Re: ScopingSSTC

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: Jan Wagner <jwagner@xxxxxxxxx>

Hi,

Your question has already received a lot of answers, but here's my 
$0.02 as well...

On Wed, 14 Dec 2005, Tesla list wrote:
> Original poster: "Alexander Turkin" <alex_3@xxxxxxx>
>   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??????

You can, when the GDT is disconnected from any "hot" (=mains powered) circuit.

You can, too, with the GDT connected to a running circuit that has 
been isolated from the mains (battery, isolation xfrm)

Differential measurement is seldom necessary with SSTCs. 
"Differential" usually means you use two channels A,B and plot the 
waveform A-B, or use an active differential probe.

A floating measurement with mains powered circuits is a more likely 
scenario in SSTC devel. Either use a handheld industrial oscilloscope 
intended for the task (plastic or rubber encasing with >600VAC 
isolation, e.g. Fluke ScopeMeter series), or a desktop oscilloscope 
and float the circuit(!).

 - Jan

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 Helsinki University of Technology