[sdiy] Littleman VCO error (555 chip inverted)

[David Reichert]

Jimmy, I se why you might think so, but it's wired properly.

Normally, pin 1 goes to ground and pin 8 is set to a voltage somewhere
above ground. On this schematic, pin 1 is connected to a -12V source and
pin 8 goes to ground. This is the same as if pin 1 went to ground and
pin 8 was connected to a +12 V. What matters isn't which one is
connected to ground, but rather the relative voltage between the two
pins.

Dave

-----Original Message-----
From: owner-synth-diy at dropmix.xs4all.nl
[mailto:owner-synth-diy at dropmix.xs4all.nl] On Behalf Of Jimmy Gogas
Sent: February 12, 2002 8:30 PM
To: synth-diy at dropmix.xs4all.nl
Subject: [sdiy] Littleman VCO error (555 chip inverted)

I'm looking at the Littleman VCO circuit, and I think that the 555 chip
is 
inverted (mirrored --> 1 should be 8, 2 should be 7, etc.). Can anyone 
confirm that? I was also wondering if anyone can spot any other errors
on 
the VCO (or anything you would improve on). Finally, does anyone have a
clue 
about how this thing works? I know what the 555 chip does, but what
exactly 
do the two pnp transistors do? How about the op-amps? And why are the 
resistors next to the PITCH connected like that? (Any other comments 
appreciated).

The shematics of the Littleman VCO can be seen at : 
www.itn.liu.se/~nikro/littleman/littleman.pdf

Thanks in advance.



_________________________________________________________________
Send and receive Hotmail on your mobile device: http://mobile.msn.com