converting switches to triggers (was: trigger inputs on toys)

[Chris ('the Hex')]

At 09:55 AM 4/28/98 EDT, Michael LeeRaven McAdow wrote:
>A little while ago I fixed a 1/8" jack into the circuit of a toy (some cheezy
>medical doctor toy) and got it to trigger from my Accent trigger 

This is probably a blatant newbie question, but I think it may help not only
me but a lot of newcomers who've done some noodling but don't have a strong
EE background (or a even a weak one :-/ ).  Is there a common circuit or
method for converting a switch -- just an open or closed junction, like the
buttons on the
toys being described in the previous post -- to a trigger input?  I imagine
this is a common mod, but I've not yet come across a simple explanation of
how it works.  Any takers?  If there are good references for this sort of
thing that I should be looking in, you could just post the names of these
books to the list...

Cheers,
Chris