Devi Ever DIY Aenima Oscillation points?

[DarkNDubby]

Hey there, I bought a Devi Ever TP/ AE DIY kit, and I've got it all soldered, wired and working, but I have a question about the oscillation points that are in the Devi schematic. http://www.deviever.com/fx/forum/download/file.php?id=2080&t=1

There are two extra holes in the PCB labeled AE 1 & AE2 which I am assume are the oscillation points. And I believe I read somewhere (on the retired Devi forum) that you just join them to make it work. Is that all I need to do? Also, would it be possible to use a pot instead of a switch so that I could control the amount of oscillation? Finally, if I used a pot, what resistance value should I use to guarantee that i could go from a fully oscillating signal to full non-oscillating signal? I hope the question makes sense... I'm just a poor noob trying to figure this stuff out. Any help would be greatly appreciated.

[Jero]

Yea, you just connect the two points, usually with a switch so that you have the on/off (connected/disconnected) option. If you put a pot there, it will change similarly to what you want. I doubt you will get it to turn the oscillation off, though it might. It's different than replacing a fixed resistor, where you already have resistance between two points. Try 10k, 100k, 500k and 1meg. The wider sweeps might just work out. Another option, and the one I'd go with, is to find a switching pot. All the way down/left is off, then it clicks on and goes through the sweep of the pot as you rotate it right.

[DarkNDubby]

Thanks, Jero! I already built the pedal with a pot, so I'd like to use a pot instead of a switch if at all possible. As far as a switching pot goes, that sounds ideal. Do you know if they sell on small bear or any other site? I was looking on small bear, but its possible I just don't know what I am looking for...

[DarkNDubby]

One more thing, as a curious noob, if typically run a signal through a 100k pot as a volume, it will sweep from full volume to completely quiet, right? Shouldn't the same thing apply if I used a 100k pot to attenuate the oscillation?

[Jero]

One more thing, as a curious noob, if typically run a signal through a 100k pot as a volume, it will sweep from full volume to completely quiet, right? Shouldn't the same thing apply if I used a 100k pot to attenuate the oscillation?

Not necessarily , because you are making a connection that shouldn't be, not replacing a fixed resistor like the volume control. That's what I was saying before. I think that pot being in between those two points will always have them connected, regardless of where the rotation is, thus you need a switch to disconnect the two points. However, if you use a large value pot, like 1meg, you might find a spot in the rotation that cuts the signal. Just try it, it's pretty simple to de-solder 2 wires.

I don't know if smallbear carries the switching pots, I don't order from them usually. Might have a 10k one I think, I could send you.

[DarkNDubby]

Thanks so much for the help. I've got 500k and 100k pots to try at home. Hopefully it works. If not, I may have to hit you up on that switching pot offer.

[IEatCats]

You could also try a push pull pot, so that you can mount the on/off in the same knob. It may be a bit prone to accidental shut-offs when playing, but it's an option.

[Jero]

You could also try a push pull pot, so that you can mount the on/off in the same knob. It may be a bit prone to accidental shut-offs when playing, but it's an option.

The one I mentioned turns off with a hard twist to the left, so no accidental off's. However, it might be easier to find those.

[DarkNDubby]

I'll try the normal pots this weekend. I really like the idea of Jero's switch pots rather than the push pull. It's a shame they are difficult to find. I've been searching around online, but nothing yet...

I can't wait to hear what the Aenima sounds like with oscillation. That pedal is so freakin LOUD.

[DarkNDubby]

Great news! I used a 500k pot to join the oscillation points, and at full turn counterclockwise, you can't hear the oscillation effect. The oscillation is wild though... Not quite sure how I'd use it yet. Thanks again, guys, for the help.

[Jero]

Right on! Glad it ended up working out for you. You should post video/clip if you can.

[IEatCats]

Does anyone know exactly how the oscillation works? I'm just trying to figure out how the feedback loop causes oscillation.

[Jero]

Does anyone know exactly how the oscillation works? I'm just trying to figure out how the feedback loop causes oscillation.

Feedback loops literally feed the out signal back to the input and it starts to overload depending on the setup. Kind of the the same idea in the aenima/tp, but in various choice places in the circuit.

[IEatCats]

Does anyone know exactly how the oscillation works? I'm just trying to figure out how the feedback loop causes oscillation.

Feedback loops literally feed the out signal back to the input and it starts to overload depending on the setup. Kind of the the same idea in the aenima/tp, but in various choice places in the circuit.

So, the oscillation is just the signal feeding back, and overloading the transistor? It's just a "feature" from running too much gain into a transistor, that it overloads and produces an oscillation, or is there any other concept in there I'm not grasping?

[Jero]

So, the oscillation is just the signal feeding back, and overloading the transistor? It's just a "feature" from running too much gain into a transistor, that it overloads and produces an oscillation, or is there any other concept in there I'm not grasping?

For oscillation with the Aenima, the output of the entire circuit is fed back to the input of the last gain stage/output of second gain stage. This means (some of) all that signal coming out the pedal will go back into the last transistor stage, which is boosting the regular signal, and REboosting the fed back signal. It will continue to do this as long as the connection is made. Thus sound explosion &/or overload.
The general idea is to get signal coming out, to go back in, and then back out (aka feed back). So you can put them just about anywhere, if it follows that. Now, variations will occur based on placement in the circuit because of interactions with other components/filters/etc.

Another way to think about it is guitar feedback. Your guitar makes noise, which then gets amplified, and pushed out the speaker. If the sound is loud enough/you're close enough, you're guitar will then also pick up the sound from the speakers, as well as the vibrations/sound from the strings. This will then get amplified AGAIN, come back out the speakers, and back to the guitar, then back to the amp, back to the guitar...feedback! That's how I understand it at least. I'm no expert by any means.

I bet you could use the AE & TP oscillation points, on just the AE, or just the TP. It would also be a good idea to change the 10k/100k/220k to a 250k pot instead, so you could go through AE/TP/US and anything in between.

ae_tp_nd_us.gif (19.18 KiB) Viewed 2775 times