Zombie Chorus ticks and noisy.

[nguitar12]

Hello everyone. I have built Zombie Chorus based on the following schematic.

http://www.geofex.com/PCB_layouts/Layouts/zombie.pdf

I have done the Mark Hammer's anti tick mod but still I hear a small amount of ticking. (even using a 9v battery)



Also there is some white noise even when the guitar is not playing. I love the chorus sound of this pedal. I really want to make it a useable pedal. Anyone can help me on this?

[anotherjim]

Have you put it in a metal case that's grounded to the output jack yet? Is LFO pot wiring as short as possible?

[Mark Hammer]

Low current op-amp, if you're not already using one.

[carfranca]

Add a 0.1uF cap between 6-7 pins of the opamp.

[Kipper4]

Put a cap from the two x 10k lfo biasing resistors node to gnd.

[MrStab]

I have a very vague memory of Mark (i think) saying that the only way to mitigate this is by giving the LFO section its own Vref. Even then, i think some people still had issues with it.

A combination of things such as the above, using a low-power op-amp for the LFO (eg. TL062), using a decoupling RC network for the audio section and keeping the LFO away from the audio path on the layout will get the tick as low as you can get it. if you can afford to filter out very low frequencies from the audio path, this may also help.

also, make the the LFO isn't sharing a dual or quad op-amp with U1a or U1b.

[Cozybuilder]

My ZC doesn't tick. Heres the schematic:



I use a different setup for V+ now: +9V ⇢ 1N5817 ⇢ 47R ⇢ 2 caps in parallel to ground (100uF Electro & 100nF MLCC) = knee at about 34 hz.

[deadastronaut]

i built a ZC ages ago, and did the recommended 'anti tick' mods and it was fine....very nice chorus.