11-03-2023, 01:04 PM
An NTSC 405 line sub-carrier and sync pulse generator is easy to implement with a hand full of TTL chips.
The master oscillator operates at 10,631,250Hz. This is supplied to two divider circuits, one divide-by-four to produce the sub-carrier frequency of 2,657,812.5Hz. The other is a divide-by-525 network to realise the H2 frequency of 20,250Hz. Two further divider networks are required to produce the standard 405 sync pulse train. Divide-by-405 = 50hz. Divide-by-2 for the line sync pulses.
Geordie McBoyne.
The master oscillator operates at 10,631,250Hz. This is supplied to two divider circuits, one divide-by-four to produce the sub-carrier frequency of 2,657,812.5Hz. The other is a divide-by-525 network to realise the H2 frequency of 20,250Hz. Two further divider networks are required to produce the standard 405 sync pulse train. Divide-by-405 = 50hz. Divide-by-2 for the line sync pulses.
Geordie McBoyne.
