Oscilloclock.com

Handcrafted Scope Clocks with circle graphics

Category: Hardware

  • New design on the way?

    Well, I think that’s what’s going on….

    In a desperate attempt to save his blog from becoming the all too familiar not-updated-in-5-years dead blog, the senior technician has resorted to seeking help from one of his sons, previously referred to as the 1st junior technician. Although my knowledge on CRTs and electronics is close to none compared to that of the senior technician, I will give you some updates on the recent activities of the main man himself, who I am sure all of you are eagerly awaiting the return of.

    Amid the COVID-19 crisis, the senior technician has been lucky enough to be able to work at home. You would think that without his everyday commute of two hours, he would be more relaxed and able to spend more time with his family members. However, he is instead spending excessive time in front of the computer. At first, I speculated that he was having a rough time with his work. Or was he? Under closer examination, I realized that the additional time spent on the PC was actually something related to Oscilloclock. Something about a brand new design: “once-in-a-decade refresh,” and some such. Not really sure how significant this is to you all, but judging from the look on his face when he emerges from his room for dinner, it must be something BIG!

    Another clue that the Oscilloclock Lab is heavily active is the vast array of international deliveries to our home in the past half year. Shipments from countries that you’ve never heard of, in all shapes and sizes, arriving so frequently that I can’t help feeling for the poor postman who has to carry these heavy objects up to our door. I must tell you, there is nothing worse than hearing the bell ring and rushing down to the door anticipating your own Amazon delivery of a new pair of shoes, and instead seeing a massive box from Montenegro containing who-knows-what-type-of-CRT.

    The master craftsman’s work could very well be hindered by the noise from his two highly energised teenagers, [Oscillokid] and [Oscilloboy]. So how does he maintain concentration? The secret is a well-positioned cave. His workshop is intentionally situated at the very edge of the house. He simply closes the lone door to the shop, to avoid hearing a dinner-call or a request for more screen time from his Oscillosons. Until, of course, the commander-in-chief of the household raises her voice!

    So there it is, a brief update on what’s going on and how the senior technician’s doing. Rest assured that he is working very hard on his projects, and has not in the least swayed from his passion; indeed, he is more immersed than ever. He will no doubt inform all of you anxious readers of his magnificent projects once they are ready for exposure. Until then, thanks for reading, and stay safe!

  • Connect !!

    Connect !!

    These days, just about everyone has an old oscilloscope lying around. You know, an old, dusty, derelict scope handed down from Grandpa (or Grandma). Well, [Paul] had something even better – an old Tektronix 602 X-Y Monitor! Could an Oscilloclock Control Board drive this vintage beauty? Absolutely. Could I make an aesthetically pleasing case? Definitely. How about time sync via WiFi? Stock standard!

    Presenting the Oscilloclock Connect:

    Here’s what it looks like plugged in to my fabulous old Tektronix 620 monitor:

    And why not have a pair of Connects drive a Tek 601 and 602?

    The Build

    The main component of the Connect is, of course, a standard Oscilloclock Control Board. As usual, all 121 parts on Paul’s board were individually mounted and soldered by hand. The board then was programmed and underwent rigorous inspection and testing. Finally, the board was cleaned to remove flux and renegade flecks of solder, and sprayed with HV coating for humidity protection and – arguably more importantly – to give it its glorious sheen.

    The case was custom-made and professionally machined right here in Japan from 6mm-thick sheets of pure cast acrylic (not extruded). This is an extremely transparent, hard, high grade acrylic – and Oscilloclocks deserve nothing less!

    The case was sprayed with a special acrylic cleaner and static protection solution, before fitting the various components. Naturally, every part was cherry-picked, right down to the three BNC connectors – they needed an aesthetically pleasing colour, but they also had to have a shaft long enough to mount through 6mm-thick acrylic!

    Finally, the physical interface! The knob was chosen for its perfect finger-fit and delicate aluminium/black tones, which gently contrast with the rest of the unit.

    The Compatibility Crisis

    Over the years, many folks have observed that the scope at hand has an “X-Y mode”, and asked if they could just ‘plug in’ an Oscilloclock Control Board. “Is it compatible?” Unfortunately, the response has usually been disappointing.

    You see, creating figures and characters with Circle Graphics relies on the scope’s ability to turn the beam on and off at split-second intervals. This feature is called a “Z-axis input”. While many scopes from the 80’s and beyond do sport such an input, there are two common limitations:

    Limitation 1: AC-coupled Z-axis inputs

    Capacitive coupling – effective at isolating the input from cathode potential (-1260V !)

    The input is connected to the CRT’s grid or cathode circuit via a capacitor. This is a low-cost, effective way to isolate the (usually) very high negative voltage of the grid circuit from the input.

    The problem here is that the capacitor, by its very nature, removes the edges from the pulse. The controller is no longer able to control the beam on/off timing, and you end up with uneven blanking across the segments, as shown in the screenshot at right.

    Depending on the values of the capacitor and the surrounding resistors, the symptoms may not be severe. However, the best way to resolve this problem (while still keeping the oscilloscope’s original circuit intact) is to insert an isolated DC blanking amplifier directly in series with the grid (or cathode). See the Kikusui 537 Oscilloclock for an example of this.

    LIMITATION 2: INSUFFICIENT BLANKING AMPLIFICATION

    Most oscilloscopes tend to require at least +5V on the Z-axis input to noticeably blank the beam. The Connect, however, is only capable of delivering +2.5V. It works just fine if you set the scope’s Intensity control very low, but as you increase intensity, the blanking quickly becomes ineffective.

    Below we have a beautiful Japanese YEW (Yokogawa Electric Works) 3667 storage scope. The left shot is misleading due to the camera exposure; the displayed image is actually extremely dim. The right shot shows the same* image with the intensity control increased – the image is bright, but there is no blanking!

    * Astute readers will observe that the time is significantly different between the two shots. This is a result of the WiFi NTP sync kicking in right in the middle! More (or less) astute readers may also notice that the scope’s trace rotation is not adjusted very well…

    Of course, it would be a simple matter to incorporate a pre-amplifier for the Z-axis, which would solve this problem. This will be introduced with the next Control Board revision!

    Like what you see?

    Nothing brings more joy than connecting this bundle of usefulness into a woefully unused old oscilloscope or X-Y monitor. If this is of interest to you, visit the Availability page for more information, and of course see the Gallery for other unique creations!

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  • The VGA Cube!

    The VGA Cube!

    It’s been a long while since I wrote about the 3″ VGA Display assembly, which was used for an RWR indicator in a fighter cockpit simulator.

    The customer came back and requested four more. But could I stack the boards to make the units more compact? Of course!!

    This particular assembly is rather tall because the client requested an in-built mains supply board, sitting at the bottom. The normal configuration using an external power pack is half the height. (In which case it’s not quite a “cube”…)

    With green filter and replica RWR escutcheon fabricated by the customer. How real is that!!

    And if you aren’t into aircraft indicators, you could always have a bit of fun!

    Is a VGA Cube right for you?

    Maybe. Or maybe not! These units incorporate binary blanking – I.e. The beam is either on or off; no shades of grey. Hence any VGA image composed of thick line art like RWR will display well, but shaded or coloured displays such as an attitude / horizon indicator would not work so well.

    Below is a Windows XP login screen… Not exactly a flattering image!!

    VGA Board – better and better

    The latest VGA Board rev 1.1x is small and cute, and is compatible with the standard Oscilloclock Deflection and Power Boards.

    In keeping with tradition, the VGA Board employs entirely analogue techniques to generate the horizontal and vertical sweep, triggered by incoming sync pulses. A high-speed analogue comparator with adjustable levelling is used to convert analogue RGB into binary blanking. Naturally, inputs are ESD protected so you can’t easily blow the chips!

    New VGA Board revision (left) – meaner and leaner!

    Like what you see?

    VGA Cubes are like any other Oscilloclock product – each unit is hand-crafted to order and fully tested so that I can optimise for the selected CRT and provide a decent satisfaction guarantee. To date I’ve made five – and always happy to discuss a sixth! If you have a passion for raster rendering, let me know!

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  • Crafted Cooling

    So how “hand-crafted” really are these Oscilloclocks? Well, even these tiny little washers that absorb fan vibrations are individually punched out by hand from a silicone sheet…

    Clearly hand-crafted…

    Speaking of fans and heat, I realise now that the site is disappointingly devoid of details on dissipation. Let’s fill the void!

    Fan Fundamentals

    Depending on the CRT used, Oscilloclocks nominally consume 8-12W of power. Around half of this goes directly to the CRT heater and CRT Board (blanking amplifier). This heat is dissipated in the large, cavernous CRT housing, and is not really much of an issue.

    However the other half is spent by the electronics – with the heat dissipated into the relatively less voluminous control unit enclosure. Acrylic isn’t great at conducting heat, so (especially in hot climes) things can get a little toasty!

    To keep things cool and prolong the life of the electronics, the control unit features a small fan, driven by a temperature-sensitive speed controller on the Power Board.

    But screwing the fan directly to the acrylic is a big no-no! Even this tiny fan vibrates somewhat at low speeds, and we definitely don’t want this jitter amplified by the case. People would go crazy. Pets would have a fit. No-one would sleep at night, and traffic and rail transport would grind to a halt with all the tired, irritable drivers out there. Socio-political equilibrium would be disrupted, and global chaos would ensue.

    To avoid all of that, we simply need…

    A Silicon Fan mounting

    I originally started looking for a solution when building the Model 1. All I wanted was a nice rubber gasket – one side affixed to the case, the other to the fan. With all the right holes and clearance.

    Well, I scoured the internet, and for the tiny 15 and 20mm square fan sizes I had in mind, there just wasn’t anything available off-the-shelf. And I had no intention of having 500 units made to my specifications in a low-cost country. No, I realised I would have to roll my own solution.

    Silicone punching tools to the rescue!!

    Tools of the trade – cutting block and hole punches

    Several years have passed, but the rudimentary process is still rudimentary. The first key part is the gasket. I use a ruler and paper cutter to cut out a square piece of silicone slightly larger than the fan. I then mark out and punch out the necessary holes. This is really easy stuff!

    Cut and punched gasket – ignore the dust and lint!

    The screw head and the washer/nut assembly need some cushioning, to avoid direct contact with the acrylic and with the fan body. This is where those tiny silicone washers come in. I punch a 2mm hole first, and then a 4mm hole around the first hole. And a washer is born!

    Almost got everything now!

    Silicone is a rather sticky substance, so at this point I remove lint and dust from the parts using a piece of tape.

    Next, we need to mount the gasket and fan to the case. Naked screws would pick up and transmit too much radial vibration, so I cover them with a thin sheath of rubber tubing. It’s not perfect, but if helps.

    Oops, in this photo I’ve forgotten the rubber sheathing

    The final pieces are the filter, and a washer to hold it in place in the recess at the rear of the case. Fortunately, these items are readily available.

    And that’s all there is to it. Voila!

    The final product – yes, the edges aren’t quite straight…

    These techniques have been used to varying degrees in numerous models, including the Oscilloblock, the Model 1-S, and the CopperClock. See the Gallery for more!

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  • X-Y-Z Core – Revamped

    X-Y-Z Core – Revamped

    Avid followers may have noticed an absence of fresh posts recently… What gives?

    I’m happy to report that it’s only because Oscilloclock has been absolutely run off its feet in 2016, producing more crazy CRT based devices than ever before. There just hasn’t been time to do justice to the blog!

    The good news here is there are lots of posts in the backlog. Let’s start out with this one:

    Yet Another CRT clock fanatic?

    I was approached by [Mike], who wanted to design his own CRT clock from scratch, but didn’t want to mess with the high voltage circuitry involved. Could I help out with an X-Y-Z display assembly, and he would do the rest? You bet!

    Here is the newly revamped Oscilloclock X-Y-Z Core, shipped out in Q2 2016:

    Oscilloclock XYZ Core

    And here is what [Mike] was able to with it, after implementing a totally fresh controller design incorporating Circle Graphics:

    oscilloclock-xyz-core-customer-clock-implementation-01
    [Mike]’s setup – A home-grown controller board, the X-Y-Z Core, and a 3KP1(F) CRT

    Here is [Mike’s] story in his own words:

    I was thinking of building a Nixie clock, but when I discovered the vector graphic clocks that Aaron and others had built, I knew I needed to build one. I felt comfortable that I could recreate my own version of the digital logic and the low-voltage analog signals, but didn’t really want to tackle the deflection amp or the high voltage circuitry. Buying the Oscilloclock XYZ display solved that problem. Everything arrived as and when promised, and I was beyond impressed by the care and workmanship that’s evident in everything from the boards to the harnesses to the documentation!

    I based my controller board on a Cypress PSOC 5LP chip, which allows me to implement all of the digital logic in its on-board programmable logic fabric. The 80MHz 32 bit ARM processor allows me to program 100% in C, which enabled me to create my own version of the software fairly easily. (I tip my hat to those who have done it all in 8-bit assembly!)

    Remaining work includes improving my signal quality, which doesn’t yet fully exploit the bandwidth and linearity of the Oscilloclock boards, designing an interesting enclosure, and adding a few software features.

    Good luck [Mike] with the rest of your implementation!!!

    Key features

    This unit is the latest incarnation in a series started in 2015, for a client who needed a custom Head Up Display solution. The boards have undergone through several revisions since then to optimize performance. This particular kit was pre-configured and fully tested to support 3RPx, 3KPx and 3WPx CRT types, and features:

    • Cathode to deflection voltage of 1875V
    • Digital blanking (grid modulation), safely isolated at 2.2kV continuous working voltage
    • Precision deflection amplifier capable of driving +/- 275V with 0.1% linearity
    • 0-5V analog X and Y inputs with 2.5V reference output [Option RS]
    • TTL/CMOS compatible high-frequency blanking input
    • Dim/Bright digital input with PWM support
    • Power Off digital input
    • Temperature-controlled fan with Failure and Overtemp safety features
    • CRT rotation coil supply (+/-5V)
    • CRT heater soft start / inrush current limiting
    oscilloclock-xyz-set-16001-01-01
    Oscilloclock X-Y-Z Core set – as shipped

    Like what you see?

    X-Y-Z displays are cool. But so are my other unique creations! See the Gallery, and stay tuned!

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