Octave up prototype

[Dutchie]

He there, ( this is my first post , whooohooo   )

I ( tried to ) designed a octave up circuit and although it works there are some things i cant figure out.  ( see schematic below )

1) why are the R's to ground before the diodes so important? can't make em too big or else the octave fx is not really there any more. any thought on that? i cant figure it out

2) Why is it that when I put the Diodes in the other direction the fx is also not there, I figured it doesnt make a difference wich way the face, what am I missing here?

PS i put an extra C before the second inverting opamp on the breadboard. i fiddled with the design on the breadb. so i dont think al the values are the same on the schematic.


anybody wanna try it out on their breadb's and tell me what they think?

[Alpha579]

Cool circuit   ! it took me a bit to get to grips with the circuit  :oops: , but know i get it. Turning the diodes around shouldnt be a problem. It sould sound exactly the same. What diodes are you using?

[Dutchie]

Thought that too bout the diodes, but on the breadboard it seems otherwise?!?!?!?! i dont get it

[Dutchie]

btw i used 1n4148's, got no Ge's around now, but i guess they would be beter cous they dont have such a large voltage drop ?!?
and as result beter fading of the notes ( do i have this right )


You guys wouldnt believe i got a EE degree haha, Technical computerscience as major, but is spend years calculating the most difficult differentials and intergrator fomulas, i should know it al.....but i dont...seems kinda ironic I dont have an idea sometimes how it all works hehe. Never really worked in that field think that that is the problem. went to software development. I also just graduated the Conservatory of rotterdam ( E-guitar ). I'm also a bachelor of music now. Whooohooo......why am i telling all this??? hmmm donno.

Check http://www.yvovanheijningen.nl for some sound's of me playing.

I'm trying to combine the 2 studies...i think that my point lol...nvrmnd

[Gus]

did you look ing schematics?

http://www.diystompboxes.com/pedals/ousb.gif

Gus

[Dutchie]

He nice, almost the same idea, can you explain the output "stage"?

woudnt it be better to buffer the output?

how the resistors and diodes work together? iow why u did what u did?? hehe

[Tim Escobedo]

I don't know the "whys", but you may need a DC path on the cathode side of the diodes if you flip them both around.

It's similar to a idea I did on the Octup Blender.

[petemoore]

Octup Blender]  
 Put a 10M resistor on the OA feedback loop?
 It's not often I see anything larger than 1M there, IWW because the max gain of generic OA's is set at 1M...does that make the amp approach or hit the rails to get nice squaring in prep for the diodes.?
 Looks pretty spiffy...any sound clips around of that one?

[Arno van der Heijden]

Hey Dutchie,

I'm really jealous of you because you got guitar lessons from Leendert Haaksma!  

[DUTCH MODE]

Hoe is ie in het echt? Speelt ie nog op z'n zelfgebouwde versterkers?

[puretube]

...so they`re properly biased... (the diodes)

[Dutchie]

[Dutch]
Leendert is coole gast. heb nu geen les meer van em he ben afgestudeerd. En hij bouwt inderdaad mooi amps.
[/Dutch]

Tim, Im gonna try your design to see how they compare

[cedric]

hey Dutchi.. let's see those home built amps! (or did you have some guy design the circuit for it?).

- ced