[sdiy] passive ring mod question

[TIm Daugard]

Since no one else in answering, I guess I will. If you are using the traditional
two transformers and a ring diode set, then the connections to the transformers
can have one lead grounded and the other connected to the center pin of the
connector. The problem comes with the connections to the center taps of the
transformers or the connections to the diodes (depending on the configuration
you use.)

The diodes need a current path that changes direction. if you have a signal
source that goes above and below ground, then one side of the path can be
grounded (we're talking about the audio path in an RF ring modulator - called a
balanced modulator.)

If your signal is always above ground then you will need to level shift the
signal to ground. This involves at least one capacitor and resistor. The center
conductor of the audio modulation signal has to be connected to the cap. the
other side of the cap is connected to the resistor. The other side of the
resistor is connected to ground. The junction of the resistor and cap are
connected to one of the transformer center taps while the other center tap is
connected to ground and the ground pin on the connector.

This connection scheme wastes some of your audio modulation signal in and is no
good for a DC modulation voltage.

Tim Daugard
AG4GZ 30.4078N 86.6227W
http://home.sprintmail.com/~daugard/synth.htm

. . . and where is everybody? I was waiting to hear some of the other answers to
this. Don't tell me everyone is answering in private. I'm going back to 1)
lurking, 2) taxes, 3) the stock market, 4) trying to get a good running copy of
GCC for my computer, since you all are moving on to uP based discussions. I have
gotten a bootable version of Linux going so no I can boot to Linux instead of
DOS. D**m it, y'all keep adding more things to my list of things to do. . . and
some one just called and wants me to come out of retirement.


----- Original Message ----- 
From: "Pat Kammerer" <spivkurl at wearerecords.com>
To: "sdiy" <synth-diy at dropmix.xs4all.nl>
Sent: Tuesday, February 08, 2005 10:27 AM
Subject: [sdiy] passive ring mod question


> Hi all,
>
> I just had a quick question.  I've built several passive ring modulators in
> the past, but for jacks I've always used 1/4".  I want to incorporate my
> latest ring mod into my modular.  I use banana jacks for this though.  Each
> input and the output have two leads, so how do I wire this.  I'm assuming I
> would ground one of each right?  How would I know which one, and does it
> matter which one?
>
> Thank you!
> Pat
>