photonic juergulator rev 1

[Bret608]

Hey Jimi, in the midst of a crazy and stressful week at work I managed to find time to finish my build using Miro's layout. I think this is an awesome circuit! Thanks for putting this out there for the community. I hooked it up to my test box last night and had a blast.

So, I did used the 1n34 and 1n60 as you suggest. For Q1, I have an old General Electric 2n1305. It's not very leaky and measures at about 49 hfe using R.G.'s method. For Q2, I have a BC549c in there with 550 or so hfe. Do those sound like a good combination gain-wise? I've actually got 2n3565s but it sounds so good as is I may keep that setup intact.

Sonic impressions--at first blush, it sounds similar to the Keeley Fuzzhead I did recently (and I couldn't tell you how close that sounds to the original). Not totally unlike my Albini-specs Percolator, but less dark and compressed. But then I started playing with the percolate knob. This is where the magic happens! I cranked it, hit a power chord, and just let it ring out. It just sustained and bloomed into this ear-pleasing harmonic feedback. Just to clarify why that was so special, I was playing through a stock Blues Jr. with the pre and master volumes both at 4, and a Mustang with some fairly low output pickups! Never had a pedal that could do this at bedroom-ish volume.

I'll have to play with the focus knob more to figure out what works best with my setup. I like what it does but can't describe it. Is there a setting on that knob that would make the most sense with my setup?

All the best,

Bret

[pinkjimiphoton]

just sweep it til ya find the sweet spot bro, that has more of an effect on the "feel" and bloom than the tone. it's subtle, but it's there.
really psyched you liked it.
any transistors that sound good to YOU are the CORRECT ones.

[Bret608]

Thanks again--will mess around with it some more tonight. Forgot to mention--even without any power supply filtering, it's not particularly noisy. No more so than my other one, which was on the Madbean Pepper Spray board. That has a 100uf filter cap.

When I box this, I may just put it in a sparkly pink box and call it the "Photonic Pinkulator"! I mean, I wouldn't really label it or anything (not a big decal fan), just a fun nickname in your honor. 

[pinkjimiphoton]

swirl paint a psychedelic box, pink, magenta and lime green....

i would add a simple power supply filter. i didn't show it on the vero or schem, but i usually use a 100-220u cap across the power jack pos and ground at the very least, but usually i do something like this:



depends on the pedal. some don't need psu filtering, some do, some don't seem to wanna work with it even.
but i usually use a scrap of vero and put the crap all on there, but you could solder it to the back of the power jack too if ya wanted to.

[Bret608]

Thanks man, that is super easy. I may add this on when I box it.

You will laugh over this. I realized I had kind of rushed when I tested this and found, first off, that I had Q2 in backwards. I flipped it and it suddenly sounded way meaner. However, it had this kind of weird, mis-biased, sub-octave thing going. I took a good look at my work next to Miro's layout, and found the 10k resistor next to Q1 was only linking the bottom four rows, not the bottom five as it should be. Fixed that and all is good!

Now, I'm just trying to get my head wrapped around it all! This is one mean box. I've built both Albini and stock specs Percs as well, so this was educational. Those versions are both pretty smooth and compressed even with the different amounts of gain on tap. I think the Jerkulator lineage brings its own goods to the table. It's got this edgier, more octave- or synth-overtone-laden sound compared to those other two versions. It sounds borderline-bias-starved, but will sustain really long--it's just fat and nasty on single notes. Chords have this dying amp, almost atonal thing going. More sixties fuzz-like, if that makes any sense. I even listened to some clips of straight-up Jerkulator build just to see how it compares.

So, hats off to you! You brought together the best of these circuits. I goofed around with a DMM just to see what the voltages are like. Looks like the focus and percolate controls actually allow you to vary the Q1 and Q2 emitter voltages--is that right?

[pinkjimiphoton]

yep, they control the gain to both stages and let ya dial it in.
i'll let miro know about the mistake!!!

not surprised a reverse beta sounds better at q2...often pinouts don't match the data sheets!!

sounds to me like you got it perfect bro.

[Bret608]

Oh, it was my mistake, not Miro's, unfortunately! I didn't follow his layout correctly, so the fix on that 10k resistor was to get it in line with his mapping of the vero. Sorry I wasn't too clear there.

Yeah, it is really interesting how this thing works with the reverse betas--it's true of both positions. I mean, following the schem/layout gets the meanest sound, but flipping the transistors can help you dial it in to taste.

[pinkjimiphoton]

i routinely flip transistors. whichever way it sounds the best is how i leave it!!! lol

sometimes they just plain sound better.

[machine.cuisine]

Nice circuit, I want to say "thanks" to Pink Jimi.  I've spent the last couple of days messing with various HP circuits and mods.  The Juergulator sounds the best for my rig. 

I'm Using a Ge PNP and a Ge NPN.  Si NPN ain't bad at all (bc547), but the Ge seems to be a little bit sweeter.  Any random Ge PNP in Q1 sounds good to me, slightly different textures/gain/tone...it's hard to pick one...

My only mod (at this point) is to omit the clippers at the output - they don't seem to do much for me besides compress the signal.

[pinkjimiphoton]

welcome to the forum!! glad ya like it.

the clipper at the end i don't think is necessary. ge diodes there give a bit more octaves tho.

[pinkjimiphoton]

revisited this last nite was quite surprised how differently the controls seem to work depending on the type and gain of q1.

lower gain ge definitely won for the pnp. i tried by ear several (shoot, maybe 20) different transisters from ge to si and gains around 20 on q1 gave better fuzz than a 3906 did definitely. tried ac128, a bunch of russians mn or mp or whatever the cyrillic is on it, and a bunch of others. on mine, q2 is hardwired to a switch to switch between si or ge.

but there's some little teeny tall tophat looking thing i can't make the numbers out on, i'd ordered a bag of 50 to try 'em and thought they were bunk. but in this they sound great... the gain on my meter (most stuff is packed up) was coming up at hfe of 18. little bastidge SCREAMS.

putting in a much higher (leakier) gain ac128 that was reading around 300 and it became almost more like a clean compressory boost with a hint of grit to it. very similar to the 3906. 5089 was even "cleaner"... the lower gain also seems to  be louder...

my theory on that is that by not putting out as much, it's not hitting the second transistor as hard, so rather than driving it into clipping as it would with a high gain stage before it it's able to amplify more, with clipping on the peaks instead of the severe compression you get when driving the base of q2 to clipping non stop. try it and see.

the funny thing is that i built a jerkulator, same values specified by tim escobedo, and it sounded great. i gave it to house of lord's guitarist jimi bell, who's a local guy and an awesome musician as well as a beautiful cat.  anyways... the escobedo circuit sounds more like the ge circuit, with a 3904/6 combo...

surprisingly similar. i don't know if the control change i tried to implement is making this happen,  as otherwise the circuit is nearly identical, a dumbed down dumbed down version with a couple extra "range" knobs instead of fixed resistances. i would think the fuzz would be different with the same transistors.

maybe it was the gain?

anyways... onwards n upwards, good peeps....

[Natman]

Hey guys, I am planning to build one of these. I'm still a bit of a newb though, so I have a question:

I want to integrate the Perc and Focus knobs, but I already have a pcb using the Madbean Pepper Spray layout so I'm trying to figure out where they should go. 

Jimi Photon -can you help a brother out?     

PS. This all started with the Catalinbread Karma Suture for me. I've been eyeing a HP clone for years but that Cbread pushed me over the edge. I like the idea of more knobs for better fine tuning.   

[pinkjimiphoton]

i'd have to see the schematic of bean's pedal bro. i dunno what he did. i have so many schematics it makes my ass hurt.

basically, this is a dumbed down version of a escobedo's harmonic jerkulator, which was itself a dumbed-down version of the interfax harmonic percolator.

if you look at the schematic in this thread, you'll see all i did was replace two resistors with two pots,  one was a 1m resistor as i recall, so i figured out whatever resistance i could tag on both sides of a 500k pot to get above and below the original values... that way the original setting is there as well as above and below it, and tho you may think you could just do it with a 1m pot, parts of the range would be useless, and parts the transistor would cut off even. by adding resistors you can "tune" what part of the pot's variable resistance is most useful... or as useful as such a compromise can be.

same with the other resistor. look at the schematics and compare them... you'll see what's what. if you get stuck, hollar back, and please DO post the schematic... if it's something easy enough to do, i'll help ya figure it out. but.. caveats apply.

madbeans pedal may have different circuitry from mine, and mine is extremely dependent on using the proper transistors to really get the sound...the extra knobs come with a price. read this thread.

if you use too-high gain in q1, it doesn't work as well in the juergulator.... and i reccomend germanium here if possible.

look forward to seeing bean's take.

peace, and welcome to the forum

[digi2t]

Great quotes for signatures;

any transistors that sound good to YOU are the CORRECT ones.

and

i routinely flip transistors. whichever way it sounds the best is how i leave it!!!

Like a black double brested suit, they are simply timeless classics. 

[pinkjimiphoton]

i've read about reverse biasing from jack orman and rg and many others, and sometimes, in a fuzz, you get better tone that way.
i don't know why reverse biasing has such effect, but it may be phasing, or it could be cuz of the way it changes the gain... take a fartier distortion with a lower gain, and squash it good into a loud stage and i believe it's definitely louder than slamming a signal into a second stage... the first way is more dynamic if ya bias i right, the second way will get you more unrelenting compressed 60's fuzzzzzzzzzzzzzzzzzzzzzzzzeeeeee goodness but it may not be what you're looking for.
i don't think it's gonna damage the transistors too much, and if it does, i lay out with... hey.... it's a distortion box, that hiss is vintage, dewwwwwwd...

[mac]

Jimi,
If you put a pot between emiters you can get octave up sounds out of it.
This is my version of the percolator that uses two germs,

My only mod (at this point) is to omit the clippers at the output - they don't seem to do much for me besides compress the signal.

+1

mac

[pinkjimiphoton]

that is a thing of beauty mac!!! well done!! i wanna try it with my circuit, a 5 knob percolator would probably be awesome!

i can get octaves with the juerg too, but they are octave down mostly... little octave up. so that mod would probably bring it even more to life!

[machine.cuisine]

Jimi,
If you put a pot between emiters you can get octave up sounds out of it.
This is my version of the percolator that uses two germs,

Thanks for sharing the idea and schematic.  Just when I thought I was done with all the Percolator breadboarding....

[machine.cuisine]

Jimi,
If you put a pot between emiters you can get octave up sounds out of it.
This is my version of the percolator that uses two germs,

Thanks for sharing the idea and schematic.  Just when I thought I was done with all the Percolator breadboarding....

Not much luck here getting octave ups, just throwing resistors in between the emitters.  Maybe Mac's octave ups are a product of the double Ge and his particular/precise biasing?  I am not done trying, but initial outlook is bleak.

Another note - I am going back to 100k on input, because this lets a fuller guitar frequency range in.  However, I do like the somewhat "darker" harmonic feedback/tones with the 10k input - and, since this is DIY I am just gonna add a switch that drops a 10k across the 100k input pot.....will be called PINK Mode.

Actually, a lot of my testing has involved turning up my pedal-testing Peavey Pacer 100's volume and holding guitar up to induce feedback....I am listening for organic and wide-range feedback tones.

[mac]

Not much luck here getting octave ups, just throwing resistors in between the emitters.  Maybe Mac's octave ups are a product of the double Ge and his particular/precise biasing?  I am not done trying, but initial outlook is bleak.

Yeap. Two germs needed, and due to the very nature of them you'll need to tweak values. Besides, it dates from 2007, a lot of weather changes since then 
IIRC, I put pots at both colllectors, from C to B and between emiters, until I sounded good.
Later I managed to get octave up using ge and si, or two si, but I can't find it in my notes...

mac