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So, I'm trying to help a friend out. I fixed one of his favorite pedals a couple years ago. MXR Phase 90, script logo, bud box. He had shipped it to a friend to use. When it arrived it was dead. The input buffer ic, input cap, and the third ic in the phase shifting stage were all dead. Started with the cap, then the input ic, and then the phase shifting ic. I changed them in that order to make sure I didn't do something I shouldn't have.

I tested it out, and everything was working. I gave it back to him thinking I just did him a solid. He said thanks and that was that. Come to find out it didn't sound the same to him. He couldn't really explain it, but from what I gather it didn't sound as vibrant as it used to. And with his lack of electronics knowledge I'm not sure he's blaming me for the parts that I used. So I took it back. I socketed the ic's so I've been trying different ones to try and find something that sounds best. TL071 sounds best so far so that's what I've gone with.

I tested the phase circuit with my signal tester and I get phase at each ic.

I sat and listened to is swirl by itself with just a guitar plugged in and I noticed that the pedal drifts. Sometimes the swirl gets really loud and sometimes it is really quiet. If I unplug the guitar and plug it back in the pedal sounds at its best for a short time and then it drifts off again.

I'm thinking the two tantalum caps are starting to drift and that is causing some of the issues.

The question is, if I have to change anymore of the caps then what should I use? I used a Panasonic film cap for the input cap.

Thanks for any help

Well, anyway. C10 was bad. I found the voltages should be everywhere after bread boarding the LFO. They're only stationary if it isn't working right.

I'm not sure where this should be posted. The Duovibe isn't a current project or an old project and I don't think it's an extra project either. But I think the origins are from this forum. So here it goes.

I'm wondering if someone can help me. I've built one from the Effectslayout blog on perf board. My signal passes through fine. But it doesn't vibe at all. The led lights and if I touch the led with a jumper to the positive 9v it warbles like it's supposed to.

Now, I know. I should post a big picture of the perf board if I really want help. But what I really want is to know how the LFO works so I can better understand where my mistake can be found.

I've looked at the LFO on the Tremulus Lune because it's very similar and there are a lot of of posts on other forums about it. But I haven't found a good explanation as to how it works.

One thing I've noticed is that my voltages are not similar and I'm not sure if they'd be much different. In the Lune the second side of the opamp voltages are much lower. Should the DuoVibe LFO voltages also be lower for the second stage?

I've tried new pots, and new caps in the LFO. I've looked for bridges and missed solder joints. The mistake isn't obvious.

Here are my voltages;

1. 7.6v
2. 7.6v
3. 7.8v
4. Ground
5. 8.25v
6. 8.14v
7. 8.54v
8. 8.6v

I've attached a copy of the LFO schematic and a copy of the layout for reference.

The layout uses the second side of the opamp in the first stage of the LFO.

Thank you for any help.

Jacob

Thanks Brian. I'm building the 2015 version. I'll try that mod. I just ordered from Small Bear. Maybe they will let me change it since it hasn't shipped yet.

Thanks guys. That cap from pin 2 to ground didn't do anything. I might have to try some different chips. I hate to buy more of them. It's cutting into my project fund. I just need one good one to base the rest of them on.

Anyone have good luck with Mklec chips?

Currently building my second Cave Dweller. The first was on vero board, this one is with a MadBean PCB. I get the same results in both pedals. I get this fuzzy/bad repeat. No matter how many PT2399's I use. These being the only chips I have and the only ones I have to go from, I'm not sure if there is an issue with the chips or the build or this is how it's supposed to sound. I've tried eleven of them.

All the voltages are really close to the ones in the instructions.

Should I expect a nice clean repeat? Or is that just the chip?

Ok, so Envelope Filter is a definite. Delay is a giant maybe. I'm thinking about building a Cave Dweller on Vero. Mostly as a starting point for delays. Also as a tester for chips. I may etch a pcb if I get enough stuff to do all at once. But that might be a while.

Now, it appears that the only PT2399's on EBay are the same as Tayda. Is there one standard brand?

I'm finishing up my last big build and I need some suggestions for the next. I'm getting ready to order supplies and need to make up my mind in the next couple days.

I've done almost twenty pedals at this point. Fuzz, overdrives, phasers, compressors, and a couple reverbs. So I'm at my next step. Maybe something a little harder. I've been looking for delays but I don't want to waste money on PT2399's if I don't have to. I like to order on odd IC, and one extra. But I'd rather not order 5 or more to get a pedal to work. It's not fun or cost effective. Are they really that bad?

And are there other pedals I'm not thinking of? Maybe a cocked Wah or auto wah or synth sounding pedal. Something that is fun to build and play.

Prefabbed PCB would be best. Any suggestions?

Your going to have to change your handle to VanDirvChuck!

Ha! Done...

$20! Seriously! I might order one for the enclosure.  Because, you know, being chinese, im not sure i would trust anything else that comes in the kit.

Be interested to know what you think of the finished product vanderchuck.

Edit: oh...optical illusion. That enclosures not drilled hah...

It's totally drilled out. I'm actually not going to build it as is. It's going to be for a friend and it might end up in the style of the OCD or Bluesbreaker. I really just wanted the enclosure.

With true bypass, you wouldn't need Q9 and Q4, the FET switching. Q8 (or Q10) would then be redundant and could be eliminated. Also, everything after the volume wiper could go, too. Then you're left with 4 FETs, 1 BJT, and one dual op-amp. So, yeah, it could be a simplified OD3.

Thanks, I didn't think of that. It doesn't make sens when looking at the BOM and the schematic together. The pcb has a spot for the foot switch that doesn't match the one in the kit. From first glance it looks like it looks like it's not true bypass.

I could do way worse than the od3. You're right. That's for sure. But I don't recognize the BOM either. One PNP,  one jrc4558, and four FETS. Sounds more like a phaser than an OverDirve.

Edit: My phone is now autocrorecting OverDirve.

I'm not kidding at all. That says OverDirve. I have a sense of humor so it's worth $20.00 to me.

I need to know what it's supposed to be. I can put any OD or Distortion in it I want. But part of me wants to know if it's a pile of parts that don't work or if the crappy PCB actually works. This is the schematic in the ebay description.



If this looks familiar it's because it is the Boss OD3 schem.



But the BOM doesn't match the schem. No big surprise there. Here is the full description.

http://vi.raptor.ebaydesc.com/ws/eBayISAPI.dll?ViewItemDescV4&item=111644879772&category=41416&pm=1&ds=0&t=1431347806554

Here is the item.
http://m.ebay.com/itm/121647413914?nav=SEARCH

There's also an equally odd Distortion and a Delay.
Anyone have any guesses?

Nice first etch man.
You'll find the timing varies in proportion to the area being etched. A large area creates a bigger reaction, which heats the etchant, creating a faster reaction.
It's pretty much all artistry and experience- with only a hint of the repeatability of science.

That may be some of the best etch advice I've ever heard. Thanks man. Never thought of that.

Thanks everyone! (Insert smiley face thing here.)