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which pad for power on new Road Rage to hook to Pasty Face?

Started by dont-tase-me-bro, May 10, 2014, 07:39:15 PM

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dont-tase-me-bro

Stupid question, I am stumped.  The new version Road Rage is all done, hooking it up to a Pasty Face.

Do I take off the power pad labeled -9v, or 9v?

And then hook that up to the round hole that says -9v on the main Pasty Face?  I would assume -9 on the Road Rage, to -9 round pad on the Pasty Face, but am thinking I may also destroy something.

Thanks,
Pat
I thought this would save me money.

rullywowr

You got it!  If you are using PNP germaniums, you must hook up the -9v pad from the RR to the -9V pad on the Pastyface.  The Pastyface is a "positive ground" effect, so the RR uses a charge pump to get you that -9v you need to make the PNP transistors sing.



  DIY Guitar Pedal PCB projects!

dont-tase-me-bro

Thank you.  One last question (hopefully) - do I run just one ground from the road rage to the pasty face, or two?  The Pasty Face has two ground spots
I thought this would save me money.

RobA

You only need one ground to go to the PastyFace board. It doesn't need to come from the RR board really. You can ground both of them from a star location if you want. It's best to avoid setting up a situation where the grounds form a complete loop though.
Affiliations: Music Unfolding (musicunfolding.com), software based effects and Rock•it Frog (rock.it-frog.com), DIY effects (coming soon).

alanp

Positive and negative ground are misleading terms. Ground is ground. Negative nine volts is negative nine volts, relative to ground. Pastyface runs on -9V. It's like saying you're driving on the center-right side of the road, rather than just the left side.
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dont-tase-me-bro

Thanks again.  Finishing it tonight.  You guys are great.
I thought this would save me money.

dont-tase-me-bro

I have perfect bypass, but no power. 

What does the square pad on the three pin voltage regulator indicate?  I wonder if I have that in backwards.  I put it in the way the picture looked, with the flat end toward the side.

I also put in every road rage component.  Not sure if that was unnecessary for just positive ground.
I thought this would save me money.

selfdestroyer

Quote from: dont-tase-me-bro on May 10, 2014, 11:48:54 PM
I have perfect bypass, but no power. 

What does the square pad on the three pin voltage regulator indicate?  I wonder if I have that in backwards.  I put it in the way the picture looked, with the flat end toward the side.

I also put in every road rage component.  Not sure if that was unnecessary for just positive ground.

The square pad represents Pin 1 of the Volt Reg.

RobA

The orientation of the regulator would have the square pad going with the input pin of the regulator.

You don't need to use the regulator for the -9V output. You don't need most of the parts to get the 9V output. The doc has a section that will tel you what to omit. But, the -9V out should still work with those parts in place, it'll just be less efficient.

So, you aren't getting any power at the -9V pad?

One thing to note is that the orientation of an indicator LED will depend on which voltage you hook it up to, the input 9V or the -9V from the RR. Either will work, but you have get the orientation the right way around.
Affiliations: Music Unfolding (musicunfolding.com), software based effects and Rock•it Frog (rock.it-frog.com), DIY effects (coming soon).

dont-tase-me-bro

Thank you.  That's part of where I went wrong.  When I always looked at the omit section, I misinterpreted it, thinking -9 was not what I was doing.

If I were to not use a inverter, and just leave the pedal normal, could just use a positive tip power cable, like a moog pedal?  I know you can't daisy chain them.  My power supply has all the taps individually isolated.
I thought this would save me money.

dont-tase-me-bro

I didn't jumper the pads on the 8 pin chip, because I bought the item below from small bear. 

http://www.smallbearelec.com/servlet/Detail?no=794
I thought this would save me money.

dont-tase-me-bro

one last thing I thought of - can I use any ground off of the road rage, or does it have to be the one next to the -9?

sorry for all the questions
I thought this would save me money.

RobA

Quote from: dont-tase-me-bro on May 11, 2014, 05:18:53 AM
...
If I were to not use a inverter, and just leave the pedal normal, could just use a positive tip power cable, like a moog pedal?  I know you can't daisy chain them.  My power supply has all the taps individually isolated.
If the power supply is truly isolated, galvanically isolated, then you can power pedal from the same supply as others pedals that use a +9V power rail. But, you don't need to use a different power jack/plug arrangement. The standard negative tip will work fine. Think of it this way, the power supply doesn't care which side of the power you consider to be ground. It just has two potentials coming off of it, one 9 volts more positive than the other. If you hook the more positive side to ground, that makes it zero and the more negative side is at -9V compared to that. But, the reason it has to be isolated to do this is that if in one pedal you hook the positive side to ground and in another you hook the negative side to ground, you've created a dead short in the power supply. If it is a truly isolated supply, then each tap is an independent, floating potential and you can do with them whatever you want.

In general, I think it is still a good idea to pretend like you don't have an isolated supply and solve the issue with something like the RoadRage. The reason I say that is that if you need to get a power supply in an emergency, or borrow one some time, it's harder to find a truly isolated supply.

Quote
I didn't jumper the pads on the 8 pin chip, because I bought the item below from small bear. 

http://www.smallbearelec.com/servlet/Detail?no=794
You did this the right way. Also, I think the LT1054 is the better choice. It is overkill for this effect's supply current needs, but  my experience with them has the LT1054 being the cleanest and most stable of the charge pumps I've tested.

Quote
one last thing I thought of - can I use any ground off of the road rage, or does it have to be the one next to the -9?

sorry for all the questions
No problem at all on the questions, everyone here is happy to help. The ground pads of most any effect PCB will all be hooked together by the ground plane (or ground traces) on the PCB. So, unless there is something really subtle going on with the circuit, which ground pad you use won't matter.

But, I did just go look at the new 2014 RoadRage. If you are doing that one, you want to hook the positive terminal of the power supply to the + and the negative terminal (ground) to the - pads on the PCB. I assume the grounds and "-" pad are all still hooked directly to each other, but this could be one of those cases where using that pad for the ground connection has purpose in the layout. Charge pumps are more finicky than most circuits we work with. The "+" pad is important to hook the supply up to for sure, because this is the pad that is before the 1N5817 and the 10Ω filtering resistor.
Affiliations: Music Unfolding (musicunfolding.com), software based effects and Rock•it Frog (rock.it-frog.com), DIY effects (coming soon).

dont-tase-me-bro

Thank you again.  This was definitely a learning experience, but I get the positive ground thing now.  My next project is the bumble bee, which is in a drawer, ready to go with both PCBs, so now I know what to do for its road rage.  I have some 1776 3pdt boards coming in the mail tomorrow, so I think I might finish the pasty face with that.  after this, now I know to flip ground and power.  my current road rage literally has every possible component soldered in

as I was doing this road rage and populating every single space, it did seem excessive to have that many components on the board.  noob  thinking was to omit nothing, because positive ground means +9, which isn't listed on the omit section

i have another set of different PNP transistors, so I'll make a another road raged pasty face in the near future.  Thanks again for the help.  I would not have figured this out
I thought this would save me money.

RobA

You're welcome, I'm glad I could help a bit. Like alanp said above, the term positive ground is misleading. It would be good if it would be replaced by something like negative power rail effect, but I'm afraid it's too entrenched to go away. The good side of having a completely populated RR is that you can use it to build a split rail design now ;). I keep a a fully populated RoadRage at hand with my breadboards because it's an easy way to try all sorts of circuits. Good luck on the next builds. It can be confusing at first, but after just a little experience the weird quirks get to be more predictable.
Affiliations: Music Unfolding (musicunfolding.com), software based effects and Rock•it Frog (rock.it-frog.com), DIY effects (coming soon).