Low Impedance and Low Pass Filter functions on a multimeter

[giacomo]

Hi, i have found these two function on a new 60€ multimeter, the Extech EX350 and i am wondering... How much can they be usefull ? Are they usefull on a cheap multimeter like this ? (it seems the only one), but most important, when i should use them ?

Maybe it is simple, i do not know, but it seemed a nice idea for a short tutorial

[David Hess]

This is the kind of meter than an electrician would use.

The low pass mode is for AC voltage measurements on pulse modulated waveforms like from VFDs (variable frequency drives) and inverters.

Low impedance AC mode is used to make accurate voltage measurements where coupling into an open circuit would otherwise give a false reading with a high impedance meter.