Harmonic Percolator (with some mods)

[snk]

Hello,
I have taken the layout of the Harmonic Percolator from Iviark, and tweaked it a bit :
- First, I tried to make it more compact, as I think one could use smaller capacitors; Now, it doesn't feature any link, less cuts, and a couple rows and lines less.
- Then, i added two 1nF capacitors, as i have read that it helped improving the sound of the pedal ();
- Also, i decided to try with values in between the "stock" version (which should sound rawer) and the "Albini" version (which is supposed to be smoother). I don't know if it makes sense, but i hope to get in the ballpark of the Harmonic Percolator sound
- I also replaced a 4k7 resistor with a 10K pot ("symmetry").
- I upped a bit the input capacitor...
- I plan to replace the 20K resistor with a 20K/2K switch (lower values are supposed to increasze the octave-down effect).



(NOTE : I didn't draw the pot and switch wiring : i am planning to use the same one than on Tagboardeffect)

If everything goes well, I am planning to build it in the next days. Prior to this, I am submitting the layout to the community in order to get a "double check" and some suggestions :
- Does the layout look ok ? I checked a couple times, and i think i didn't miss any component, but i have moved everything quite a few times and it is easy to miss something
- Does the mods make sense ? Is it wise to try "halfway values", or should i better stick to either the "ALbini" or the "Stock" version ?
- Do you have any feedback/tips (I mean : which mods are the best sounding / the more interesting ? Did you try some of them yourself) ?

[rutabaga bob]

Duck...wanna weigh in here?  ;-)

[duck_arse]

any coffee in the pot, bob?

anyone that's seen my vero build knows I can't offer any advice on the layout. check this thread for some findings on mods and things:
https://www.diystompboxes.com/smfforum/index.php?topic=122054.0

dino had some stuff about percolators, must have been in another nuther thread.

[snk]

Thank you !
I had read several HP threads, but didn't see this one : there are lots of infos to learn.

I upped R1 to 1M5, and put a 6k8 and 10k trimmer at R4.

Great : this is more or less what i planned to do (2.2M resistor for R1, and 20K trimmer for R4, or a switch).
Did you try any other values than 1M5 prior to sticking to this value ?
For R4, do you think it would give interesting results to have an external pot instead of an internal trimmer ?
Is 6.8K the smaller "good sounding" value ?

[duck_arse]

from memory, iwas trying to do as little changes as I could, starting with what dino had found, so I left that 1M5 resistor well alone.

R4 the clippers resistor? try it on the breadboard, you might only find a 3 position switch useful.

most likely I chose 6k8 so the trimpot was about centred for 1V on Q1 collector, another of dino's starting numbers.

have you picked any starting transistors?

[snk]

Thanks, I will take that into consideration.

have you picked any starting transistors?

Not yet : i will first cut the vero, put the resistors, caps, and solder sockets for the transistors. Then, only, i will dive into my bag of transistors

[digi2t]

Here's what I had come across in my percolating breadboard trials;

https://www.diystompboxes.com/smfforum/index.php?topic=99596.msg874656#msg874656

https://www.diystompboxes.com/smfforum/index.php?topic=99596.msg874706#msg874706

https://www.diystompboxes.com/smfforum/index.php?topic=99596.msg874830#msg874830

And the missing video from that last post is here;

[digi2t]

Here we go. I had a vero made up, but never got around to committing everything to an actual schematic.

[snk]

Thank you so much, Digi2T !
I am considering using the Harmonic Percolator (where every component seem to be prone to tweaks) as a good starting point to learn breadboarding
I may build one from your specs on vero, and then mess around with breadboard to see how each component change the sound...

[Rob Strand]

Here's what I had come across in my percolating breadboard trials;

A good recipe for Percolated Giblet.

After all these years and variations of the Percolator maybe one of the key voltages is Collector to Emitter voltage of Q1 instead of the collector voltage?   It seems most builds end-up with with Q1 VCE voltages around 0.15V to 0.5V;  and maybe the good range is a little narrower than that perhaps around 0.2V.