Re: PWM Controller question

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: humanb-at-chaoticuniverse-dot-com 

The radio tower thing was a semi-conductive (not
semiconductor) blackberry vine tossed between the AM
tower and the wire mesh screen surrounding it. This
caused some nice arcing that contained the audio being
broadcast by the station.

Do you have a schematic of your work? Sounds like a
great idea, keep us in formed of your progress.

Regards,

David Trimmell

On Tue, 22 Jun 2004 00:29:46 -0500, "tcbfw" wrote:

 >
 > David,
 >
 > Dan's explanation of this being a means to keep the
 > coil operating at
 > resonate freq. during long arks makes sense, but as
 > this is a first attempt
 > at this combined VVTC/SSTC topology it will not be my
 > primary concern. The
 > tubes I've chosen to try this with are 810 triodes, so
 > far I've gotten the
 > sockets wired to 4 independent filament transformers,
 > it take about 200
 > watts to light them up, finished the PWM controller
 > board tonight, but still
 > have to wind the grid transformers - same basic design
 > Dan used in his
 > PlasmaSonic - just need a few more turns (takes about
 > 180Volts to switch
 > that tube full on/off).
 >
 > But enough about me and my project, with your (don't
 > ask) statement I've
 > just got to know more . . . How much power was that AM
 > station putting out ?
 > What was you experimental semiconductor ? Could you
 > "hear" the unit as it
 > burned up ?
 >
 > Can't wait for an answer,
 > Phil
 >
 > ----- Original Message -----
 > From: "Tesla list" <tesla-at-pupman-dot-com>
 > To: <tesla-at-pupman-dot-com>
 > Sent: Sunday, June 20, 2004 7:59 PM
 > Subject: RE: PWM Controller question
 >
 >
 > > Original poster: "David Trimmell"
 > <humanb-at-chaoticuniverse-dot-com>
 > >
 > > Hey that is a good question, I wondered about that
 > also. But, Phil, you
 > > got my interest; you are going to Audio Modulate a
 > "H-Bridge" of vacuum
 > > tubes!? Holly cow! What mode? Triodes, Pentodes?
Heck
 > you have me
 > > salivating on what possible design you may use?!! Of
 > course, you can
 > > also do it with IGBT's and drop the filament power
 > needs and voltage
 > > issues. I think Dan's PlasmaSonic design is good,
but
 > I could see some
 > > improvements in using (possibly) rail modulation.
 > Real high power plasma
 > > audio modulation will be seriously cool! I have seen
 > it while arcing
 > > something "semi-grounded" to a AM radio station
tower
 > many years past
 > > (don't ask!). My grid modulated VTTC has been the
 > closest I have seen
 > > yet, but quality was unreliable.
 > >
 > > Regards,
 > >
 > > David Trimmell
 > >
 > Original poster: "Eastern Voltage Research
Corporation"
 > <dhmccauley-at-easternvoltageresearch-dot-com>
 >
 > This small feedback signal was a very basic attempt at
 > allowing the system
 > to maintain constant tune even under longer arcs and
 > is basically inferior compared to the self-resonant
 > topologies in use today.
 > This small feedback idea was one of Richie Burnett's
 > and it does work to
 > some extent.
 >
 > Dan
 >
 > > -----Original Message-----
 > > From: Tesla list [mailto:tesla-at-pupman-dot-com]
 > > Sent: Sunday, June 20, 2004 4:02 PM
 > > To: tesla-at-pupman-dot-com
 > > Subject: PWM Controller question
 > >
 > > Original poster: "tcbfw" <tcbfw-at-charter-dot-net>
 > >
 > > Dan, or anyone else that might know the answer.
 > >
 > > Looking at your PlasmaSonic SSTC design,
 > > more specifically the TL494 PWM Controller.
 > > You have a feedback signal from the positive rail
 > able to change the
 > > frequency the circuit oscillates at, could you
 > explain what the overall
 > > goal
 > > of that would be ?
 > > I wanted to use the same controller IC, but drive an
 > H bridge of tubes,
 > > this
 > > will make my positive rail in the thousand rather
 > than hundred volt
 > > range,
 > > so the value of R27 thru R30 will be adjusted.
 > > Just don't understand the need to have the frequency
 > change with the
 > > power .
 > > . .
 > >
 > > Thanks,
 > > Phil
 > >
 > >