[sdiy] Passive Ring Modulator

[patchell]

    While transformers are a must for RF work, they are not needed in the
audio range.  A little clever design you should be able to come up with a
circuit that just uses opamps...or course, there is the caveat that this
will sound different.

cyborgzero at comcast.net wrote:

> 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
> > > > > >
> > > > > >
> > > > > >
> > > > >
> > >
> >

--
 -Jim
------------------------------------------------
* Visit:http://www.silcom.com/~patchell/
*-----------------------------------------------
*I'm sure glad Merry Christmas comes just once a year
* -Yogi Yorgensen
------------------------------------------------