Doepfer

Hi Dieter,

I would definitely buy two or three such modules!! I think it would be very useful for making a quantised - easier to play! - Theremin sound more natural. And the same would go for the Ribbon Controller. I think there would be many other applications - even to help Keith Emerson with a Brocken hand :-)

David


www.movingisliving.co.uk

Sent from my iPhone 

> On 19 Nov 2014, at 08:05, yahoo@doepfer.de [Doepfer_a100] <Doepfer_a100@yahoogroups.com> wrote:
> 
> > Hi,
> >
> > I'm wondering how to do two things.
> > 1) To create a CV based (proportional to) on the rate of change of another CV
> > 2) To create a gate when there is a step in a CV. This is particularly but not exclusively the output of a Intellijel
> > uScale - so when there is a new pitch I would like to create a gate.
> >
> > Hoping there is maybe a simple solution,
> >
> > David
> 
> I couldn't stop thinking about a simple solution. Mathematically it's nothing but the derivation of the incoming CV. Electronically
> it's a differentiator or high pass. So I tried it last night: A 47nF capacitor and a 100k resistor (wired as the earlier mentioned
> high pass) does the job. As the CV output of the 47n/100k combo is a bit small (only in the 5-100mV range) the signal has to be
> amplified. I tried successfully a x50 amplifier, but probably an amplifier with adjustable gain would be a better solution to be
> able to adjust the sensitivity. The circuit generates an output voltage that is proportional to the change of the CV input: a
> quickly rising CV generates a high positive voltage, a slowly rising CV a small positive voltage. When the input CV does not change
> the output reads 0V. When the incoming CV falls the CV output becomes negative.
> 
> To obtain trigger signals two comparators with adjustable thresholds for both rising/falling threshold can be added to generate 2
> independent triggers for rising/falling detection (which could be or-wired too). Another idea would be to rectify the CV output and
> add only one comparator which then detects the CV changes in both directions. We could develop such a module provided that there are
> sufficient inquiries. As usual most of the time would probably take the front panel design (which sockets, controls, LEDs at which
> position). The electronics is quite simple.
> 
> A total different approach is to generate a CV from the rate of trigger signals coming from the quantizer A-156. For this kind of a
> frequency to voltage generator has to be patched, e.g. an A-162 followed by a A-170 or A-171-2. The A-162 generates pulses with
> constant length which are integrated by a slew limiter (nothing but a 6dB low pass with very low frequency) to obtain a CV. If gate
> signals correlating with the original CV the quantizer is not necessary. In this case the gate signal is used directly to trigger
> the A-162.
> 
> Best wishes
> Dieter Doepfer
> 
>