[sdiy] Help with lm339

[J C]

Just to follow up.  The following is the circuit I used incorporating
Ian's suggestion which adds state LEDs to the Ray Wilson envelope
generator:
http://home.cfl.rr.com/entropy/ADSRMod.jpg

A picture here of my first modules with the ADSR in the center:
http://home.cfl.rr.com/entropy/mods.jpg

A couple of notes - the PAIA MIDI2CV has a power ON/OFF with a
momentary Reset position (this works as a great ALL NOTES OFF switch
without having the control voltages ramp down if you only use the
Power ON/OFF).  It also has a selector switch to select between the
V/Hz and the 1V/Oct option.  I also seperated the CV outs and the
S-Gates and tied an LED to the gates.  The LEDs are indespensable for
me to show which outputs have activity.

The ADSR has the above state LED mod as well as a single Ken Stone
Utility LFO whose variable pulse out can be hard-switched to the ADSR
gate to provide repeating envelopes.

The last module is the Ray Wilson VCO with an extra output added
(labeled MOD) which can switch between the VCO outputs with a control
voltage or the SEL pot (the LEDs show which output is selected)  and
be attenuated from -1 to 1 via the Mod pot.

A humble beginning to modular madness.