Question about shutter release cables

[The Diabolical Dr Z]

Hello. A while ago I bought a shutter release cable switch for my MZ-6 
(ZX-L), because when working with hand-held long lenses, I usually need 
both hands for focussing and camera support, and consequently lack a limb 
to press the shutter button. When I received the switch, I felt a bit 
cheated for paying � 42 (which was a bargain; most shops here ask about � 
70) for what essentially is a walkman headphone cord with a button that 
shorts the three leads together; short one lead to mass and the thing 
focusses/calculates the exposure, short the third lead to the other two and 
the thing trips the shutter. I probably could have fabricated one myself 
for � 2 or so. Now, I don't mind paying top money for decent stuff, but 
this mark-up is ridiculous IMHO.

Now of course, Pentax uses a different cable release for nearly each model. 
This one has a mini stereo jack, and only one or two other cameras (the 
*ist and another, I think) accept this plug. However, I also have an SFX 
and two winder-equipped M-series cameras that all use a three-pole cable 
release (with two different plugs, of course). I have already tried 
tripping the shutter on the SFX by touching the poles of the cable switch 
socket with jeweller's forceps, and yes, it works.

So, I was wondering... does anyone here know (and is willing to share that 
knowledge ;-)) if ALL pentax electric able release switches operate on this 
same priciple? Because if so, I can simply make plug adapters for the 
different systems, and use the MZ-6's cable to operate all cameras. I'd be 
happy to put the "how-to" drawings on the web somewhere.

And yes, I'm cheap ;-).
TIA,
Z.