Getting a frame pulse early !
Posted: Sun Nov 18, 2012 7:57 pm
I chuck this idea into the ring and see if it rebounds. (I'm sure it will!)
I haven't seen it mentioned before, although it probably has.
As I read it, the standard method of recovering the missing frame pulse is, as has been said, 'The missing the bus' method......... setting a multi vib to be retriggered at each line and it only finishing its cycle when the line pulse is missing at line 32, and so giving the frame pulse.
Suppose this recovered frame pulse triggers yet another multi vib whose timing was one whole frame, 80ms, but whose timing could be adjusted a few ms, or parts of a ms, either way, by a low value pot in the RC timing cct.
Using this o/p from the 80ms vib. as the new frame pulse, one would not miss the bus if the timing of the 80ms multi vib were set very slightly less.
So, one is using a previously recovered frame pulse to give one the present pulse, as it were, and its timing is adjustable plus or minus to suit. I cannot see a problem with that, but I daresay that there is.
I haven't seen it mentioned before, although it probably has.
As I read it, the standard method of recovering the missing frame pulse is, as has been said, 'The missing the bus' method......... setting a multi vib to be retriggered at each line and it only finishing its cycle when the line pulse is missing at line 32, and so giving the frame pulse.
Suppose this recovered frame pulse triggers yet another multi vib whose timing was one whole frame, 80ms, but whose timing could be adjusted a few ms, or parts of a ms, either way, by a low value pot in the RC timing cct.
Using this o/p from the 80ms vib. as the new frame pulse, one would not miss the bus if the timing of the 80ms multi vib were set very slightly less.
So, one is using a previously recovered frame pulse to give one the present pulse, as it were, and its timing is adjustable plus or minus to suit. I cannot see a problem with that, but I daresay that there is.