Harmonic Percolator - make one!

[Mark Hammer]

you could use a 2p6t rotary on that thing!

Um, you DO realize that's what I'm doing, right?

[alparent]

Okay, video card problem solved.  1=Orpheum, 2=Bosstone, 3=Octavia, 4=Dist+, 5= Percolator, 6=almost a Controfuzz

That's what you get when an effects guy says he's working on is six pack!

[Mark Hammer]

I'm just glad it's not a two-four!! (Canadian joke)

[pinkjimiphoton]

screw it, maybe i WILL build one of these.

i built the harmonic jerkulator as one of my first builds, and it lived on my pedalboard until recently. it makes a great "helper" pedal to boost other things.

the percolator is more overdrive/fuzz, the jerkulator is more of a nice transistor preamp boost imho.

mark... i guess i know what i'll be doing later today.

stupid pedal trick coming...with the percolator AND the jerkulator, so peeps can see what they sound like.

that said, i did breadboard the perc, and liked the jerk better. but...we'll see, i do need one in my collection.

god...i'm gonna have to sell off stuff soon, i'm running out of room to store things...6 milk crates full of pedals at this point, not counting multieffects, racks, standalones..

and i've built 75% of them. it's madness!!

thanks mark for the inspiration bro!

[pinkjimiphoton]

 mark,,
is this the exact schem you used?

any subs, or close-enoughs?

[Mark Hammer]

You're welcome, I think. 

I stuck about 96% to the schem.  Differences are:

56nf instead of 50nf input cap (.05uf kind of disappeared with big ceramic disc caps)
Regular electro instead of tantalum for 47uf
2SB33 instead of 2N404
100k output pot instead of 50k

None of that should have made much of a difference.

You're gonna like this.  I know you by now. 

[Pyr0]

I must try this one again. I built one on vero using Sabro's layout which is based on a schematic by ringworm, but most of the component values are totally different to the one above. I never bothered to box it up as it just didn't sound right. I should be able to swap them in my existing board.

[pinkjimiphoton]

You're welcome, I think. 

I stuck about 96% to the schem.  Differences are:

56nf instead of 50nf input cap (.05uf kind of disappeared with big ceramic disc caps)
Regular electro instead of tantalum for 47uf
2SB33 instead of 2N404
100k output pot instead of 50k

None of that should have made much of a difference.

You're gonna like this.  I know you by now. 

hahahah!! yah, i guess by now... well, i dicked around with DIYLC, and here's an as yet unverified veroboard layout as per brian's layout for the peppermill...

but i mean, looking at it, it looks ok to me. i'm beginning to trust my layout abilities, even if i do seem to screw up the actual construction. lol...



for ref, brian's schematic....i didn't bother with the switch, i'll just want the ge's most likely



i don't believe there's any mistakes...i was gonna dick around building a fuzzrite, but this has piqued my interest again, so i'll build it up.
gonna probably sub to next closest values, but may try dialing in some with a file.

you know me...pretty lazy!! so next closest values will probably be it.

if someone would be so kind to peek at my latest disgrace, i'd love that. before i build it, for a change, i mean..

[Jazznoise]

So, Mark, got any clips? We can have a race between Jimi and yourself! 

[pinkjimiphoton]

it's ON!!



mark is gonna win, cuz i am not gonna get a chance until at least tomorrow or monday to start building.

[Paul Marossy]

I tried to do one on perf real quick but all I can get it to do is squeal. I must have a mistake somewhere but I can't find it. 

[pinkjimiphoton]

at least you got a squeal...i got nothin', pisses me off as i mix and matched resistors to get the "proper" values.

have tried several combos of transistors, nothing. the voltages seem reasonable. oy.

i'll try this pos tomorrow, and try and sus it out.

i don't see any mistake with my vero, anybody else see something screwy?

[Quackzed]

try it without the diodes? other than that r2 and r4 seem to be the main bias resistors, a little smaller bigger on either one may swing the bias into/out of the sweet spot. 1st id try a 100k variable resistor on r2. tweak and see if you can get it to pass sound... a variable 100k on r2 will probably work, if not swap the 100k pot over to r4 and try it there instead, one or the other should allow it to bias up... if not and all else is correct, socket the trannies and try different gains hfe's... not tested but a logical approach anyway...

[Paul Marossy]

R2? On my schematic R2 is the pot right before the output jack...

[Jazznoise]

Try making C4 smaller and removing C5, Jimi. The schematic version I'm looking at has a 100nF between the base of both transistors, but no cap from there to ground.

It's been linked already here, but to clarify: http://topopiccione.atspace.com/pjimages/HarmonicPercolator.sch.png

[Gus]

Mark Hammer

The 47uf cap that "AC grounds" the emitters does matter.  A Tantalum 47uf will do a better job than a 47uf Aluminum electrolytic.

The HP is two gain stages in series with the power supply being divided up between the stages.  The biasing used for each stage makes sure there is no DC current path except the via collector resistors and transistors (ignoring any leakage paths in the caps)

I have built two circuits somewhat like this one a Si PNP, NPN transistor version and one a Si NPN version.  You need to get the stages adjusted just right for what you want in the sound.  I used a 100uf Aluminum electrolytic at the emitters

Even the output volume control value makes a difference due to the loading of the "top" transistor collector

EDIT  pinkjimiphoton measure the emitter node voltage to ground measure the "top" and "bottom" collector to ground voltages.  For adjusting bias I would adjust the collector to base resistor values.  This circuit has a number of things that interact and adjusting it might take a few iterations.

There are a few threads at this site about the HP it might be good to find them all and combine them and/or have a link to the threads.

[Quackzed]

R2? On my schematic R2 is the pot right before the output jack...

i was referring to the pepper spray schem, on the toopocione sp? schem it would be r3 & r4...
but the collector to base resistor values may be better to alter the bias, as gus mentioned...
just tryin to help... probably a mistake on my part...

[Gus]

pinkjimiphoton

Looking at the vero, noted the part numbers do not match the vero part numbers?

no need for R00 the 100K control acts as an antipop
The 3.9meg R4 is wrong you have it Q2 B to +9 it should be Q2 B to C
R5, C7, D2 and D3 are not wired correctly

[pinkjimiphoton]

pinkjimiphoton

Looking at the vero, noted the part numbers do not match the vero part numbers?

no need for R00 the 100K control acts as an antipop
The 3.9meg R4 is wrong you have it Q2 B to +9 it should be Q2 B to C
R5, C7, D2 and D3 are not wired correctly

hmmm,....on the pepperspray schem linked to earlier in the thread, r4 goes from b+ to q2 base, not b to c. is the madbean schem wrong?

10-4 on R5 and d2/d3...i completely see my screw up now, the high side of R5 should be connected to the high side of D2...right now, there's no output possible, as it doesn't even connect, tho c7 should still be connecting to the output, i just shouldn't have any clipping.

but c7 as shown on the pepperspray schem i posted is coming from the b + rail, right to the top of the output pot, which is what my vero has, too, it matches the schematic i was working from. weird.

so you're saying the 3.9 r4 should be q2 b&c? where do i take the output from, q2 c?

i looked thru all the threads on the HP here yesterday, and left way more confused than when i came in. seems like nothing but conflicting info.

so...the george giblet one is right, correct? cuz looking at it, and comparing it to brians, it's not the same circuit.

ay...it's not the same, my brain hurts, and i definitely just spotted more problems with my vero. it's getting deleted, be back..

[Gus]

The pepper spray schematic in one of your posts shows the 3.9 meg Q2 B to C.  The 91K is the collector resistor for the top transistor.
C7 then connects to the collector and 91k and 3.9meg node and then to the diodes and volume control

The information about the HP is not conflicting.  It seems there were different versions made.  Pick the version you want to build.

Then there are all the different variations of the original that people have built.