Ludwig Phase II Clone Debugging and Miscellany

[artifus]

rocker pot toe down = gnd (from: http://geofex.com/Article_Folders/Ludwig_P2/Ludwig%20Phase%20II%20Clone.pdf)

[Vince_b]

rocker pot toe down = gnd (from: http://geofex.com/Article_Folders/Ludwig_P2/Ludwig%20Phase%20II%20Clone.pdf)

I'm sure that it may be really obvious for most people, but for some reason it does confuse me.

Does it mean that I got it reversed? the ground should go to lug 3?

[digi2t]

rocker pot toe down = gnd (from: http://geofex.com/Article_Folders/Ludwig_P2/Ludwig%20Phase%20II%20Clone.pdf)

I'm sure that it may be really obvious for most people, but for some reason it does confuse me.

Does it mean that I got it reversed? the ground should go to lug 3?

Try to think of it as where the wiper (lug 2) is going when you toe down, or heel down. Just look at the rotation of the gear as you move the pedal, and imagine the wiper moving towards one lug or the other. In this case, you want to go to ground when you're completely heel down, so lug 3 in your picture.

A word of advice; I trimmed down the rubber bumpers on my pedal with an Exacto. I only left about 1/8" showing, just enough to cushion the end of the travel between heel and toe. You have plenty of rotation available on the pot, so you best use it to maximize the sweep through the filters. Once the bumpers are trimmed, set your pot that it's completely at the end of the rotation when you're heel down (ground side). Just leave a TINY amount of play, to compensate for the heel side bumpers. If you find that you're between teeth on the gear, just rotate the pot itself slightly to get you there. Set there, with the trimmer resistances I published here, http://www.diystompboxes.com/smfforum/index.php?topic=95132.120 , in the quick set up guide, you should be good to go.

Needless to say, I'm dying to hear yours in action .

[digi2t]

@vince AWW CRAP!!!!! I MESSED UP!!!

CORRECTION

Try to think of it as where the wiper (lug 2) is going when you toe down, or heel down. Just look at the rotation of the gear as you move the pedal, and imagine the wiper moving towards one lug or the other. In this case, you want to go to ground when you're completely heel down, so lug 3 in your picture.

The ground goes to LUG 1 in you picture. Sorry for the mess up. Toe down to ground is correct.

Insofar as setting up the pot is concerned, step 1) of the procedure is incorrect, and should read as follows;

"1) Install your pot in your pedal. One pole goes to ground, the wiper should be on this side of the pot when in toe down position. Adjust the pot position so as the pot sweep is completely at the end of it's travel when the treadle is completely heel down. In other word, bottom the pedal, bottoms the pot."

Everything else is OK, including what I said about trimming the rubber bumpers.

My apologies if I threw you a red herring. I must of had a major brain fart that day.

Dino

*EDIT* - I've PM'd Aron, and asked him to correct step 1) of the procedure, posted in reply #139 of this thread. It should read as follows;

1) Install your pot in your pedal. One pole goes to ground, the wiper should be on this side of the pot when in toe down position. Adjust the pot position so as the pot sweep is completely at the end of it's travel when the treadle is completely heel down. In other word, bottom the pedal, bottoms the pot. If you wish, you may also trim the rubber toe/heel bumpers, if you're using a Dunlop type shell, to maximize the amount of sweep. If you do, you can take them down to about 1/8" (3mm), which is enough to cushion the impact. In any case, assure to leave a bit of play on the pot rotation in heel down, to accomodate the deflection of the rubber bumpers. This will avoid having the rack gear jump a tooth if you push heel down too hard.

[Vince_b]

No problem Dino, I knew that it could be really confusing although it seems very simple  

I won't trim the rubber bumpers because the wah shell that I'm using right now is only temporary. It's a bass Crybaby with a spring in it and I'm pretty sure that this is far from ideal for the Ludwig. But I've bought a "standard" Crybaby shell from a forum member and I should  receive it soon.

[RonaldB]

I finally managed to get the ludwig clone working.
I had a hard time finding the right powaer adapter. I got a trafo that outputs 30V ac now and delivers 39V DC when rectified.
I had a problem that after the BD677 transistor I didn't got the wanted voltages. So I did some testing and found out that when I left the BD677 out I got a nice 36V DC in the circuit.
It worked right away and after some quick tuning up (thanks Dino for the quick reference sheet), I got filter sounds out of it.

But the problem know is that i have a loud humm or oscillation, When I turn RF65 it gets louder or softer but never gone.
What is a good place to start to get ridd of this oscillation?

Best regards
RonaldB

[digi2t]

I finally managed to get the ludwig clone working.
I had a hard time finding the right powaer adapter. I got a trafo that outputs 30V ac now and delivers 39V DC when rectified.
I had a problem that after the BD677 transistor I didn't got the wanted voltages. So I did some testing and found out that when I left the BD677 out I got a nice 36V DC in the circuit.
It worked right away and after some quick tuning up (thanks Dino for the quick reference sheet), I got filter sounds out of it.

But the problem know is that i have a loud humm or oscillation, When I turn RF65 it gets louder or softer but never gone.
What is a good place to start to get ridd of this oscillation?

Best regards
RonaldB

Hmmm...

OK, try this; First, turn R65 completely to one side, where it's the most quiet. Now, work with R55, or R77, AND REMEMBER TO COUNT YOUR TURNS!! Start with R55, and slowly turn it one way. If it makes no difference, or gets worse, back up to your starting point, and go the other way. If it doesn't get better with R55, then repeat the procedure with R77. If that reduces your noise, you can put R65 back to the specified setting.

Don't worry too much about affecting the tonal character of the unit by playing with these trimmers. They will however induce oscillation in the circuit if they're too far out of whack. From what I've seen, the adjustment of these two trimmers has no "hard and fast rule" either. They seem to be different on every unit. They might be there to compensate for slight (or great?) differences in one transistor to the next, in the filter sections. I've had them centered on one unit, while on another they're 90% to one side or the other to kill the oscillation.

Let us know the results.

[RonaldB]

I finally managed to get the ludwig clone working.
I had a hard time finding the right powaer adapter. I got a trafo that outputs 30V ac now and delivers 39V DC when rectified.
I had a problem that after the BD677 transistor I didn't got the wanted voltages. So I did some testing and found out that when I left the BD677 out I got a nice 36V DC in the circuit.
It worked right away and after some quick tuning up (thanks Dino for the quick reference sheet), I got filter sounds out of it.

But the problem know is that i have a loud humm or oscillation, When I turn RF65 it gets louder or softer but never gone.
What is a good place to start to get ridd of this oscillation?

Best regards
RonaldB

Hmmm...

OK, try this; First, turn R65 completely to one side, where it's the most quiet. Now, work with R55, or R77, AND REMEMBER TO COUNT YOUR TURNS!! Start with R55, and slowly turn it one way. If it makes no difference, or gets worse, back up to your starting point, and go the other way. If it doesn't get better with R55, then repeat the procedure with R77. If that reduces your noise, you can put R65 back to the specified setting.

Don't worry too much about affecting the tonal character of the unit by playing with these trimmers. They will however induce oscillation in the circuit if they're too far out of whack. From what I've seen, the adjustment of these two trimmers has no "hard and fast rule" either. They seem to be different on every unit. They might be there to compensate for slight (or great?) differences in one transistor to the next, in the filter sections. I've had them centered on one unit, while on another they're 90% to one side or the other to kill the oscillation.

Let us know the results.

Unfortuantly this didn't solved the problem.
I tried, after adjusting R65 for the lowest noise point, adjusting R55 and R77. The oscilation went a little lower, but still audioble. I went lower in pitch.

ROnaldB

[digi2t]

OK, plan B...

Check transistor voltages. Comparitive numbers can be found in R.G.'s build article.

[R.G.]

I am suspicious that the hum may be power supply ripple. The Q6 transistor is a regulator, and wipes off some of the inevitable hum from rectifying AC from a transformer.

One can get the right DC voltage but have ripple.  If the frequency/pitch of the hum is always the same, suspect that it's ripple.

As a test and possible fix, temporarily connect at much larger capacitance across C11 or C6. 470uF/50V or larger should work well.  The existing 47uF value is marginal unless some additional regulation is used in this application.

[RonaldB]

I am suspicious that the hum may be power supply ripple. The Q6 transistor is a regulator, and wipes off some of the inevitable hum from rectifying AC from a transformer.

One can get the right DC voltage but have ripple.  If the frequency/pitch of the hum is always the same, suspect that it's ripple.

As a test and possible fix, temporarily connect at much larger capacitance across C11 or C6. 470uF/50V or larger should work well.  The existing 47uF value is marginal unless some additional regulation is used in this application.

This helped, the humm is still there but I need to check through my rig to see how bad it is.
Is it better to buy a new BD677 and put it in? Or it there an other solution for the filtering.

thanks,\RonaldB

[digi2t]

Just a suggestion,

Maybe it's best to go with "the known", rather than "the unknown". In this case, the power supply you're using is "the unknown". As far as I know, Keppy and myself have used the (basically) same power supply units. Insofar as my unit is concerned, I never had a problem with power supply noise. I don't believe Keppy did either.

If you're getting 36VDC, I'm assuming that's because the Zener is doing it's job. But, I would still recommend the power supply scheme spec'd by R.G.. It works, it's not that expensive, and will most definately take "the unknown" out of the equation.

For the PS I used, the info is here; http://www.diystompboxes.com/smfforum/index.php?topic=95132.100 , about halfway down the page.

Keep us posted.
Dino

[R.G.]

If that helped, the problem really is ripple voltage.  That's good, because you know what to do to fix it. That's bad, because the problem is that you don't have high enough input voltage to run the regulator properly.

So no, replacing Q6 will probably not help. The real problem is that your input DC voltage isn't high enough to regulate properly, and that is letting the ripple through.

The voltage regulator of which Q6 is a part is a very simple, crude voltage regulator. It's advantage is that it's simple (!) and cheap - or was cheap at the time the LP2 was designed. The simplest answer is to get a different and larger voltage supply to feed the circuit. Your transformer is not putting out enough voltage. I'm sure this is unwelcome news since you had a problem finding this one.

Here are the solutions I can think of at the moment:
1. Get a different transformer with a little bigger voltage.
2. Get a different transformer with a lower voltage and construct an external voltage doubler/rectifier/filter circuit to get up to about 40-50Vdc.
3. Design and build a better regulator circuit that can work with the lower available DC voltage. This may or may not be simple to do. It's the least likely to succeed simply.
4. Change out the zener diode for a lower one which will let the regulator wipe out the ripple, and hope that the circuit works OK-ish on the lower DC voltage. This might possibly work, but also might not allow the circuit to work right. I worry about this approach with a complicated discrete circuit like this one. I view this as purely experimental.

I listed the approaches in the order I'd try them if it was my own.

> I simul-posted with Dino. <

[RonaldB]

If that helped, the problem really is ripple voltage.  That's good, because you know what to do to fix it. That's bad, because the problem is that you don't have high enough input voltage to run the regulator properly.

So no, replacing Q6 will probably not help. The real problem is that your input DC voltage isn't high enough to regulate properly, and that is letting the ripple through.

The voltage regulator of which Q6 is a part is a very simple, crude voltage regulator. It's advantage is that it's simple (!) and cheap - or was cheap at the time the LP2 was designed. The simplest answer is to get a different and larger voltage supply to feed the circuit. Your transformer is not putting out enough voltage. I'm sure this is unwelcome news since you had a problem finding this one.

Here are the solutions I can think of at the moment:
1. Get a different transformer with a little bigger voltage.
2. Get a different transformer with a lower voltage and construct an external voltage doubler/rectifier/filter circuit to get up to about 40-50Vdc.
3. Design and build a better regulator circuit that can work with the lower available DC voltage. This may or may not be simple to do. It's the least likely to succeed simply.
4. Change out the zener diode for a lower one which will let the regulator wipe out the ripple, and hope that the circuit works OK-ish on the lower DC voltage. This might possibly work, but also might not allow the circuit to work right. I worry about this approach with a complicated discrete circuit like this one. I view this as purely experimental.

I listed the approaches in the order I'd try them if it was my own.

> I simul-posted with Dino. <

Just a suggestion,

Maybe it's best to go with "the known", rather than "the unknown". In this case, the power supply you're using is "the unknown". As far as I know, Keppy and myself have used the (basically) same power supply units. Insofar as my unit is concerned, I never had a problem with power supply noise. I don't believe Keppy did either.

If you're getting 36VDC, I'm assuming that's because the Zener is doing it's job. But, I would still recommend the power supply scheme spec'd by R.G.. It works, it's not that expensive, and will most definately take "the unknown" out of the equation.

For the PS I used, the info is here; http://www.diystompboxes.com/smfforum/index.php?topic=95132.100 , about halfway down the page.

Keep us posted.
Dino

Thanks Dine and R.G.
for the tips. I shall keep you posted on witch direction I will go.
I think i will try 2 differant things:
- First i will try getting a lower zener.
- second get a new adapter.

I did tested it yesterday on my rig but there is still humm but less then it was before as expected.

RonaldB

[wavley]

I FINALLY got to order my parts for this!!!!! Only after working massive amounts of time fixing a science emergency last month.  Plus, I'm almost done with my biggest home improvement project so I might actually have time to built it. 

I'm so excited and I just can't hide it, I'm about to loose control and I think I like it!

[digi2t]

I FINALLY got to order my parts for this!!!!! Only after working massive amounts of time fixing a science emergency last month.  Plus, I'm almost done with my biggest home improvement project so I might actually have time to built it. 

I'm so excited and I just can't hide it, I'm about to loose control and I think I like it!

Dude... don`t forget to order some oxy-contin along with those parts. 

Seriously, keep us posted. New Ludwig builds are painfully slow in revealing themselves.

[Govmnt_Lacky]

New Ludwig builds are painfully slow in revealing themselves.

Got my board populated with everything but pots and LEDs 

Trying to figure out what to do with the enclosure. I would love to do an etch but, I suck at etching 

Still trying to get a hold of a good 10KB pot for my external CV control. "See For Sale thread" 

Unfortunately, I need to muster the courage to start on the enclosure or at least find someone who is willing to etch it for me! Hint...Hint... 

[wavley]

The Mouser project document needs to have 25 2n5551 transistors and it only has 16.  I was stuffing my pcb yesterday and ran out of devices!  That's OK, I have to make another order for some other stuff, just a warning to those that just click the Mouser doc, I did it to make sure I wasn't out of stock on something and miss it.  I may have transistors that work here, I haven't had the chance to look.

[digi2t]

The Mouser project document needs to have 25 2n5551 transistors and it only has 16.  I was stuffing my pcb yesterday and ran out of devices!  That's OK, I have to make another order for some other stuff, just a warning to those that just click the Mouser doc, I did it to make sure I wasn't out of stock on something and miss it.  I may have transistors that work here, I haven't had the chance to look.

Yo Waverly, you might want to try 2N5088`s in the QF1, QF2, QF3, and QF4 slots. I found that they sound smoother than the 5551`s.

[theehman]

The Mouser project document needs to have 25 2n5551 transistors and it only has 16.  I was stuffing my pcb yesterday and ran out of devices!  That's OK, I have to make another order for some other stuff, just a warning to those that just click the Mouser doc, I did it to make sure I wasn't out of stock on something and miss it.  I may have transistors that work here, I haven't had the chance to look.

BOM updated.  Don't know how that happened, but thanks for the update.

https://www.mouser.com/ProjectManager/ProjectDetail.aspx?AccessID=9e9fb9c47d