Mains voltage zero crossing detector with optical isolated output

Cute. There are probably other ways to use the phototransistors. After all, they are transistors, so shouldn't be wasted. How about making an optically commutated flipflop?

Like I said, "brainless hip shot". Possibly good concept, but Larkinesque... doesn't hit CMOS threshold sufficiently, because it wasn't actually checked for good values... if any such values exist.

But your idea to get away from the totem (I presume) and drive an R-S flop would work sharply. ...Jim Thompson

All the values are in plain sight, you moron.

You are automatically hostile to ideas. Especially ones that are not yours. Extra-especially ideas you don't understand.

Try with the caps c-b instead of c-e, 56 pF maybe. Use those transistors!

Or separate the phototransistors, ground the emitters, add weak pullups, and go into two uP port pins. The pullups may be free inside the uP.

But not as cute as the totem pole.

Indeed! And they don't meet a sufficient excursion to properly trip a CMOS gate, or inverter, or what ever... I checked it. Indeed a clever idea, but it doesn't quite work.

What? You are offended that I think your idea of driving a flip-flop has possibilities? You're the moron. Why are you so full of hate? ...Jim Thompson

Post your schematic ;-) ...Jim Thompson

All 300 feet of it!

That would require major digging. I always had a habit of properly documenting my stuff even as a kid, and have some really archaic ones. Somewhere. Like this circuit that was used to muffle the "wrist-whack" you got when turning on an industrial angle grinder, depeloped by yours truly:

Pre-1975 stuff is partially gone though, on account of a move across a large pond. I am pretty sure I chucked the disco-light module.

I think I have pretty much everything I've ever done... mostly due to a technician/secretary named Jim Foster who documented everything I ever doodled.

Unfortunately it's somewhere in five 4-drawer cabinets and isn't indexed :-( But at least everything is in a labeled folder.

That's the stuff prior to around 1985, when I went CAD. Most of that CAD stuff has been copied off of floppies onto CD's ...Jim Thompson

I'd still have to do that. Although the usefulness would be rather limited. For example, the IC in the link above has become unobtanium long since. Same for all those Ge-transistors in my youth projects.

And I say it doesn't work. Show us that it does (without fudging values :-) ...Jim Thompson

It gets down to about 1.2 volts out of 5, 0.24 of Vcc, good enough. A minor tweak gets it down to about 0.8.

Show us the full simulation setup, or breadboard, whichever way you "proved" it. My PSpice sim shows it barely drops 2.5V, quite marginal to drive CMOS reliably.

And show us that "minor tweak". ...Jim Thompson

until

Oh, drop dead, you tiresome old hag.

until

Now that wasn't nice! ;)

Jamie

until

is

Accuracy comes first.

until

is

Your usual response when you really have no solution.

You can't prove you're right, because the @#$%ing circuit, while an amusing concept, falls apart in real life.

You tiresome old moron. ...Jim Thompson