So here I am with Ken McIntosh at Rochester in 1979 as I televise Ken's composition doll "Felix the Cat" Felix was used by a number of experimental broadcasters as a convenient subject during hours of testing... The high contrast features were instantly recognizable.
At the event I presented a slide lecture covering the age of electromechanical scanning television technology which lasted until the early 1930's.
Over the years I have refined the presentation and built robust equipment to use in my live demonstrations. The following photos show you the equipment in use today.
In 1993 I designed and built the following equipment.
By 1930 there were 20 stations in the US licensed for experimental television broadcasting. Most were using 60 line progressive scan at 15 frames per second. Some others were using 45 lines from 3 interlaced spirals of 15 holes and the same 15 frames per second. I elected to use the 60 line format.
I built the frames from sheet aluminum.... To produce 15 frames per second, the scanning disk has to rotate at 1200 RPM. I did not have access to a synchronous motor for that speed... I found that 1800 RPM motors from old teletype machines were relatively easy to find. I connected the motor to the disk with a minature rubber timing belt and 1:1 1/2 ratio cogged pulleys.
The 16" scanning disk is the aluminum core of an old radio transcription disk... This was not such a good choice because the metal is so soft that it was a DOG! to drill #79 holes into.
The lense was salvaged from an old Sawyer film strip projector. To televise a portrait size picture places the sitter about 8 feet from the camera.
The unit sits on a hinged platform that permits the camera to be tilted about 5 degrees.
The pickup photo cell is of the photomultiplier type salvaged from an old Kodak commercial photo printer.. The cell is out of spec for the color work it is designed for but works just fine for this service... It has a target area about 1 1/2" in diameter so I did not have to provide any condensing optics on the back side of the disk.
The photocell is housed in a 12 oz. spray can with an IC pre-amp under the white plastic cap. The power supply is housed in a salvaged RS-232 interface box on top of the unit. Inside is a +/- 12 volt supply for the amplifier and a 350 volt supply for the photomultiplier tube..
The photo tube would have a much higher output if it were operated on 700 to 900 volts but I did not have a convenient and small supply. I realized that cheap electronic camera flash units put out about 350 volts to flash the xenon tube. So I found an old Polaroid flash attachment at a local fleamarket for $2 and I was in business! I need two 150W flood lights to light my subject... A little warm but no hair has caught on fire yet!