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Are these germanium or silicon? Ive seen differing descriptions online. Has anyone use them and if so, how do they sound, say in comparison with a oa126?

Staff/Studio manager in the art department at a small university. Mostly I fix things and maintain the equipment, and provide technical support to the students.

Stannous (tin) chloride is used to etch aluminum plate for printmaking and similar processes, we use it at my work.  It etchs more evenly and is a more stable reaction. I dont think it produces hydrogen gas, and doesnt produce much heat. Im not sure if it is easily available.

Yeah its not ruined, its a piece of metal, just sand it clean and start over. FeCl will work cold, it just takes a bit longer. I prefer it room temp, the etch is more controllable and clean. (no under biting). It can take an hour or two depending on how deep an etch you want.

For aluminum, I prefer stannous chloride. Ferric chloride is meant more for copper, dont reuse ferric chloride that you use to etch aluminum (with copper, you can do many, many boards before its spent), and make sure you have decent ventilation.

Ferric chloride works best around 35 baume (1.32 specific gravity) ,I believe higher densities will etch slower, or less reliably, at least with copper, but I forget why exactly. But the strength is impossible to know without a hydrometer, dont sweat it, for what we are doing it will be fine.   

Its unlikely the ferric chloride has gone bad, we use ferric chloride baths at my work, and change them once a year, it shouldnt break down, except from alot of use, and still, it would probably just etch slow. More likely the aluminum is oxidized, or otherwise not clean.

Ive built with tayda greenie film caps for c2,c4,c7 and a tayda tantalum for c4. Ive heard its important (i forget why) to use a tantalum for the 47uf, Tayda doesnt carry that value, so i got some off ebay. I used some other generic 100pf silver mica from somewhere. I used generic 5% resistors.

I used a ebay russian mp16b for the 404a and a tayda pn3565. For the diodes, any germanium diode should work for the first pair (of course, theres some variation), the second pair I liked a set off oa126s.

I built several and they sound pretty much exactly like the ones in the albini videos. 

Ah thanks, sorry, didnt see them there.

The Harmonic percolator clone (pepperspray?) build doc, is no longer on the main page, as it was discontinued, but isnt on the discontinued projects page. Anyone have a link to the doc? - i need to etch a few more. 

They should be noted, at least in the build docs. Also positive lead goes to the square pad. Note that film and ceramic caps arent polarized, so they can go either way.

Is there a board in general you are asking about? All the projects ive seen here, have had the polarities marked, so im a bit confused.

Triple and quad, (and more) ganged pots do exist ive seen them, mostly at electronics surplus stores, but why would you want to do this? The space you save by cramming them in an enclosure with a rotary switch, isnt going to be much over having 3 smaller pedals, no?

I cant see why a dual gang pots wouldnt work. Hooking up to the same set of lugs seems problematic , say if one pedal has a connection to a shared ground, on say pin2, and the other pedal's pin2 is not intended to go to ground. It will in that case go to ground, cause there is no resistance, even if pedal 2 is powered on and pedal 1 is not.    

i think the ideal gains for the harmonic percolator are lower than that. Ive built several, they sound like the videos online (certainly not just a muddy overdrive,)  with the ge with a hfe vaguely around 50. I used mp16b russian transistors, but really it doesnt seem that picky. 7 out of 10 transistors out of the bag sound right. I used the pn3565 out of the bag without measuring. Hopefully someone can give you better advice.

Are you using the albini specs? And a tantalum for the 47uf (I forget why, but Ive heard its actually important)?   

Ok thanks, ill try those, yeah, I prefer to etch my own, it feels more proper, and I have access to a good etching setup. In general, is there ethical questions, if i take the grind customs schematic and make my own layout?

Ive never built a glitteratti but I like them in overdrives in general, and it calls for a silicon diode, so it should work well. But socket it. I tend to like an OA126 with another regular fv ge diode on the other side for asymmetrical clipping in overdrives in general.

I used a cavedweller with a theremin which is also a line level instrument (into a pa amp) and it was a non-issue. It was a the dub edition, and I did add some diodes to clamp the volume when it goes into runaway oscillation, but i assume that would happen regardless of the input signal. There isnt any op-amp or clipping stage to overload. Actually, I find most non-overdrive/fuzz/distortion pedals work fine enough (at least for most settings) even when they really shouldnt, the biggest issue is changing any highpass and lowpass filters to accomodate the larger range. 

If it is an issue, I suppose you could always build a very simple pedal to attenuate the keyboards signal down to guitar levels before  going into any pedals.