In the selection and use of a sensor, the necessary considerations, so as expected. Considerations include:
1. Identification of the actual signal.
This stage includes the nominal value and the sensor measurement range, the physical condition of the environment where the measurement is made, the required measurement speed, and others.
2. Identify the required output signal.
Most of the output produced by current standard 4-20 mA (example at a temperature sensor) or the voltage is scaled to represent the magnitude of the sensor measurement range. There may be other needs sepertai impedansioutput isolation, and others. In some cases it may be necessary digital conversion on output.
3. Choosing the right sensor.
Based on the first step, we select the sensor according to the specifications range and environment. Furthermore, the price and availability of the sensor should also be considered.
4. Designing an appropriate signal conditioner.
With signal conditioning, the output of the sensor output signal is converted into a form that we need.
Sensors can be divided into two types, namely physical sensors and chemical sensors. Physics sensor detects the magnitude of a quantity based on the laws of physics. Examples of physical sensors are light sensors, sound sensors, chemical sensors, force sensors, speed sensors and acceleration sensors, and temperature sensors. While the chemical sensor detects the amount of a chemical substance by altering the amount of chemical into electrical quantities. Typically involves several chemical reactions.
Examples of chemical sensor is a pH sensor, oxygen sensor, explosion sensors, and gas sensors. There is another classification based on the purpose of energy sources, namely the passive sensor and active sensor. To convert the physical properties or chemical to electrical quantities passive sensors do not memerlukanbantuan energy sources, for example, is termocouple. Termocouple produces an output voltage proportional to the temperature at the termcouple connection.
In contrast to active sensors, to convert the physical properties or chemical to electrical quantities of active sensor requires the help of an energy source. There are 6 types of gesture classification sensor, namely:
1. Mechanical, eg, length, area, mass flow, force, torque, pressure, velocity, acceleration, acoustic gel length and others.
2. Thermal, example: temperature, heat, entropy, heat flow and others.
3. Electrical, example: voltage, current, charge, resistance, frequency and others.
4. Magnetic, eg field intensity, flux density and others.
5. Radiant, for example: the intensity, wavelength, polarization and others.
6. Chemical, for example: the composition, concentration, pH, reaction speed and others.