[sdiy] Body capacitance problem?

[Dave Kendall]

Hi all.

Possibly a dumb newbie question, I don't know....
I'm working on an experimental circuit which uses a dual monostable 
(CD4538). The R/C combination is 1M and 100nF which gives a measured 
pulse of just under 100ms.
There is a flying lead about 2 1/2 inches long connecting a trigger 
source to the positive going input of the monostable. All unused inputs 
are terminated as per the datasheets.
I notice that touching this lead with a finger will cause the pulse to 
be emitted, when no trigger pulse is being sent to the input. Leaving 
your finger there produces no further pulses, but removing and touching 
it again will trigger it again, every time.

Is this body capacitance?

I hope to eventually have a very short trace connecting to the trigger 
input (rather than a long wire), but am slightly concerned that this 
might still be a problem.

Anyone come across this before?

Any advice gratefully received. :-)

cheers,
Dave