On Thursday, December 6, 2001, at 06:23 AM, Tkacs, Ken wrote:
>
> If you feed a sine into both inputs of a ring modulator, you get a sine
> an
> octave higher, not a rectified sine. It outputs the sum and difference
> signals, so the sum of "1" and "1" is "2 (doubled frequency)," and the
> difference is zero. This only works for sines, of course, because any
> more
> complex signal gets immediately non-linear.
>
> I'm not sure where you're getting the rectification from. You can do
> some
> rectification with a few diodes, but that's usually used for AC power.
> For
> audio applications, there're ways of rigging an op-amp to do that, I
> think.
But isn't a ring mod a four quadrant multiplier? If the input voltage
at x
and y is both -1, won't the result be 1? So if I had a guitar signal
into X,
and square wave swinging from +1/-1 at every zero crossing of the guitar
signal, wouldn't that result in rectification? If I do it with a triangle
and square:
X
+1 /\ /\
/ \ / \
0 +------+-----+-------+-------------------------------
\ /
-1 \/
Y
+1 ------- --------
0 -------------------------------------------------
-1 -------
Degrees:
0: 0 ∗ 0 = 0
45: .5 ∗ 1 = 1
90: 1 ∗ 1 = 1
...
225: -.5 ∗ -1 = .5
270: -1 ∗ -1 = 1
Isn't that rectifying the triangle?
Tomy