Mark Willis wrote:

> I'd lean towards a PIC chip as well, myself.  12C508A, OTP part for a
> "forever unchanged" design, a /JW (windowed) part if you expect to
> ever need to change the time period or software, (you could use a few
> stacked (series) Shift Registers and jumpers/traces and cut/short
> jumpers for a programmable time in the low uSec resolution range, too;

  Many options.  We await the 8-pin device with EEPROM.  Can presently
be done by using an 8-pin EEPROM in addition, but then a 16F84 becomes
cheaper (presumably...).  You can have a device like a Stamp to which
you connect a (laptop) PC to set its frequency(/ies, duty cycle etc.)
and then disconnect and let it run until next calibration.

--
  Cheers,
        Paul B.