Rat Mod- Momentary Feedback

[theADHDhero]

So I want to mod my Rat 2 to have a momentary switch to stomp on to make the pedal feedback like a Boss DF2 can. Any tips?
I also have a Digi Death Metal pedal I can also use, but I feel the Rat is a little bit simpler set up so I thought it would be easier to get in there and interrupt the signal

[patrick398]

Did i bit of digging and eventually found a DF-2 schematic, i have to say it's a lot more complicated than i thought it might be. I initially thought (not really knowing anything about the pedal) that the momentary switch might just be upping the gain on the second op amp or something. Turns out there's a lot more going on: envelope detection and 'fundamental detector' which i think is some kind of pitch to voltage converter, i guess that's how it always feeds back in tune?

It don't think it's going to be a case of 'modding' a Rat, more like redesigning the whole thing.

http://experimentalistsanonymous.com/diy/Schematics/Distortion%20Boost%20and%20Overdrive/BOSS%20DF2.pdf

[Fancy Lime]

The Fundamental Detector in the DF-2 is essentially the same as in the OC-2. It's just a flip-flop triggered by positive and negative peak detectors. In the DF-2, this fundamental wave then drives a phase-locked loop (PLL), which creates the simulated feedback. This is then filtered to turn the PLL's output  square wave into something more musical and has a very slow envelope imposed on it, which is triggered by the footswitch.

No rocket surgery but almost certainly a b!+(# to tune just right so it works at all. I wouldn't know, I haven't tried, but it sure looks like it. As Norm Looper said here:
https://www.nutsvolts.com/magazine/article/designers_guide_to_reliable_oscillators_and_timers_part_3
"Designing with PLLs in production circuits is reserved to those with the courage of the thoroughly uninformed. But you can have a lot of fun playing with them!"
So I don't want to discourage anyone.

Cheers,
Andy


EDIT: See here also:
https://www.diystompboxes.com/smfforum/index.php?topic=118577.0

[theADHDhero]

So my thought, rather than replicating the actual set up, I could just add a non-latching DPDT switch into the system, that when pressed, sends the signal directly through a Si diode, which should drive the signal up.

And then if I place the switch in the last stretch of the whole circuit so that when not pressed down, it is basically bypassed, but when pressed, the outward bound signal hits just the Diode on its way out.

Does that make sense?

[Nitefly182]

It's impractical to mod your Rat to achieve this goal but a DF2 is just a DS1 with the feedback system built around it. The feedback system is the bulk of the parts and rather complex. Since a Rat is very simple you would have a much easier time taking the Pedal PCB DF2 clone board and splicing a Rat circuit in place of the DS1 circuit. Then you should be able to have your Rat with the feedback function.

[theADHDhero]

It's impractical to mod your Rat to achieve this goal but a DF2 is just a DS1 with the feedback system built around it. The feedback system is the bulk of the parts and rather complex. Since a Rat is very simple you would have a much easier time taking the Pedal PCB DF2 clone board and splicing a Rat circuit in place of the DS1 circuit. Then you should be able to have your Rat with the feedback function.

Well, my goal was never to recreate the system, rather just recreate a similar function.

But in this instance, you are suggesting purchasing a DF2 or DF2 clone and that is what I am trying to avoid having to do. If I am just going to have to purchase a DF2, I would just use the DF2 as in.

[Nitefly182]

It's impractical to mod your Rat to achieve this goal but a DF2 is just a DS1 with the feedback system built around it. The feedback system is the bulk of the parts and rather complex. Since a Rat is very simple you would have a much easier time taking the Pedal PCB DF2 clone board and splicing a Rat circuit in place of the DS1 circuit. Then you should be able to have your Rat with the feedback function.

Well, my goal was never to recreate the system, rather just recreate a similar function.

But in this instance, you are suggesting purchasing a DF2 or DF2 clone and that is what I am trying to avoid having to do. If I am just going to have to purchase a DF2, I would just use the DF2 as in.

So the Rat part of the equation isn't actually important at all? Its just a thing that exists and you want it to do this other thing too? I figured you wanted the actual functionality of the DF2 just with a Rat as the distortion circuit.

Nothing you can do to just make more gain or volume in a Rat is going to be even remotely close to the effect the DF2 produces. You would just be getting blast of increased signal and the luck of the draw feedback that your room/amp/guitar produces in the moment.

[theADHDhero]

It's impractical to mod your Rat to achieve this goal but a DF2 is just a DS1 with the feedback system built around it. The feedback system is the bulk of the parts and rather complex. Since a Rat is very simple you would have a much easier time taking the Pedal PCB DF2 clone board and splicing a Rat circuit in place of the DS1 circuit. Then you should be able to have your Rat with the feedback function.

Well, my goal was never to recreate the system, rather just recreate a similar function.

But in this instance, you are suggesting purchasing a DF2 or DF2 clone and that is what I am trying to avoid having to do. If I am just going to have to purchase a DF2, I would just use the DF2 as in.

So the Rat part of the equation isn't actually important at all? Its just a thing that exists and you want it to do this other thing too? I figured you wanted the actual functionality of the DF2 just with a Rat as the distortion circuit.

Nothing you can do to just make more gain or volume in a Rat is going to be even remotely close to the effect the DF2 produces. You would just be getting blast of increased signal and the luck of the draw feedback that your room/amp/guitar produces in the moment.

Yes exactly! I am just bored and felt like getting experimental. So what you're saying is is that it is very unlikely to replicate the same effect as a DF2, but the blast of increased signal could work (pending the room) but it would be a crapshoot?

Additionally, I did not mean to seem like I was sh*tting on your initial plan. In regards to putting 2 pedals together kind of idea: I have a Digitech Death Metal I was going to mod just for the learning experience. Any thoughts on if parts from that could be utilized for this project?

Also thank y'all for being so helpful! I asked this similar question on a different but similar forum and the responses I got were mostly trolls

[Nitefly182]

I think taking the infrastructure of the DF2 and dropping different distortion circuits into it could be very interesting. Especially with something maybe more textured than the DS1 circuit like a fuzz. It wouldn't be a mod to your rat but I don't think it would be a super difficult project if you can read a schem and start with the PedalPCB Backfeeder board as your basic framework.

And yes no real feedback as a result of being loud and distorted is going to sound like the synthesized feedback produced at unity volume by the DF2. The appeal of the DF2 was supposed to be the level of control it afforded you. If you're interested in that quality the Digitech Freqout is a vastly superior product.

IMO this is not a very DIY-able effect, especially if you don't want to invest in trying the DF2 idea. You're just left with trying to induce feedback the old fashioned way which just takes volume and luck.