Rangemaster (change in voltages neg grnd to pos ?)

[analog kid]

Ok first let me say how sort of embarrased I am to even be posting this . but hey sometimes I guess we can all be stumped by the simplest of things.  I mean I go from cloning an a/da flanger from my own board to confused by a friggin Rangemaster.  Well anyway here's the thing
   I was putting together a run of the mill RM for a buddy, already had the crkt done, biased up sweetly,etc.. and while dressing the box I , by habit , drilled it for DC jack, thought well no biggie I'll just neg ground the PNP circuit, Of all the things I've done in electronics that's something I've actually never tried doing (for obvious reasons) so that's what we'll do right?    Well not so fast
Upon switching to Neg ground I am getting a Collector vltge of around 2v (which it should be I would think with Neg ground)  BUT NOW My Emitter is over 8v and this is using the same couple of trannies that were biased perfectly w/o struggle when Positive grounded.
  So with the variable r's  for 3.9k and 100k I began to attempt biasing  the transistor and no matter how I setup the two resistors I could not  get below 8v.        ( btw I did find a thread referring to keeley's Java boost where a guy posted the vltgs from his unit and DID have Emitter/ base of over 8v! hmmm..)
  I thought well maybve I accidently grabbed the wrong OC44's when I switched to Pos ground and they are super low gain , so tried many Ge's from 50-120hfe and no matter I still can't get b and e under that 8v area with any tuning config of the two resistors.    SO THEN , thought maybe for some odd reason I need a larger boost pot , swapped in a 20kB and YES it did drop the bias voltage down a little bit to where not i can get it in the 7.something vlt area but still this isn't normal to try this hard. 
Last ditch attempt since I have seen schems with a lower value for the 470k to base R,    I drop a 220k in here , and I SUDDENLY GET 7.2v with near stock values for the bias resistors, However the Collector unfortunately comes up along with the B and E coming down into 7v range, rising suddenly all the way to 7vlts itself.    
I am kind of lost here guys. anyone who's had these experiences Neg grnding a PNP rangemaster  OR who may just have the explanation and solution to what I'm experiencing here. and as I said I'm slightly embarrased to be having trouble with this    and before anyone says it , I know all this could be solved simply going back to Pos ground but  1) I have a box ready with DC jack and 2) it's now a mystery and a challenge as to WHY the higher bias vltg  thanks guys

[petemoore]

  Not at all sure what you've got going, a better start would be with a schematic and transistor type [pnp/npn]. 
  Yupp, basically the stuff outlined in the Debugging thread would make things clearer.
  I  get the idea you've reverse polarized the transistor and E bypass cap in the circuit?

[R.G.]

I tell people and tell people and tell people that it's not that simple -: in practice :- to switch from positive ground to negative ground.

In theory, yes. In practice, it is not so simple.

I agree with pete, it's likely that you didn't do the conversion completely. That's the best guess with the info you've given us.

But a quick solution? Put it back to positive ground.

[analog kid]

sorry guys, No I didn't mention that I built the "circuit" (a different rangemaster layout both times) two separate times pos ground and then Negative grounded it and it behaved the SAME WAY both times .  Meaning that it went from biased correct to up and over 8v , not being able to bring it down by conventional means  IN separate builds.    I understand Pete asking for Tranny type and schem but ya know It's just a rangemaster circuit, any little mods like Pulldowns and diode protection , temp stability , cap switching that I did I can assure you they are correct and not causing any deviation from the basic of the RM crkt.   As far as tranny type as I said I am having this result with as many different Ge's as I can try. and obviously their all PNP.
  If it does help though , the one I am currently trying to get biased right  is  built from the Strip layout that Torchy did of the Java boost (just leaving off the Treble pot )  and yes before anyone says "the layout has errors"  I know this and this one IS correct and built correct.    Not that I am immune to error and Of course I could still find something   HOWEVER the point here is I think that , the same result when going from Pos ground to Neg ground  Two times with two crkts.   It's obviously something consistent.
sorry guys I'm not being snide. I realize there's ALOT of beginners on here that ask the same questions over and over about the same crkts.   This is the reason I was hesitant to post this, I mean , I wouldn't respond to this thread myself prob , just expecting the daily RM or TS question.    I
  I thought this may really just be some little quirk in the flipping of the ground's effect on the tranny that might require a tad diff approach in biasing.      No tips on the lowering of the 470k yeilding me the proper 7.0v range on the E and B  but raising my C too high? maybe a happy medium value here will keep my C/B  "on" enough and still allow my getting  E in the proper range.   RG as far as the effect functioning which I forgot to mention.  No oscillations , issues with battery vs. jack powering and the effect on signal is fine and dandy .  Just not able to get in that sweet bias spot for the E and B!!  at least not without the transistor getting too close to "off".
         Thanks for any help if you still want to

[petemoore]

but ya know It's just a rangemaster circuit,
  I count at least two.
   any little mods like Pulldowns and diode protection , temp stability , cap switching that I did I can assure you they are correct and not causing any deviation from the basic of the RM crkt.   As far as tranny type as I said I am having this result with as many different Ge's as I can try. and obviously their all PNP.
  PNP pos Gnd rangmaster circuit when wired right, good tranny etc. works every time, this cannot be said for any PNP Neg Gnd. derivations, which has rather poor track record, not something I've built. Alluring yes, works good when wired as shown, every time, no.
  If you want a 'wire it right 'n fire it up' Neg Gnd. Rangemaster, use an NPN.
  Any of them may require diddling with the bias.

[hairyandy]

I'm not sure what your issue is with the voltages not coming out quite right, but I've done more than a few PNP Neg GND Rangemasters and they've all been fine, aside from the occasional crappy transistor.  Maybe try checking against my stripboard layout here:

http://aronnelson.com/gallery/album26/Rangemaster

This layout is verified and I've used it to build a ton of RMs.

Good luck,

Andy

[analog kid]

You count at least two rm circuits you mean? well if you're only speaking of variations of a RM circuit I think we can assume it's basically the same thing , not much to be changed I mean but anyway .  I digress, I can tell you exactly what layouts I've done ( now that I count again , it's 3 in a row that I built and tried Neg ground pnp with and ended with this result of  B and E over 8vlts and not tuning down into range...at least with same Rb1 adn Re values /  they've been Phillip's Rangeblaster layout Fuzzcentral, the GGG layout for PNP Neg ground and finally Torchy's Java Layout which is neg ground as well, but leaving out the Tone pot on this layout)
   Seems awful strange that All 3 of these attempts, all with different components, all using many transistors and variable r's for Rb1 and Re , all ended up the same results in difficulty biasing B and E.  I should also say that I have tried flipping the tranny around just in case (since it's wierd to me having the Emitter take the place of the Collector in voltage reading)  and that I also used batteries on all 3 crkts so not a common PS for all.
  Update :  I did get closer by being able to bias Emitter to the 6.8v-7.2v range  but replacing the 470k with a 330k  but still then having to really use odd Rb1/Re values stop Collector from turning the tranny off.  Meaning it (Collector) wants to sit as high in voltage as the other pins UNLESS I set Rb1  very very low , down to like 10k or something!!  and never any lower than about 4v with  B and E still in the 7v area. Seemed to sound right when set here but I just don't know about having Resistor values that far off the mark, as RG explains how they set the freq response!     With voltages of  E  7v  B 6.85   C 4.9  I   believe I had values of 330k for the other base r ,  5k (rb) and around 10k (Re1)!!!            so I wonder if this points any possible answers out to anyone?   
Thanks for the help. And YES Andy I almost used your strip layout man, I only decided not to cause i wasn't positive about the verified status and was too lazy to give it a checking over ( getting sick of looking at RM by then  ) and Torchy's having the parallel caps already incorporated so playing with sockets was easy was also a plus.   I will look it over against his  but the other wierd thing is , I KNOW His layout is good too.           this is just downright wierd to me, I will keep looking at possible common things between all three PNP Neg grd crkts I used , maybe it is something I've done but I don't see it.

[analog kid]

 Hey just found this , check it out
http://www.diystompboxes.com/smfforum/index.php?topic=41414.0
  Is it not just "me" here?  I mean , those are the voltages that mine , and all my neg ground builds, WANT to have when set up normal and what I'm fighting against!!  thinking that I'm not going to be getting that nice harmonic dist  out of the Ge if the Emitter is not in that proper 7v area. And although everything is working at these voltages , that's really the way it sounds. like it doesn't have the cream to it, just a sort of sterile booster.  Again this is my question , and more is making me wonder if it's something inherent to going to a neg ground pnp with this crkt causing the voltage B and E ( when flipped from B and C) to jump up about a volt?    I wouldn't know how to explain it IF it was which is why I am asking  ; )

[analog kid]

  Ok , sorry to keep slamming my thread here but I thought i'd let you guys know I've gotten closer to the 7v area with the Neg ground  ( and there's something to the pnp neg ground versions biasing a bit higher I think, based on forumites' experiences I really do)  anyway
  with a 330k in place of 470k  , and right now a 25k boost pot (which I'm gonna try 10k again ) I am able to get closer down to around 7v and still have the collector not so high it's OFF ( 5.5v or so )  and not having too unacceptable Re1 (between 40-100k)  and Rb (5k)    with the 5k value for Rb  raising Re1 to it's highest value will allow a lower (6.6-7v) bias but at the expense of the Emitter raising with it.   A lower Re1 value  towards the 40k or so  will bring  Emitter to a more acceptable 2-3v but again at the expense of back to a higher bias vltg towards 8v with an emitter vltg of 2.5.
] So  I guess my only question is now , what is an "ACCEPTABLE"  Emitter voltage for the RM biasing.  I am getting very nice creamy crunchy boost. and no splatting , etc.. to my ears even of to the  7v   6.9  5.5v  , But I assume it's best to trade off a bit of the 7v bias range for a more reasonable Collector value of at  max 4.5v!!
  THOUGH I don't hear any real difference in the effect with Collector vltg from 2.2v up to near 6v! where it begins abruptly to splat then turn off.
    So I guess this will be an acceptable setup but I'd like an opinion ( RG??)  on what the  minimum B to C drop should be.   THANKS!!!

[petemoore]

  I read through that sorta, and came up with this.
  thinking that I'm not going to be getting that nice harmonic dist  out of the Ge if the *Emitter is not in that proper 7v area. And although everything is working at these voltages ,
  I believe it is the collector which is to sit around 7/9ths the supply voltage.
  Starting with 1 circuit, stated, 1 transistor type [stated as NPN, PNP], and battery voltage above circuit bias voltage points makes it easier for me to sort out if we're talking about a:
  PNP Pos Gnd. with PNP transistor
  PNP Neg Gnd. with PNP Transistor
  PNP Neg Gnd with PNP transistor upside down
  NPN transistor in a Neg Gnd NPN Circuit
  All other possible variations, including miswires of the Rangmaster.
  This circuit in particular, simple as it looks on any one of the many schematics, has many variations and each one depends on having the right type transistor, often enough confused as it is, I too often misread/mistype/mis-understand..so I state that I don't know exactly what we're talking about without debugging information, looking at 1 circuit at a time.
  But you mentioned PNP POS Gnd. hairyandy 

I'm not sure what your issue is with the voltages not coming out quite right, but I've done more than a few PNP Neg GND Rangemasters and they've all been fine according to the stripboard layout here:
  Andy, do you believe the stripboard is the cure, or that PNP Neg gnd RM's 'should' always work?
  Not to be contrare', because it is possible layout could have a 'problems' effect, but I suspect the problems A.K. is having are duplicitive of the problems others have had with the circuit.

[hairyandy]

hairyandy:  I'm not sure what your issue is with the voltages not coming out quite right, but I've done more than a few PNP Neg GND Rangemasters and they've all been fine according to the stripboard layout here:
  Andy, do you believe the stripboard is the cure, or that PNP Neg gnd RM's 'should' always work?
  Not to be contrare', because it is possible layout could have a 'problems' effect, but I suspect the problems A.K. is having are duplicitive of the problems others have had with the circuit.

Pete, I don't believe that the stripboard is the cure at all.  I believe that the current flow should be the same, or at least REALLY close to the same, regardless of the medium as long as the connections are the same as well.  I just measured one of my PNP Neg. GND Rangemasters with a Mullard OC44 to see where my voltages are.  I got this:

Collector:  1.69v
Base:  6.93v
Emitter:  7.38v

The Emitter is a little bit higher than I would like but I didn't use a trimpot for this one (it's an earlier build of mine).  I used the stock RM resistor values.  Whether these are "correct" voltages or not, this thing sounds GREAT!  I would assume that because the polarity for a PNP Neg. GND effect is essentially "backwards" from a PNP Pos. GND effect from the point of view of the transistor, it follows that the desired voltages for the Collector and the Emitter would also be reversed?  In that case my voltages and the original voltages that Nate (aka Analog Kid) are seeing are fine.  Am I wrong?  If I am wrong then it sure sounds great to be wrong because this thing sounds killer!

Andy