Rangemaster and grounding

[CodeMonk]

I'm looking at building this version of the Rangemaster.


However, its positive ground, and I would like a negative ground.
I already order an OC44. So I would like to stick with this design.
Unless there is another (maybe better) design around that uses a negative ground and the OC44?

Thanks.

[DougH]

Search for "negative ground" and there is a lot of info on how to convert pos. gnd circuit to neg. gnd, limitations, problems it can cause, etc, etc.

[petemoore]

  IOW...
You want a Pos Gnd. scheme for your PNP.
  Or you want a Neg Gnd. scheme for your NPN.
  ...or...you might feel you want to try a ground conversion schematic.
  The last isn't actually a suggestion, but more of a warning. You might get lucky. or work around the block trying to make it quit misbehaving, then convert it to one of the two simpler, [known to work every time when correctly wired] versions, listed above.

[Solidhex]

Yo

  I've built a couple negative ground Rangemasters which pnp transistors and they sounded just as good as the positive ground versions. There's a schem at General Guitar Gadgets, http://www.generalguitargadgets.com/diagrams/geb_rm_sc_pn.gif
  I actually built one into an enclosure with a green ringer.

--Brad

[CodeMonk]

Yeah, I did some searching last night before I posted.
Found a few threads where someone mention building a negative ground RM, but not how they did it.
Later, after more searching, found a mention of something called a "charge pump" on GEO so I looked there and found that info ( http://www.geofex.com/circuits/+9_to_-9.htm ).

Solidhex, what transistor did you use for yours?
I may be giving that one a shot.

I tried a few months ago building the Austin Trebleblaster from GEO, but had poor results. I used an NTE transistor, which apparently was a POS (I made a thread about it). It was the only thing I could get locally (if you call 60 miles away locally ).

I was ordering some stuff online last night (bunch of 2N5089's and other stuff), and saw the OC44 there and thought I would give it another try. I wasn't until I ordered everything that I noticed the RM was positive ground.
I guess I could just stick with a battery since I am guessing that the RM doesn't use much juice.
I hate using batteries. I'm not made of money...yet .

Thanks to all.

[soulsonic]

Yeah, I did some searching last night before I posted.
Found a few threads where someone mention building a negative ground RM, but not how they did it.
Later, after more searching, found a mention of something called a "charge pump" on GEO so I looked there and found that info ( http://www.geofex.com/circuits/+9_to_-9.htm ).

Yes, that's it, use a MAX1044 (or TC1044, or ICL7660S, etc...) to make a negative supply. I've done this and it works great. I built a quad booster that had an opamp boost, a SHO, a MiniBooster, and a traditional PNP Rangemaster all sharing the same board and supply and ground and all that and it worked awesome with the charge pump chip giving the Rangemaster the negative supply it wants. It's an extra $1,50 to $2 worth of parts that solves a million headaches!

[Solidhex]

Whoa

  Charge pump neato, I gotta try that. I used a house numbered Raythen pnp transistor Codemonk.  I prefer higher gains for my rangemasters...

--Brad

[DougH]

I guess I don't really understand why you want it to be negative ground, unless you have an existing power supply that is neg gnd that you want to use. In that case I agree that the charge pump is a good idea. Otherwise just use a battery and call it a day. I have a few pos gnd circuits and they work fine. I keep thinking, if you use an isolated plastic DC jack, you should be able to wire it "backwards" and allow your power supply to power a positive ground circuit. But I haven't thought it through completely, I'm still on my 1st cup of coffee, and I know this has been covered before and should be in the archives somewhere.

[petemoore]

  It's a wonderful idea with any PS circuit, especially the ones that go here, there, then over there too...to test that there is no continuity between +/- before applying the power.
  Of course when I mixed +, and -, and ground...' -' and '+' were all connected, that causes a direct short.

[CodeMonk]

I've got an array of the standard pedals (Boss, Ibanez, DIY, etc.)
And I have a 1 Spot power adapter which works great for me.
All my pedals run off of that power supply.

[analogmike]

charge pump will be REALLY noisy. We build them with negative ground with no problems, the articles and schematics posted above should get you going.