inverted lfo - just another opamp?

[kvb]

http://www.tonepad.com/getFile.asp?id=84

I'm looking at the lune and wondering how I might use this platform to do something similar to what is decribed by Boscorelli in Mo' Trem'lo
Stompboxology  Vol. 4, No. 4. A treble-to-bass-wobble tremelo.

First I just want to ask. In the case of the lune's LFO, is it possible to run a second out-of-phase vtl5cX with another buffer/opamp that is connected at its negative-input to IC2b's + in?

[kvb]

Yeah, I knew it was probably a search first Q - and I did. Just wierd some times when a search seems to lead nowhere. Then you try again and find a bunch of stuff. 

Well I guess I found the answer which seems to be a simple YES, http://www.commonsound.org/panneur/panneurscheme.gif but I wonder why the second buffer for LEDb has the 1M resistors. the two buffers are not identical. I'm sure there is a reason. Any one know why?

[Seljer]

Yeah, I knew it was probably a search first Q - and I did. Just wierd some times when a search seems to lead nowhere. Then you try again and find a bunch of stuff. 

Well I guess I found the answer which seems to be a simple YES, http://www.commonsound.org/panneur/panneurscheme.gif but I wonder why the second buffer for LEDb has the 1M resistors. the two buffers are not identical. I'm sure there is a reason. Any one know why?

the bottom one is set up so it can be used as both an inverting buffer and a non-inverting buffer

[kvb]

Yes, but is has those 1M resistors on the neg-in and in the NFB loop.
so, this means that the signal at neg-in is voltage divided, and the amp's NFB is restricted.
and these would mean that the buffer's input is attenuated, but then the signal is boosted back up to unity?

I imagine there is something going on related to biasing the opamps because when the circuit is in sync-mode and pan mode the + in of the top opamp is no longer connected to Vb. (I think the scheme has the pan/trem labeled backwards, the top connection is pan the bottom is trem.) 

[slacker]

The output from the inverting input isn't attenuated. The gain of an inverting opamp stage is set by the equation
Vout = Vin x (feedback resistor/input resistor) so in this  case
Vout = Vin x (1M/1M) or Vout = Vin x 1 so the output is the same level as the input only inverted when the signal is fed into the inverting input.
You don't necessarily need an extra opamp to get an inverted output from the LFO. If you hook up an LED and current limiting resistor between 9 volts and the output of the LFO, with the anode of the LED towards 9 volts and the cathode towards the output, then the LED with get brighter as the LFO sweeps down and dimmer as it sweeps up.
Have a look at this thread http://www.diystompboxes.com/smfforum/index.php?topic=33221.0 especially reply number 9.

[kvb]

Yes, I saw that, but was not sure if that was a working solution or not.  Before I posted I had thought that diodes could be able to be working on either side of the wave, but I did not know exactly how to make it happen.  I'll try that. Besides, I could just hook up a couple of regular LEDs, first - to see if they alternate.

In case anyone is wondering why I don't just go for the stereo panner - I might - but the thing is pretty large and a gob of knobs.
If what I am attempting works out I could have a unique Lune with a mod that others might want to try.
We'll see.