excuse my ignorance but i never had a desmagnetiser ^^
Anyway a kick in the face of my student will help to demagnetise him ^^ ... and and another kick in the face of the other teacher who suggested him that "yes my circuit is better than Tuco's ... just try to put a magnet and you will see mine dont even cry ..."
Whatever!!! i didnt used any feedback for offset cancel because i used correctly my flip circuit and i changed the preamp gain to put the minimal output value closer as possible of ground (i think with an instrumentation amp i'll obtain something really precious but the application doesnt demand that complexity), then any desired output will need or an attenuation or a gain (thats why i put the non inverter ) anyway i can power @ 3V3 quietly and have a pretty confortable output with enough range to be measured and exploited
my output is a clean out with a simple circuit
For the interested people following this story ..
what my "colleague" did ...
he read the aplication note but he misunderstood one fact ...
in the AN flip circuit and filters are suited in that way that the incoming flip causes an alternative output that changes its amplitude with the variations of the angle ... then its fair to use a controlled rectifier ... like
but when your signal is a clean line dc-like, the effect of that block is nooothing... even worst it adds switching peaks to the output that become worst if a post amp is added and adds a response time against external soft fields veeery slow...
i'll add the sketch of the circuit (just for info)
in the attached figure replaced the cd4053 (that he put) (cuz multisim doesnt have it ^^ ... but in real world it doesnt work it only add spikes to the signel and slow the response ...