Re: ScopingSSTC

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: Steve Ward <steve.ward@xxxxxxxxx>

If the GDT wires happen to be connected to the MOSFETs, and the
MOSFETS connected to your 120/240V mains, then by connecting the
grounded scope probe to the source/emitter of the device will either
connect your scope probe to neutral, or worse, to a live wire,
shorting it out!  In this case, a differential probe uses 2 high
impedance probes (no possibilty of a short) which basically supplies
your own "floating" reference point.  This is great for SSTCs where
some of the switching devices are floating around at a few hundred
volts, where you obviously cant ground reference it.

Steve W

On 12/14/05, Tesla list <tesla@xxxxxxxxxx> wrote:
> Original poster: "Alexander Turkin" <alex_3@xxxxxxx>
>
> Hi everyone!
>
>     I cannot understand the purpose of differential measurment. Why
> can't I check the form of the signal by connecting the neutral probe
> of the scope to one end of GDT and the other probe to another eng of
> GDT?????? I think that it would be OK, because i DON't touch
> anything, but the wires of GDT (i mean the secondary winding, of course)
>
> Thanks.
>
>
>