Fresh from Oscilloclock Labs – a new VectorClock creation, commissioned for the office of a world-famous film and television director:
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!
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!
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.
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.
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?
Those of you who own, or are building, an Oscilloclock may have realized how tedious it is to create a new character or drawing. My little Casper (October, Seasonal Treats post) required a grueling 5 hours to get him looking good!
The current method – Painful
I have another blog post series in progress describing the theory behind Circle Graphics figure display, so I won’t elaborate on details, but the current process of getting a figure from paper to screen is very much manual:
Roughly sketch out your figure on graph paper.
Split out your lines and curves into blanked circle and line segments.
For each segment, roughly ascertain the circle’s radius (width and height) and centre coordinates.
Type the numbers into the code file, in PIC assembly language syntax.
Build the code and Program the PIC.
Easy?
NO.The figure looks NOTHING like you expect. The size is wrong. The edges don’t meet up. The curvature is out. The thing is upside down. All of the above!
Repeat steps 3, 4, 5 for several hours. Drink coffee. Redraw and repeat for yet another few hours. … …
Finally – Celebrate the birth of a new figure!
The Easier Way
The new Oscilloclock Figure Creator utility allows you to easily create and modify font characters, graphic images, and sprites – interactively.
By the time you read this post, you must have seen the term “Circle Graphics” in a thousand places across the site.
In fact, “Circle Graphics” is not an official term – I just use it to describe how shapes are drawn on these clocks:
Everything you see on this screen is made up of CIRCLES! Blank out part of a circle and you get an arc. Squish an arc and you get a line. This clock simply draws circles, lines, and arcs of different sizes at various points around the screen. It does it quickly. And it does it very, very well!
The effect of using circles is beautiful – shapes are smooth and precise, with no jagged edges or pixelation.
Making “perfect” circles
I carry on as if it were some incredible new concept or discovery, like the Higgs boson. But in fact, the analog technique of constructing perfect circles, ovals, and lines on a CRT is very, very old. These figures are really part of a class of shapes called Lissajous Figures.