SOLVED How to reverse "flipped" PNP circuit back to positive ground?

[MBFX]

EDIT: THE SOLUTION IS TO UNDERSTAND THE DIFFERENCE BETWEEN POWER AND GROUND VS. POSITIVE AND NEGATIVE POLARITY. IF YOU THINK IN POLARITY, YOU'RE FUCKED AND YOUR PEDAL WON'T WORK.

The way to edit the veroboard layout below is to flip the electrolytic capacitors around. Remove the diode, because it's the wrong way in the vero layout as posted and it's better to have it on the barrel connector. Connect the power rail (labeled 9V) to the sleeve of your barrel connector. Connect the ground rail to the tip. From there, you're going to want to plug it in - make sure you are using a "backwards" power cable, such as this:

Reverse Polarity Cable – 2.1mm Straight – 18″ – Voodoo Lab

voodoolab.com

You can make one, but I've had a hard time finding DC connectors small enough to be worth it.


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Original post:

The following PNP Germanium transistor using circuit references negative voltage. I want it to reference positive voltage, so it can be in the same box as a positive reference voltage Germanium Fuzz Face, using a shared Lumberg power connector. No battery. I am too inexperienced to simply walk into Mordor.

I look at the schematic, and I can understand the difference. On a breadboard, I understand the difference. I look at this vero layout, and my brain short circuits. What is the actual difference here? I don't understand how I would change it to make the positive rail Vref.



VERO LAYOUT I USED, PRETEND THE DIODE ISN'T THERE:


SCHEMATIC FOR ABOVE, PRETEND THE DIODE/OTHER WEIRD THINGS AREN'T THERE:

 

[steviejr92]

When I read that, it feels like I'm not taking something into account.... bear with me.

Forgetting the diode (I put them on the power connector), I reverse the order of the caps and transistor, and the power leads. Aren't the resistors now connected to the wrong legs of the transistor? Do I need to account for that, and redraw the vero layout "mirrored"? Same question re: the pot, since when I flip the transistor but nothing else it's now tied to emitter

I see what you’re saying about the transistor legs. While I don’t have a scientific answer for you…the transistor will still function correctly, the resistors will be in there correct spots regardless of the reversing of polarities. The truth is by “flipping” the circuit, the emitter now takes on the job of the collector and so it needs the collectors network in order to function and vice versa.

 

[MBFX]

I see the RM schematic. I was wrong. That circuit requires positive Vcc (and “negative” ground). Do you have a schematic for the FF?

Not one specific to the layout but it's the basic PNP fuzz face with custom resistor values to make it bias correctly. I'm sure it is the same as the Dallas arbiter schematic in most ways I'm abandoning the thread though, I'm going to figure it out when I can, I'm going to repost my question in a way that does not muddy the waters, and I will also explain the fix so it's all on the top level post. You can ignore for now.

@steviejr92

Marking your result as the solution for now as it's the closest we're going to get with my description of the problem, I think. Thank you.

 

[gonzo]

That schematic is drawn oddly. The 9v + is written twice, and is meant to be all ground wires. -9v is all power. If the diode isn't the right way or the caps +/- isnt seeing the same polarity it also won't work. Don't have any other pedals plugged into the power supply or daisy chain.

 

[giovanni]

Ok sorry I clearly haven’t had enough caffeine today. I see what you’re saying. It should be easy to convert the RM to “positive ground”. I need pen and paper to work through that since I am having a hard time understanding the schematic you posted. In particular the +V pin connected to the diode seems fishy (could it be a mistake?) because the other side is then connected to ground.

 

[steviejr92]

I wish I could help more man! If i had more info to give i would!

 

[MBFX]

I'm sure it's a very simple problem that I don't yet have the tools to explain, and if I did, I would not have the problem!

I agree that the schematic is funny looking. I omitted the diode because it's obviously wrong, and I hate the way he draws PNP transistors and power rails. I'm glad it isn't just me.

@gonzo thank you, that confirms my suspicion on why things aren't working together.

I made some pretty extensive edits to my top level post, and I'm going to come back to this in a few days when I have time

 

[gonzo]

I build a lot of these. You could wire it up without a board. The yellow one in back has a leg free for the pot. The bottom rail wire is the +9v. The front one is for a full on all the time with no pot on the collector

Also the yellow one is missing a power cap. I ran out.

 

[giovanni]

I rewrote the schematic to use negative power (“positive ground”). It’s basically the same as the original with different rails and the diode mistake corrected. That 47nF cap for power filtering seems a bit low, maybe they meant 47uF? Also I don’t think that 47nF across the feedback resistor has to be polarized, you should be able to use a film cap or box cap.
Anyways here it is:

 

[MBFX]

@gonzo I'm not sure I'm up to a P2P build quite yet. I really like sockets. Feels like a safety net, when Ge transistors are $8 each.

I rewrote the schematic to use negative power (“positive ground”). It’s basically the same as the original with different rails and the diode mistake corrected. That 47nF cap for power filtering seems a bit low, maybe they meant 47uF? Also I don’t think that 47nF across the feedback resistor has to be polarized, you should be able to use a film cap or box cap.
Anyways here it is:

View attachment 65578

That matches what I have wired up, minus the diode. I can take your schematic, and put the power at the "top" so to speak, so things are oriented "the right way". The disconnect I have is understanding how that would translate to the vero layout. What is functionally different, other than what we are calling the power rails?

 

[giovanni]

Functionally my schematic uses a different ground plane. That means all ground connections will go to this other plane rather than the one you had before. This includes jack sleeves. I assume this is reflected in the vero layout somehow? I’ve never used vero, although it should be pretty simple.

How are you powering the FF?

 

[MBFX]

That helps, thank you. The FF is this general topology:



Using this layout:

 

[MBFX]

I have figured it out! Thanks to everyone who helped. The solution is now in the top-level post.