P <> N ... that is the question?
- Kregg
- Breadboard Brother
I read comments and articles all of the time that say something to the effect of, "positive and negative grounded pedals can't be daisy chained."
So, to all of the closet geniuses out there ... is there a way to work these misfits into a pedal chain without complications?
Surely someone must have come up with a gadget by now ... right?
So, to all of the closet geniuses out there ... is there a way to work these misfits into a pedal chain without complications?
Surely someone must have come up with a gadget by now ... right?
"Political correctness is a doctrine, fostered by a delusional, illogical minority, and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a turd by the clean end."
- Hides-His-Eyes
- Tube Twister
MAX1044 IC.
Testing, testing, won too fwee
- JiM
- Diode Debunker
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You actually can do this, as long as the power supplies are completely isolated (ground referencies floating relative to each other).Kregg wrote:I read comments and articles all of the time that say something to the effect of, "positive and negative grounded pedals can't be daisy chained."
This can be done with batteries, separate AC/DC converters, or a "power brick" with isolated channels (most aren't).
Or you can use a gizmo like these, which are basically isolated DC/DC converters :
http://www.godlyke.com/_product_88356/G ... D_ISOLATOR
http://www.thegigrig.com/acatalog/TheGi ... ttery.html
Of course, having a proper -9V power supply enables sharing the same ground reference, instead of shifting things up and down and relying on DC-blocking caps at the input and output of each pedal.Hides-His-Eyes wrote:MAX1044 IC.
I only give negative feedback.
- RnFR
- Old Solderhand
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or you can simply flip the circuit upside down using the negative rail for ground and the positive for power- the same way pnp transistors are incorporated into npn circuits. some people have reported motorboating low end oscillation, but with proper power supply decoupling, I've never had a problem.
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- DrNomis
- Old Solderhand
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- my favorite amplifier: Self-Built Valve Amp Head :)
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I just spent some time helping a guy called Chile,fix a bad hum issue in his Tonebender Professional Mk 2 pedal,it turns out that his pedal used three Ge PNP germanium transistors,anyway,i discovered the source of his problem after looking at the schematic he used to build from,you know what I noticed straight away?,whoever drew the schematic,made some fundamental mistakes when drawing the schematic so it would use the negative earth system,I'll explain....
The point in the schematic which should have gone to the negative battery terminal,was connected to circuit ground,and the battery positive was connected to circuit ground also,and it was drawn in a way that made the volume control look like it was connected to circuit ground on both outer solder lugs...
So,I posted a pic of a corrected schematic for him,he PMed me saying thankyou for helping him out.....
The point in the schematic which should have gone to the negative battery terminal,was connected to circuit ground,and the battery positive was connected to circuit ground also,and it was drawn in a way that made the volume control look like it was connected to circuit ground on both outer solder lugs...
So,I posted a pic of a corrected schematic for him,he PMed me saying thankyou for helping him out.....
Genius is not all about 99% perspiration, and 1% inspiration - sometimes the solution is staring you right in the face.-Frequencycentral.
- DrNomis
- Old Solderhand
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The moral of that story is that sometimes it is better to keep a pedal,with PNP Ge transistors,wired so that the ground is positive,and just power it with a battery,i do that all the time and it just works fine,even when I chain negative grounded effects with positive grounded effects,and relatively few hum issues too....
Genius is not all about 99% perspiration, and 1% inspiration - sometimes the solution is staring you right in the face.-Frequencycentral.
- JiM
- Diode Debunker
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Proco Rat
MXR MicroAmp in a volume pedal
TubeDriver (w/ NoS russian tube and big muff tone contol) + Phase 45 (w/ univibe cap ratio)
Dallas Rangemaster (w/ noisy OC75, negative ground)
SubCaster tube booster (w/ NoS russian tube, PtP)
Hot Harmonics
Music From Outer Space SubCommander in progress
Crackle Not OK
Simple bass blender in a 1590A
Bazz Fuss with a photo-darlington - Location: France
- Has thanked: 70 times
- Been thanked: 66 times
- Contact:
That's exactly what i did with my RangeMaster clone.RnFR wrote:or you can simply flip the circuit upside down using the negative rail for ground and the positive for power- the same way pnp transistors are incorporated into npn circuits. some people have reported motorboating low end oscillation, but with proper power supply decoupling, I've never had a problem.
It's a bit noisy (hiss), but i guess it's just the fault of the old OC75.
I only give negative feedback.
- DrNomis
- Old Solderhand
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RnFr,
Hey thanks for bringing this to my attention,much appreciated....
Hey thanks for bringing this to my attention,much appreciated....
Genius is not all about 99% perspiration, and 1% inspiration - sometimes the solution is staring you right in the face.-Frequencycentral.
- DrNomis
- Old Solderhand
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- my favorite amplifier: Self-Built Valve Amp Head :)
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- Location: Darwin,Northern Territory Australia
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I guess that this is something that's going to be a perenial problem....
Genius is not all about 99% perspiration, and 1% inspiration - sometimes the solution is staring you right in the face.-Frequencycentral.