Ludwig Phase II Clone Debugging and Miscellany

[digi2t]

Ahhhhh.... so THAT'S where you've been hiding lately!!

And I thought that stirring up the poop over at FSB was taking up all your time. 

Welcome home bro. 

[Govmnt_Lacky]

Ahhhhh.... so THAT'S where you've been hiding lately!!

And I thought that stirring up the poop over at FSB was taking up all your time. 

Welcome home bro. 

Ha! Nothing like getting insulted, defending yourself, and getting punished for it.... and by moderators! 

I have had my "forum issues" as of late but... refocus and get back to enjoying this fine hobby/distraction 

[hangingmonkey]

I'm building the Ludwig from an etched PCB, I had a few questions (so far)

1 the unmarked resistor to the left of RF33, do I leave that empty, or jumper?

2 I read RGs answer about this on the other page but I just wanted to clarify... The dc1/dc2 pads, do I just connect the power to either one of those, if so do I need to add any jumpers anywhere?

3 I bought a 48vdc for this, it's rated at 380mA, is that enough juice?

4 this pedal has 2 inputs right? What are they for?
Thanks for your help, I'll be sure to post up a build report when this monster is finished, although I'm probably more likely to post up further questions here first!

[digi2t]

1 the unmarked resistor to the left of RF33, do I leave that empty, or jumper?

This is for an optional 1M resistor. Later units came with it piggybacked to the existing resistor. Experiments on original units revealed that it helped tame some of the harsher high frequencies. You can leave it out for now, and test once you've got it running. DO NOT insert a jumper here.

2 I read RGs answer about this on the other page but I just wanted to clarify... The dc1/dc2 pads, do I just connect the power to either one of those, if so do I need to add any jumpers anywhere?

Judging by your question 3, if you're planning on using a DC power supply, then you'll be using AC/+DC1 for the POSITIVE, and Pwr Com for the NEGATIVE.

3 I bought a 48vdc for this, it's rated at 380mA, is that enough juice?

From the build doc; 48Vdc/0.125A wall adapter, Mouser P/N709-GS06U-8P1J, $13.65. Yup... you got enough power.

4 this pedal has 2 inputs right? What are they for?

One Hi-Z, and one Lo-Z input.
Hi-Z, think Guitars, Basses, Instruments, etc.
Lo-Z, think Microphones, Pro Audio Equipment, etc.

Now, go forth, and yoyo-fy

[hangingmonkey]

Thanks Dino. I'll get on the case and get this baby completed. (I still have an unfinished infinitphase on the shelf uncompleted)

[digi2t]

Thanks Dino. I'll get on the case and get this baby completed. (I still have an unfinished infinitphase on the shelf uncompleted)

Funny you should mention the Infinitphase. I'm breadboarding a sample/hold circuit for mine right now. Mike from Prophesysound was nice enough to give me an outline of how the sample/hold, and stereo output are arranged, a while back. I'm planning on integrating both mods, starting with the sample/hold.

Just out of curiosity... is it "unfinished", or "uncompleted"? 

[hangingmonkey]

Sample hold sounds interesting although i dont think ive seen any videos demonstrating the sound but im sure youll post up a vid once you get it working.

My infinitphase is mostly populated, the offboard wiring has made me put it on the shelf till there comes an opportunity during annual leave when i have a few days to work on it. Probably wont be till next year sometime unfortunately:(

[Keppy]

I'm finishing up a couple of Phase IIs and I'm having a baffling problem. The oscillator works. The flipflop works when triggered manually (collectors flip from 0 to 13-14v). However, the flipflop does not respond to the oscillator. I've metered every component connecting them and within both sections, and the values are correct. I've audio probed the collectors of the flipflop transistors, and I can hear ticking on whichever one is off (the one that's on has collector at ground), but it just won't flip on its own. I thought maybe the oscillator was set up wrong and ticking high instead of low, but metering it shows it's ticking low as it should. What's the deal?

Background: I'm using the 6027 PUT in the oscillator with a 5.1k Ralt. The oscillator page of R.G.'s manual says to use Ralt=4.7k or 5.1k, but his schem shows it as 3.3k.

[Keppy]

Just to be clear, I should also add that both builds have exactly the same problem.

[Keppy]

I changed Ralt to 3.3k in one unit with no improvement.

[Keppy]

I removed C3 and coupled the oscillator to the bases of the flipflop transistors (as in Boss bypass switching) rather than the collector bias network (as in the PII schem) using .01uf caps. Now I can hear the flipflop affecting the output, but it doesn't seem to be latching. The transistors go back to their previous state after the oscillator tick instead of remaining flipped until the next tick, so the filters tick instead of sweeping. If I turn the animation off, I can still work the flipflop manually and it latches.

[R.G.]

I'll take a look at that.

Discrete flipflops were problematic without really careful design, I was told. They were the 'past generation' stuff when I was an engineerling with TIC.

It may need some tinkering, or some 'dirtying up' of the modern devices to work like the transistors in the original.

[Keppy]

I'm seeing something else problematic now. The Animation mode is switched by grounding Q7, Q8, or neither (the "echo" transistors). The problem is that when one of those transistors is off, its collector is still affected by the voltage divider on the other transistor's collector. When you ground the base of one transistor, the collector of the other one swings the whole supply voltage instead of half, which causes the voltage divider on the first to still swing from half supply to full supply.

That means that the echo transistors only have the correct swing in the middle switch position. In the other positions, the active transistor has a double swing, while the inactive one still swings just as much as if it was active. It looks to me like the switch should ground the collectors rather than the bases. Has anyone using the 2nd run boards had problems with the Animation modes?

[digi2t]

Has anyone using the 2nd run boards had problems with the Animation modes?

As far as I know Kep, you're the only one I've seen using the 6027 for the animation. I've done two builds with the 2646, and both worked fine. Hopefully this will get sorted out.

[Keppy]

As far as I know Kep, you're the only one I've seen using the 6027 for the animation. I've done two builds with the 2646, and both worked fine. Hopefully this will get sorted out.

I thought Ry used a 6027 and he got his working. The problem in the post you quoted, though, wasn't with the oscillator, it's with Q7 & Q8. Have you noticed any issue using different settings on the Animation toggle?

[digi2t]

I'll check it out tomorrow. I haven't played with in a while, so from memory, I don't think I have any issues with it, but I'll let you know.

So, if I understand correctly, you have LFO on both, but not on FFM, or Fuzz Repeats only. Dumb it down for me, just so I know what I'm listening for.

[Ry]

I never got my oscillator running...and wow, I don't remember what I used, that was a couple years ago.  I may have given up and bought an original that I stumbled across and put the DIY one aside.  That said, I've been meaning to dust my build off and try to troubleshoot it, now I'm inspired!

[Keppy]

I never got my oscillator running...and wow, I don't remember what I used, that was a couple years ago.  I may have given up and bought an original that I stumbled across and put the DIY one aside.  That said, I've been meaning to dust my build off and try to troubleshoot it, now I'm inspired!

Crap. That might mean the PUT version doesn't work (I found your old post where you said what you used). I better order some UJTs. Mine definitely oscillates, but apparently the output is different enough that it won't trigger the flipflop.

So, if I understand correctly, you have LFO on both, but not on FFM, or Fuzz Repeats only. Dumb it down for me, just so I know what I'm listening for.

Forget the LFO. That, as far as I can tell, is a separate problem. While I was poking at it I found what appears to me to be a mistake in the implementation of Q7 & Q8. Those transistors are supposed to copy the output of the flipflop, but in my builds they don't, and looking at the schematic I believe the error is in the implementation, not in my builds. Here are the tests:

Auditory test:
Animation on, Intens. FFM and Intens. Fuzz Rpt. all the way up, rocker centered, Counter mode. Start with the Animation toggle set to Both.
1) Do you hear both the Fuzz Repeat and the automatic filter sweeps?
2) When you move the toggle to Fuzz Rpt. does the filter sweep stop? Do the Fuzz Repeats just continue, or do they get more intense?
3) When you move the toggle to FFM, do the Fuzz Repeats stop? Does the filter sweep change at all from the center toggle position?

Meter test:
Animation on, rate all the way down, R4 (internal speed trimmer) all the way down.
1) Measure the voltage on Q7 collector with the toggle switch in all three positions
2) Repeat for Q8

I'm pretty sure the meter test will reveal different voltages than what's in the build doc (as mine does when triggered manually), but it remains to be seen if that will audibly affect the different modes. I can't tell on mine until I get the other problem sorted out. Thanks Dino.

[digi2t]

Got a busy day today, but I'll have time to check it out tonight.

Sit tight bro... I'll run through your requests, and report back.

[Ry]

Keppy, your builds are doing exactly what mine was (as I recall).  While this sounds frustrating to you, I'm really excited that you may have uncovered why mine isn't working.  I put this thing aside after spending close to a month debugging it almost exactly two years ago...I would love to get my clone running!