crying metal detector help needed

[dave_j_fan]

This one i  made
transistors selected bc547 .pin diagram is matched .

but coils made from enamelled aluminum wires.

after making

1.when i take metal near right side coil it works as we can hear frequency change
2.but oscilation is always there smallbuzz there even without metal
nearby one coil


youtube video shown  it gets silent without metal nearby

how can i fix it?please suggest modification or tuning

[tepalia02]

I never tried one. But I think this problem can be gone by changing the values of the capacitor used. You can give a try to this ckt.
https://www.circuitstoday.com/metal-detector-circuit

[dave_j_fan]

that is radio assisted...i want to do stand alone one

[tepalia02]

Oh I see. This video shows a standalone metal detector. I can see it is quite similar to your circuit. But I can see that the capacitor values are different:

[ledtester]

There is a very simple metal detector kit you can get on ebay/aliexpress for about $1 that looks like this:



and here is a video explaining how it works:

Building a metal detector & how does it work -- DiodeGoneWild
https://youtu.be/Bs9U15qQo0E

In subsequent videos DiodeGoneWild goes on to develop his own design.