Ok. I got this design for a 12 volt powered desktop computer that I 
put in a solid white oak minitower case from a local woodwright. It 
had a couple of brass screws that held the top on.  I figured it'd 
be really neat to have one screw for power/up/dn, and the other for 
system reset, using a touch lamp switch circuit. 
 
Well, copy the circuit out of a radshk book, and it don't work. I 
check this thing six ways from sunday and it don't work.  Take it 
into a friend who knows a little, and on his bench, it works fine. 
Now, this is offa regular 9 volt battery. take it on home, and it 
is dead meat. battery still at 9vdc, still drawing 50 ma... to run 
a 555 IC, which would crank anywhere between 15 and 150 khz. So, I 
fire up my 1000 watt inverter, run the 1/2" electric drill, and 
V'oila! the touch circuit works... 
 
In a DC home, your body is not exposed 24 hours a day to a 60 cycle 
AC magnetic field, so when you touch a reset line of a 555 IC that 
is oscillating, you don't have any electric oscillation in your body 
to create the harmonics that the IC uses to trigger the switch. God 
only knows what your body does with those harmonics. 
 
But, in any case, I hadda put a regular switch on the computer. 
For design factors of a wood computer see my next post.
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