On 29/03/2018, Simon Hobson <[email protected]> wrote: > Edward Bartolo <[email protected]> wrote: > >> What you wrote reminded me of a dangerous filter that consists of two >> high voltage series-connected capacitors connected in parallel with >> the mains with their middle point earthed. Since these capacitors are >> almost certainly the same value they will devide the mains voltage by >> two. This fact can be verified with a high impedance voltmeter >> connected with the disconnected earth connector and one terminal of >> the mains supply. > > Yes. Doesn't need to be that high an impedance meter either, a while ago (as > part of a discussion in another forum) I just did a quick check with a basic > digital multimeter and measured about 95V on my Macbook Pro. And as I > mentioned, there's enough current there to be able to feel it.
When I was studying Physics for my A Levels and at university, all my professors insisted upon using high impedance voltmeters. A cheap digital voltmeter/multimeter can easily have an impedance of a few megaohms which is quite high. I remember, once I had a practical Physics experiment that involved getting the characteristics for a transistor. My fellow students used old moving coil voltmeters and got terrible results. I asked to be granted permission to use a digital voltmeter for the experiment and got excellent results for all three characteristics. After, that the university physics lab was equipped with new digital voltmeters. _______________________________________________ Dng mailing list [email protected] https://mailinglists.dyne.org/cgi-bin/mailman/listinfo/dng
