[sdiy] Passive Ring Modulator

[cyborgzero at comcast.net]

I wonder if it would be worth it to wind your own xformer? Perhaps use
a toroid instead of a straight core?

I have wound my own xformers for quite a few projects, and, IMHO,
sometimes it seems to end up having better results than when I have
sat around waiting for weeks for a particular part, only to be
somewhat dissapointed by the replacement and go back to my
handwound...

I have piles of TDK ferrite toroids laying around here. ;) Mostly
pulled from TV chassis at work, and they are ripe for the wrapping. ;)


Rob

----- Original Message -----
From: "John L Marshall" <john.l.marshall at gte.net>
To: <cyborgzero at comcast.net>; "Synth (E-mail)"
<synth-diy at dropmix.xs4all.nl>
Sent: Friday, July 12, 2002 7:55 PM
Subject: Re: [sdiy] Passive Ring Modulator


> One technique to improve rejection is to use transformers with split
> windings instead of center tapped windings. If the windings are
bifilar, two
> wires in parallel, then the inductance and capacitance will be
nearly
> identical. But if the windings are not bifilar, split windings will
still
> still help.
>
> Where the center tap ought to be, put a small trim pot (50 ohms).
Attach
> each trim pot end to each winding and the wiper becomes the new
center tap.
> Do this for each transformer.
>
> Adjusting for minimum feedthrough will be a challenge.
>
> Take care,
> John
> --------------------------------------------------------------------
-------
> Pacific Northwest DIY Synthesizer meeting, July 20, 2002
> See: www.sound-photo.com
> --------------------------------------------------------------------
-------
>
> ----- Original Message -----
> From: <cyborgzero at comcast.net>
> To: "Synth (E-mail)" <synth-diy at dropmix.xs4all.nl>
> Sent: Friday, July 12, 2002 2:43 PM
> Subject: Re: [sdiy] Passive Ring Modulator
>
>
> > Yes, I am *definitely* interested in this two diode ring approach,
> > since the key issue with passives is they fact that they have a
> > problem with carrier rejection. Anything that would increase that
> > would be good in my book. ;)
> >
> > Rob
> >
> > ----- Original Message -----
> > From: "Steve Begin" <Steve.Begin at pwgsc.gc.ca>
> > To: "Synth (E-mail)" <synth-diy at dropmix.xs4all.nl>
> > Sent: Friday, July 12, 2002 12:29 PM
> > Subject: RE: [sdiy] Passive Ring Modulator
> >
> >
> > > Awesome!  I found a 42TL028 transformer on mouser.com hopefully
that
> > is the
> > > same thing.  I will try to order a few. Thanks a lot!
> > >
> > > How is the second diode ring connected in the design you have?
> > >
> > > Steve Begin
> > >
> > >
> > > -----Original Message-----
> > > From: ian [mailto:deviant at custard.org]
> > > Sent: Friday, July 12, 2002 12:55 PM
> > > To: Steve Begin
> > > Cc: Synth (E-mail)
> > > Subject: Re: [sdiy] Passive Ring Modulator
> > >
> > >
> > > Hi Steve,
> > > I have a boxful of ringmods much like this sitting on my desk
right
> > now! I
> > > haven't had a chance to try them out yet, but other people who
have
> > tried
> > > them say they sound great. The design I have was given to me by
a
> > > colleague, and it comes from the Amateur Radio Relay League
> > handbook. It
> > > differs slightly from the one on sonicstate, as it has two diode
> > rings,
> > > which is supposed to provide better carrier rejection than the
> > single
> > > diode ring design. As for the transformers, the ringmods I have
use
> > one
> > > from Mouser, marked TL028 down one side and 0109S down the
other.
> > > Ian
> > >
> > >
> > > On Fri, 12 Jul 2002, Steve Begin wrote:
> > >
> > > > Hi, I'm new to the list, not new to analog (am I gonna get in
> > trouble if I
> > > > spell it like that?)
> > > >  gear, but fairly inexperienced when it comes to circuitry.
> > > >
> > > > I've got a question, has anybody had any experience with a
passive
> > ring
> > > > modulator design like this one?
> > > > http://www.sonicstate.com/synthfool/ringmod.html
> > > >
> > > > I'm interested in it since it looks very easy to make and
cheap
> > and if it
> > > > doesn't work as well as other designs it doesn't bother me
that
> > much.
> > > > However,  I guess the stancor a-4713 driver transformers are
no
> > longer in
> > > > production and I can't seem to find anything information on
them
> > at all,
> > > let
> > > > alone a reference to a part I could use as a substitute.
> > > > I'd really appreciate it if somebody could give me any
direction
> > at all
> > > > here.
> > > >
> > > > The other thing I was wondering about (and I'm sure it's
probably
> > > painfully
> > > > obvious to a lot of you) was half or full normalled patch
bays.
> > When you
> > > > split a signal doesn't it affect the impedance or something
along
> > those
> > > > lines?  I thought it would be a bad thing to do but I haven't
seen
> > anybody
> > > > mention any problems with that.
> > > > How about combining signals without a mixer?  I'm almost
positive
> > you get
> > > > problems doing that.
> > > >
> > > > Thanks!
> > > >
> > > > > Steve Begin
> > > > >
> > > > >
> > > > >
> > > >
> >
>