Any professional opinions on this?
One sec lemme upload it..
http://webpages.charter.net/dawill/I...F%20Driver.gif
- For 6V6 PSE

Tim

--
In the immortal words of Ned Flanders: "No foot longs!"
Website @ http://webpages.charter.net/dawill/tmoranwms

Phil Allison wrote:
"Tim Williams" wrote in message
...

Any professional opinions on this?
One sec lemme upload it..
http://webpages.charter.net/dawill/I...F%20Driver.gif
- For 6V6 PSE




** The one diode load and NFB point that connects some "plate" to ground
via 1 kohm are a bit mysterious ?

I'm suspecting that the diode represents the grid-cathode "diode" in a
fixed-bias power amp stage. And (maybe it's a long shot) the enigmatic
"plate" might be the plate of the same PA.

I'll admit I got a little lost when trying to think through the biasing
scheme. There also appears to be negative feedback for signal here, too.

Did you actually SPICE this, Tim? Or are you flying by the seat of your
pants like most of the rest of us?

Cheers,
Fred
--
+--------------------------------------------+
| Music: http://www3.telus.net/dogstarmusic/ |
| Projects, Vacuum Tubes & other stuff: |
| http://www.dogstar.dantimax.dk |
+--------------------------------------------+

"Fred Nachbaur" wrote in message
.. .


Phil Allison wrote:
"Tim Williams" wrote in message
...

Any professional opinions on this?
One sec lemme upload it..
http://webpages.charter.net/dawill/I...F%20Driver.gif
- For 6V6 PSE




** The one diode load and NFB point that connects some "plate" to
ground
via 1 kohm are a bit mysterious ?

I'm suspecting that the diode represents the grid-cathode "diode" in a
fixed-bias power amp stage.


** I reckon it is meant to be a LED ;-)


And (maybe it's a long shot) the enigmatic
"plate" might be the plate of the same PA.


** With a 1 kohm to deck ????



I'll admit I got a little lost when trying to think through the biasing
scheme. There also appears to be negative feedback for signal here, too.

Did you actually SPICE this, Tim? Or are you flying by the seat of your
pants like most of the rest of us?



** Plenty of action with the joy stick while doing that SOP flying.




......... Phil

Phil Allison wrote:

"Tim Williams" wrote in message
...
Any professional opinions on this?
One sec lemme upload it..
http://webpages.charter.net/dawill/I...F%20Driver.gif
- For 6V6 PSE


** The one diode load and NFB point that connects some "plate" to ground
via 1 kohm are a bit mysterious ?

........... Phil

Nope, the diode and 1k are acting as a cathode voltage limiting network for
V2.

It isn't clear what the circuit is for, since there is no point nominated for
output.

Maybe its some type of limiter or compressor.

Patrick Turner.

"Patrick Turner" wrote in message
...


Phil Allison wrote:

"Tim Williams" wrote in message
...
Any professional opinions on this?
One sec lemme upload it..

http://webpages.charter.net/dawill/I...F%20Driver.gif
- For 6V6 PSE


** The one diode load and NFB point that connects some "plate" to
ground
via 1 kohm are a bit mysterious ?

........... Phil

Nope, the diode and 1k are acting as a cathode voltage limiting network
for
V2.


** I thought of that right off - then dismissed it as absurd.

It says " RL = 1.2 k " .... bit of a giveaway.



It isn't clear what the circuit is for, since there is no point nominated
for
output.


** RL is not an output ??


Maybe its some type of limiter or compressor.


** Very mysterious.



............... Phil

"Phil Allison" wrote in message
...
** The one diode load and NFB point that connects some "plate" to ground
via 1 kohm are a bit mysterious ?

Ok I'll be more clear with that.. the diode and resistor represent the
grid diode (yes, Derf of a pair of 6V6s in parallel (PSE). Purely
for show. Feedback comes from their collective plate (not OPT sec.,
since this has to be isolated - notice anything suspicious about the
specific voltage?

Tim

--
In the immortal words of Ned Flanders: "No foot longs!"
Website @ http://webpages.charter.net/dawill/tmoranwms

"Fred Nachbaur" wrote in message
.. .
I'm suspecting that the diode represents the grid-cathode "diode" in a
fixed-bias power amp stage.

Yeppers...

And (maybe it's a long shot) the enigmatic
"plate" might be the plate of the same PA.

Zero bias at 160V looks pretty linear so I'm going to give it a shot.
4W for two tubes (running 8W Pd BTW) and no power transformer, I'll take
that. :-)

I'll admit I got a little lost when trying to think through the biasing
scheme. There also appears to be negative feedback for signal here, too.

Hint: assume output cathode at 0V (as is the goal in biasing, think
I forgot to mention that too?), 1st K @ -100V.

Did you actually SPICE this, Tim? Or are you flying by the seat of your
pants like most of the rest of us?

Wassa spice?

Tim

--
In the immortal words of Ned Flanders: "No foot longs!"
Website @ http://webpages.charter.net/dawill/tmoranwms

"Tim Williams" wrote in message
...
"Phil Allison" wrote in message
...
** The one diode load and NFB point that connects some "plate" to
ground
via 1 kohm are a bit mysterious ?

Ok I'll be more clear with that.. the diode and resistor represent the
grid diode (yes, Derf of a pair of 6V6s in parallel (PSE). Purely
for show. Feedback comes from their collective plate (not OPT sec.,
since this has to be isolated - notice anything suspicious about the
specific voltage?



** The 6V6's plates are at zero volts ??


......... Phil

"Fred Nachbaur" wrote in message
.. .


Phil Allison wrote:
"Tim Williams" wrote in message
...

Any professional opinions on this?
One sec lemme upload it..
http://webpages.charter.net/dawill/I...F%20Driver.gif
- For 6V6 PSE




** The one diode load and NFB point that connects some "plate" to
ground
via 1 kohm are a bit mysterious ?

I'm suspecting that the diode represents the grid-cathode "diode" in a
fixed-bias power amp stage. And (maybe it's a long shot) the enigmatic
"plate" might be the plate of the same PA.

I'll admit I got a little lost when trying to think through the biasing
scheme. There also appears to be negative feedback for signal here, too.

Did you actually SPICE this, Tim? Or are you flying by the seat of your
pants like most of the rest of us?


Talkin' about Schizophrenic connections to the topic... Am i using bad
models, or are [available] pentode models really weak in SPICE? I haven't
spent much time with spice, and could be doing something wrong, but I've
intentionally ran sims on circuits *i know* would go into wild oscillations,
and got clean output. I know i should probably tweak the circuits for stay
C and so on, but ... Do you get the same results on the bench as youu do on
SPICE (small-signal triodes seem to work ok)?
Cheers,
Fred
--
+--------------------------------------------+
| Music: http://www3.telus.net/dogstarmusic/ |
| Projects, Vacuum Tubes & other stuff: |
| http://www.dogstar.dantimax.dk |
+--------------------------------------------+

Phil Allison wrote:

"Patrick Turner" wrote in message
...


Phil Allison wrote:

"Tim Williams" wrote in message
...
Any professional opinions on this?
One sec lemme upload it..

http://webpages.charter.net/dawill/I...F%20Driver.gif
- For 6V6 PSE


** The one diode load and NFB point that connects some "plate" to
ground
via 1 kohm are a bit mysterious ?

........... Phil

Nope, the diode and 1k are acting as a cathode voltage limiting network
for
V2.

** I thought of that right off - then dismissed it as absurd.

It says " RL = 1.2 k " .... bit of a giveaway.

It isn't clear what the circuit is for, since there is no point nominated
for
output.

** RL is not an output ??

Maybe its some type of limiter or compressor.

** Very mysterious.

.............. Phil

If RL = 1.2k, its a poor type of load unless the output is a tiny voltage.
So I am not sure of the purpose, but the operating voltages are
clearly calculatable, and what would be the output waveform.
There is note saying "NFB from the plate", but none comes from there.

Mysterious it is, and perhaps our Tim could explain its function.....

I had a client bring me an old 1940 synthesizer, with about 10 tubes,
and a keyboard, and lots of switches and bundled wiring looms.
I have not the feintest idea what makes it work, and it don't work,
and the complexity is about 40 dB worse than Tim's
tiny tot of a circuit, and I ain't loosin sleep over it.

Patrick Turner.

"Phil Allison" wrote in message
...
** The 6V6's plates are at zero volts ??

Uhm...no...they're at +150...1.2k SE OPT load...

Tim

--
In the immortal words of Ned Flanders: "No foot longs!"
Website @ http://webpages.charter.net/dawill/tmoranwms