[sdiy] super simple portamento / slide / glide / slew limiting circuit?

[Todd Sines]

Trying to mod my Roland CMU-810 synth expander module for portamento / slide / glide / slew limiting over the CV input.
[and maybe audio in]

Anyone done this, or can suggest a proper portamento circuit that could be used to add to the input ..

The electro-music post suggests it'd be as simple as 3 components: a pot, a cap, and an op-amp... 
http://electro-music.com/forum/post-149264.html

Thanks,


+odd