It was possible of course, but there are good reasons they were intrinsically linked: The AC power line frequency was used for the vertical refresh rate for tw

It was possible of course, but there are good reasons they were intrinsically linked: The AC power line frequency was used for the vertical refresh rate for two reasons. The first reason was that the television's vacuum tube was susceptible to interference from the unit's power supply, including residual ripple. This could cause drifting horizontal bars (hum bars). Using the same frequency reduced this, and made interference static on the screen and therefore less obtrusive. The second reason was that television studios would use AC lamps, filming at a different frequency would cause strobing. https://en.wikipedia.org/wiki/Refresh_rate#Televisions https://en.wikipedia.org/wiki/Refresh_rate#Televisions