After a few months of research for the problems of discrimination and “Coil Error” in the Felezjoo PI, I finally find a temporary solution that can make the device more useful. this problem is often encountered when the components used do not match the detailed description given by the developer of FelezJoo. Since the source code is not available, it is necessary to find a hardware solution.
The detection of metals in this type of detector is based on the calculation of the delay caused by the metals around the coil. This delay is the origin of these problems of FelezJoo. Resistance R11 (390 Ohm) can be adjusted directly to change this delay in an RL circuit.
The Pot R11 5K 2W can be tuned to find the optimal value that needed to obtain a good super value (A B C).
This Trimmer can be replaced by a fix resistor after finding the optimal value.
The next video show the modified detector with the Pot 5K and the discrimination function.