While NBTV is not synonomous with mechanical television, it is beyond question that the mechanical nature of early TV technology is one of its appeals. For that reason, most NBTV enthusiasts build at least one mechanical televisor, with the first typically based on a classic Nipkow disc. My original intention was to take this approach and build a basic 32-line televisor compatible the the NBTVA standard. I gradually acquired some of the basic parts, including a fine 32-line disk from Peter Yanczer. The disc is meticulously crafted (CNC no doubt) and finished in a dull black, so there is no messy painting to be done. I ordered the disc with a mounting hub for a 1/4-inch shaft (a bargain at $12!) and everything arrived in perfect shape with the disc reinforced by a plywood plate for shipping! Clearly there was going to be no need to deal with image defects caused by imperfections in the disc - a not-uncommon occurence when you try to drill your own for the first time.
I was slowly accumulating parts for a monitor, but changes at work resulted in less time for project tinkering and I actually started to wonder if I could ever get a working televisor up to speed. As a result of following the work of members of the Narrow-Band Television Association (NBTVA), I had become familiar with the amazing work of Denis Asseman from Belgium. In addition to an interest in restoring early mechanical television equipment, Denis also creates incredible working replicas of such equipment, several examples of which can be seen on his extensive website. These are working, museum quality replicas that are identical, in all respects, to the original apparatus. One of his more recent efforts involved the 1934 Daily Express Television kit.
In 1934, the London Daily Express newspaper, in an effort to spur interest in television and expand the viewing base for the BBC TV transmissions, published a full-page article on the construction of a basic 30-line televisor that was compatible with the Baird standards. What is more, a kit of parts for the unit, engineered by Mervyn Sound and Vision, Ltd., was offered for sale through Selfreges department store:
The kit retailed for £5:9:6
Speed regulation was entirely manual. The AC/DC universal motor was designed to be powered from the Mains. A large adjustable dropping resistor (the green coil in the left/front view above) was in series with the Mains voltage and a wire-wound reostat (the shaft with the knob in the left/front view above). With the reostat set at mid-range, the adjustable resistor was set to provide approximately 750 RPM from the belt-driven disc. The viewer would emply the reostat control as a "fine-adjustment" to attempt to hold the image in sync and phase. The neon image tube (visible on the left side of the right/rear image above) would be connected, with minimal external ciruitry, to the plate circuit of the audio output stage of the broadcast receiver being used to receive the television signals.
What made Denis's Daily Express project a bit different from his previous efforts was that he made up a number of replica kits and offered the "extras" for sale. These kits were done to his usual exacting standards, right down to the packaging, and the kits themselves were significantly collectible.
This kind of quality doesn't come cheap, but a televisor built from the kit would certainly be worth bringing to antique wireless meetings to demonstrate both the technology and hardware of early television. While the mechanics of the kit were identical to the original, the included electronics were thoroughly modern, assuring precise syncronization of the disc and quality video display via a neon tube replica with internal high-brightness LEDs.
So, as I write this in mid-October of 2005, a replica Daily Express Television Kit is winging its way over the Atlantic from Belgium. As I make progress with the project, the headings below will become active links to pages with construction and other documentation. It should be an interesting adventure, combining Art Deco mechanics with space-age electronics, so let the adventure begin!
Assembling the Televisor Mechanics
Ralph Creates a Cabinet
The Finished Project