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Fylde Electronic Laboratories Ltd: Displacement Measurement using LVDTs.


A device which can measure displacement using the relative position of two inductors is called an LVDT (Linear Variable Displacement Transducer.) These devices typically have a moving part (usually a rod) which attaches to the test point and a fixed part : both parts carry one or more inductors.

Some devices have built in electronics requiring only a steady (DC) voltage to energise them and giving a relatively friendly output often scaled in V/mm.

The following modules are suitable for use with DC LVDTs.

Bridge Amplifiers for use with DC LVDTs


A bridge amplifier with a complete set of features controlled manually from its front panel.


When many channels of DC LVDTs are used, this module provides a cost effective solution. On board jumpers are used rather than front panel controls.

Some LVDTs do not have built in electronics and have to be energised by a varying (AC) voltage which couples from the fixed inductor to the moving inductor. The strength of the coupling is proportional to the relative displacement of the two inductors. Special modules called Carrier Amplifiers are used to carry out this signal conditioning.

Carrier Amplifiers


A dual channel module with on board jumpers to set the gain. Front edge controls are provided for balance and gain adjustment. Each channel shares the same 3 kHz oscillator.

The FE-366-TA bridge amplifier and FE-346-CA carrier amplifier units are Micro Analog 2 modules which can be connected by USB to make a displacement data acquisistion system. Free FYLDE MADAQ software is supplied with all USB systems.




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