[sdiy] Re: LVM

[crystal]

greetings fellow synthologists,


> >    OTOH, most chips for single-supply will run up to 5.5V-7V, so that
> > should be good enough.
>
> 5.5V means I could use my huge stock pile of TTL chips!



yeah, that pile of  TTL chips would be a great addition to a 'one Li-ion
battery with aV-V converter chip'  synth that Roman mentioned      .....
:>}~



>
> >    And if it were me, I'd run it straight from 5V, not bipolar, and use
a
> > very good clean 2.5V reference for mid-biasing circuits.
>
> All my designs use a reference between 0 and 12V. It's not always at 1/2
the
> supply. I use a reference for each module that needs one. They range
anywhere
> from 1.5 V to one module that has a reference for 1/2 supply, 1/2 supply +
1.5
> V, 1/2 supply - 1.5V. Another module has reference points at 1/3 rd supply
and
> 2/3 rds supply.
>
> I'm a beleiver in local references that keep noise of the reference lines.
The
> additional cost is minimal.
>

seems reasonable.

i don't see what the big deal is:  make a 5V synthesizer or make a +/-12V
synthesizer, whatever floats your boat. in my two (and a half) homebuilts i
have used all kinds of different voltages IC chips. it's mostly +/-12V, but
occasionally i have used 5V chips, and some other odd things. i use
transistors (or quad opAmps) to level shift when needed. a little extra
soldering.

and yes, with modern Opamps it is easy to get better precision than 'back in
the day'.

> And, when a filter is swept, you often get HUGE
> overloads.

>I don't think that's relevant, though. An amp will overload at 2V if
>it's running on a 2V supply.


yes, that is why it's relevant. if a signal jumps to 2V from the VCF then
it's distortion time both for the OTA and the opamp.

happy DIYing,
crystal