Jitter in VCOs

[Paul Perry]

At 03:08 AM 17/07/97 -0700, jean-charles maillet wrote:

>Has anyone done a comparative test of VCO architectures with a spectrum
>analyser ?!

.......not me, no. But a cheap way to get an intuitive idea of the ammount
of jitter on a vco might be to look at it on a cro while unsynchronised and
attempt to stabilise the image with just varying the scope sweep
adjust.....a 'moving slightly but coherent' image implies a non-jittery vco.

so far as the aesthetics are concerned, the jitter distribution would be
everything.....it would be ironic if the reason 'older' synths are more
popular is because the regulator caps are drying out and the resultant hum
is modulating everything! in most synths the designs would resist AM
modulation to some degree (particularly op amp based ckts) but there is
every scope for FM being put on the vcos.
I suspect that spring in the VCS3 is a magnetic field detector, either by
the pickup coil or via the springs themselves. My brain hurts when I think
what audio modulation of the vcf might do.

paul perry melb aust