Mains voltage zero crossing detector with optical isolated output

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You can also check out our FAQ or forums and maybe you'll find what you were looking for. Or maybe you should try heading home."

Grant.

Did you clear your cache before trying it again?

OP wanted it to work on 60Hz and on 50Hz and presumably 115V +/- 10% and 240V +/- 10%

The only invariant I can see with that mess is the zero cross,

No, was using Chrome, so I just tried Safari, Firefox and MSIE, same 403 error, maybe the site locking out foreigners?

Grant.

t.net ---

If you can compare the line against a phase shifted version of itself ( the heavily filtered part), then the triggering is invariant with line amplitude, and depending on your technique for estimating the zero crossing from a bracketing trigger pulse, it can also be invariant with frequency.

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Right, but if there is a nonzero fixed offset relative to the zero crossing in the triggers driving the PLL, it's not going to know it.

My little 3-part thing, with the phase lead cap, does pretty well from

You criticized Blogg's reference saying, "Probably glitch sensitive."

Wonder how yours does with hash near the zero crossing ?:-) ...Jim Thompson

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ide quoted text -

IEEE 519 standards for total harmonic voltage distortion allows for a THD of 10% in "Dedicated Systems =95 Factories" and 5% in "General Applications =95 Office Buildings/Schools" .And that is just long term steady state, no telling what could be happening transiently. JL's circuit will be jumping all over the place.

Hash? Don't they measure it in grams and smoke that stuff in California? :)

The hosting company may have locked out a block of IP addresses for attempted hacking or a DOS attack. :(

Well, there is a little deadband, and it's not super-fast, so it won't be as twichy as it might. A really fast circuit may be a liability. But I'm not sure how one would even define the perfect zcd for the AC line. Bandpass filter? PLL? Might make some things worse. And in most applications that I can think of, I'm not sure it much matters. Like, if you're doing phase control power, it's not going to matter much if you nail the zero to a tenth of a degree, or if there's some jitter. You're starting with all the slop of the AC power line.

Really good phase control would use the first part of the cycle, not the last (so, no triacs) and digitize the delivered energy, shutting off when the target amount was hit. But then, why not just PWM the AC line?

Situation normal, I don't think we know what the OP is ultimately trying to do.

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Then any zero-crossing detector will jump all over the place. The question becomes: how much does it matter?

The distortion I see on AC power lines is predominantly symmetric flat-topping, from all the rectifier-capacitor loads I assume. The zero crossing is still, by definition, the zero crossing, which was asked for here. I don't think my circuit, with the capacitive lead hack, will do badly. If it does, don't use it.

You're very energetic at researching standards and criticizing circuits. Why not put some of your wisdom and energy into designing something better, and posting it here?

I actually did a light controller that way for OmniComp/GenRad back in my disco days ;-)

Also did a neon controller that passed (or skipped) full cycles so I didn't toast the HV transformer with phase control.

Yep. The questions are never posed like the specifications we're used to seeing. ...Jim Thompson

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Your circuit and the dual LED emitter optos are only intended for AC line monitoring applications, they are not a breakthrough in ZCD technology. The circuit in the EDN link, or some variant of it, is simple and cheap enough, although the stuff with the zener and transistor defeat some of the advantages of the original idea. The OP did not want the zero crossing for the purpose of reducing turn-on surge, he wanted it for a timing baseline for half cycle by half cycle RMS voltage control in a lamp dimmer application.

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=A0 =A0...Jim Thompson

I've seen a few examples of that, fet or igbt in the middle of a diode bridge

and since unlike a triac you can turn it off at anytime it is easy to add short circuit protection

-Lasse

-Lasse

No man. It's called ganja and is measured in the kilograms.

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Well, with two parts for the basic function, it is pretty cool. And since I've never seen it anywhere else, I hereby declare it to be a breakthrough.

So, design something better and post it here. Is your skill set limited to complaining? Check one box:

YES / /

NO / /

Shows that I've never been to California, doesn't it? :)