Falstad is good for quick and dirty trials, but I am not sure how good it is for simulating a complete complex circuit.
If you are going to put in the effort, I would suggest using the KiCAD schematic capture, I have never simulated with it but it is possible and it probably is of professional quality.
The bonus advantage, is once you have the schematic in KiCAD, you could design a PCB for it and have it manufactured.
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I’ve heard of kicad but never worked with it. I will give it a shot. In the meantime i hope someone who has experience with kicad wants to join in and put the schematic in kicad.
The last thing i want to try before i start learning kicad is to change R26 from 47k to 39k. Dont know if that makes a difference but since i can access this resistor fairly easy why not?
The point of my suggestion that you remove R22 was in order to disconnect RB from that node, in order to detach the resonance circuit from the filter network, but as I said, after having made that suggestion, I read one of your earlier posts where you mentioned removing U6, which is another way of accomplishing more or less the same thing. I was trying to explain that there was no need to implement my earlier suggestion that you remove R22. Sorry for the confusion.
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I decided to look at the output of my VCFQ. Q is at zero for all of these shots. The Low Pass Filter looks a bit cleaner than the MFOS filter, but still has a spike. I think that what we’re looking at is filter ripple. The 24dB filter simply eliminates more of it by doubling the number of poles.
Unfiltered Square Wave (~400Hz):
Low Pass Output (Fully Open – Max):
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Yes no problem mate. Thanks for the clarification.
Ok yes sounds logical. more roll off, less ripple on the 24db filter.
Little spikey there.