[sdiy] Ray Wilson Filter question

[Fredrik Carlqvist]

Would this mod be an improvement with other OTAs as well? (NE5517, CA3080)


Fredrik C


-----Original Message-----
From: owner-synth-diy at dropmix.xs4all.nl
[mailto:owner-synth-diy at dropmix.xs4all.nl] On Behalf Of harrybissell
Sent: Sunday, October 31, 2004 20:41
To: synth at oldmail.charlielamm.com
Cc: synth-diy at dropmix.xs4all.nl
Subject: Re: [sdiy] Ray Wilson Filter question

well OK I'd change this thought...


> --Put a 1K resistor in between the - input of the OTA and ground...right
> now, as Ray did it, this signal goes straight to ground. This 1K
> additional resistor guarantees that the current added with the mod doesn't
> go straight to ground, but instead goes into the - input as desired.
>

The additional resistor forms two things... one is that the resistance from
each
input of the OTA to ground is 1K.  This balance will help offset voltage in
the
first place.  Two is that the 1M / 1K make a huge voltage divider, dropping
the DC
level down to useful levels...  like about +/-15mV at the inverting input.

But hookup-wise you are golden !

H^) harry