[sdiy] twilight zone question

[Mike I]

Hi Jason,
About an hour ago I looked at Ken's site and the schemo for his clock
divider module and some other divider module - both circuits use LM358 in
the same way at the inputs..... I forget which CGS circuit you have, but
either one should be able to be connected directly to the 0 to 5V outputs of
the PIC processor (caveat: I don't know anything about this Blacet module,
and I assume it puts out TTL-compatible logic levels). There should be no
need for an intervening 0 to +15V level translation, the LM358 in the
existing CGS board will do a 0/+5 to 0/+15 translation directly. I would
advise against replacing the LM358 in the CGS board with TL072 though. If
you look at the TL072 specsheets, the inputs should not be brought any
closer than 3 to 4 volts of the most negative supply rail  (in your case,
ground). The LM358 inputs can be brought right down to ground and it will
still behave properly.
Good luck,
Mike