[Cyborg] heart circuit

[Eric Boyd]

Heart circuit an all it's cute glory:

http://sensebridge.net/files/HeartCircuit.jpg

Chung-Hay - I'm still planning to make one for you.  I have all the 
parts it's just a matter of soldering together a second one :-). 
Unfortunately the battery holder I designed this one around is more 
cumbersome on the back than I had anticipated so it's rather difficult 
to actually stitch it into things.  Not sure how I am going to resolve 
that problem, because I think that battery holders are ugly and I don't 
really want to put it on the front... I'm open to suggestions.

Thanks to everyone who helped with / commented on the design - I'm 
actually really pleased with how it came out, although I have a huge 
list of things to redesign before I make more boards :-)

Also, Arduino sleep_mode() is really excellent and easy to use.  I did 
some current measurements and using sleep mode cuts power consumption 
for this small circuit (that basically flashes LEDs ~once a second on an 
interrupt generated by the polar receiver) to 1/15th of it's previous 
value (average consumption 2.4mA vs 34mA).  That's AWESOME!

Eric