[sdiy] VC and CV keys

[harrybissell]

Hi Pat....

Usually the CV is less than the supply voltage. Usually it can be up to equal
to the supply
voltage with no ill effects (in properly designed circuits).  The overall range
is reduced for
a couple of reasons...

if you have a 12-15V supply... that is a 12-15 OCTAVE range... maybe way too
big to
be practical.

If you mix signals that are already at +/-12 (or 15)... the result WILL exceed
the supply
range and it will clip.

So, a lot of synths are set up for +/-5V or 0-10V or +/-10V signal levels.

A good reason to limit the voltage range of all the pots... is that you can
make that voltage
clean and regulated.  I actually DO use zener diodes to make a supply for these
pots (frequency
 etc...).  This eliminates noise from the power supply getting into the mix.

You can always limit the outputs to the range you want, and not do any special
protection to
the inputs.

I use 25K to 100K pots for most of my modules... I use the really high values
only where needed... usually Lag times and Attack / Decay times

H^) harry

Pat Kammerer wrote:

> Hi all,
>
> I've just got two questions, and you all seem to know what you're doing, so
> I'm sure someone will be able to help.
>
> 1)  Is it true that to protect components in a circuit, the CV will need to
> be below the supply voltage of the circuit?  Would this be best done by
> having the CV supply lower than the supply of any of your modules, are by
> limiting the input with zener?  Maybe I'm missing a method, any help
> appreciated.
>
> 2)  I am building a CV keyboard, and I know the basics of getting CV, Gate,
> and trigger outputs of the switches.  My question is, does anyone have
> recommendations for the resistor chain?  What values have you used with
> success, and do you use trimmers?  In my protoboarding, I've been using 2M
> panel mount trim pots (intended for tube circuits), but these seem to not
> have the correct senesetivity or range for finetuning, while they are fine
> for just learning the basic circuit layout.
>
> Thanks in advance!
> Pat