Oscilloclock.com

Handcrafted Scope Clocks with circle graphics

Category: Hardware

  • 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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  • The Oscilloclock Core

    The Oscilloclock Core

    Over the years, folks out there have reached out to me with all sorts of crazy ideas about cases and housings for scope clocks and custom CRT displays. Here are some interesting examples:

    • The console of a vintage pipe organ
    • An ancient grandfather clock
    • A cylindrical case made of some exotic wood
    • A “cathedral” style vintage radio

    Essentially, these people wanted just the innards of an Oscilloclock, which they would build into their own case. Could I help out?

    Absolutely! For people who want to roll their own cases, and who have experience handling high voltage electronics and CRTs, I occasionally prepare custom board sets that are lovingly hand-assembled, tested, and tweaked for optimum performance with a given CRT. Here we go:

    The Oscilloclock Core

    Oscilloclock Core, hand-crafted in 2015 for a discerning customer in Germany
    An Oscilloclock Core, hand-crafted in 2015 for a discerning customer in Germany
    The standard Oscilloclock Core layout, on a test acrylic mounting
    The standard Oscilloclock Core layout, on a test acrylic mounting

    I supplied this particular unit with an 8SJ42J Chinese-made CRT, just for testing purposes. This is a 3″ PDA tube with a highly restrictive rectangular viewing area, but the customer found it just great for checking things out!

    Oscilloclock Core - complete set for 8SJ42J - 03
    Oscilloclock Core - complete set for 8SJ42J - 06
    Oscilloclock Core - complete set for 8SJ42J - 02

    What comes with it?

    Here’s what’s comprises the typical Oscilloclock Core:

    • 1 x Fully assembled and programmed Control Board (optional on-board GPS)
    • 1 x Fully assembled Deflection Board (latest ultra-linear revision)
    • 1 x Fully assembled Power Board optimised for a given CRT (latest revision with options: onboard high-bandwidth blanking amplifier, rotation coil supply, auto fan speed control, unblanking plate modulation, and isolated bright/dim input)
    • 1 x Fully assembled CRT Board (optional; an external blanking amplifier recommended when the CRT cable is longer than 50cm)
    • 1 x Rotary encoder
    • 1 x Worldwide 9V power supply (high quality wall wort unit, commercial ratings)
    • 1 x Garmin GPS unit with 5m cable; wired to board-side connector (not required for onboard GPS)
    • 1 x Set of standard inter-board and CRT harnesses for testing and reference (10kV/3kV silicone melt-proof used for HV cables, other LV cabling also heat-resistant)
    • 1 x Cast acrylic test mounting assembly, fitted with the boards, ready for testing out-of-the-box with your CRT
    • 1 x Ceramic adjustment screwdriver
    • Service documentation (schematics, board layouts, complete Digikey BOMs, harness specs)
    • All components are latest available types sourced within the last 6 months, 0.1% or 1% tolerance resistors, minimum 2 x rated working voltage capacitors, all lovingly hand-mounted by myself
    • All boards sprayed with HV lacquer for moisture and arcing protection
    • 2-week satisfaction guarantee. But no long-term warranty on board-only purchases

    Naturally, the lengths of all harnesses and inter-board cabling can be customized according to the owner’s requirements. And there is also an Oscilloclock Core Cube arrangement, where the boards are stacked to reduce the length and width of the overall unit.

    What CRTs does it support?

    The Power Board and Deflection Board are increasingly flexible with each revision, but I insist on performing all configuration of the Core here in my lab. This allows me to tweak for maximum performance, and provide a proper satisfaction guarantee.

    Typically I work with the owner to recommend a CRT based on preferences such as size, colour, and aesthetics. However in cases where the owner already has a CRT in mind, and I don’t have the particular CRT or a close equivalent, I ask the owner to send me one to test against. Or, I simply procure one; after all, one can never have too many CRTs!  (Though my better half does not agree…)

    The current Oscilloclock Core board revisions meet the following operating parameters:

    • Maximum cathode to deflection voltage of 2175V
    • Maximum accelerator voltage of 3525V for PDA type CRTs
    • 6.3V heater, max 0.7A
    • Support for “Deflection Blanking” CRTs (see treatise here)
    • CRT rotation coil supply (+/-5V)
    • Precision deflection amplifier capable of driving +/- 275V with 0.1% linearity

    Like what you see?

    Check out the Availability page for more information, and of course see the Gallery for some unique CRT creations – many with an Oscilloclock Core at their heart!

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