[R-390] in rush current limiters

Sun, 22 Dec 2002 17:48:35 -0800

>
> A three-terminal regulator configured as a constant
> current source would not need a ground connection.
> Just a heatsink.

Is this practical in an AC circuit?  Perhaps two circuits could be
configured for each half-cycle and diode isolated.

Think it is a bit of overkill, though.  The oscillators don't appear to be
that sensitive to typical changes in filament voltage.

Fun to think about, though.

Bill

----- Original Message -----
From: "Jim Shorney" <[email protected]>
To: "Bill Smith" <[email protected]>; <[email protected]>
Sent: Sunday, December 22, 2002 5:32 PM
Subject: Re: [R-390] in rush current limiters

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>
> On Sun, 22 Dec 2002 16:03:01 -0800, Bill Smith wrote:
>
> >The current is 300 ma.  AC.  It is simply the filament current of two
6-volt
> >miniature tubes (v508-6BA6/5749, V701-6BA6/5749) in series.  The source
> >voltage is about 25 volts.  12 volts is taken by the two tubes in series,
> >and the ballast and decoupling inductors
> >drop the other 13 volts.
>
>
> Thanks for the info.  This makes the comment about using a diode
> somewhat puzzling.  ISTM that a diode is going to half-wave rectify the
> AC filament voltage and change the whole game about what exactly '300
> mA' is.  Which would start another never-ending thread, no doubt.
>
>
> >The idea is to build a 9-pin miniature tube plug-in replacement with no
> >modification to the R-390A.  Only two wires are fed to the ballast
socket.
> >Ground is not available unless obtained by a tertiary wire or the socket
> >shield.
>
>
> A three-terminal regulator configured as a constant current source would
not need a ground connection.  Just a heatsink.
>
>
>
> - --
> Jim Shorney      -->.<--Put complaints in this box
> [email protected]
> [email protected]
> Ham Radio NU0C
> Lincoln, NE, USA
> EN10PT
> http://incolor.inetnebr.com/jshorney/
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