simple crossfade circuit???

[Paul Perry]

At 08:20 AM 3/06/98 -0700, dan mcmullen  wrote:
>i need to crossfade between two signal sources using a fader type pot.  is
>there any way to do this other than using a dual pot with inverse audio
>tapers on the 2 paths?  do such things even exist?

.....people have said in the past that it is possible to dissemble some pots
and rebuild "backwards".....(actually this is for rotary pots)..
if you only need one, then you can use 2 gearwheels one on each shaft so you
turn 
one and the other turns backwards, this meccano aproach used to be common in
homebrewed ham radio gear..
if you have sliders, you can have an 'X' arrangement so one slider going up
pulls 
the other down, but you need a specially made slotted arm.

Easy to do with a linear pot and one op amp, that is what I do..
inputs A and B go to opposite ends of a 100K pot, the wiper arm of which
goes to earth.
Each end of the pot also has a 100k resistor going to the - input of the op
amp, which has
a suitable fbk resistor etc. End of story :)

paul perry melbourne australia
still looking for the Radiation Laboratory 'Computing Linkages' volume...
will pay cash