> 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