John Logie Baird, Scottish television experimenter, (b: August 13, 1888 d. June 14, 1946) began experimenting with televiion in 1922 from his Frith Street atic in London's Soho. Three years later he demonstrated a mechanical scanning system to the Royal Institution. He called his device the 'Televisor'. It used a 16-line scanning disk camera and the receiver had a neon tube as a light source.

Baird's first transmission, in March 1925, was of a simple mask but he later used a puppet called 'Stooky Bill' and later still showed the first live image, a picture of a solicitor's junior clerk from the business below Baird's flat. Baird sent the first television pictures down a phone line, between Glasgow and London a distance of 625km, in 1927. In 1928, he made the first transatlantic transmissions and later also developed a colour TV system.

Baird was unable to obtain the patent for his 'Televisor' because it contained the already patented Nipkow disk, but eventually found backing for his invention. The Baird Television Company was formed and, in 1926, the first 30-line Baird 'televisor' was put on the market. The Televisor was also available in kit form for home assembly...

The Nipkow Disk...

This is a mechanically spinning disk with a series of equally distanced holes of equal diameter. These holes are positioned to form a single-turn spiral starting from an external radial point of the disk and proceeding to the center of the disk. The holes, when the disk rotates, trace circular ring surfaces, with inner and outer daimeter depending on each hole's position on the disk and thickness equal to each hole's diameter. These surfaces may or may not partly overlap, depending on the exact construction of the disk.

A lens projects an image of the scene in front of it directly onto the disk. Each hole in the spiral takes a horizontal "slice" through the image which is picked up as a pattern of light and dark by a sensor. If a light powered by a signal from the sensor is placed behind a second Nipkow disk rotating in synch at the same speed and direction, the image can be reproduced line-by-line, however it remains no larger than the one projected onto the original receiving disk (Source: Wikipedia)

The BTS 84/- Disc Television Receiver Kit

The origin of this particular kit is unknown, as I have been unable to find any reference to BTS or their "Disc Television Receiver" but the kit is clearly of the Baird Televisor type. John (G8KKU) bought the kit into MKARS in a black dustbin bag one Monday night (my thanks to him) and, when I got it home I found what was left of the kit to be in excellent condition. Present is the plywood base, the 'Television Disc', the mounting bracket and various other small parts, including the original rubber drive belt (which is now solid). Sadly the motor and electronics are missing. However the manual is included (which I will shortly make available for download) as well as a very large 'blueprint' which is in very good condition (see below).

The blueprint is marked with a 1934 copyright and, according to the manual, the receiver could display broadcasts from the London National Station on a wavelength of 261 metres. The signal was recognisable as "something like a low pitched whistle with another varying high pitched whistle superimposed on it".

The manual further advises "Provided the radio receiver is of good quality and gives a strong output signal, the results obtained from the B.T.S. television receiver will be outstanding. Although the image is not large it is remarkably clear and will provide hours of pleasure to the user".

If you know anything about British Television Supplies Limited of Bush House, London WC2 and their 84/- Disc Television Receiver, please email me: andy_c_brown@hotmail.com