[sdiy] simple 2164 linear to expo CV?

[Neil Johnson]

Hi Neil,

> hey neil, i saw your name in the SSI datasheet and looking forward to
> breadboarding that 3-pole vcf, thanks for your reply.

It's a nice-sounding filter.  There are audio examples of the earlier
incarnation of that filter on my web page:
https://www.njohnson.co.uk/index.php?menu=2&submenu=0&subsubmenu=1

> yes exactly, 0-5v linear cv to 0-5v exponential cv. not too fussed over

Should be a straightforward circuit to set up.  Give me a shout
off-list if you get stuck.

> should i just leave the MODE pin n.c. for this? will breadboard it today.

Shouldn't matter too much at this stage.

>  i never
> thought of using a -5v zener reference. is that for when you can't trust
> the actual rails?

NEVER trust the rails!

> i noticed that most designs by Thomas Henry for
> example that I've built usually will just reference to the rails...

In principle, if the rails are clean and stable and free of noise then
there should be no problems.
Reality is not so kind...

> maybe this isn't a problem for me, cause in my diy modular i can adjust
> my lm317/337 power supply to ensure it's at +/- 15.0V?

You will only read 15.0V at one point.  If you read at the terminals
of the PSU then as you move away from the terminals the voltage will
drop.  If you read at the furthest point from the PSU then points
closer to the PSU will read higher.

Just use a 5V1 zener if you don't feel the need to go to the expense
of a proper voltage reference.  There's also a reason why I
specifically stated that zener voltage ;)

Cheers,
Neil