555 LFO causing interference / noise

[wax+wire]

I've got two projects with 555 based LFOs.  one is an APC/Atari Punk Console (so that is a lot of 555s in a box) - the other is based on Graham's Phat Philter Bank for the Casio SK5, a mono Voltage Controlled Filter.

I find that the LFO affects the output regardless of whether the control voltage line is connected or not!

Crazy.  In the Filter circuit it introduced a very obvious *click* in time with the rate of the LFO, and in the APC turning on the LFO (though still not connecting CV lines) causes pitch changes.

Do I need to shield my CV lines - could that be the problem?
What else could it be?

Thanks in advance

[wax+wire]

if anyone else is having this problem:

https://sites.google.com/site/flofxdiy/deticking-lfo

I ended up sticking a 100nF cap over the positive/negative terminals which reduced the clicking significantly - but it is still slightly present.