[sdiy] passive ring modulator transformers

[Scott Gravenhorst]

In this image:

http://scott.joviansynth.com/diode_ring_modulators.gif

There are two schematics, one for the well known diode/transformer ring 
modulator and another for a version of the same circuit using resistors.

I've not tried either one of these.  Someone had posted these to SDIY 
some years ago and I squirreled them away.  I remember that there was 
something not ideal about the resistor method and that adding opamps to 
the design could improve it.  I also have a schematic I drew using 
opamps, but I won't post that because I never tested it.

Here:

http://scott.joviansynth.com/diode_ring_mod_2.gif

is another transformerless circuit which I did not test which uses opamps.