At 01:43 AM 1/10/98 -0200, you wrote:
>    I need some help from the list...
>
>    I need transmitter data with:
>        - low power (2mA max.)
>        - moderated cost (<  $3)
>        - distance: 5 cm (2 inch)  across the wood (can't use optical
>devices)
>
>    I thought in a inductive transmitter, but...  any ideas how can I do
>this ?
>
>
>-regards
>Marcelo Rib
>

You've just described the transmitter used in the Heart Rate monitors
from the Polar company.  They are like magic - they use almost no
power.  Their TX distance is over a foot. Thet come in a sealed
enclosure that includes the battery.  The battery is good for a couple
years!

They don't release schematics, but someone may want to take one apart
and check it out.

Eric Engler