Doepfer

I think this could be done easily enough, by feeding a linear FM CV through a resistor into the correct point in the expo converter, in a similar way to that shown for the same effect on the A-110 schematic. (A precautionary protection diode would also be needed to protect the possibility of damaging the transistors of the expo converter.)

There is a small downside, in that all the CV voltages applied would have to be sufficiently 'balanced' to ensure that the oscillator doesn't actually stop oscillating, but I suspect this would be so noticeable in practice it wouldn't be a major problem avoiding such combinations.

I'm too busy with other stuff to try this out myself, but if anyone needs some guidance on what to do/where to add the few bits and/or experiment, I can probably help out.

Tim

--- In Doepfer_a100@yahoogroups.com, Denis Gökdag <q-art@...> wrote:
>
> Hi,
> 
> I've recently received my second A-143-9 quadrature LFO. I'll be using the two for creating FM spectra a lot as this module has such a beautifully clean sinewave and the combination with the A-132-2 is ideal for FM index modulation.
> 
> In this context it would be interesting to know wether anybody has modded his A-143-9 to have linear FM inputs? Ideally, I'd like to add a 3-way switch that selects between the current exponential  modulation, DC-coupled linear and AC-coupled linear FM modes for the CV 2 input....
> 
> Any ideas?
> 
> Cheers,
> Denis Goekdag
> Surround SFX
>