AVR-Chat

Leave it to John to hit the nail on the head.  My Tiny25 device will be 
in an extremely "noisy"
environment, specifically, inside a model railroad locomotive.  The 
power comes from the rails
(which is itself a noisy pickup source), through a bridge rectifier, 
into a  .01 µF cap, into a 78L05
and into a .1 µF cap, then into the Tiny25 and a pair of switching NPNs 
(BC847s, if anyone cares).

   So, what do you think, John?   I need for this thing to start up 
whenever the locomotive sees
power (it is designed for NMRA DCC (Digital Command and Control) so the 
DC supply level
should be fairly bconstant, between 12 and 18 VDC).  Startup is not 
*CRUCIAL*, if the beacon
doesn't start,m the user can simply lift the locomotive off the track 
and replace it again.   No space
for a 'reset" button, and certainly no space for more than a tiny cap 
and a 1/8th watt resistor.  I would
]prefer that startup be FAIRLY reliable, but again, it is not *CRUCIAL*.

avrFreak