ARP Odyssey Oscillators

brother303 · Joined: Nov 02, 2010 Posts: 139 Location: ruhr-area/germany

Hi all,

just started etching a board for this cool project,thanks to Andy for offering this to the diy community.

One question : The circuit works on +/-15V. Is it possible to run it on +/-12V in an eurorack modular? Are any changes required for 12V operation?

Thanks and best regards
Greg

brother303 · Joined: Nov 02, 2010 Posts: 139 Location: ruhr-area/germany

Hi again,

glitched · Joined: Mar 25, 2006 Posts: 80 Location: phila., pa USA

By the way, in addition to brother303's question, I'd like to know the following: If I send the layout to someplace like guitarpcb.com and have it etched, will it come out correctly? That is, is the drawing scaled correctly (100%) and in the proper format? I've neither etched a pcb, nor had anything etched for me, so this is important.

Is the layout "optimized" or do you think it would be better to wait for Magic Smoke or someone to manufacture the board?

brother303 · Joined: Nov 02, 2010 Posts: 139 Location: ruhr-area/germany

Hi Glitched,

I sent the layout to a local pcb-service and the pcb came out perfectly!
Give guitarpcb a try and you won`t be dissapointed. Hail the Master

Anyone got an answer on the 12 vs. 15V question?
I can`t believe that no one gave a try on the 12V solution?!? sigh

Pleaze help me out... Please

Cheers
Greg

brother303 · Joined: Nov 02, 2010 Posts: 139 Location: ruhr-area/germany

Hi all,

vco built - sounds awesome! Especially the sync is absolutely great!! thumb up

I build a little +/-15V-psu and placed it inside my modular case next to the 12V supply.

Tempcos from Bridechamber, 2k works very well. Tracking over 4 octaves is perfect,5 octaves possible with 2 cents off,but still ok.

One little quirk - the vcos lock to each other when tuned extremly close together. How to avoid this?

I tried bigger elkos (47uF instead of 10uF),added some 22R resistors to the +/- psu lines and also mounted additional 100nf decoupling caps to the 3086 with no effect.

Any idea how to get rid of this locking-effects?

Thanks and best regards
Greg

glitched · Joined: Mar 25, 2006 Posts: 80 Location: phila., pa USA

Look at page 1, near the bottom. Looks like it has to do with grounding.

By the way, I can totally make this project now. I went with guitarpcb.com for a small LFO project I found and the boards look great!

I sure wish someone had an answer on the +-12v implementation, though. It's probably just a change in resistors. Any help? I'd love to put this in my eurorack.

LektroiD · Posted: Sun Jan 16, 2011 10:26 pm Post subject:

brother303 · Joined: Nov 02, 2010 Posts: 139 Location: ruhr-area/germany

Hi,

Sebo · Joined: Apr 27, 2007 Posts: 564 Location: Argentina

Hi:
I just built this dual VCO, I didn't calibrated properly yet, but it seem to be working right.
Thank you AndyR1960 for sharing!!!

I think I have an issue, the RingMod out is mounted over a very high DC offset, about 9V, so the signal swings from 6V to 12V.
Is this normal?
I've checked the circuit and all seems to be OK.
Thank you.

Jaba · Joined: Feb 27, 2009 Posts: 48 Location: Genova, Italy

Hi Sebo,

I built this double VCO board too and, after the usual troubleshooting (I ALWAYS make some mistakes), it works perfectly.

The RingMod output has a strong DC offset in mine too, but from the schematic I would say it's just designed to be so, not an error or a building mistake.
I don't remember the exact amount of DC offset; your '6V to 12V' may well be right. I can measure it tonight and report tomorrow if you like.

All outputs are positive-only; I added output level shifters, but forgot to level-shift this ringmod output, oops!

I modified the board a little in order to have sync input, sync output and LFO option in both oscillators, so that they are now an identical pair; it was easy and worked fine.

This board is just GREAT, tracks well and sounds gorgeous. I am very happy with it. Thank you Andy, thank you ARP, thank you electro.music forum !

Sebo · Joined: Apr 27, 2007 Posts: 564 Location: Argentina

Hi Jaba:
Thanks for your reply.
I did level shifters for the output too, and when doing them I discover the DC level of the RingMod out.
If that is a normal behaviour, I just made the level shifter according to that, just want to be sure I didn't make a mistake.
Thank you.

Sebo

LetterBeacon · Joined: Mar 18, 2008 Posts: 454 Location: London, UK

Do you have schematics for the level shifters? I'd be very interested in seeing them.

Thank you.

Jaba · Joined: Feb 27, 2009 Posts: 48 Location: Genova, Italy

Hi,
a schematic for a level shifter circuit was already shown in this thread here:
http://electro-music.com/forum/topic-28604-175.html

this is a direct link to the jpg file:
http://electro-music.com/forum/download.php?id=15822

but if you really want your output to be exactly -5V to +5V, then you'll have to change the resistors' values a bit depending on the actual values of your signals, and maybe on your OpAmps offset error too.
I believe that the values shown were intended for converting a 0 to +5V signal into a -5V to +5V one.

LetterBeacon · Joined: Mar 18, 2008 Posts: 454 Location: London, UK

Ah yes, I'd seen that before. I think I started a layout for that a while back.

Did you use four TL071 for each output or just one TL074?

Jaba · Joined: Feb 27, 2009 Posts: 48 Location: Genova, Italy

I used one TL074, but I think it does not make much of a difference

Sebo · Joined: Apr 27, 2007 Posts: 564 Location: Argentina

I used a similar circuit, but used an inverter before each level shifter, for some reason I'm feel better knowing that the outputs have the original phase.

frequencycentral · Joined: May 25, 2008 Posts: 186 Location: UK

Broadwave · Posted: Tue Jan 31, 2012 3:18 am Post subject:

I've just finished working on single VCO versions of both the MkI and MkII. There's no Ring Mod on board, but they both have seperate 0-10v outputs to feed into the ARP Ring Mod.

The tracking is great on both of them, and I have to admit that the sync on the MKI seems much tighter and more aggressive than the MKII, especially when put through the RM Smile

The MKI is a much simpler design with fewer odd value resistors and no hard to find transistors. I'll get the details up in a few weeks once I'm back from holiday.

I'm currently working on the 2600 VCO - although it's almost identical to the MKII, I've squeezed the triangle and sine wave shapers onto the same Euro rack sized PCB... Sounding great at the moment Very Happy

LektroiD · Posted: Sat Mar 03, 2012 3:35 pm Post subject:

Would anyone in the UK kindly help me out with a few missing parts?

I just made a huge order from Rapid and stupidly missed these...

680pF x2 (preferably poly, since it's cheaper)
2n5459 x5
2n5910 x2
1.87 TC x2 (I appreciate this one may be difficult to source)

If anyone who's built this has bought excess of some or all of these components, I'd be happy to trade or buy your spares. Preferably from one source to save postage, but I don't mind either way, just as long as I get this up and running. Please PM if you can help out.

There was one question about this though, how to match a PNP with a NPN? And if neither the tempco or transistors are thermally coupled (and therefore not actually doing anything), could this be substituted with a fixed metal film & unmatched transistors?

Many thanks in advance...

LektroiD · Posted: Sun Mar 04, 2012 11:25 am Post subject:

I assume nobody has these parts since nobody replied, so I tried the alternatives suggested above:

2N5910 > 2N3906
BF245 > FETs

I used a 470pF (and also tried a 1000pF) in place of the 680pF, as they are the closest I have

...It doesn't work

Not sure which parts I'd be best to swap out, or maybe I should just wait until all the parts I need materialise

LetterBeacon · Joined: Mar 18, 2008 Posts: 454 Location: London, UK

Hi Lektroid,

I have a few left over bits and bobs from my build, including the elusive 2N5910 that you can have. I'm away from where I keep my electronics bits until next weekend. If you PM me closer to next weekend to remind me, I can have a look through and see what I can dig out.

LektroiD · Posted: Sun Mar 04, 2012 10:38 pm Post subject:

Sebo · Joined: Apr 27, 2007 Posts: 564 Location: Argentina

LektroiD · Posted: Thu Mar 08, 2012 5:04 am Post subject: