John Wilson wrote:

>(There used to be a Motorola chip that got 60 Hz from a 3.579 MHz color

burst xtal, but they aren't available any more so I slapped this thing

Perhaps you mean the National MM5369? (I think that's the right
number...) I have one of those - I used it in college to make the time
base for a home-made frequency counter.

Note that overall, the 60 Hz AC power line is more 'accurate' than
nearly any signal source you can build yourself. It may drift away from
exactly 60 Hz at times, but averaged over time it is extremely accurate.
(I think the term would be it is 'accurate', but not 'precise'). So,
stealing a bit of 60 Hz out of your power supply is simpler and more
accurate than building a crystal-based circuit.

Meanwhile, another way to do 'divide-by-n' without using lots of weird
flip-flop configurations is to use one-shots. This works for dividing
relatively low freqs, where the input freq is known.


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