These types of transducers are mostly used as secondary transducers and their output is calibrated in terms of input quantity. It can be used to measure force, pressure, displacement etc. Oscillatory transducer consists of following parts
- Mechanical linkage
- Frequency modulator
- Force summing member
Mechanical linkage: This is used to link the input quantity to the secondary transducer, i.e. oscillatory transducer, by actuating it. It may include gears or some other linkage system.
Oscillator: As we know oscillator are used to generate desired frequency. The oscillator used here consists of LC tank/circuit. The output frequency is generated according to the input source.
Frequency Modulator: The output frequency from the oscillator may need some modification for telemetry purpose. This modulation is achieved by frequency modulator. After modulation the output frequency is suitable for telemetry purpose.
Force Summing Member: This is used to change the capacitance or inductance of an LC oscillator circuit. It transfers the pressure to mechanical linkage.
Working of Oscillator Transducer
Working of oscillator transducer can be explained from the figure as:
- The quantity to be measured like pressure is applied to the force summing device which transfers this pressure to mechanical linkage.
- Mechanical linkage responds according to the magnitude of the pressure.
- Mechanical linkage drives the dielectric medium inside the capacitor.
- The movement of the dielectric medium inside the capacitor tends to change the capacitance.
- Frequency of oscillator depends on capacitance and inductance. In case of change of any of these quantities the frequency changes.
- The output of oscillator is a modulated output and can be modulated and calibrated in terms of pressure or force applied.
Advantages of Oscillator Transducer
- This transducer measures both dynamic and static phenomena.
- This transducer is very useful for telemetry applications.
Disadvantages of Oscillator Transducer
- This transducer has very hunted temperature range.
- It has a poor thermal stability.
- It has a low accuracy and therefore is used only in low accuracy applications.