octave selection switch

rubendelacosta · Joined: Dec 25, 2005 Posts: 153 Location: lisbon

hi all!

i'm looking for a good octave selection rotary switch schematic.
anyone knows of a good one?
sorry if this was already coverd...

regards,
ruben

andrewF · Posted: Mon May 23, 2011 8:04 pm Post subject:

check out Takeda's farm VCO III
The oct switch is in the bottom left corner and includes R5, R6, R9, pot 2, D1 and the op amp buffer. It works very well.

Posted Image, might have been reduced in size. Click Image to view fullscreen.

Posted Image, might have been reduced in size. Click Image to view fullscreen.

diablojoy · Posted: Mon May 23, 2011 8:46 pm Post subject:

you do need to match your resistors very closely in the voltage divider section
try looking at rykhard's work on this

www.damian.deathlehem.com/schematic.html

I did a board from rykhard's schematic with some slight changes quite some time ago
but it was for both octave and semitones ie 2 x 12 position rotary switches
it involved using some 0.1% SMT resistors so there wasn't much interest at the time . It is very accurate though and i still do have the cct somewhere here

sneakthief · Joined: Jul 24, 2006 Posts: 569 Location: Berlin

http://www.elby-designs.com/synth-modules/octave/octave.htm

for sale here: http://www.elby-designs.com/shopping/contents/en-uk/p151.html

rubendelacosta · Joined: Dec 25, 2005 Posts: 153 Location: lisbon

thanks a lot!
looks very simple.

sonicwarrior · Joined: Dec 22, 2005 Posts: 266 Location: Cologne, Germany

diablojoy · Posted: Sun Jul 08, 2012 2:18 am Post subject:

http://electro-music.com/forum/viewtopic.php?highlight=octave+semitone+switch&t=37689

the switches are an alpha from memory 1 pole 12 position
switch spacing is 35 mm centre to centre
I do still have some boards but they require a small kludge Embarassed

need to cut one trace and run a wire
SMT resistors are 1206 0.1% x 21
recomend LT1057 inplace of TL072 for the best accuracy