R.G.´s Brownface Vibrato update

[Morocotopo]

Hi fellows, long time since I´ve been here. Never stopped building, though, it´s in my blood by now. Dang!

   Anyway, I recently made a Brownface Vibrato, I had built one when it first popped up here a few years ago but I wanted a smaller one for the pedalboard. Once built, I found ticking in the audio, and also, this thing works wonderfully before a OD / distortion, but, it gets kind of hissy in that situation. So I set to solve this issues.
   First the hissing: I replaced C2, the power filter cap, with a 470 uF (was 47uF). That quieted the hiss quite a bit, still some but not overbearing. to reduce it further I believe you have to start to mess with impedances, gate / base resistors, etc. Not this time.
   Then the ticking: I started to investigate the issue. The ticking was relative to the depth pot, at minimum depth there was none, so not really a grounding / power issue but an audio issue. Looked at the LFO waveform in the scope, it´s a sort of a deformed triangle, but has a spike at some point. I came to the conclusion that the FETs that produce the tremolo were changing resistance abruptly (FETs are very fast) at some point, and I remembered that in the bypass circuits of most Boss pedals, there are "slow down" caps in the flip flops to avoid the FETs to switch too quickly and make a pop. So I added a 100n cap across R12 and R21, and voilá: ticking gone! Not really sure how it works, I think that they slow the control signal to the FETs enough to eliminate any abrupt change, and so that avoids them making noises.
   So now I have a beautiful, beautiful harmonic tremolo that works great.
   Thanks R.G. for a really nice pedal!!

Cheers