photonic juergulator revisited

[pinkjimiphoton]

built this earlier, as i'd given the original away a ways back...


one ge sounded incredible, better than all the rest. imagine my surprise when i had mis-sorted, and the "pnp germanium" ended up being an NPN germanium...

ac176 to the rescue, yo.

changes from old juerg

harmonics pot now 1 meg, raised from 100k. input lug is wiper (pin 2) rather than pin 3 as before. big difference.

ground unused lug of perc pot. (lug 3)

output volume pot raised to 100k rather than 50k.

power supply 9.79vdc

q1 ac 176 npn
hfe 95
uf 119mv

c 2.01v
b 1.94v
e 8.42v

q2 bc550 npn
hfe 415
uf 699mv

c 9.05v
b 8.50v (drops from there all the way to zero as the 47u cap discharges.. that cap is the key thing in this )
e 8.48v

stupid pedal trick imminent of course...



i think i got this right... will try and draw a proper schematic tomorrow.

works much better than the previous version... go figure.

the layout on tagboardeffects will work.... just swap out the two pots and add the ge npn as q1.

i damn near went crazy trying transistors in this... that cap make shit nuts!! if i pulled the pnp, i got a much better signal... at first... clear and loud and harmonic... til the cap began to discharge, at which point it would de-percolate.

people with issues trying to get this circuit up, power down between transistor swaps, and short that cap or it will make you fucking CRAZY.

FWIW, every 176 i tried worked. none of the pnp's i had, ge or si sounded as good. <shrugs>

a REAL high gain darlington may be worth trying in q2. q1 seems to wanna see around 100 if npn, and 50 or so if pnp.

this is the weirdest circuit on the planet. <smh>

[pinkjimiphoton]

hi guys,
i gave this to someone a year or so ago, and was bored today, so yep, built a NEW one.
a tagboard effects dot blogspot dot com exclusive...
ok, first, a couple subtle changes to the circuit you MAY wanna try...
first, make the input the WIPER - pin 2 - of the harmonics pot. leave harmonics pin one where it is, and put pin 3 to where pin 2 used to be
up top.
this will make a subtle difference in the way the pot responds, kinda like the old les paul wiring, it shouldn't matter but it does,
next, make that harmonic pot 1 MEG instead of 100k. the combination of the different wiring and the larger pot make a significant difference.
next up, the first connection on the upper left has to go to perc pot 2. perc pot 1 will stay on row 3 hole one.
take perc pot pin 3 and ground it. that will make that and the tweak (actually i was gonna call it focus) pot work better.

ok, now transitors.
this is the photonic juergulator mk 2 here my friends...

make 'em both npn. make q1 germanium, make q2 silicon.

will work on the board as already populated and FUCK lot easier to get it going...
i was plugging pnp's in forever, and found one that sounded REALLY good. i was amazed, the circuit came to life.

next change... output pot, take it up to 100k instead of 50k. opens it up more.

in the end, i used the following for transistors with ridiculously good results...

turns out i had mis-sorted some transistors, and what i thought was an ac125 was actually an ac176..... an npn, not a pnp.

so
q1 :
ge ac176 npn
hfe: 95
uf: 119mv
c 2.01
b 1.94
e 8.42

q2
si bc550 npn
hfe 415
uf 699mv
c 9,05
b 8.50 and dropping when my meter hit it...it's all about the biggass cap and the tied transistors
e 8.48


voltage was 9.79

that's it... i know it seems weird, but every subsequent 176 i tried worked great.

something about that cap makes the whole thing weird. power down between transistor swaps, or it will make you crazy

sorry for any hassle caused, these changes are easily reversible if you prefer the original juergulator.

finally,

make thev 47n input cap 470n instead, now them knobs can percolate. it's all about that fucking electro between the transistors... it holds a charge or something, i guess thats how the harmonics percolate.... if i was swapping transistors, it would still work.... for a minute or so... then fade out. makes it damnably hard to find good transistors, ya gotta short that cap to ground after power down if ya want any predictability i think., the bigger cap lets more bass in, and pretty much every npn ge i've tried around 100hfe, as well as every PNP around FIFTY hfe as long as it's ge seems to work.
make your head spin faster than linda blair at a pea soup cannery.
i'm still tinkering, will have a new schem drawn up soon with everything. really vast improvement, way less hit-or-miss AND can use the same vero miro cooked up.
ya gotta love that.

[pinkjimiphoton]

prototype built and working.

ALL the knobs work well now, way more fuzz..

i believe the whole percolation thing comes down to that 47u cap holding a charge of "harmonics" and "percolating" them... if ya pull the ge transistor out, it will keep working and sound the same.... for a while... til the cap discharges.

so... if building a juerg or perc or jerk, my advice to save much hassle, heartache and time, is power down between each transistor swap, and discharge that electro. or expect ridiculous results.

turn knobs... watch nothing happen... then suddenly change when the cap starts discharging. can be VERY frustrating!!!!! if ya power down between swaps and discharge it tho, every time ya power up it will work right. if the cap isn't discharged? fuhgeddaboudit!!

[jalmonsalmon]

...

... i think i got this right... will try and draw a proper schematic tomorrow.

works much better than the previous version... go figure.

the layout on tagboardeffects will work.... just swap out the two pots and add the ge npn as q1.

i damn near went crazy trying transistors in this... that cap make shit nuts!! if i pulled the pnp, i got a much better signal... at first... clear and loud and harmonic... til the cap began to discharge, at which point it would de-percolate.

people with issues trying to get this circuit up, power down between transistor swaps, and short that cap or it will make you fucking CRAZY.

FWIW, every 176 i tried worked. none of the pnp's i had, ge or si sounded as good. <shrugs>

a REAL high gain darlington may be worth trying in q2. q1 seems to wanna see around 100 if npn, and 50 or so if pnp.

this is the weirdest circuit on the planet. <smh>

Hey PinkJimiPhoton, check this schematic for any errors... whipped it up real fast and now my head hurts
I am about 90% sure it is good but there is also that chance for errors.
I may have to build this pedal from IvIarks layout on vero... thing sounds gnarley!
Cheers!

[pinkjimiphoton]

HEY BRO!

here's the original juerg schem



you made one tiny mistake, or i did , up top... on the perc control

i fixeded it.



thank u!
hope ya enjoy the fuzz

[jalmonsalmon]

Mistake??? I never make mistakes!
just kiddin! quick question though.
Looking at the PERK on your original schematic, I noticed that lug 1 is not connected at all, lug 2 goes to 47R to ground and lug 3 to 47K to the collector of Q2
And the correction you made on my schematic rendering has the lugs backwards ( ... lug 2 is going to 47K and 3 going to the 47R to ground...)
I can flip that pot around and match it to the original but would that really matter? It seems the pot will have the same effect but going the other direction... anywho! that is trivial and I cannot wait to make one of these.
If you want me to send you my corrected schemo, let me know. I can even knock out a PCB with it. However with this one... I would rather use VERO.
Thanks jimi!

[pinkjimiphoton]

i don't think it matters, bu if you wanna revise it, cool!!

here's the stupid pedal trick

[Dingleberry]

That sounds so sweet!
Gotta try it with russian pnp germaniums, have a plenty of them with gains around 50.
Thanks and maximum respect for the effort to make that obscure circuit sound like that.
I see some breadboarding ahead this weekend.

-T

[pinkjimiphoton]

awesome, have fun!!