The AC operated synchronizer was a true synchronous motor and had 6 or 8 "teeth" or poles on its rotor, depending if it ran at 900 or 1200 RPM. In the latter case, the smaller motor was known as a "phonic" motor. This motor's winding was supplied by either the AC line or by an amplified form of the line scanning frequency derived from the television stations signal. Coupled to the same shaft was a secondary or "synchronizer" motor.
These motors were usually of a variety that used brushes and had relatively poor speed regulation characteristics, but induction motors were also used. The larger, or "main " motor was an AC or DC variable speed, rheostat controlled motor. The second way to achieve synchronizim was to drive the disk with two motors, one much more powerful that the other. If viewers could see a recognizable image for more than a few seconds, they would be delighted. Note the wire to the rheostat in his left hand. This 1928 photo shows Hugo Gernsback watching television. The fact was that final-final adjustments would be required every few seconds. Using a "course control" rheostat and setting it to cause the motor to operate at the approximate correct speed, the rheostat given to the viewer then provided a "fine control" and final adjustment for speed. Instead, a variable speed motor was used with a speed controlling rheostat on the end of a cable long enough to reach to the viewer. This severely limited the number of potential viewers, because if a viewer were located in a different electrical power grid, there was no way to hold synchronization with the television station. As a result, there were numerous comparatively small power stations spread throughout the United States. However, in 1928 the typical electrical power station supplied relatively few customers. The first is to have a synchronous system, where all of the motors were of the sort that would run synchronous to the AC line frequency. In the time frame of 1928, there were two ways to accomplish synchronization in the early mechanical systems. This was the method of synchronization he used in his color television demonstration of 1928. He then connected the two alternators together with a switch and the two disks would immediately begin running at the same speed and phase relation. He used this arrangement at both the camera and receiver disks, placed a room apart.
#BAIRD TELEVISOR GENERATOR#
Speed motors with a small AC generator connected to the motor shaft. A bit later, wanting to separate the camera from the receiver, J. Set up in this manner, the disks were absolutely synchronized. So that strong lighting could be placed in the vicinity of the camera disk without interfering with the viewing disk. They then placed a light barrier, usually a curtain or a wall between the disks In their earliest work of some of the first experimenters used a line shaft some 4 to 6 feet long and driven by a single motor.
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