[sdiy] transformer buffering, terminology lost - simple question and live in

[Anthony Bisset]

> I'm wondering what you mean by "shunting" resistor.

I think I misused the term shunting..  I meant adding a resister
in series to the primary winding of the transformer so as to prevent too
much current from flowing to ground and killing the pre-transformer output.
I don't have enough knowledge yet, but I assumed current allows the signal
to exist? So if we cut the amount of current that can flow, i guessed it
would leave some signal on the non-inverted output.


> Did you put the resistor in
> parallel with the transformer's primary?  If so, this won't limit current into the
> transformer primary except if the loading on the OpAmp's output is above spec.  A series
> resistor will limit the current, but doing so will also limit the output of the
> transformer's secondary.   Two transformers of the same type with primary windings in
> series and with the proper series resistance might be able to give you both an inverted
> and noninverted version of the signal that will have closer to equivalent output levels.
>  I'm also not sure if the driving circuit you attached to the primaries likes an
> inductive load.

Ahh, now the inductive load angle is probably where this went wrong very
early.  My test case was a dual slew generator which is probably
complicated by the output being 0-5 and not exactly ac...  although i did
get an inverted output from the transformer the non-inverted signal
appeared unavailable and i'm probably taxing it.


> I'm also curious why you've used a transformer, maybe there's something else going on
> here you've not stated,

Well, the system is 10 panels.  And i have nearly 45 inverted outputs.
building envelope followers for all these would be a chore, and i just
happened to come across 70+ etal transformers.  A friend and I looked at
their signal response and I liked the roll-off they provided and the mild
distortion.  So, it was partly asthetic and partly functional.  I work a
lot with feedback (think mbv, fennez, not silly noise music, but melodic
sound field).. so these seemed a good addition to the system.

> I think that the spectrum and probably delay of the signal signal,

how many picoseconds or microseconds does a transformer like this bring?
in my world this delay could be very helpful for producing the type of
washes and sound fields i enjoy.

> Did you do this because a transformer is a passive component with no need of a power supply?

This and the above reasons, plus providence.

I'm going to re-read the response as i'm learning a lot and good advice
all around.  If i tap the signal before the serges output resisters like
Mr. Ridley was saying, i may get a more appropriate response from the
module.

Last question, kinda silly, but is running a signal through a coil
(primary of the transformer) to ground at all bad for the hardware driving
the circuit?  I'll experiment.  If i have to use 2 transformers in series
that could be cool, although I won't have any left over for my
ringmodulation tree i want to build (multi-tap cascading ringmodulator).

thanks all, as usual i'm learning so much.
-a
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