De "ticking" the tap tempo tremelo

[EDLK]

I have built two of Taylor Livingstons tap tempo tremolo pedal circuits
Both have had the same problem. Ticking in the first three wave forms.
I have been through all 16 pages of taylors thread and have not been able to solve this
I am looking for someone to take this on for debugging or repair.
I have to get my board back together and cannot spend any more time on this
I will pay bench fees, I love the pedal I just cannot live with the tick
Any one interested?  

[slacker]

It probably ticks with the first 3 waveforms because they're ramp up, ramp down and square which all have sharp edges. If your LDR is fast enough these sharp edges will give an almost instantaneous change in volume of what ever is going through the pedal at the time whether that's audio or just background hiss, this is what gives the ticks. This is probably why some people don't have this problem, they've got slower LDRs which will round off the sharp edges.

I would try putting a capacitor from the base of TR1 to ground, this should smooth the edges slightly reducing the chances of it ticking, you'll have to experiment with values, but hopefully that should cure it. 

[EDLK]

Thanks very much for the insightful reply.
It make good sense to me, however, I must confess that I do not know how to execute your suggestion.
Would you mind walking me through it.
I am not sure what TR 1 is, or how to attach a cap from its base to ground. I also have not idea what size cap to start with?
Thank again
EDLK

[EDLK]

Also
Any idea why the visable LED being connected or disconnected affects the ticking volume?

[Taylor]

I thought about this some, and I'm not sure this idea will work.

The "LFO" going into the base of the transistor is at that point actually a high frequency PWM signal (around 20khz as I recall). Smoothing the edges of this signal wouldn't have the  effect of smoothing the final waveform, but it might cause irregularities in the LFO.

[cloudscapes]

Also
Any idea why the visable LED being connected or disconnected affects the ticking volume?

Each time an LED ticks with a sharp edge, it's pulling a current draw from the rest of the circuit. Either smooth it out with a cap, or give it it's own ground rail straight to the power supply, or both!

[Taylor]

The digital/LED ground is completely separate from the audio ground on this PCB, connecting only at the point where ground connects to the PCB. The cap won't smooth it as it's PWM when it enters the optocoupler.