Hello,
I understand that you can trigger on AC loss using the timeout feature of your oscilloscope (mine is a rigol MSO5000. Yes, I'm using a differential probe).

But I'm uncertain how to trigger on low RMS voltage. Like, below 110V AC. I tried searching online without finding anything useful. Just a bunch of info on generally triggering.

How would I trigger on low RMS voltage?

Thanks!

Edit: See picture for what I'm looking for.

 

should be able to simply select falling instead of rising edge.

 

should be able to simply select falling instead of rising edge.

Umm, I was asking about the RMS voltage. Recall that AC goes both positive and negative. I'm not looking for either edge. I'm looking for the RMS value.

I added a picture to my OP for clarity.

 

 

Umm, I was asking about the RMS voltage. Recall that AC goes both positive and negative. I'm not looking for either edge. I'm looking for the RMS value.

I added a picture to my OP for clarity.

A carefully set Runt trigger should find it.

 

So you want to view just one cycle if it falls below the normal peak?

For that your will likely have to add some external circuitry.

 

So you want to view just one cycle if it falls below the normal peak?

For that your will likely have to add some external circuitry.

I'm actually expecting a dip on either side of the wave, but a reduced wave is totally possible.

I was thinking of using the zone trigger, but I didn't know if there's a specific way of triggering on AC voltage problems. It seems a general enough type of error, whether that be AC mains or a sine wave, that it'd have a dedicated function to trigger off of. But I guess not.

 

You need a peak detect circuit and one that resets before the next cycle. Follow this with a comparator circuit that triggers when the peak voltage exceeds a given threshold voltage. The decision has to be made at a given point after the peak detection.

Or you can sample the waveform digitally and make the decision in software.

 

What is the range of frequencies and amplitudes?

Is the low you want to detect an absolute voltage or is it relative to the previous cycle?

 

What is the range of frequencies and amplitudes?

Is the low you want to detect an absolute voltage or is it relative to the previous cycle?

Frequency is 60hz, but the dip, whether it be on the positive or the negative side, is what I'm looking for and it will be higher frequency. IDK what frequency though. A relay speed is what I'm trying to measure.

The voltages are relative to the previous cycle. Depending on what part of the cycle I'm on I'll need to measure positive/negative voltage.

E.G. On the positive half-cycle, I'll be measuring a negative voltage and on the negative going half cycle I'll have to measure a positive going voltage.

 

Well, I got the name wrong. It's the zone trigger I'm looking for, not the window trigger. The problem is that the zone trigger is in the MSO5000 manual, but not in the menu. I'm on the latest firmware, so IDK why it's not in the trigger menu like it's supposed to be.

 

And it turns out that the zone trigger is in the main menu... okay.
This would be great if, like other scopes, it could do more than a rectangle or could do more than two rectangles.

 

Ah, I can use the pass/fail feature! Cool!

 

A relay speed is what I'm trying to measure.

so connect one of spare relay contacts to a DC circuit and then you have clean flanks

 

Ah, I can use the pass/fail feature! Cool!

Can you elaborate the details for the benefit of the community here?

 

Can you elaborate the details for the benefit of the community here?

I have a PC. It has a UPS. When the AC switches on, it tends to cause the UPS to switch to backup power. I wanted to see the AC waveform to see how bad the wiring in our house is. This is a research project. I don't expect to fix anything at this time.

 

Let me rephrase my question:
The details of the pass/fail trigger setup on your scope.

 

Let me rephrase my question:
The details of the pass/fail trigger setup on your scope.

I don't understand what exactly you're asking for.

You access the pass/fail tigger and set up the mask giving deviations in div or mdiv from the current waveform. You can then tell the scope to "stop" and to "beep" when this happens so that you can see what failed and how it failed.

It's really quite limited in the sense that 20ms is the largest time base I can use. After that, the div/mdiv become so small that the scope triggers far too easily.

So, I'm uncertain if I can capture the whole event is just 12 full waves, but I'm trying.

If you'd be more clear on what info you're interested in, I'll happily share.

 

The details of the actual buttons, menus and settings in your scope, required to access that specific trigger functionality.

But never mind, I found that my scope doesn't have those options installed. It is in the manual, but not on the scope itself.

 

The details of the actual buttons, menus and settings in your scope, required to access that specific trigger functionality.
...

For future reference then, it's in the "start menu" of my scope. I may be able to access it a different, way, but I haven't noticed that other way yet.

It's kinda weird. Both zone and pass/fail triggers have to be accessed through the "start menu".