Mosrite Thrown together but

[petemoore]

  Not all that Fuzzy, the attacks seem...rough...
  I tried 5089's and some 2n2222's and tin can [lower gain, and sounded lower gain] types, mostly the gain went up/down with Q swaps, otherwise no real change in the overall sound.
  Plenty of boost.
  I'm guessing the use of a 250k resistor between the collectors [the gain pot] instead of 350k might have something to do with it. Also a 250k volume pot...but that would mainly cause increased output.
 
 

[petemoore]

  That's cause you left the second .05 cap out, the Q1C > Q2B cap.
  I used 4 pin sockets so I can try different value caps there,  .0v/.0uf didn't sound too good.
  .068uf is really cool, .022uf is thin on that side, ..no .047's around.
  I used .015 and .0022 on either side of the tone control, still a thin sound available despite the .1uf input cap.
  I also decided to make all the R's 440k.
  All's well that ends well !!
  Low battery trick makes it squashcomp/distort real neat.
  The mix control seems to go from basic fuzz to Mangly Sizzling Distorto tones, exp. w a preboost, sounds smashed.
  Useful Device !!! It's already in a pretty nice box, I'm going to fix it up some more and use it...Funny Fuzz is a blast to play!!!
 

[Gus]

when I built a Si version some years ago.

  I picked reistor values for collector current and bias point.

The emitter Rs drop the gain because they are not bypassed

I like this circuit at about 2 to 2.5VDC at the collectors

http://www.diystompboxes.com/pedals/gusRitefuzz.gif

If you set the balance just right you can get an octave up.

[analog kid]

 " I like this circuit biased at 2-2.5v at the collectors"
    Hey gus, does that go for a Germ version as well? I assume so.  i have an original Fuzzrite that just sounds a bit TOO gaty and well 'crappy' fuzz. I know this crkt isn't the smoothest fuzz but I do think there's an issue with this one. I don't remember the vltgs right now but I think I had an extremely low Emitter vltg on Q2 where there should've been more.That may be backwards I don't remember but someone suggested "clipping" (argghhh!) the coupling cap before it to see if the vltg came  up then. I have yet to try anything due to the way it's wired and those little Eyelets , you almost HAVE to cut leads!
anyway If SO on the vltgs for either version being relative, PETE could you post your Q1/Q2 vltgs so that I could use them as a reference!?
   Someone also put it out there that my unit may not have been "original" , stock, because the Q1 and Q2 germaniums were of different type RCA part#'s
Well I have since verified that it IS INDEED original .  There is one 2N404 i think and the other a 1613 or the like (??)
          Don't mean to hijack your thread Pete!!!  I just really would LOVE to get my old Mosrite up to snuff sounding as good as it can. I know R's can drift with time espec. those old 5% (or more ) carb comps that may already be so far off spec to begin with! so maybe I need to think about that too.
getting vltgs biased correct is my goal obviously
thanks

[brett]

Cool thread Pete
I just took my fuzzrite out of my lineup coz it was a bit too harsh (ok for that "Satisfaction" "busted trombone" style fuzz, but not much else).
These ideas make me think I should re-bias or at least drop the batttery voltage and see if there's some smoother tones available.
You guys kill me with all your knowledge and endless experiementation.  Keep it up.
cheers

[Gus]

I have not built a Ge or heard a Ge real one.

I built the circuit thinking how would I use Si transistors in that type of circuit.

One would need to measure a "good" Ge real one to work out how to clone it or even find out how the circuit was "designed"  What collector voltages what gain of the transistor were both half the same or did they have different operating points as part of the design.

[petemoore]

Q1
C  .78  [That's low for this Si
B  .55  [not far, .17 actually,
Q2
C  .19  [Even lower than Q1 if that's possible, this Ge is cramped !
B  .06  [Ground is exactly how far from base???<
  What can you build if you have only 470k resistors?
  Thanks for the RiteFuzz diagram Gus! That scheme for biasing looks much more conventional..I don't know what I'm going to do !
  But ask a silly question !!!
  Rippin Q1E, Q2E and Ground all apart looks difficult. Guiseppe wanted me to ask what happens if I were to leave the emitters connected, but introduce a resistance to ground 'under them'...lift the offboard ground and insert a small resistor there?
   I kind of like the idea of having switchable collector resistors, 10k looks much more comparable/reasonable than 470k's [440k's In my case] for collector resistors ...I don't happen to have a 4pdt to build a Fuzzrite/Ritefuzz circuits in a box ..this would lift all the bias voltages by converting the bias scheme above/below the transistor...
   Kind of surprizing anything even gets past those transistors with them biased so near to ground !
  The thing does neat tricks though, and even approaches 'normal distorter' sound when mix is set mostly toward Q1, otherwise it can have a 'env fil' type of sweep sound for about 2 seconds after attack...sort of a secondary ghost tone...splatty/ducky/raunchy...yet somehow not terribly gatey...^should be tho...gets that 'Is that your amp breaking?' sound to it.
  Does super job when pressed into Post-Octave Fuzz use.
  Ge NpN in Q2 sounded different...
 

[petemoore]

  I put in switchable collector resistors...11k's / 440k's..one side of a DPDT.
  Output shot up ten fold or so, Needs Smaller output pot value with ~10k on each collector. Still splatty and raunchy, smoother available as the mix knob is turned left.
  I put a 100ohm between ground and each emitter...causing intractable oscillating. I split the emitters, now Q1 has a 120ohm, Q2 has 100ohm. This smoothed out the 10k's sound at collectors, further squelching the 440k on collector sound... 

[petemoore]

  50k volume pot is a bit small for the 220k operation
  680's on the emitters ~10k's on the collectors...
  *680's on emitters 220k on the collectors...
  *This is monster Fuzz, but needs help, it'll gate pretty good if I try to make sustain. However with a gain/clip circuit in front of it, really nice Fuzz is very easily tuned in. Attack has lots of variation, chords are very thick, the between attack/sustain there is a 'pronunciation' of notes...alot of gain and frequency variation in repsonse to input voltage/frequency.
  And...it has pleased me very much indeed!...sounds really great with a faded battery, I think LM317 might be in order on this one.
  The collector resistor selector switch imparts a rediculous amount of boost, best flipped when volume control is set @<1.

[analog kid]

Thanks guys (Pete)


at mine looked like though! It was like that , so small of a B/E drop that It didn't look like much could be getting though as Pete said.
I do also remember noticing that mine gated a bit less was a bit smoother with a lower battery voltage in there. But it does fuzz and can sound "OK" if pushed with something but looking at these voltages I'd say there can be a major improvement

(input tranny)
Q1  C /  3.8v
        B/   100mV
Q2  C/  75mv
      B/  58mv
YOU SEE WHAT I MEAN? even for Germanium that looks a problem to me at Q2. 
As i said  I was thinking of cutting the .05uf Cap between  Q1 Coll and Q2 Base to see if the voltage came up. but have put that off. ; )

   a question :  One of the drawbacks of the old units is of course there is no input jack switching but instead an On/Off switch. Now I  know most times if that is left on accidentally it's just gonna kill the battery BUT I wonder with the age on this thing (*mine dates to '65-66)  enough times with that power left on, the old components and Germanium Trannies... What's the chances of something getting a bit flakey due to this?
My first suspect of this would be the 25uf Ducati cap with V- connected . there was corrosion on the batt/clip one time

Also I don't know if you're wiring your silicon vers. clones anyway resembling this BUT the DPDT wiring is very wierd on this thing!! take a look it's like this. I for the life of me can't understand how this thing switches effect/ bypass. GROUND effectively at 4 out of 6 lugs on a DPDT?!!?? does it like effectively 'kill' the transistor and give some type of 'buffered ' signal or something. It DEFINITELY not TB or Input always connected Switching.
 

in jack + crkt in    -    middle lugs tied together   -                  jack ground                  -
  out jack+ crkt out -      and to Q1/2 Emitters      -        batt V+ and Ducati 25uf + side  -

[petemoore]

 Q1  C /  3.8v
        B/   100mV
  Your collector is higher than mine...on this one
Q2  C/  75mv
      B/  58mv
YOU SEE WHAT I MEAN? even for Germanium that looks a problem to me at Q2.  I think those look even more rediculous than what's acceptable, of course I had a flash like that when I measured the voltages I was getting...these are alot lower yet. You said Germanium...if there is no viable circuit problem causing this bias, I would begin to suspect a different tranny may exhibit a different [hopefully wider swing available] bias.
As i said  I was thinking of cutting the .05uf Cap between  Q1 Coll and Q2 Base to see if the voltage came up. but have put that off. ; )
  Possible, this is an oldie, perhaps you could pull just one end...I kind of don't think that's it thought, what type of cap is it?
   a question :  One of the drawbacks of the old units is of course there is no input jack switching but instead an On/Off switch. Now I  know most times if that is left on accidentally it's just gonna kill the battery BUT I wonder with the age on this thing (*mine dates to '65-66)  enough times with that power left on, the old components and Germanium Trannies... What's the chances of something getting a bit flakey due to this?
  Ge tranny's do have...someone say 25 years?...more? a shelf life...hit or miss depending on type of construction/environment etc.
My first suspect of this would be the 25uf Ducati cap with V- connected . there was corrosion on the batt/clip one time. Electrolytic caps have a shelf life more like 10 years, the better new ones anyway. It is a shame that you'd have to mess with your 'racing cap', Ducati, just to see if it's operational, I don't think you'd notice a tone difference changing cap brands there unless the Ducati is bad.

Also I don't know if you're wiring your silicon vers. clones anyway resembling this BUT the DPDT wiring is very wierd on this thing!! take a look it's like this. I for the life of me can't understand how this thing switches effect/ bypass. GROUND effectively at 4 out of 6 lugs on a DPDT?!!?? does it like effectively 'kill' the transistor and give some type of 'buffered ' signal or something. It DEFINITELY not TB or Input always connected Switching.
  As far as the switching, I don't follow what you have there, or only good enough to say I'd think about scrapping that and using a true bypass scheme.
  Scratch all that...this circuit is so easy to scratch up, I would just whip one up on perfboard and tweek that...
  My RiteFuzz/~Fuzzrite thang got a good going over play-wise, there is a great 60's 'TONK' tone in it, needs a wash but isn't exactly dirty. It's amazingly adjustable really, setting that mix knob just right...
  Smooth to splatty Fuzz, Booster w/Lotsa character sound available too...that mix knob works great!
  I'm pretty sure I'm glad I couldn't find another .002 and subbed a .015uf instead at Q2's input.
  And the 'small window' of swing room does a great job after a clipper, ...compression and frequency shifts and all...really cool stuff...great second stage of dual clipping!
   

[analog kid]

I did pull the .05uf cap and Q2 Base away from one another and there was no impact on the C/B voltages of Q2.  And also the Big Cermamic Disc tested good at about 41nan (It's a 20% tol)

Looking at the schematic now it seems that that Ducati cap is just there for " filtering?" purposes
It's just between -9v and Ground So if it was bad that wouldn't really cause any biasing problems would it. and if so it wouldn't be that Q1 is biasing but Q2 NOT.
I wish I could find a link to this original vers. schematic so I could post it. I was told once by RG that mine couldn't be original cause they didn't have 2N408 germaniums in them.  Mine obviously is original though, not just from physical appearance but also the schem I have shows exactly as mine is Q1 2N2613 Q2 2N408 and all traces exactly as it is in that schematic.
As far as the switching, I don't follow what you have there, or only good enough to say I'd think about scrapping that and using a true bypass scheme.
  Scratch all that...this circuit is so easy to scratch up, I would just whip one up on perfboard and tweek that
  that would be fiine if I wanted to build one diy. I'm sure you understand that I want to get my vintage unit running properly.  the fact that its' so simple of a circuit to me means all the more reason why it should be fairly easy get it biased right.
I hate to pull the other two leads of Q2 to do it, but I may consider your observation about germanium life and stick a  good PNP(maybe even a silicon as Gus suggested once before) to see if it biases well! I don't know how much that would tell me though? seeing that it may have different biasing with the surrounding components but AT LEAST it should tell me if the 2N408 is bad!!

what's your thoughts? Thanks

[analog kid]

Oh here's something else
I also checked the B/C resistor on that Q2 with the Base disconnected,  and it is reading to within spec (1.1M and it's a 1Meg resistor) 
However when I put the transistor Base back into the equation ( 1M R between C and B) all of sudden I get a 1K reading across that resistor.
  Actually I think that's just the B/C resistance of the Tranny but shouldn't I get the larger 1Meg when it's across there?

[petemoore]

Oh here's something else
I also checked the B/C resistor on that Q2 with the Base disconnected,  and it is reading to within spec (1.1M and it's a 1Meg resistor) 
However when I put the transistor Base back into the equation ( 1M R between C and B) all of sudden I get a 1K reading across that resistor.  
  The schematic I built from for the Fuzzrite showed all 470k resistors, where is/are these 1meg resistors in yours?
  Actually I think that's just the B/C resistance of the Tranny but shouldn't I get the larger 1Meg when it's across there? Would seem so, in cases where I don't necessarily understand and suspect, I look for comparators to help me decide if...in this case if the transistor...here's what I'd do.
  while base is disconnected measure B/C resistance, compare that to the B/C resistance of normal, known good Ge transistor...because 1k B/C resistance does not sound right.

[analog kid]

I did that pete. I pulled out one of my old GT109's and first one I grabbed ( hfe of 57) I believe measured apprx 300k !!! would that be right?  I've never measured R of a transitor unconnected.
YES I'd like there to be a pretty sure fire way of KNOWING that the tranny is "dead" (ouch!!) before I would go to the painful process of clipping it out of there and putting in a "SCAB" Germanium!!!
I did fire it up and play thru it too. It is just way to gated , lighter plucking on the strings it extremely splatty / gated. however the Fuzz really seems it would sound AWESOME, cause hitting the strings pretty heavy , it's not so gated and there's a real razor edge , almost ODish Fuzz!!!


And the 1Meg is the Base/ Collector R on Q2 , as I stated.
 
I think the Original Ge' Version is very different component -wise from the silicons. Either the silicon versions floating around the web OR the original "TZ82"(?)versions!   
I wish I could Link to that schem of the original ( that's the 1965 era model btw) I  think the one I have has  'fffworks'  listed in the author/site line  in  the corner box .  In case that tips anyone to "who/where" those schematics under that Name are on the net ; )
Another thing the Original has a "Depth" pot, not a "blend/mix" , I've not looked at the schems to see if  they are wired the same. I think so actually
If I find a link I'll post it  (that  okay??)
OR Pete , PM me and I'll send it to you if I can find a harddrive copy!
    Thanks again , you're being very helpful as usual.

[analog kid]

 Here it is , I found it!
http://eu11.stripper.jp/pulcino/blog/archives/cat_mosrite_fuzzrite.html
There's a nice little site here that has the ORIGINAL Ge' Fuzzrite schem AND PICS!!!! Hope I'm aloud to link to it  ; O   I'll remove it if not , aron.

I wish I'd have had this when I was discussing with R.G. and Gus about whether My unit was 'original' and never been tampered with!  RG stated that " the original never used a 2N408 as it was mostly used in Logic cicuits in the day"  Well I was pretty sure mine was stock cause by appearance little doubt the circuit was untampered  But I never realized there were actual pics of them in the crkt on the web, else I'd have linked to them in that Old thread.l

Dragonfly also did one of his very nice Vero's of "this" Fuzzrite! That's the one I'd love to 'hear' some people trying! (hint hint PETE ; )   But please take a look at the schem and let me know what I should look at for attempt at biasing Q2 collector BEFORE I'd have to yank it from the board and test the crkt with a good PNP.
Hope this helps with ideas for biasing ,etc. my old unit
thanks  ( maybe I should resurrect my old thread concerning this issue? it was only less than a year ago. )_

[8mileshigh]

Analog,

I built Dragonfly's Si and Ge versions and they're completely different sounding circuits.  The Si version is very compressed sounding where the Ge version is more open sounding and has that "room full of a million mosquitos" fuzz tone.  I'm not certain if it working 100% because it only sounds good with the fuzz dimed.  My first thoughts were that the Q1 isn't biased correctly but I won't have time to play with the circuit until after xmas.  My Ge clone is not gatey or splatty, not compared to the silicon version anyway.

Chris

[analog kid]

Thanks, yes I was aware of how different the two version were EVEN when i hijacked into this thread and asked about the voltages on the silicon version.  BUT I was quite interested to hear that Pete also ran into the very strange almost miniscule C/B drop  on this circuit.
I was just trying to get any ideas . however when I saw that Dragonfly had put together a vero of the EXACT correct original Ge version I now realize that If I"m not gonna find anyone with working experience with a vintage unit  that ANYONE who's built his vero is who I need to talk to !!!
So hint hint,  Could you give me your Q1 and Q2  Collector and Base vltgs please?
  I hate to yank that original 2n408 Ge out of there unless I know I can't rebias it and that it's DEAD!!!
and hearing you say that you built it (all stock values I trust!, and yours is not splatty at all, I now also know that the hearsay is not neccessarily true that harsh and a bit splatty is just the way these sounded!!
  thanks man I appreciate that little bit of info when you've a chance

[Gus]

analog kid

   Thans for the lik to the other schematic.  If I have some time I will think about troubleshooting ideas.  I think leaving the stock unit alone until you know more is a very good idea

  In the "new" schematic check the voltage across C2.

  What I would do is build the fragment of the circuit around Q2 to understand Ges in this circuit,  R4,R5,R3 and Q2 are all you need to measure voltages, try different Hfe transistors and make  R3 100k, 220K, 330K, 470K etc... I would try 470K, 1 meg,  2 meg to start take some measurements with different  hfe transistors and R3 values .

The 2nd stage works at much lower current than the first stage 22K first stage vs 147K 2nd collector resistors.  Maybe your unit is working like it did when new.

[analog kid]

thanks gus, no prob on the schem , If I wish I'd have posted that link when I started the thread concerning My Fuzzrite!
  Across C2 is  apprx 4.5v  I say apprx cause I had a bit of a weak bat in there.

I don't know I can't imagine that it was like THIS when new, unless it was a Dud then ? I mean it's not just some minor gating/splattiness. which some old fuzzes just do. This is Major GATING!! And of course the fact that Q2 C/B are within 20mv of each other.  that just can't be ok
8miles is the only one i've heard of who owns or has built an original version Mosrite Fuzzrite. (I'm sure Dragonfly's built it too or I'd assume since he did the vero)  so I 'm gonna have him check his voltages. BUT you're right... There's NO REASON not to just whip up this little circuit if nothing but for Test and research purposes! I don't know why I hadn't thought of that yet 

  also another thing, looking at the schematic... Is there any reason that R4 would measure less than it's true value? of course testing with no power connected, I am getting a reading of 47k across R4 (*100k) !  it's between the 22k Q1 collector R and the 47k to Q2's collector. So I'm not seeing a reason why I shouldn't get the TRUE ohms across R4.  NO?         If so , I have been leaning towards this resistor as a possible problem for awhile now, Especially seeing that it's in direct line with Q2's collector,  But as  I said (and glad you agree) I just can't bring myself to do much tampering w/o know FOR SURE of the reason for why I do it!!!   It took me alot of gumption to pull C4 from Q2 base.
Oh hold on now, I guess that if anything , having Too Low of a value in line with Q2's collector (R4) that this would allow a Higher Collector voltage right? well then that wouldn't be much of a problem to fix since the Collector is obviously Low Enough
 
thanks for the help here, I'll vero up that little circuit for testing today right after I finish decaling my A/DA Flanger clone!! Pics and Build report hopefully soon to come. I never do get round to doing those : 0