[sdiy] how do I modulate a VCO using a S&H without messing up tuning? need Help!!!!!

[Danjel van Tijn]

I used this nice little single chip Sample and Hold circuit from Ray Wilson:

http://www.musicfromouterspace.com/analogsynth/singlechipsampleandhold/singlechipsampleandhold.html

Then I modified my x0xb0x (essentially a 303) to have a CV IN by adding a
jack and connecting the CV in to pin 5 of IC 11 (I did not cut any traces so
that my CV in is mixed with the CVs generated by the sequencer.)

The schematic is here:
http://www.ladyada.net/make/x0xb0x/files/mainboard_beta.png (look at the
left side, middle)

THe problem is that this totally messes up the tuning! My S&H circuit
totally drops the tuning down several octaves.
Should I couple the CV from my circuit with a capacitor so that the DC
component of the CV is removed and then allI I am mixing in is changes in
voltages (modulation)????

I guess I am getting confused about how I mix CV's together.... this is easy
if I am using opamps but I find I keep getting ocnfused by the 303 circuitry
and how they do things (sorry I am new to this!)

any help is hugely appreciated! I built this box for a performance on
saturday and I need to get it working!



thanks,
Danjel
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