Linear Variable Differential Transformer

– exploit the magnetic induction change from the primary coil to the secondary two coils
– in a state of equilibrium, the magnetic core is centered and the two secondary coils receive the same flux
– in an unbalanced state, the flux on one coil rises and the other falls
– the voltage generated on the secondary by the change in magnetic core position

– linear relationship when the core is still around the equilibrium position

Figure 3.29 LVDT as position sensor: (a) LVDT construction, (b) electric current, (c) LVDT test frame, (d) LVDT characteristic

– sensitive phase detector circuit with LVDT displacement reader

Figure 3.30 Completed LVDT electronic test