On Sat, 27 Feb 1999 20:03:35 -0500, you wrote:

>Gus Calabrese wrote:
><snip>
>> 4)   Any cool suggestions on power management?
>> Gus Calabrese
>
>Gus, light blocking is a nice solution but it requires light,
>n almost 100% of the cases it is a power pig solution.
Not necessarily - for a sampling rate of 3 per second, you could 
easily use a very short LED pulse, say a low-current LED at 2mA, with
a  5uS pulse, which works out as 0.03 uA avarage - hardly a power pig!
  
>
>There are some other ways to sense objects without the use
>of light.
>
>- sound
>- pressure
>- physical switches
>- infrared sensing
>- doppler sensors
>- capacitive sensors
>- light change (use ambient light)
>- weight
Magnetism (hall effect / reed switch / inductive)