Off-Board Wiring Question.

[RRJackson]

I've really been wanting to try the Pigdog Driver build that's been going around, but I'm confused by the offboard wiring. I'd like to apologize right up front for my ignorance in these matters. I've wired up guitars for decades, but that's normally about the limits of my technical ability. I've been pushing myself to understand these circuits a little better and sometimes I hit an impasse. I hope I'm not wasting too much bandwidth.

So here, there's what looks like 2-conductor wire running to the input and output. But then, for example on the connection to the input you can see both a blue and a yellow lead vanish into the jacket and then at the other end there's just one conductor. Was one of those the shielding braid stuffed into shrink tubing? Or is that two conductors that are joined inside the jacket somehow? I hate to be this thick-skulled, but I've been pounding away at this build for a couple of days and I'm becoming despondent. I think I'm going to have to start an Emo band if I can't figure it out soon...and at my age that would be an unfortunate occurrence.

-Rob

[mth5044]

Welcome to the forum! Don't take what I'm about to say as indisputable truth, but this is my take on the wiring.

The input and output wires are shielded cables. The blue is what is caring signal. The 'yellow' wire is acrual the shield of the cable with yellow shrink wrap containing a twisted bunch of the shield of the wire. Shielded wire is typically only soldered to one end to use it's shielding effectively. The input wire is a prime example.

The output wire has one end of its shield tied to ground on the jack. The other end is connected to the switch. I'm ASSUMING the red wire on the center lug is for an LED. When the switch is thrown, connecting the signal to the circuit, the red LED wire connects to ground via the yellow wrapped shield, illuminating the LED.

Hope that makes sense!

[RRJackson]

I appreciate the reply.

I'm sorry. I replied before that sank in. Yes, than you very much!

-Rob

[PRR]

What Matt said is right.

The "yellow" *appears* to be a sleeve slipped over the bare shield. You can see a bit of raw stranding just where it slips into the grey jacket. (Except where there is also a black shrink-wrap covering this gap.) This is VERY detailed meticulous work, more suited to tight aircraft wiring than a little 9-lug switch.

The shield should cover as much of the "live" wire as possible, and grounded at one end. A "shield" can also be used to connect several ground-points together. However you do not want "ground" to circulate in a big closed loop, that encourages troubles. Here, the main ground is the heavy wire across the rear. The signal leads to the front switch have their grounded shields. And we need "ground" *at* the switch for something (maybe to mute the unused mode, maybe to jazz the LED). The builder decided it was fine to get this ground from back to front with one of the signal shields. Using both shields is not necessary and usually a bad plan.

If still un-clear (it's tricky), build it like that but leave the "extra" shield available at the switch. Leave the box bottom off. Set the pedal on your power amp, over the transformer. The way the pedal is wired, there is no large ground-loop and the open-box hum/buzz is probably lower. Now solder the "extra" shield-end to where the other shield-end is on the switch. Try again. The hum/buzz is probably significantly louder? It's a "maybe" question because there are SO many other sources of hum/buzz that a pedal-size ground-loop may not matter. However the way that builder did it is a best-bet approach.

[RRJackson]

Well, I'm in over my head. I do appreciate all the kind help, but I've put in about 75 hours on this circuit and I still can't make it work. This hasn't exactly been a confidence-building week.

If anyone ever wants to do a simple layout of this effect I'll be happy to contribute to your capacitor fund. 

My most recent trainwreck.



-Rob

[Cozybuilder]

Sometimes its easier to see what you have when you can compare it to a schematic. I drew this up from the tagboard effect wiring diagram "Pigdog Driver (Competition Special Treble Booster)"



On your photo, I see a 470ohm, and a 68K resistor, and don't see either the 470K or 3K9 resistors. The power filter cap has the pos connected to the battery +, but I don't see a connection for the neg side. I can't read the cap values. It looks like there is a second transistor next to the power filter cap, with one lead disconnected. In other words, the photo is very different from the schematic.

I think the best thing to do is gather the correct components first (470K and 3K9 resistors), verify the cap values, and follow the schematic above to see where your wiring errors are. Some things are right, some are not.

[RRJackson]

Well, I used to trimmer instead of the 3K9 because bias on those germanium transistors can be critical and I prefer to be able to dial that in. The positive side of the power lead is at the input jack, which is out-of-frame. However, the 470 ohm resistor instead of a 470K may well be the culprit! Sometimes I really do amazingly bone-headed things and this could very well be the bone-headed move I will associate with July of 2015!

Thank you! Lemme see if that's it!

-Rob

[PRR]

> put in about 75 hours

That's way too much.

I'll throw this in: it is a ONE transistor circuit (right?). It does not NEED shielded wire to "work". It might be buzzy out in the open, but if you put it in a metal box it may be quite quiet without shielding.

And that shielded wire you used is way awkward for small stuff, and "too good" for audio.

IMHO: tear off all the coax, re-do with basic small wire. Keep your ins and outs straight. (How many times have I shoved signal INto an OUT jack and got frustrated?)

Voltage readings may be a clue.

[LightSoundGeometry]

similarly related, I tried the turret/tag board stuff and found that the noise was coming from my bad wiring..the shorter the wires the better ..I had a squeal that was eliminated by making the wires short as I could get them

[karbomusic]

but I've put in about 75 hours on this circuit and I still can't make it work.

Did it work when you were testing it on the breadboard? That may have saved you 70 of those. 

As far as internally shielded wires. A properly assembled/grounded metal pedal enclosure is going to act as a mini faraday cage and prevent most external noise from getting in. This leaves internally shielded cables mostly protecting from internal interference which most of the time requires hi gain to be an issue. Anecdotally, I have yet to even build a high gain pedal where the actual internal wires required shielding. Yes, I know many have had this problem but the point is, doing so in this build probably isn't worth the roadblock it could be causing for a circuit that isn't even working yet.

[RRJackson]

> put in about 75 hours

That's way too much.

I'll throw this in: it is a ONE transistor circuit (right?). It does not NEED shielded wire to "work". It might be buzzy out in the open, but if you put it in a metal box it may be quite quiet without shielding.

And that shielded wire you used is way awkward for small stuff, and "too good" for audio.

IMHO: tear off all the coax, re-do with basic small wire. Keep your ins and outs straight. (How many times have I shoved signal INto an OUT jack and got frustrated?)

Voltage readings may be a clue.

I'm actually really confused about what purpose a lot of those connections serve, anyway. Making those little cables was hugely annoying. I wish the layout had just clearly identified in, out, ground and power without all that daisy-chained shielding and stuff.

Because I LOVE Rangemasters. Getting a really good tuneable Rangemaster circuit that can be quickly adapted to both the instrument and amplifier is a big deal, but this layout has been endlessly confusing.

Although, to be fair, I may have screwed it up right from the outset with that 470 ohm resistor. Hopefully I can swap that out shortly and see what's up. Wife's off, though. My will is not currently my own. 

-Rob

[LightSoundGeometry]

dont feel bad, I literally stayed up 72 hours working on a compressor ...made me think I could survive naked and afraid

[RRJackson]

Cozy, you are a scholar and a gentleman! I subbed the 470K for the 470 and it fired right up! Good eyes, there! I really appreciate it. I was starting to go nuts.

-Rob

Sometimes its easier to see what you have when you can compare it to a schematic. I drew this up from the tagboard effect wiring diagram "Pigdog Driver (Competition Special Treble Booster)"



On your photo, I see a 470ohm, and a 68K resistor, and don't see either the 470K or 3K9 resistors. The power filter cap has the pos connected to the battery +, but I don't see a connection for the neg side. I can't read the cap values. It looks like there is a second transistor next to the power filter cap, with one lead disconnected. In other words, the photo is very different from the schematic.

I think the best thing to do is gather the correct components first (470K and 3K9 resistors), verify the cap values, and follow the schematic above to see where your wiring errors are. Some things are right, some are not.

[RRJackson]

BTW, I wanted to mention this as a little footnote. Ever since I first saw that Pigdog I've been like, "Rangemaster with an infinitely variable input cap! Greatest thing ever!"

In practice, this circuit seems to lose some of its "peakiness" or something, even rolled all the way back to its, "toppiest" position it just doesn't sound as, "mean" as a Plain Jane Rangemaster.

I wonder if there's some kind of loading or something that's smoothing out the response as a result of that variable-capacitor setup.

In any case, I really appreciate the assistance in getting the circuit up and going. Even if the end result isn't the, "Magic Box" I'd been selling myself. Especially with really expensive stuff like this that I'd never buy commercially. I mean, what are those pedals, something like $500 when you can find one and the guy only built something like 22 of them the last time he did a run. So I get all, "Magic Box I can't afford must have all the answers!" Heh...because, you know...

I run a tiny little guitar business and I've been building some very simple effects over the last few weeks as I wait for a shipment to come in. I was going a little insane tracking the ship every day on VesselFinder.com and decided to try out some things I'd always been curious about, this being one of them. I appreciate you all for helping with my Group Therapy. 

-Rob Jackson

[karbomusic]

In practice, this circuit seems to lose some of its "peakiness" or something, even rolled all the way back to its, "toppiest" position it just doesn't sound as, "mean" as a Plain Jane Rangemaster.

Mother nature is like a big ole apple pie, you can't make any slice bigger without making some other slice smaller. Sometimes the slice that ends up smaller is completely irrelevant, many times not. That's the challenge most of the time.

[smallbearelec]

Hi--

I'm sorry that I did not know of your interest in RMs earlier. I also like the RM, and I did my version using in low-gain NPN germanium devices set up as a Darlington pair. You get RM tone inexpensively, and with no need for second power supply on your board. Here is the breadboard poop:

http://diy.smallbearelec.com/HowTos/BreadboardGeDarlingtonRMs/BreadboardGeDarlingtonRMs.htm

and here is the soldered build in a custom-made enclosure:

http://diy.smallbearelec.com/Projects/OhMyDarlingRM/OhMyDarling.htm

[RRJackson]

OOOHHHH! Another Magic Box!!! Thank You! I'm a-gonna have to try this right out!

-Rob

Hi--

I'm sorry that I did not know of your interest in RMs earlier. I also like the RM, and I did my version using in low-gain NPN germanium devices set up as a Darlington pair. You get RM tone inexpensively, and with no need for second power supply on your board. Here is the breadboard poop:

http://diy.smallbearelec.com/HowTos/BreadboardGeDarlingtonRMs/BreadboardGeDarlingtonRMs.htm

and here is the soldered build in a custom-made enclosure:

http://diy.smallbearelec.com/Projects/OhMyDarlingRM/OhMyDarling.htm