But the real Frank Buss method would be to pipe that 400Hz into a uC and
run a timer in there. A software loop would keep adjusting the timer's
overflow register until the timer does exactly 96 rollovers per 400Hz
cycle. Then use that timer overflow signal to toggle a port pin which
will now deliver exactly 19.2kHz at 50% duty cycle. This method should
require the least in parts. Heck, the uC doesn't even need a stable
clock, it can run off its on-chip RC oscillator. Best case it'll be two
components, the uC itself and a 0.1uF bypass cap.
Of course us analog guys will always have run out of timers by the time
a function such as this is added into the mix. Somehow there are never
enough timers ...
Mike, I can't see your posts because you probably use the google domain.
But if you want to build something around a 4046 here is the recipe,
figure 2:
http://www.mlecmn.net/~lyle/pc-syn/pc-syn.htm
The divider would be a bit more cumbersome because you have to provide a
divide ration of 48 in this circuit. Most likely needs two chips instead
of that one. But I am sure you can piece that together. Your 400Hz goes
into pin 14 and your 19.2kHz emerge at pin 4. The timing parts to the
right of the 4046 may also need some changes, that's where the datasheet
comes in.
If this runs at voltages <5V I suggest to use 74HC series chips. The PLL
comes in that family as well, would be called 74HC4046.