Patent ID: 7064662

Claim:
An apparatus for locating an object comprising: (a) a master transmitter unit with a means for transmitting a signal and a means for controlling said means for transmitting; (b) at least one servant receiver having (1) an output unit, said output unit having means for attracting a user's attention and a servant output battery for powering said output unit; (2) a comparator unit operatively connected to said output unit whereby said comparator unit activates said output unit powered by said servant output battery, said comparator unit drawing negligible current from said servant output battery; and (3) a signal receiver unit for receipt of said signal generated by said transmitter unit, said signal from said master transmitter unit generating a current in said signal receiver unit thereby activating said comparator unit to activate said servant output battery to power said output unit; whereby said at least one servant receiver uses negligible current from said servant output battery until activated by a signal from said master transmitter unit, so that the effective life of said servant output battery in said servant unit, if said servant unit is unused, is approximately the same as the life of said servant output battery; wherein said comparator unit is matched to said signal receiver unit to achieve a sensitivity of at least 0.1 millivolts.