[sdiy] Serge and multiples

[harry]

Hi Magnus (et al)  inline

Magnus Danielson wrote:

> From: "Happy Harry" <paia2720 at hotmail.com>
> Subject: Re: [sdiy] Serge and multiples
> Date: Mon, 05 Mar 2001 15:20:19 -0000
>
> > Most folk worry about inputs. Bipolar processes are pretty good
> > for static handling. If you were REALLY leery, you could split that
> > series output resistor, and use MOV, zener, or fast diodes to the rails to
> > either eat the static discharge, or direct it to a place where it can
> > dissipate harmlessly.
>
> Certainly a good idea. Some thought should be spent so that you do not
> add excess nonlinearity when not wanted. Also, some of these can be
> temperature sensitive, which would not be good at a CV input. If just
> some considerations are taken it is safe from both persepectives.

Martin pointed out that 100K is often considered "protection enough" for static...

and most inputs are 100K or so. I was thinking output protection.  Diodes to
plus and minus rails should be invisible to the circuit... temperature
notwithstanding.

>
>
> > But I've never seen a bipolar opamp die of static discharge at the output,
> > or even degraded operation. This is more likely if you are using a voltage
> > follower (output tied to inverting input) than a
> > unity gain inverting stage (with resistors in the feedback).
> >
> > Still I would not worry... I'm not landing my synth on MARS if you know what
> > I mean  ;^)
>
> But if you make a synth and sell it, you don't know where their acid
> house trips take them... surely you are a grownup boy enought to seen
> that happend before? ;^)

Only had one of those with a synth in tow... when the short circuit caused the
transformer wiring to burst into flames... in a TOTALLY dark room... the
overall effect was nearly heart-stopping !!! Ince the lights were on... it was
just
some ordinary melted insulation on 22ga. wire.

Diodes / Zeners / output protection would not have helped. A power supply
fuse would have been appropriate... or a supply that could not deliver 10-20
amps into that short !!!   ;^)

H^) harry

>
>
> Cheers,
> Magnus