[sdiy] super simple portamento / slide / glide / slew limitingcircuit?

[Todd Sines]

hi everyone,

Thanks all for the help.

But... maybe I wasn't clear..

This is intended to modify the Roland DG series CMU-810. It's essentially an analog synth tabletop expander that sounds a lot like an SH-101, MC-202 or SH-09.
http://matrixsynth.blogspot.com/2009/10/roland-cmu-810-compusynth-modded-analog.html
[in the end I'd love mine to end up like this one, but for now, I just wish to add portamento]

What's different about this compared to the rest is that there's no portamento of the incoming CV / gate jacks.
So I'd like to cut the track for incoming CV, insert this _SUPER_ simple portamento circuit before it starts triggering the osc.
As I'm sure you know, Roland follows a linear pitch scale so I don't need a switchable or dual mode circuit.

Something about the first circuit from EM seems closer to what I need [versus circuits that need their own power, etc].

Is this helping or did I miss something from before? because it seems like all of these circuits are for much more complex applications, no?

Thanks... in advance!


+odd
--
On Jul 13, 2011, at 4:14 PM, David G Dixon wrote:

>> http://www.elby-designs.com/asm-2/glide/glide-asm2-about.htm
>> 
>> Switchable lin and log response. One dual op amp, two 
>> resistors, cap, pot, switch.
> 
> I don't like that circuit at all!  The comparator will oscillate in linear
> mode, generating about a 10V p-p sine wave at about 7400 Hz or so which
> takes a very long time to dampen out.  This will create high-frequency
> warble of several mV in the output.  I believe this circuit requires a large
> resistor in the negative feedback loop of the comparator -- 100k gives a
> smooth approach to the input voltage with rapid damping (less than half a
> millisecond).  Also, the buffer benefits from a capacitive load protection
> network.  Finally, the switch could be much simpler -- an SPDT will do if
> it's hooked up properly.
> 
> Again, email me privately for details.
>