LFO question, MS-20 filter

[WhenBoredomPeaks]

Hi!

I wanna build Tim Escobedo's 9V MS-20 filter circuit + i wanna couple it with some better, probably stand alone LFO borrowed from the syth world. So i could use that module for other projects too.

For example, here is this: http://www.musicfromouterspace.com/analogsynth/coolnewlfo.html

My problem that it looks like that its LFO is going from +12V to -12V which is a huge 24V swing. But i think Escobedo's circuit is meant for 9V to 0V swing.
That linked LFO uses parts i seen in 9V guitar circuits, so if i would supply its +12V rail with +9V and its -12V rail with 0V, would it swing from 0V to 9V and back with a normal waveshape (like it would with the original supply) or it wouldn't work at all?

If it won't work, what are the better 0-9V LFOs out there?

+Bonus question: If i gonna build that LFO into it's own box, and it gonna have it's own power supply, then i could avoid LFO clock noise right?

[MoltenVoltage]

Our Tempo Wave Sequencer chip MV-53 is a much better choice in my very biased opinion. 

http://www.moltenvoltage.com/mv-53.html

One of the schematics shows how to hook it into a Dr.Q filter circuit

The video also shows how it can be used as a stand alone unit to power and sync a variety of other pedals.

[WhenBoredomPeaks]

Our Tempo Wave Sequencer chip MV-53 is a much better choice in my very biased opinion.  

http://www.moltenvoltage.com/mv-53.html

One of the schematics shows how to hook it into a Dr.Q filter circuit

The video also shows how it can be used as a stand alone unit to power and sync a variety of other pedals.

If you can tell me some substitutions of the TS 924 which i can find here and you ship to Hungary then i think you sold it. Maybe i gonna throw in some tap tempo stuff too.
edit: what are the common 3,3V stabilizators? I can't find one in the 78xx family.

[daverdave]

If you were gonna change the supply votage of the lfo you posted then you'd have to create a midpoint voltage, ie +4.5V. So +4.5V would be like your 0V mark and the waveform would swing between +9V and 0V if you understand.

[WhenBoredomPeaks]

If you were gonna change the supply votage of the lfo you posted then you'd have to create a midpoint voltage, ie +4.5V. So +4.5V would be like your 0V mark and the waveform would swing between +9V and 0V if you understand.

It means that if i make a +4,5V voltage with the usual Vref voltage "making" stuff, (two same valued resistor connected to 9V and 0V, and 4,5 is tapped from between the two) i should connect everything marked with ground on the original schematic to that +4,5V voltage?

Edit: While we are at creating a Vref, why is there so many ways of it?

Escobedo do it by 100KOhm resistor going to +9V and two LEDs going to 0V.
That LFO link do it by a 47uF cap going to +9V and a 47uF cap going to 0V.
In guitar effects  it is usually 100KOhm resistor to 9V and a 100KOhm resistor to 0V.  

[daverdave]

the caps are there for decoupling I imagine, there's a bunch of ways of doing it. Basicallt the 2 resistors form a voltage divider, it doesn't matter what value of resistors are used as long as they are the same value, but higher values would be better such as 100k or 47k. Not too sure what the leds are for, could be for power protection or somet, I'd have to look at the schematic.

[daverdave]

Yeah, most stuff mark ground would be connected to vref, I think, possibly not everthing though, the inputs of the opamps connected to ground would be connected to vref for example.

[MoltenVoltage]

This is the voltage regulator we always use:
http://www.mouser.com/ProductDetail/STMicroelectronics/L78L33ACZ/?qs=sGAEpiMZZMvYvv22R2xfeHKcMESSre7vuutQnwWARJI%3d

L78L33ACZ
ST Microelectronics

The chip will be more stable if you give it an independent regulator which is HIGHLY recommended.

You don't need to use rail op amps like the TS924, but you get more extreme effects when you do.  The schematic on the datasheet shows how to convert the MV-53 output to a more usable LFO that goes rail to rail, but you can use a regular op amp, you just won't get the full 9 volt swing.

[WhenBoredomPeaks]

It looks like that i gonna try to build both LFOs. (the MFOS and the MoltenVoltage)

Here's an other question related to the MFOS one.
The problem: on the original, grounds are at "true" 0V, while i have them at 4,5V.
Here's an explanation:

Original vs. my version. (to make the voltage swing more stompbox and MS-20 filter "friendly")
+12V   vs.    +9V
  0V     vs.   +4,5V
-12V    vs.     0v

I have problems with the grounds marked with this: on the original schematics.
I marked the problematic ones.



My guesses:

1. I think the first one should be connected to 4,5V as the inputs of the opamps.
2. I have no idea here, but i think we should stay with the VREF 4,5V.
3. Maybe VREF too?
4. I think opposed to 4,5V, i think i should connect that to 0V because i never seen transistors and LEDS connected to two positive voltages.

(+ the grounds at the output jacks and the enclosure shielding should beconnected to 0V instead of VREF imo)