@xekon I measured the phase angle between mains (250vac at the lab) and the output of the module powered by a cleanish 5V.
Yes, I used a 2ch scope. The 1000V rated high impedance inputs don’t cause too much added phase shift. If your scope can’t take the voltage, a resistor divider is fine enough to bring it down, just gotta be careful with that there live wire.
It’s an Okay scope I had access to, it automatically found the phase shift and gave me a value in microseconds of the shift, which I converted into radians (and then degrees) according to the frequency, which was 49.8Hz, or something thereabouts. phase angle in degrees is… (time delay/period)*360 … might need correcting there.
Interested to know if you get similar results or manage to get a clean signal from the voltage transformer without the smoothing (so the flat tops are visible), without the opamp! But it does sound like you need a better scope with more resolution.
At the moment my conclusion, similar to Robert’s but for different reasons it seems, is that the modules are useful as amplitude and frequency measurement devices, but not for super-accurate monitoring.
This discussion has got me thinking about another test to make on the transformer component, sans module, might have another go at it.
Well, my take on mains voltage… mains voltage is nasty, but not too nasty. If it were, it wouldn’t be in the walls of our houses. I’ve had a few shocks, not that bad. An experienced sparky said to me he used to test wires with his thumb nail. Could’ve been taking me for a ride. But I duly took it on board regardless, and after flipping a breaker for electrical work, I test wires (including neutral and earth) with my thumb nail before handling it properly, after all, better safe than sorry.
I jest, a little.
But get this. You might know, in the EU, the standard socket outlet is 230Vac and there is NOTHING stopping a child from sticking a metal skewer into that live connection. THAT is dangerous. At least in the UK we have the plastic gate-things which require an earth pin to be inserted for the live to be revealed and accessible.
Interestingly perhaps, I was going to say that since you’ve done your own wiring (first time?) you might want to get a professional to take a look. I wasn’t going to say this at first, didn’t want to patronise you. I’ve had the fortune of being shown how to do house wiring and take it for granted now, despite it not being my profession per se, really glad someone showed me.
And I read now… electrical fires cause many more deaths than electrical shocks. I don’t mean to minimise the deaths that do occur because of shock either.
If we’re going to talk safety, we might as well get our priorities straight innit.