How to increase metal detection

[sribangaram]

Dear friends i am doing metal detector project have searched in google and try to make the one circuit 2 pnp transistors based that is working well but that is detecting very short range I wont to increase the long range so please give me the suggestion how to increase detection range

 

[AK48]

you cannot drive 300 kilometers with a wheelbarrow, to increase the detection depth you have to increase the power delivered by the transistor which drives the coil, so forget the BC 557 and forget your diagram, if you really want to make a powerful metal detector and acquire a solid knowledge of the subject, then have a look at: https://www.geotech1.com/forums/forum.php

 

[vfone]

If you search on Google for "metal detector schematic" first 10 returns shows detectors not very complicated, but having performances maybe 10x better than the one you posted.