Single supply op-amp query

[Dan Higdon]

> From: 	MACHINE MEDIA[SMTP:cdmaster at netcom.com]
> Btw, part deux, is this for a PAiA Theremax??  I just built one last week.  
> I'm still trying to get it work right. The range of motion (distance from the 
> antennae) for pitch and volume seem a bit too short -- a few inches.  The 
> gate/velocity feature only seems to work if you remove your hand from the 
> volume antennae *very* quickly  (I'm a skinny tai chi player who can beat 
> a rat trap but I can only manage to trigger it only about half the time).

My theremax does the same thing.  I'm glad to hear that I'm not the only one
who has trouble getting it to gate.  I'm neither skinny, nor into tai chi, and I can
only get it to trigger about 1 time in 3! :-)
The volume is VERY close, but I find that you get used to that after a while.  Though
it limits dynamic expression a little, it allows you to clearly articulate notes without
whipping your hand up and down by a few feet (some mental image, huh?).
The pitch works fine, but you have that darn inverse squared distance behavior
I spoke about on some list or another recently.  That makes it very hard to
play "real" notes, because the remembered hand positions fail if the theremax
is a different distance from you (or temperature!) than when you last played.
Oh well, noone said it would be easy. :-(

Later,
Dan Higdon (hdan at charybdis.com)