[sdiy] Low Cost Comb Filter Methods

Edward Schultheis edwardschultheis at me.com
Fri Jun 15 04:28:56 CEST 2018

This dude is obviously just phishing for free copyrighted material.
 Don’t even give him the one of day based on the jackass response he just gave.
 People suuuuuck!

Edward Schultheis

Sent from me!

> On Jun 14, 2018, at 7:06 PM, Andrew Simper <andy at cytomic.com> wrote:
> Hi Neil,
> Thanks for pointing that out, I didn't take a loop at the part number and there was no regular symbol of the current arrow at the inputs like there is meant to be on the op-amp inputs to differential it from a regular op-amp as shown in figure 4 part (b) here: http://www.ti.com/lit/an/snoa653/snoa653.pdf .
> Can you please give me the theory of operation of an ideal "Norton op-amp"? Once I have those equations I can add this as a new device to my solver and re-generate the code. As an example the defining equations for an ideal op-amp are here:
> http://qucs.sourceforge.net/tech/node67.html
> Thanks!
> Andy
>> On Fri, 15 Jun 2018 at 00:26, Neil Johnson <neil.johnson71 at gmail.com> wrote:
>> Hi,
>> Andy wrote:
>> >> If anyone is interested in the linear case then here are the equations to solve the circuit:
>> >> https://cytomic.com/files/dsp/comb-filter-resonator-equations.pdf
>> >>
>> >> and here is an implementation in python generator by my circuit solver:
>> >> https://cytomic.com/files/dsp/comb-filter-resonator.py
>> >>
>> >> and a plot of the filtering of a sawtooth given one set of component values:
>> >> https://cytomic.com/files/dsp/comb-filter-resonator.png
>> Brian wrote:
>> > There’s one error in your reproduction of the schematic, though. rp is not supposed to be grounded, but should be connected to the +V supply. How much does that change the equations? It should reverse the current through the resistor, at the very least.
>> And also note that the op-amp used is a Norton op-amp, so it draws
>> current on its inputs.  That will change the equations.
>> Neil
>> -- 
>> http://www.njohnson.co.uk
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