Hey Rick, I have some BC 548, both B and C - would they fit? Or should I stick to the 547s you used???
Also, why did you use a 100k LIN and not LOG for VOLUME? And why a 100k for the GAIN, instead of the 50K of the original?
Just comparing the BC547C with the BC548C on their datasheets, they appear to have the same gain, the 'B' version has too little gain though, and probably wouldn't be suitable. You should socket the transistors though, just in case they don't work for some reason.
Volume - I'm going to build mine with a trimpot or resistor voltage divider (to achieve unity between the bypassed and effected signals) instead of a Volume control - you don't usually see tremolos with volume controls. As to 'why Lin and not Log', I've built a lot of synth stuff, where Lin in used for signals and Log for control voltages. Different pot manufacturers label their pots differently too, an 0MEG Lin is 'A', an Alpha Lin is 'B' - very confusing.
Gain - having a 100K instead of a 50K allows more resistance between the cathode and ground, and therefore more clean headroom. Again, I'm building mine without a gain control, I'll use a 100K resistor instead - you don't ususally see tremolos with gain controls either. I will also be using 100K resistors for both the plate resistors, again aiming for a clean sound.
So mine will just have two pots - 'Speed' and 'Depth'.
I've also made a few improvements to the design - just tweaks here and there - and one of the resistor values I posted was wrong (doh! - the first 4K7 at the emitter of the second transistor should be 47K), so hold off from building it for a day or two, to give me time to update the schematic.
