Hi Mark and all,
The very circuit you need was used in the little DIY Clef Microsynth to
detect new notes from the pitch CV even when playing legato. The whole
article in Practical Electronics is on Anders Sponton's website. Its a
simple circuit involving a couple of op-amps or comparators (I can't
remember which) but all the awkward things like time constants and
trigger levels have been worked out for you.
See
http://omega.tellus.vallentuna.se/anders/ Go to Synths and then down
to Practical Electronics.
Regards,
Tony Allgood Penrith, Cumbria, England
Oakley Modular Synth and TB3030:
www.techrepairs.freeserve.co.uk/projects.htm
My music: www.mp3.com/taklamakan