Re: ScopingSSTC

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: Jan Wagner <jwagner@xxxxxxxxx>

Tesla list wrote:

> Original poster: "Alexander Turkin" <alex_3@xxxxxxx>
> I'm going to watch the signal, coming from Gate Drive Transformer (I 
> don't have an H-bridge yet)
>
> 1) Can I connect the probe of ONE channel to the GDT secondary 
> (WITHOUT an H-bridge)?
> I can't see the reasons against. The GDT act as an isolation transformer.

In 1) of course you can connect one scope channel to the GDT output! :-))

See for example the GDT testing setup here

 http://users.tkk.fi/~jwagner/tesla/SSTC/schem/gdt-testcircuit-large.gif

It shows where to connect the scope, just in case ;-). In addition, 
the GDT output is symmetric so it doesn't matter which way around you 
connect the scope probe's ground clip and the tip.

For a simple test you don't need R1 and C4. For details on them see 
the part about "Testing" in
 http://users.tkk.fi/~jwagner/tesla/SSTC/general-sstc-notes-gatedrv.htm

> 2) What is floating...........?

A "floating" circuit is galvanically fully isolated from something else.

Which means there's no DC path between the circuit and the "something 
else" - no shared voltages or shared ground. If there's any kind of 
connection then it is 'only' an inductive one, like an isolating transformer.

In your GDT test setup, the "something else" would be the mains 
voltage supply and the mains ground that the Scope connects to.

The GDT secondary is already "floating" because up until you connect 
the scope probe to it, it doesn't have any connection to the mains 
voltages and mains ground. So, nothing nasty can happen.

- Jan