> #1  Pulse has to be high for one second plus/minus =85. how
> much precision ?

20MHz crystal will allow down to 200ns

> #4  You can use a potentiometer into an ADC.  I guess you would
> want to translate the incoming voltage into a logarithmic time function
> such as    time delay =3D n**(ADC-voltage * m).  This could be done
> with a lookup table.

Don't know if the time delay needs to be 'infinitely' variable. The pot
can be broken down into segments to act more like a rotary switch.
eg 0-100 =3D 1 sec, 101 - 200 =3D 2s etc or whatever increments are
most useful

> Instead of a potentiometer , you could have a pair of buttons

Perhaps a pushbutton to over-ride the pot, or have the highest value
(eg > 1000) of the pot =3D never

Joe=20

--=20
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