About the CS5

[Jeremy Brookes]

>Is there anybody who knows how I can get the portamento working on my 
Yamaha
>CS5?
>I control it from my Doepfer Analog Sequenser but that doesn?t give me any
>portamento option. Can one "reroute" the portamento inside the CS5 so I 
can
>get the effect when it is controlled from an external source? Same goes 
for
>all other synths with this "problem"...
>
>Another question: How is the easiest way of converting a V/Oct CV to Hz/V
>(without midi)? I know Korg had a converter back in the days but how about
>building one?
...if you have a spare V/Oct synth..no matter how primitive....then let it
generate a clean note, and feed this to a simple (one chip) Freq to Volt
convertor...... this is the only simple way IMHO if you want something in 
tune.

The beauty is, if you want MIDI to drive a Hz/V synth, you can take the
output from
a module & do this.

The portamento is likely to be harder, but it is usually possible to 
arrange a
light dependant resistor/led combo with the ldr replacing the resistor that 
delays the charging of the capacitor holding the CV for the oscillator..
but this is very circuit specific.. don't know what a CS5 looks like here.

Now reading the question again it looks like the CV in must bypass the 
whole
portamento section, if the portamento has no effect when the Doepfer is 
running
it. But it would be possible to make a portamento circuit fairly easily, to 
go
between the Doepfer and the CS5.... and if the Doepfer has a spare CV out, 
then
you can use the ldr trick here, and not have to hack the CS5 at all.

This is quite common according to the manual with my Kenton MIDI-CV 
interface. Most old analogs CV and Gate inputs bypass the Portamento 
circuit. That's why people like Kenton implement the portamento in the 
interface. Has the benefit of allowing you to switch the portamento on and 
off or change the rate under MIDI control. Great for just sliding 
individual notes, as in TB-303. Alternatively add an external portamento 
circuit between the output of the analog sequencer and the CV input to the 
CS5. Plenty of circuits abound on the 'net for this; there are even two on 
my home page (http://homepages.enterprise.net/jezz/)