strange locator

[gold24h]

About five years ago my brother got in contact with a man from arizona,a very old man,this man supposably had built a very simple locator with easy available parts,he sent my brother the information on how to build it,he promissed it would easily pick up a single coin,building the device was easy but the operating instructions were confusing,after building it and not understanding how to use it my brother contacted the man again,his wife said he had had a stroke and was in very bad health so my brother never bothered them again.
The unit consisted of a selanoid coil on the end of a rod,the two wires from the coil went to a little amplifier that you buy from radio shack,then the output from the amp went to a device called a cell sensor,you can buy it on the internet,it measures electromagnetic feilds.The whole setup is very sesative,it picks up natural signals and shows the streanth on a meter.You are suppose to point the coil out in front of you at a slight down angle and slowly sweep it,you have to set the threshhold on the sensor first,the problem is we never understood are you looking for an increase in signal or decrease,you are suppose to get two signal lines and where the cross is the treasure.The closer to the ground the higher the signal,the meter goes full scale if you get it within one foot of the ground,the man said he had found many things in the deseart with this setup,does anybody have any ideas about this.