🚀 go-pugleaf

What's the correct way to drive TTL from an op-amp?  I'm proposing to do some
kind of threshold detection by sending an op-amp output into a Schmitt; the
op-amp seems unable to pull *low* enough to make the Schmitt input see
a low level.  I suppose I could go out and buy one of those fancy op-amps
that drives all the way to the - rail, but I'd rather have a simple fix I
can do from my junkbox.

The only thing that's worked so far is something like

	        .1 uf
	|\   +---||---+
  opamp	| >--*        *-----> to schmitt input
	|/   +-v^v^v^-+
	        1k or so

... which apparently creates a pulse low enough to kick the schmitt down if
the falling edge is fast enough, but s'pose I want to respond to an output
that drops more slowly??

_H*