Update. I was working on this thing last august and part of september till other stuff came in between and I had to catch some nasty behaviour. A design may sound excellen but will still be as weak as it's weakest link. In this case I introduced a problem I had not ran into in the breadboard variant. The breadboard version was powered by 15 volts from my lab power supply. Because I wanted to be able to power the thing from 9 volts externally I used a Traco 5 to 15 volts DCDC concerter. Going from 9 to 5 volts (7805) and then back to 15 is not very energy efficient but the TCA740 in the circuit draws way too much current for a MAX1044 voltage doubler like solution. Furthermore the Traco's are excellent in their performance vs the size. They do have one drawback and that is that there's a strict limit to the amount of (supply filtering) capacitance that can be added to the output.
So I had way too much LFO noise. Tickticktick that is. And the origin...transfer through the supply lines.
So yesterday I modified the PCB I Made to add a couple of 100 ohms resistors and add filtering capacitancd after these. Brings down the voltage a little but keeps the supply lines going to the various parts of the circuit a lot cleaner. Now this thing is so dead quiet I don't even hear from noise it's on till I touch strings.
As well,
Naturally I could adjust the design to implement rate controls, depth controls, LFO asymmetry, dry-wet mix stuff. Name em and spend days twaking the circuit for optimal performance. Till I realized countless organ players have been playing their organs with Leslies for yearrs having only a fast and a slow mode. Apparently, when the controls are not there, one can do without and spend more time and focus on the playing. Therefore I made the PCB design incorporating a bypass and a fast/slow switch only, basically holding on to the original Sferasound circuit. This way the pedal can be pot in the bottom of a pedalboard suggesting to be more of a control (like an amp footswitch) than an effect pedal.
Andd furthermore,
There's some with the opinion that SMD has no place in pedals. Resorting to (full) through hole would make this thing all but a pedal the size of a footwitch. Waste of space on a pedalboard so to say. So, SMD wherever I could, excluding electrolits beacuse of their height in SMD versions as well (or very low voltage ratings). Because of the space consumed I replaced all but the BBD bias trimmer for fixed resistors as well. Makes initial calibration a little harder though.
Pica's?
All the "upside down" caps are the later modification for the addditional supply power filtering. The little black block on the left is the Traco DCDC converter.
Copper side wilt most of the components happening. Top left some trace repairs as I has some argument with my etching tank...