lundi 5 septembre 2016


les Chapitres du  module

 Chapitre 1  :    Généralités 
 Chapitre 3  :    Les structures internes de la terre
 Chapitre 4  :    La dérive des continents

 Chapitre 5  :    Les preuves de l'expansion océanique
 Chapitre 6  :    Outils de  minéralogie
 Chapitre 7  :    Magmatisme et roches magmatiques

FSR Schmitt Trigger Oscillator
In this circuit, an oscillator is made using the FSR device as the feedback element around a Schmitt Trigger.
In this manner, a simple force-to-frequency converter is made. At zero force, the FSR is an open circuit.
Depending on the last stage of the trigger, the output remains constant, either high or low. When the FSR is
pressed, the oscillator starts, its frequency increasing with increasing force. The 2MΩ resistor at the input of
the trigger insures that the oscillator is off when FSRs with non-infinite resistance at zero force are used.
The 47kΩ resistor and the 0.47 µF capacitor control the force-to-frequency characteristic. Changes in the
“feel” of this circuit can be made by adjusting these values. The 0.1µF capacitor controls the frequency range
of the oscillator. By implementing this circuit with CMOS or TTL, a digital process can be controlled by
counting leading and/or trailing edges of the oscillator output. Suggested Schmitt Triggers are CD40106

CD4584 or 74C14

Force Sensing Resistors
An Overview of the Technology
Force Sensing Resistors (FSR) are a
polymer thick film (PTF) device which
exhibits a decrease in resistance with an
increase in the force applied to the
active surface. Its force sensitivity is
optimized for use in human touch
control of electronic devices. FSRs are
not a load cell or strain gauge, though
they have similar properties. FSRs are

not suitable for precision measurements