Dividers

[Haible_Juergen#Tel2743]

>I was just re-reading this post (really cool idea, btw), and I was 
wondering
>how
>you VC the integrator discharge.  I can figure out how to do the rest from 
you
>description.  Could you describe the VC part to me?  A schematic would be
>great if you already have one, but a simple text description would suffice.

Dan,

this is very easy! The integrator is an opamp with a capacitor in its 
feedback path.
At the output of the integrator, there's a comparator (actually another 
opamp with
a minimal amount of of positive feedback for hysteresis and to speed it up). 
The
second input of this integrator is the CV input (actually there's a  CV 
adder there,
but ...). Every time when the integrator reaches the threshold (given by the 
CV),
it is reset: A short Monoflop is triggered (some CMOS stuff), and the 
capacitor
is discharged by shorting it with a transistor.
As there's always a fixed charge amount injected into the integrator for 
each
slope of the input clock, the CV directly controls the number of charge 
amounts
needed to reach the threshold.
If the CV is zero, every single charge quantum will cause a reset, i.e. 
division
factor = 1. The higher the CV, the higher the division factor.
As for a single slope and charge quantum the threshold can only either be 
reached
or not (but nothing in between), you get a sweep thru ineger frequency 
relationships
with the turn of a knob (or with a continuous CV). It's similar to a sync 
effect, only
that ip produces subharmonics instead of harmonics (if you operate it in the 
audio
range).
As there is a frequency doubling at the input (both, rising and falling 
slopes cause
a charge injection), and a flipflop at the output, you get symmetrical 
waveforms for
every division factor!

JH.