I recently purchased 2 little voltmeters they look like the sort that would go in a control or instrument panel they are connected with just 2 wires which provide the operating supply ( they light up green and red) however the green one states it will work between 20and 500 volts and the red one between 60 and 480 volts. When they are both on the green one indicates normally around 241 volts the red one shows 235 volts why the discrepancy I know it's not much but makes you wonder if one of them is lying. Secondly I've noticed that the green one tracks voltage changes faster than the red one and that a few times the green one jumps down to 238 then up to 241 multiple times while the red one stays the same and I think can see a slight flicker in my filament lamps when this is happening incidentally both meters are connected to the same plug a 2 pin 5 amp one
Ok il rewrite my reply as I can't sleep and it will save Lisa a job here goes Mapj thankyou for a very detailed reply I recognise the waveform in picture 1 the mains waveform here is very similar although I don't think the crests are as crushed tho not far off. In picture 3 I can clearly see that the 150 cycle waveform goes to the opposite polarity a few milliseconds before the supply voltage crosses over at that point you could almost say it forms a mini sine wave all its own loosely speaking. Now I'm guessing that these effects are caused by the inductance and capacitance of not only the diodes but other parts of the wiring too. I read somewhere that even house wiring can have appreciable inductance to relatively fast moving events the comment was made in relation to the causes of audible clicks on PA systems from things like the heaters in tea urns or pie warmers which I know is a different thing altogether I just added it for completeness.
Ok il rewrite my reply as I can't sleep and it will save Lisa a job here goes Mapj thankyou for a very detailed reply I recognise the waveform in picture 1 the mains waveform here is very similar although I don't think the crests are as crushed tho not far off. In picture 3 I can clearly see that the 150 cycle waveform goes to the opposite polarity a few milliseconds before the supply voltage crosses over at that point you could almost say it forms a mini sine wave all its own loosely speaking. Now I'm guessing that these effects are caused by the inductance and capacitance of not only the diodes but other parts of the wiring too. I read somewhere that even house wiring can have appreciable inductance to relatively fast moving events the comment was made in relation to the causes of audible clicks on PA systems from things like the heaters in tea urns or pie warmers which I know is a different thing altogether I just added it for completeness.
