RE: EXTERNAL: Re: [TCML] Massive VTTC!!!

["McCauley, Daniel H" <daniel.h.mccauley@xxxxxxxx>]

Interrupting / Pulsing - that's all semantics and depends how you want to look at it, and active can mean "active high" or "active low", again all relative terminology.

But what I was trying to say before is that the filament is not being switched - only the cathode, which happens to share the same terminals in the 833.  The filament remains on at all times through a separate connection, typically an AC transformer whose output is "floating" or isolated from ground.

Dan
http://www.EasternVoltageResearch.com
Two Days until our new VTTC Staccato Controller is available!



On Thu, Nov 4, 2010 at 17:45, McCauley, Daniel H <daniel.h.mccauley@xxxxxxxx
> wrote:

> Actually, you are not switching filament to ground.  You are disconnecting
> (interrupting) the Cathode from ground.
> The filament always remains on through the AC transformer.
>
> Dan
>

The cathode in the 833C is directly heated.  In other words the filament
*IS* the cathode.  I'm not actively interrupting the connection of the
cathode to ground.  Supplying current to the gate of the SCR connects it to
ground.  With no power applied to the gate of the SCR the cathode floats.
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