--- In Doepfer_a100@yahoogroups.com , Florian Anwander
<Florian.Anwander@c...> wrote:

> Hello Dieter
>
> > If I'm not mistaken 8 S&H's and switches are required for a 4

stage analog

> > shift register (similar to the BBDs) as you need a n additional

slave S&H

> > for each stage.
> I do not think, you need an additional slave S&H, if you decouple

not

> only the s&h with the input selector, but also the trigger, which

clocks

> the s&h.
>
> > This is required to have the analogue value available to
> > forward it to the following stage as the preceeding S&H already is
> > "reloaded" from the stage before.
> I would avoid to forward the content of one stage to the other

(causes

> voltage loss and adds noise). Instead of, I suggest to use a

clocked

> 1to8 switch, to switch the output of one s&h-stage to the eight

outputs.

>
> Let me try ASCII sketch (you need courier as font for this):
>
>
> |--common part--|--for each stage-------|
>
> +-... +------out-bus-5
> | |
> +-... +------out-bus-6
> | |
> +-... +------out-bus-7
> | |
> +-... +------out-bus-8
> CV in o---| |
> +-----s&h_5--+------out-bus-1
> | | |
> +-... | +------out-bus-2
> | | |
> +-... | +------out-bus-3
> | | |
> +-... | +------out-bus-4
> CD4051 | CD4051
> |
> +-... |
> | |
> +-... |
> | |
> +-... |
> | |
> +-... |
> | |
> Clock in--| |
> +------+
> |
> +-...to s&h_6
> |
> +-...to s&h_7
> |
> +-...to s&h_8
> CD4051
>
> The assignment of the outputs at the right CD4051 has to change

round

> robbing.
>
> Not shown is a adress counter, clocked by the clock, which feeds

all

> CD4051 (of course we should not use 4051 because of the know

pitfalls).

> The outbut buses should not require adders, becaus always only one
>
>
>
> Florian

maybe it is interesting to look at the anlog shift register
of ken stone too, he offers pcb's for such a module.
he speaks of a four-stage s&h for a three-stage shift register.

best wishes

ingo