    And, we just happened to have a 3KP7 CRT in stock with exactly these characteristics.

    But in the end, [Jerry] wanted the nostalgic look of an old green-screen computer monitor, and chose the stock-standard 3KP1.

    Nice choice!!

    The longevity question

    [Jerry]’s clock shipped with a used 3KP1 CRT. Pre-owned, pre-loved, and pre-21st century.

    But we don’t sell junk. [Jerry]’s CRT was selected for its unblemished phosphor, and for its still-bright and vibrant performance. And, of course, there is the standard warranty of 1 month for a used CRT:

    But the question often comes: “How long will a CRT really last?”

    Here at Oscilloclock we don’t mince words, and we don’t use euphemisms (much!). But the fact is this – after 15 years of crafting Oscilloclocks for customers around the globe, no-one has reported having to change their CRT. Maybe it’s happened and we are oblivious. Even better!

    Our secrets to CRT longevity are:

    1. We select only the highest quality CRTs, made by reputable manufacturers. [Jerry]’s CRT was manufactured by Toshiba, a key supplier of the day.
    2. We check CRT specifications carefully, and avoid those with any hint of short lifetimes. (Some CRTs had very short expectancies, such as 1000 hours! Perhaps these were used for demanding applications where even a tiny degradation in performance could not be accepted.)
    3. Oscilloclocks employ multiple mechanisms to avoid screen burn-in (phosphor burn).
    4. Oscilloclocks employ a soft-start mechanism to minimize stress on the CRT heater.

    The Spare

    Notwithstanding our facts around longevity, [Jerry] decided to plan ahead for an eventual CRT replacement. He purchased a stunning new-old-stock Hitachi 3KP1, with quality certificate and even in its original box.

    They don’t get more original than this!

    But is a Hitachi 3KP1 better than a Toshiba 3KP1?

    We’ve compared them, and couldn’t tell any difference in performance or characteristics. We did notice one thing, though: the Hitachi is significantly heavier than the Toshiba. Hmmm….

    One day, we’ll dissect some (defunct) units, and get to the bottom of that odd observation. Stay tuned for a post!

    Like what you see? [Jerry] did. Check out our other creations!

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  • X-ray Xcitement

    Some time ago, [javadesigner] asked something that no doubt many of you have been wondering: Do Oscilloclocks emit radiation?

    Had a question about oscilloscopes – specifically cathode-ray tubes (CRTs). X-rays etc were discovered in similar tubes, and I’ve read that high kV tubes produce both beta and X-ray radiation.

    … Have you ever measured x-ray emissivity with CRTs, and if so, are there any mitigation strategies – especially for X-rays? Leaded glass enclosures, etc.?

    Great question!

    Will your faithful Oscilloclock do this to you?
    CRT used in this demo: 130BFB31

    Fortunately the answer is a clear NO. Our hand-crafted Oscilloclocks do not emit dangerous radiation.

    The general rule of thumb with CRTs (in fact, any electrical equipment operated in a vacuum) is that X-ray emission is negligible at anode voltages less than around 10kV. The accelerated electron beam simple does not have enough energy to generate X-rays when striking the phosphor screen.

    But above 10kV, X-rays can and are produced as a result of the higher-energy bombardment. The high-voltage CRTs used in television and computer monitors of the day always incorporated lead glass (strontium-barium glass), to block these X-rays. (And… to protect against implosion!)

    In any case, all Oscilloclocks operate at voltages well below 10kV, so this does not become an issue.

    A few of the CRTs in stock - 6498, D4P, 3WP1, 50SB1, CV2302. None emit X-rays!
    Just a few of our CRTs in stock – and none of them emit X-rays!

    Thats right – whether we craft your custom timepiece from a behemoth 6498 (at left, operating at 6 kilovolts), a delightful D4P (3kV), a sleek 3WP1 (1.5kV), a cute 50SB1 (1kV) or an eentsy-weentsy CV2302 (500V), you’ll be illuminated but never irradiated.

    Fascinated by electron beams and phosphor bombardment? Do you have a question that everyone else wants to ask? Query away, we love Q&A!

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  • British Beauties

    New stash!

    These beautiful vintage British* CRTs have travelled the world over the last half century. And like homing pigeons, they have found their way at last to the Oscilloclock Lab!

    From left: SE5F/P31, DHM9-11, E10-12GP, SE4DP31, SE5F/P7. Brands: Brimar, GEC, Valvo

    Here, each piece of glorious glassware will receive the attention they have craved for years. They will be cleaned, rejuvenated, and start their latter-day lives performing retro electronic miracles for loving new owners from all over the world.
    * In fact, one of these CRTs was not made by a British manufacturer. Can you spot which?

    From Unloved to Loved

    This SE4DP31 is brand new, complete with protective paper sticker that was attached at the factory to protect the front glass. It’s never been loved. Such a waste, and we will certainly rectify that, as we have done previously for similar CRTs:

    Unloved…
    Doubly loved!

    Two is better than One

    These bad boys are dual-beam CRTs. They have two electron guns and two sets of deflection plates, meaning they can display two completely independent figures at the same time.

    Valvo E10-12GP
    GEC DHM9-11

    We used one of these in the custom Aftershock Clock, to overlay standard clock faces against a map hewn entirely from Lissajous figures. The intensity (brightness) and positioning of each beam can be independently adjusted to get the overlay effect just right!

    But importantly – the innards look so cool!

    Feeling Blue?

    We’ve talked before about rare blue phosphor finds. The newly landed Brimar SE5F/P7 will one day boast both presence and persistence:

    Presence. A strong physicality, tempered by a dappled blue light ambience
    Persistence. A visual expression of impactful new, awash with memories and traces of old

    With thanks…

    We dedicate this post and the promise of seeing these CRTs reincarnated to [Atif]. Many thanks for helping these pigeons find their roost!

    Are you in a state of cathode-ray rapture? Check out other CRT related posts, and see the Gallery to see examples of vintage glassware objects given new leases on life!

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  • Zork on an OscilloTerm!

    Zork on an OscilloTerm!

    Today’s story began with a mail from [Eric], who’d read up on the Oscilloclock 3-inch VGA Assembly and wondered if it could be used to create an old-school serial terminal display on a vintage oscilloscope CRT.

    Yes it could! In fact, the Oscilloclock Lab did one better. Instead of just a VGA display controlled by an external device, we developed native terminal firmware that accepts DEC VT52 compatible commands over a serial port, and renders all text and graphics using beautiful, curvy Lissajous figures.

    The stuff of dreams. The OscilloTerm Exo B7S4.

    Demonstrating basic terminal features, connecting to a PC via serial cable
    Oh, did I mention? It’s a clock as well!

    Zork, anyone?

    Ultimately, [Eric] just wanted to play Zork. And together we made it happen.

    The CRT. The Case.

    [Eric] wanted a sleek ‘skeleton’ look. His choice of a gorgeous B7S4 CRT, mounted in custom-machined cast acrylic supports, exposes all glassware and allows for a titillating rear viewing experience.

    CRT rings and supports – originally introduced for the Oscilloblock “Summer Dusk” edition

    And with a high-transparency cast acrylic case housing the electronics, the OscilloTerm Exo can be enjoyed from every angle!

    Astute readers may wonder about the 2.1 kilovolts of high voltage coursing through their innocent-looking device. Rest assured! All internal wiring is sealed off, and Oscilloclock CRT harnesses are hand-crafted with heavy insulation and precautions taken against dust, prying fingers, rats, and even salivating cats.

    Safety in action! Mil-spec connector (left); custom-designed acrylic cap on the CRT connector (right)
    An O-ring blocks dust from entering the CRT/socket gap (picture from the Oscilloblock)

    This case and CRT mounting variation is branded the Oscilloclock Exo, and has proven its wow-factor at several public exhibits to date. We certainly love it, and [Eric] did too!

    The Terminal.

    This post would never be complete without showing you what real serial terminals from the 1970’s looked like, and explaining what they actually did! Here goes…

    DECscope VT52 (1974)
    ClickRick, CC BY-SA 3.0, via Wikimedia Commons
    ADDS Regent 40 (1979)

    Terminals such as the above were physical input/output console devices, back when computers were the size of massive refrigerators, and the operator would sit remotely – at a desk in a separate area, or even a different room.

    Gregory Lloyd, CC BY 2.0, via Wikimedia Commons

    The terminal and the remote computer were connected via a cable, and would communicate each other by sending data back and forth across the cable; mainly terminal commands and ascii encoded text. Most commonly, a serial communication protocol was used to get the data safely from one end to the other – and hence the devices were known as serial terminals or even serial consoles.

    Amusingly, they were also called dumb terminals, because they had no computing power of their own; they were only extensions of the computer to which they were connected.

    The OscilloTerm Terminal.

    [Eric] wanted a special Oscilloclock that he could also operate as a terminal, connecting it to a remote computer via cable. The remote computer would control the display, using the same serial protocol and commands as an ancient dumb terminal.

    But an Oscilloclock is anything but dumb. [Eric] wanted to keep all the standard exciting screens and features of his Oscilloclock active, and only display the special Terminal screen when the remote computer started to send commands. Then, when the commands stopped, the Oscilloclock should go back to the screen it was on!

    His wish was our command! Here’s a demo of smart screen switching in the final product:

    Some technical Comments

    Naturally, the terminal emulator firmware was written entirely in assembly language.

    PIC18F2680 – the Oscilloclock workhorse.

    We use assembly mainly because the minimalist PIC microcontroller used in the current Control Board revision has only 64K ROM, and an unbelievable 3328 bytes (yes, BYTES!) of RAM. To squeeze all the lovely Oscilloclock features in, while driving Circle Graphics real-time processing, the code and memory space has to be clean, tight, and heavily optimized at the machine code level.

    Assembly. It’s the ONLY way to squeeze it all in!

    For even more technical details, such as the list of VT52 (and VT100) commands supported by the OscilloTerm, and the various configuration parameters that can be tweaked to make the terminal emulator more ‘friendly’ when connecting to a specific device, check out the Support page. Worth a visit!

    Why Zork? And HOW?

    Zork is an interactive adventure game. But it’s old. And it’s text-based, because it was run on computers long before fancy graphics capabilities were widely available. The player explores mysterious locations, solves puzzles, and collects treasures while avoiding various hazards and creatures. All by reading text and typing commands and responses!

    [Eric] was able to play Zork by loading the game’s Z-code into a Z-machine interpreter known as Frotz, on a PC connected to the OscilloTerm. But there was trickery involved!

    1. He had to recompile a version of dfrotz (the dumb terminal version of frotz) to remove the status bar and audio from the game.
    2. He needed to wrap the dfrotz output with a custom Python script to support the OscilloTerm’s 16×8 screen and simulate the required baud rate.

    But now that’s done, he can play any Infocom game that runs in dfrotz on his OscilloTerm!

    What’s next?

    Readers would probably agree that adding a generative AI feature would be incredibly cool. For example, the War Games feature is great, but the text on the screens is all pre-programmed. What if you could interact more naturally with your Oscilloclock?

    Another one for the list!

    Are you a serial serial terminal collector? Do you want to play Zork on the oddest device imaginable? Or, you fancy a clock in the Oscilloclock Exo range? Contact us and let us know!

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