I’ve tried to build the MS-20 filter on a breadboard now, as well as on stripboard. the first I gave up on because it became too dense with wires, the strip board didn’t work at all.
I want to try again on breadboard but only cover the basics first, so I know it works.
can someone please point out where on the MS20 filter is the cv portion so that I can ignore it for now and add it on when the rest is working? thanks!
I just did a quick mock up of the components related to the CV input to be removed highlighted in red below. I could be mistaken as I’m still fairly new to electronics myself, but I’m pretty sure all it is is the CV input jack, CV level pot, and the 100kΩ resistor on the right side of the layout connecting the CV input to the middle leg of the transistor.
ah so it looks like I won’t be able to control the cutoff if I remove the CV.
The cutoff control is just a manually controlled CV, so leaving that in means leaving in most of the CV circuitry.
This probably explains why I had so much trouble finding a resonant low pass filter schematic that wasn’t specifically a VCF!
oh this is awesome thank you!
one more question, it’s implied that the op amps in the schematic are always tied to pos/neg voltage like so?
I’ve seen some schematics now that dont indicate the +/- like the above picture and didn’t know whether they were connected.
Like a KiCad Schematic?
The power pins are often grouped in a separate section of the schematic for power.
U1D ( U1 part D )
U1E ( U1 part E ) - On this component E is the power pins and on this diagram are shown close to the power header.
Note this LM324 is using +12 and GND not +12 and -12
Okay, that makes a lot of sense. What had thrown me off was the schematic I was using for a sample and hold circuit the other night (which ended up blowing up my poor 556 
)
None of the sample and hold circuits I found mentioned where power was applied, and I think my error was making the assumption to wire it up like the previous image I shared and use negative voltage
edit: Am I using the term “Schematic” where I should be saying “Circuit”?
Circuit: the way the components are connected together, for example series circuits and parallel circuits.
Schematic: the diagrams that represent the circuit.
In general, people use them interchangeably and will understand what you’re saying either way.
