[sdiy] Ripples Schematic (forked from 4-pole BPF thread)

[Chris McDowell]

Olivier, I have a couple of questions about the Ripples schematic you just posted here. (thanks, btw!)

What is the purpose of the PTCs on the rails? I was not aware of what they did, looked it up, makes sense of course. Are they just here for protection?

And what is the purpose of the schottkys near the power connector? 

I had not seen that trick of using the lm4040 for a negative reference! Must be old news I suppose, but thanks for the insight. 

Aaand using lm13700s for the extra vcas is pretty dang “duh”. For some reason I’m usually thinking “either/or” when it comes to 2164s and OTAs. Silly me! 

Thanks for sharing that, Olivier. That circuit is elegant, I’m impressed! (as a bonus, it sounds great, haha) 

Chris

On Mar 7, 2014, at 12:12 PM, Olivier Gillet <ol.gillet at gmail.com> wrote:

> This can be done with "pole-mixing". The gain ratios for the second,
> third, and fourth stages are respectively 1, 2, 1.
> 
> For a SSM2164 cascade (usable in a modular environment), you can look here:
> http://mutable-instruments.net/static/schematics/Ripples-v01.pdf
> 
> On Fri, Mar 7, 2014 at 6:49 PM, Jean-Pierre Desrochers
> <jpdesroc at oricom.ca> wrote:
>> Hi Mattias,
>> 
>> 
>>> By 12 dB/oct you mean a 4-pole BPF?
>> 
>> 
>> 12db/oct slope on each side of the bandgap.
>> One SSM2164 (4 cells) would do I think..
>> 
>> Any schematics available on the web ?
>> JP
>> 
>> 
>> 
>> Le 2014-03-07 12:12, Mattias Rickardsson a écrit :
>> 
>>> On 7 March 2014 17:33, Jean-Pierre Desrochers <jpdesroc at oricom.ca> wrote:
>>>> 
>>>> Looking for 2164 based 12db/oct bandpass filter design..
>>> 
>>> 
>>> By 12 dB/oct you mean a 4-pole BPF?
>>> 
>>> /mr  -  just to clarify in these times of bad poledancing ;-)
>> 
>> _______________________________________________
>> Synth-diy mailing list
>> Synth-diy at dropmix.xs4all.nl
>> http://dropmix.xs4all.nl/mailman/listinfo/synth-diy
> _______________________________________________
> Synth-diy mailing list
> Synth-diy at dropmix.xs4all.nl
> http://dropmix.xs4all.nl/mailman/listinfo/synth-diy