UK versus US monitor question

Eric Smith wrote on Mon, 27 Feb 2012 16:54:50 -0800 My impression is that this isn't quite true. You have to synchronize to the frequency of the broadcast and also to the exact phase of the broadcast. We are used to handling both with a single circuit, but they are separate issues. Though modern recreations of mechanical TV receivers seem to favor DC motors, many original devices used synchronous AC motors instead. So if the broacast was using the mains as a reference the receiver would, after a start up period, be in sync in terms of frequency. The phase difference between the sender and receiver would be arbitrary, of course. The way to solve that is to have the viewer adjust some knob until the picture looked right. One solution is to have the knob add some friction to the motor when pressed, causing the rotation to fall slightly allowing the picture to drift into the desired position. My father started working at RCA in 1957 and tells me that hybrid receivers (with electronic horizontal circuits and mechanical vertical) were still common at that time. I found absolutely nothing about them online. Even museums that list their TV receivers seem to jump directly http://www.earlytelevision.org/ I did see a hybrid camera at this site near the bottom of http://www.earlytelevision.org/safar_studios.html Anyway, even after mechanical and hybrid sets were forgotten there was enough line noise in typical power supplies to make it a good idea to keep the picture synchronized with the mains. And even today, with nice switching power supplies, having the TV run at the line rate makes the terrible noise that appears on the screen when someone turns on a blender in the next room remain a stationary line instead of moving all over. -- Jecel