Automating Manufacturing Systems - Process Control and ...

continuous sensors - 23.10
A rod drives
the sliding core
∆x
∆V = K∆x
where,
∆V = output voltage
K = constant for device
∆x = core displacement
AC input
signal out
Figure 23.8
An LVDT
Aside: The circuit below can be used to produce a voltage that is proportional to position.
The two diodes convert the AC wave to a half wave DC wave. The capacitor and resistor
values can be selected to act as a low pass filter. The final capacitor should be large
enough to smooth out the voltage ripple on the output.
Vac in
LVDT
Vac out
Vdc out
Figure 23.9
A Simple Signal Conditioner for an LVDT
These devices are more accurate than linear potentiometers, and have less friction.
Typical applications for these devices include measuring dimensions on parts for quality