Mains voltage zero crossing detector with optical isolated output

So a new client or long-lost relative would automatically be directed into voice mail? Ok, it's your phone.

Yes

Yes, it is. ...Jim Thompson

-- | James E.Thompson, CTO | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona 85048 Skype: Contacts Only | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at

The problem there is that it wouldn't be 90-240 volt universal. We figured that a minority of users would want to line-trigger a picosecond-resolution digital delay generator, so the extra wart isn't a big deal.

Yuck :-)

The next thing you know, you'll be getting phone calls from people on usenet. ;-)

Actually, I do. Regularly. Seeking circuit help without the pain and agony of Larkin obfuscating a logical progression to a proper solution. ...Jim Thompson

That analogy doesn't float. Your argument is more like not shooting people who enter your house uninvited. ;-)

It's downright trivial to produce an accurate edge transition at the zero crossing, with enough oomph to whack an opto-coupler into producing a sharp edge...

as I opined in a much earlier post: all it takes is a simple-minded capacitive voltage dropper to power a comparator.

So the remaining question is what kind of pulse do you want to see on the other side of the opto-coupler... positive going at each zero-crossing with what width, or what?

Please define and I'll finish the exercise. ...Jim Thompson

I was poking fun of calling you a year or so ago, jut to say hello. :)

Ah, yes! You did call me ;-) ...Jim Thompson

Perhaps like this...

Choice of comparator is left as an exercise for the student... but even a lowly LM339 will do if you can stand the 300ns of extra delay ;-)

Of course Mr. Snotnose, "company president", will say too many parts. ...Jim Thompson

Idiot. An LM339 will go nuts from the negative input swing. What did you use to model it, an ideal comparator?

Hey, 17 parts isn't bad, for an amateur. But you'll need to work on it to get it past UL.

Gotcha! But you're too dumb to know why ;-)

The 4N25 probably doesn't meet UL, but there's nothing else any worse than your approach.

You're nothing more than a narcissistic ignorant SOB who constantly needs to be on your soapbox so you can claim adequacy.

Your claim has been denied ;-) ...Jim Thompson

More on that later. Waiting to see how deeply Larkin will try to immerse his foot in the cow patty ;-)

A colleague reminds me that in 2001 we used a very similar method to power a washing machine controller for Emerson Appliance Controls Division. In fact most of the controller was on the line side of the boundary. I assure you that Emerson got UL approval. ...Jim Thompson

LM339 behaves sensibly with inputs as low as -0.6V, it'll need a pull-up on the output though,

John Larkin a écrit :

That one is pretty low count, low power, and need no clean up circuit/soft,...

I don't think there's a mean to save one opto :-(

Yes. Under most conditions. And only one input misbehaves even if you suck current out of it.

Yes. ...Jim Thompson

No. I'm working with a company right now where _everyone_ is younger than my children... with some even as young as my oldest grandchild. And they are peaches to work with. Seems their professors at RIT used some of my early circuit designs as teaching examples ;-)

And it's no piddling company... they just shipped their BILLIONETH chip! ...Jim Thompson