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!

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:


[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 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!

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 - 03Oscilloclock 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!

Heads Up!!

Recently I received a most intriguing request: I was asked to build a self-contained, super-bright X-Y display unit with 3-inch CRT, for use in an “HUD“. Hmm…

Holographic Utterance Device?
Horizontally Unstable Doohickie?

Fortunately, I didn’t need to guess any further. As I was once an avid flight simulator enthusiast, I quickly hit upon the correct meaning: Head-Up Display. This is a mechanism that overlays instrumentation or map data onto the view looking forward from the cockpit, so that the pilot doesn’t have to look down to see this information.

HUD in an F-18 aircraft. Source: AC Aviation Life

HUD in an F-18 aircraft. Source: AC Aviation Life

Wikipedia has a great introduction to HUDs and their history, but Mike’s Flight Deck has the definitive tome for flight simulator enthusiasts who want to actually build an HUD. According to Mike, the system employs various optical paraphernalia, but at the heart of the mechanism is what lies closest to my own heart – a CRT Display!

Oscilloclock 3-inch X-Y-Z display, custom-built for an HUD

An Oscilloclock 3-inch X-Y-Z display unit, optimized for use in an HUD

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VectorClock Reloaded!


Fresh from Oscilloclock Labs – a new VectorClock creation, commissioned for the office of a world-famous film and television director:

Tek 520 VectorClock - S/N 002 (image published with permission of the owner)

Tek 520 VectorClock – S/N 002 (image published with permission of the owner)

This unit is based on an original Tektronix 520 vectorscope, which is the predecessor of the 520A that was used in the first VectorClock, described here. This custom conversion employs several key enhancements, and performance has never been better!

Be sure to check out videos on my YouTube channel.

VGA display… On a 3″ scope tube!

Yes, you’ve all thrown away your lunky old CRT monitors, in favour of sleek ultra-thin LCD displays. And, you thought you’d never see another one again…

But this CRT display has a twist! It’s round. It’s small at just 3 inches diameter. And it’s awfully cute.

Oscilloclock 3-inch CRT VGA Display Assembly - overview

Last year, I was approached by a dedicated flight simulation enthusiast, who needed a radar indicator to use in a fighter cockpit replica. The indicator should employ a CRT, for the most realistic look. Could Oscilloclock design and construct such a display?

It didn’t take much convincing! Diverging only temporarily from building clocks, I took up the challenge to create my first raster-scan CRT display unit. In the ensuing months, difficulties sprang forth from every direction in the project, but ultimately I was able to avoid a diraster (sic) and deliver a functional assembly:

See more related videos on my YouTube channel

The Setup

The key component of this setup is a new prototype VGA Board that converts a VGA signal into analogue X and Y outputs. Both analogue intensity and binary blanking outputs are provided.

Oscilloclock VGA Board prototype

Oscilloclock VGA Board prototype

The X and Y outputs drive an Oscilloclock Deflection Board, while the binary blanking output drives the blanking amplifier in a CRT Board.

Oscilloclock Deflection Board - modified for ultra-linear HV output

Deflection Board – modified for ultra-linear HV output

CRT Board - heavily modified for improved frequency response

CRT Board – modified for improved frequency response

Blanking isolation, heater, and HV supplies are provided by a Power Board.

Power Board - with improved optocoupler

Power Board – with improved optocoupler

It all looks so easy! But noooo. Astute readers will recall from other posts that every Oscilloclock project involves sleepless slumbers, horrific hair-pulling, and forgotten family members. Let’s see what caused me grief this time…

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From the Archives – a 400-LED Oscilloscope

Long, long ago… In a workshop far away…

Recently, I’ve seen quite a few search hits and even an enquiry regarding the 400-LED dual-trace oscilloscope that I briefly mentioned on my History page. With renewed enthusiasm therefore, let’s take a trip down history lane and see what I was doing back in 1990!

A compact dual-trace 1MHz DC scope - what more could a high school kid want?

A compact dual-trace 1MHz DC scope – what more could a high school kid want?

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Making the Heathkit Oscilloclock

Last month’s post about the Heathkit Oscilloclock generated tremendous interest, and I’ve heard from several folks keen to try their hand at preserving their own beloved instruments.

… so let’s take a brief look at what was involved in the Heathkit OR-1 conversion!

Heathkit Oscilloclock - inside

Approaches to conversion…

There are many approaches to retrofitting a scope into an Oscilloclock, but it really boils down to how much of the original circuit you want to re-use, vs. what you will bypass with Oscilloclock boards.

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Transformer Corner part 4

Winding your own HV Transformer

In Transformer Corner Part 3, I looked at how to choose materials for a custom HV transformer. One way was to pull stuff from the junk-box – I did this in my early Prototype. The much, much better way was to use an off-the-shelf core with documented specs.

Let’s look at winding up the transformer. It’s amazingly easy to get a workable result!
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Transformer Corner part 3

Designing your own HV Transformer

In Transformer Corner Part 2, I looked at the power supply used in my early Prototype, and showed how to determine the key requirements for the HV transformer.

Now, let’s see how I could choose the materials and design the transformer – without any pesky mathematical formulae!

A hand-wound HV transfomer!

The end goal – a hand-wound HV transfomer!

Picking a core

The first challenge was to find a suitable core from my junk box. First off, recall from Part 1 that this couldn’t be iron (too ‘slow’ for 151 kHz), and it couldn’t be air (too ‘weak’ for 25mA). I suppose I could have tried plastic, milk, or even beer – but I knew better. I knew about a substance called Ferrite.

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