LFO Ticking noise in CE2 clone

[nicobenny]

Hi everyone,

I've just finished the Corrrral Chorus (BOSS CE2 Clone) from Tonepad.
It sounds very good. I added the speed pot, the vibrato switch and a rotary switch to select between 4 cap values to vary the intensity of the effect.

All of this works perfectly but there's a little glitch:
When I use the pedal on its own, wether powered via a battery or a boss PSA or Dunlop 9v power supply, I hear a ticking noise that accelerates if I turn the Rate knob clockwise. Is it LFO noise? How could I get rid of it?

When I use the pedal after my Boss TU-2 tuner (wether the 9V DC is daisy chained with it or not), the ticking noise goes away.

Any help?

Thanks in advance!

[ElectricDruid]

There's another thread about this that has a few ideas:

https://www.diystompboxes.com/smfforum/index.php?topic=67423.0

Does the circuit have a anti-pop resistor to ground in front of the input cap? If it ticks with just the guitar, but not after the tuner, it could be that the tuner output (which probably does have a resistor) is acting to drain any voltage off the input cap. Just a thought.

[Vivek]

There are some articles that say that an LFO that first creates Square waves can lead to ticking

And the solution was to add one more resistor and capacitor to "Round the Square wave", slowing the rise of the voltage




See LFO of DOD FX64

[ElectricDruid]

There are some articles that say that an LFO that first creates Square waves can lead to ticking

Yes. This is why using low-current-draw op-amps for the LFO helps, since it reduces the amount of current drawn when the square wave switches state, and hence reduces the "thump" that puts onto the power rails (which you then hear as ticking elsewhere).

Unfortunately that's not the only possible route of transmission for the ticking - it can also get into unshielded wires, as mentioned in the previous thread.

[Mark Hammer]

The first step is to make sure that a low-current dual-op-amp is being used for the LFO.  I'm sure there are many others, but the usual recommended candidates are either a TL022 or an LM358.

[bushidov]

For purely educational purposes, what op amp would cause it to tick badly if you wanted it to? Like to show someone at work "what not to do"?

[j_flanders]

Unfortunately that's not the only possible route of transmission for the ticking - it can also get into unshielded wires, as mentioned in the previous thread.

In my big box EHX Pulsar this was the case. It had the same issue: ticking after guitar/no ticking after another pedal or buffer
Inside the pedal, the (unshielded)wire from the 3PDT switch to the input jack picked up the ticking noise that 'radiated' from the rate pot. Lead dress, moving it away, routing it around that pot helped a bit.

The input jack + tip of the patch cable, which was close to/above the rate pot, also picked up the ticking noise.
Shielding the input jack it with some aluminum foil sandwiched between some Duct tape (connected to the enclosure/shield) completely solved the issue.

[DrAlx]

Unfortunately that's not the only possible route of transmission for the ticking - it can also get into unshielded wires, as mentioned in the previous thread.

In my big box EHX Pulsar this was the case. It had the same issue: ticking after guitar/no ticking after another pedal or buffer
Inside the pedal, the (unshielded)wire from the 3PDT switch to the input jack picked up the ticking noise that 'radiated' from the rate pot. Lead dress, moving it away, routing it around that pot helped a bit.

The input jack + tip of the patch cable, which was close to/above the rate pot, also picked up the ticking noise.
Shielding the input jack it with some aluminum foil sandwiched between some Duct tape (connected to the enclosure) completely solved the issue.

Beat me to it.  Yes the rate pot wires should be as short as possible (ideally they should be board mounted pots) and kept as far away from the input to the circuit.  That trick of rounding off the square wave works but I have never needed to use it in any of my builds where I managed to keep the rate pot wires short and far away from the audio bits of the circuit.

[nicobenny]

Just to tell you I got rid of the ticking just by turning the board 1/4 of a turn so that the LFO would be further away from the rate pot... And it worked! Simple fix after weeks of battling

[bushidov]

So you turned the PCB 90 degrees inside its enclosure?

[nicobenny]

Yes

[Vivek]

Just to tell you I got rid of the ticking just by turning the board 1/4 of a turn so that the LFO would be further away from the rate pot... And it worked! Simple fix after weeks of battling

Suppose that tic is being created by the LFO and is being radiated by the rate pot wires

then moving rate pot away from LFO will not change ticking


Maybe the correct answer is of the form:

"Just to tell you I got rid of the ticking just by turning the board 1/4 of a turn so that the rate pot would be further away from the XXXX ... And it worked! Simple fix after weeks of battling "

Can XXXX be the input section ?

[Vivek]

Nice to know that your pedal took a turn for the better !!

I suggest that you rotate your PCB another 90 degrees, as per the old english Proverb.

[nicobenny]

I think you're right, Vivek. It was probably the closeness with the input section that was to blame.

A little bit of rotating can indeed go a long way.