Best OCD Clone Schematics

[THRobinson]

Finally going to try building my own pedals... was on here last Fall, got some great info, bought a bunch of parts... then other projects came up and never had the chance to do anything. 

Back on track now, debating which pedal to try and saw some stuff about the OCD pedal and liked it a lot... found variations of diagrams as well, but no comments about which was the closest.

Anyone try making a clone of this pedal? Know which clone diagram is the closest?

[thermionix]

There are different versions.  I built one a couple months ago which ended up a slightly modified V4, I think anyway.  It's okay I guess, but I'm not really very impressed.  If I had spent more time with it on the breadboard, I think I would have skipped it.

[GGBB]

I've never built one but I've looked at the cicuit a fair bit. My understanding is that the basic circuit never changed very much (the new OCD 2 excepted). There are a couple of blogs I've seen that detail the differences pretty well, both sonically and electronically. Here's one: https://www.albertodessi.it/guide-e-consigli/31-fulltone-ocd-versioni/356-fulltone-ocd-all-the-7-versions.

[Elijah-Baley]

Good link about the OCD.

But I can't find the schematic of every single version because seem to me that all these versions are kind of undefined (ver. 1, 2, 3... or 1..2, 1.4, 1.x...). Of course I can find some layout or some schematic, or just some useful description of the features of the several version. I would read a page with all the schematic where I can see the evolution of the circuit.
I don't even know if I really like this pedal, once I liked it, then less, then I liked again. Now I am, at least, curious about the circuit. Maybe I may built a board with socket to experimental the different components value or parts added.

[GGBB]

Good link about the OCD.

But I can't find the schematic of every single version because seem to me that all these versions are kind of undefined (ver. 1, 2, 3... or 1..2, 1.4, 1.x...). Of course I can find some layout or some schematic, or just some useful description of the features of the several version. I would read a page with all the schematic where I can see the evolution of the circuit.
I don't even know if I really like this pedal, once I liked it, then less, then I liked again. Now I am, at least, curious about the circuit. Maybe I may built a board with socket to experimental the different components value or parts added.

The various OCD versions are not really "undefined" - in fact Fulltone states:

The OCD has received many slight tweaks over the last 12 years, often incorrectly identified as "version 2, Version 3, V4, etc." In reality there has always been only one version...Version 1, with very slight variations after that making them V1.1 through V1.7.

It wouldn't be hard to create the schematic for yourself and then share the schematic with the community - I'm sure many would appreciate it. (I did that very same thing for the RAT a few years ago.)

You can find schematics if you look hard enough and spend some time reading various blogs and forums. All the info is out there - you just need to work a little at collecting and summarizing it.

[Elijah-Baley]

Dude... that Rat MULTI schematic was for me a great inspiration!

In the OCD, the things that let me a bit confused, are right that slight variations you quoted. Maybe I really need to study better the OCD, as you said, the info should be all revealed and it's enough find out.
Who knows? I may really do all the work and share all the schematic.

I guess we will see soon, or sort of.

[thermionix]

There's already a "multi-RAT" schemo for the OCD, but up to "V3" in this case.  Don't remember where I found it, can't verify it's accuracy either.



I think V4 has a log volume pot, which I used too.  My C4/R4 are 100n/4k7, claimed here to be the JHS mod, a little less gain and low end than stock.  I also omitted D1.

[Elijah-Baley]

Thanks! I found it today. I pick up all the schematics and layouts I find. Also clone and replicas of the OCD pedal.

I would like to know how work the last version, exactly. It has some kind of buffer or maybe something more than it.

[GGBB]

Fulltone says the new version adds a JFET input buffer to raise input impedance, an output buffer to lower output impedance, and a switchable bypass buffer. According to another forum where v2 was traced, the bypass buffer is two input buffers in series, the JFETs are 2N5457, and the output buffer is a 2SC1815 BJT. The rest of the circuit is basically the same.

[THRobinson]

Weird, the auto  notification never seems to work for me on this site, glad i checked back.

Sadly a lot of whats said is over my head, still learning... But i guess my question wasn't as simple as i had hoped. Sounds like something with lots of revisions.

[GGBB]

Weird, the auto  notification never seems to work for me on this site, glad i checked back.

Sadly a lot of whats said is over my head, still learning... But i guess my question wasn't as simple as i had hoped. Sounds like something with lots of revisions.

To answer your original question about which schematic is "closest" - I think all the common ones are bang-on but they may differ in which OCD revision they reflect. But it's not like they are all completely different pedals - they are all very close. Pick one, build it, and you'll know what all OCDs sound like in general with maybe some slight tone shape differences.