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?

This scope even has a Fill mode. Castles anyone?

This scope even has a Fill mode. Castles anyone?

Lots of controls for such a tiny case...

Lots of controls for such a tiny case…


PROJECT REPORT

Subject: Dual-Trace Oscilloscope Design and Construction
Period: 7/90 – 10/90
Submitted to: Mr R. Young, Physics Department
Project Designed and Constructed by: [Aaron] (present-day Oscilloclock.com)

PROLOGUE

When students studying Grade Twelve Physics began a unit on Electronics during the third term of the year, I became increasingly involved with the apparatus used by the teacher, Mr. R. Young. As I was already familiar with most of the material set out in the unit, I often helped Mr Young construct test circuits and/or set up equipment as teaching aids. In this context, I soon came to know the oscilloscope to a great extent. Having been an electronics hobbyist for the last twelve years, I was well aware of the functions of the oscilloscope, and to use it quickly became second nature to me. I was amazed at the detail of the information which the instrument gives the user about a circuit, and felt inclined to construct my own.

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Tek 520A VectorClock!

Television broadcasting has switched from analog to digital - and if you’ve got a nice HD TV, you’ll be loving it!

But with that transition came the death of an entire breed of equipment – the Vectorscope.

Tektronix 1420 Vectorscope

Just to be clear, these are not monitors for playing ancient video games using vector graphics!!  No, the Vectorscope is (was) used to give a delightful view of the ‘vectors’ inside an NTSC or PAL video signal, describing the color components of the signal.

If you were lucky enough to be a TV broadcast technician, you’d use your Vectorscope all the time to check your vectors’ amplitudes and phase. You would even give your vectors names like ‘Jack’ and ‘Jill’, and check up on their relationships daily, just as any responsible guardian would!

But above all, you would marvel every single day at the beautiful hardware you were using, and the complex circuitry involved. Take a look at my Tektronix 526 Vectorscope, which has oodles of delicious tubes to heat my shop on a nice winter’s day:

Tektronix 526 Vectorscope

Well, it all went digital and there is no longer any need for analog color signal analysis. But dry your tears… There is something even better:

Announcing the Tek 520A VectorClock

This lovely Oscilloclock reincarnation of a Tektronix 520A, sold at Maker Faire Tokyo 2013, allows its new owner to forever relive the magic of NTSC, PAL and SECAM analog color.

Tektronix 520A VectorClock - brilliant blend of the old and new!

Tektronix 520A VectorClock – brilliant blend of the old and new!


See more related videos on my YouTube channel

The Tektronix 520A has a stunning built-in array of lights for illuminating the CRT graticules. By simply removing the bezel and external graticule, the Tek 520A morphs into a deliciously moody timepiece!

Tek 520A VectorClock - Glorious Glow

Normally, I shun CRTs with built-in graticules. Their lines detract dreadfully from an Oscilloclock image. But here! The Tek 520A’s internal vectorscope graticule is round! What better way to accentuate a Circle Graphics driven display?

Silky smooth Circle Graphics on steroids!

Silky smooth Circle Graphics on steroids!

Under the Cover…

The Tek 520A is solid-state. It can be left on 24 hours a day and not fail for many years. This makes it a perfect match for my Maximum Re-use + Minimum Invasion policy: nearly all existing circuits – HV power supply, deflection amplifiers, blanking – are put to use, with just a few (reversible) tweaks.

Tek 520A VectorClock - Maximum re-use, Minimum invasion

The Oscilloclock Power Board is mounted neatly next to its own dedicated low voltage supply. A small relay board can be seen below, for controlling the Tek’s main power unit. All cabling is HV-tolerant and neatly fastened with high-temperature cable ties.

Tek 520A VectorClock - Control Board mount and cabling

Of the more interesting reversible ‘tweaks’ needed for this retrofit, here we see a delightful little trimpot pretending to be a transistor. Quite an act, I would say!

Tek 520A VectorClock - an unorthodox transistor replacement

Like what you see?

If you love big, looming Vectorscopes and need to have one put to good use in your living room, Contact me. And be sure to subscribe from the front page, to track all the other exotic experiments and unique timepieces targeted for 2014!


Credits to [Quinn] in Canada, for providing the initial inspiration for the Tek 520A VectorClock project!

Santa in your Clock!

The world-renowned Santa Claus. How does he get in your house to deliver presents? Does he go down the chimney (if you have one)? Does he shrink and squeeze under your door? Of course not! What silly ideas.

Santa simply converts himself into pure energy and beams in!! I’ve seen this glorious event myself, and now you can too – with the latest Seasonal Treats enhancement from Oscilloclock.com.

Beam me in, Santa!

Beam me in, Santa!

Not only can you watch Santa on his travels, but you can even control where he drops his presents! Can YOU help him deliver the gifts?

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Luxury 2013 edition Model 1-S!

This 2013 edition hand-crafted scope clock exudes sophistication and elegance, to match the most refined interior – be it the boardroom or the bedroom. The 1-S boasts solid brass fittings custom-turned in Japan, ultra-transparent cast acrylic housings, and a decadent harness with chrome connectors and gold-plated pins from France. The brand-new old stock CRT was selected especially for its gentle white-blue trace and extremely long persistence, to provide a relaxing and refreshing viewing experience.

2013 luxury edition Model 1-S scope clock from Oscilloclock.com

This particular unit went on display at Maker Faire Tokyo 2013, and was sold within several hours. Enquire via the Contact page for pricing and availability of the Model 1-S and other exclusive Oscilloclocks.


See more related videos on my YouTube channel

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Oscilloclock at Maker Faire Tokyo!

Summer is over! But even as cool weather sets in, the Oscilloclock.com lab is smoking hot, preparing for…

Maker Faire Tokyo 2013

Visit the Oscilloclock.com booth, and check out the luxury 2013 edition Model 1S – to be announced in this blog at end October. One unit will go on sale at the event!

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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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A Heathkit Oscilloclock!

Anyone familiar with Heathkit®?

From 1947 to 1992, the U.S. based Heath Company produced electronic kits for everything you can imagine: radios, TVs, computers, robots, ham gear, and electronic test equipment. Yes, you guessed it – they also produced kits for oscilloscopes!

My Grandpa purchased one such scope, the Heathkit OR-1, around 1960. He wanted to kick off a new career in electronics repair, and the ‘build-your-own-equipment’ approach to training was in full bloom at the time. Also, since this was before the era of cheap overseas manufacturing, he could buy a Heathkit far cheaper than an assembled scope.

Heathkit OR-1 manual - a work of art

Heathkit OR-1 manual – a work of art

Unfortunately, Grandpa’s electronics career never really took off. But decades later, he introduced me to his gorgeous oscilloscope, and boy – did that kick MY career off! Much later, the OR-1 came to live with me. (You can read a bit more about my affinity for this scope in my History page.)

The problem is, I have too many oscilloscopes. But I don’t have enough Oscilloclocks. What more fitting way to keep Grandpa’s legacy alive, than to retrofit his Heathkit?

Heathkit OR-1 Oscilloclock

Heathkit Oscilloclock - Splash and Clock

Special features

Circle Graphics (see my earlier post) makes for smooth, graceful characters constructed entirely from lissajous figures! Never before has an oscilloscope looked so utterly delightful.

Heathkit Oscilloclock - circle graphics

The horizontal sweep frequency fine adjustment knob, conveniently located smack in the middle of the front panel, functions as the single control for the Oscilloclock. (A video showing what this control does is up on my YouTube channel.)

Heathkit Oscilloclock - single control

Eventually I might make an acrylic case, to show off not only the CRT but also Grandpa’s soldering prowess. In preparation for that, I’ve made sure that all the tubes (valves) still light up when you turn the original power switch on. What a beautiful scene!!

Heathkit Oscilloclock - tubes lit

The 5ADP2 CRT in the OR-1 is decidedly unattractive compared to other tubes I used in the Model 1 and the Prototype. It is also technically inferior, not having post-deflection acceleration. However, it has one redeeming feature – a P2 phosphor! This phosphor gives just a hint of blue, and it has a simply divine after-trace of just the right length to create soft, flowing figures while still maintaining reasonable sharpness and clarity. (Visit my earlier post for more info on the phosphorescence phenomenon!)

Heathkit Oscilloclock - P2 phosphor persistence

The Oscilloclock boards are mounted on attractive acrylic back-planes and are easily accessible from the side and top. Image size and position adjustments can be made with the case on. The case can be easily removed to reprogram the clock:

Heathkit Oscilloclock - programming

The OR-1 happened to have a trimmer control at the back, so I tucked this control inside the unit, leaving a nice big hole – perfect to mount the socket for the Garmin GPS unit. This baby never loses track of time!

Heathkit Oscilloclock - GPS socket

Like what you see?

If you have a cherished oscilloscope that you wish to preserve in entirety, but also want to put to practical use in your workshop, office, coffee shop, or museum, converting it to an Oscilloclock is a nice idea!

However, the conversion process depends heavily on the oscilloscope you have, and your preferred approach. There is no single ‘cookie-cutter’ step list, although the Oscilloclock boards are designed to be relatively flexible. In the next post, I’ve highlighted the key steps taken in converting the Heathkit OR-1. Take a look!


Lastly, a note regarding Heath Company: As far as I can tell from their web site, they are in business again, and are even planning to re-start kit production! They of course own the Heathkit logo and trademarks referred to in this article. It is my hope that rendering their logo on the Oscilloclock will not offend them.

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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Transformer Corner part 2

In Transformer Corner part 1, I introduced one of the key parts of the Oscilloclock – the HV transformer, and tried to illustrate some of the concepts and history behind it.

Next, let’s explore the Prototype’s power supply configuration. This will tell us a lot more about the transformer I had to wind!

Power supply design

My greedy little Oscilloclock wanted lots of different voltages…

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