I have an 8 x 8 grid and would like to detect where on the grid I place a metal object. I'm currently working with the TDA0161 metal detection IC, and so far have the following setup with detection range of 5mm:
I don't fancy using 64 of these ICs and am experimenting with multiplexing the coils.
I'm thinking of using 8 ICs each with 8 coils, and then using an analog switch to switch between the coils checking each position.
So far I have tried the to use the the CD4051BC, with the common I/O connected to one end of the coil in above picture, and each 8 to the other end and then to each I/O of the CD4051BC as you can see in the schematics below:
The above schematics however doesn't work.
When I use the first schematics with a single coil, it works perfect, but when using the analog switch nothing. When I measure the inductance across the single coil I get about 300 uH but when I measure the coil after it has passed through the analog switch, I get some random high number over 10 H.
The datasheets for the two ICs: