[sdiy] op amp based filter

[cheater cheater]

BTW, here's a relevant patent that implements a voltage controlled op
amp. It's what I was referring to earlier:
http://www.freepatentsonline.com/5175508.html

Incidentally, it will expire in two years.

Cheers,
D.

On Sun, Jul 25, 2010 at 19:42, cheater cheater <cheater00 at gmail.com> wrote:
> Cool. Without an actual test of how those things behave, though,
> there's little to talk about. I guess this thing needs to be made and
> tested.
>
> Cheers,
> D.
>
> On Sun, Jul 25, 2010 at 19:16, Tom Wiltshire <tom at electricdruid.net> wrote:
>> It can be done with vactrols too (Tremulus Lune, Korg PS Resonator, others, I'm sure).
>>
>> I doubt it helps with the linearity much though.
>>
>> T.
>>
>>
>> On 25 Jul 2010, at 14:49, cheater cheater wrote:
>>>
>>> What are the best ways to make a normal op amp's gain programmable
>>> with CV?
>>
>