New PD

[nelson]

Hi WM6

Many thanks for the information.
I will try after i finish my hammerhead and barracuda, that are on the bench.

Best regards

Nelson

Originally Posted by WM6

Hi Nelson,

if you or anyone wish to try, here all data needed:

I moded Security handheld metal detector model: LT-88B, producer ZhangFei, China.

Air core coils was replaced by on ferrite rod wound coil (following to keep the same inductance).

Coils data (measured at measuring frequency of 10kHz):

L1
Inductance L=1.0mH
Resistance R=1.2E
Impedance Z=62E
Quality factor Q=54

L2
Inductance L=2.5uH
Resistance R=0.1E
Impedance Z=0.18E
Quality factor Q=1.5

Wire used for both coils: enamelled copper wire 0.25mm (AWG30 or AWG31). I do not remember how many turns was wound, so you have to follow inductance, which is more correct, cause you very likely do not have the same ferrite rod.

Coils have to be tuned on maximal sensitivity by multi-direction moving both coil to reach the best position, then fixed and glued by composite resin.

R33, originally 3kOhm, was replaced by potentiometer (by which we can turn detector in Earth-magnetism sensor) of 100kOhm (look at picture).

That's all. Enjoy sensing our lovely Planet.