Common Beat balance Detectors Expanded

[jlsilicon]

I wanted to discuss about expanding upon the simple Beat Balance, and other OpAmp Metal Detectors.

Ie: If these are easy to build, then why not Expand upon them ?

The common Beat Balance , that we could start with could be :



I had made some Mods on this design - and made it very simple to build (minimal calibration).

Actually, I dropped Caps between the OpAmp inputs p2/p3 and p5/p6, and removed cap VC1.



I then connected the outputs to an Arduino, checking for Voltages and pulse Counts.

Seemed very easy to use.

[jlsilicon]

Other variations of this that I found :

[jlsilicon]

Or maybe the 555 Matchless :

[jlsilicon]

My first question :

* If I put a pair of 2n7000 (or other) FETs for High and Low on the Output of the Coil OpAmps,
could this increase its Range ?

[jlsilicon]

My first question :

* If I put a pair of 2n7000 (or other) FETs to drive High and Low on the Output of the Coil OpAmps,
could this increase its Range ?

-

Sorry that would be :