Introduction to Sensors PDF

MODULE 1 Introduction to Sensors Sensors signals and systems, classifications, and units of measurement. ENGR. RENDELL JASON M. LAGMAN  A detector is a device designed to identify the presence or absence of a...

MODULE 1 Introduction to Sensors Sensors signals and systems, classifications, and units of measurement. ENGR. RENDELL JASON M. LAGMAN  A detector is a device designed to identify the presence or absence of a specific substance, condition, or phenomenon. Example: Smoke detector identifies the presence of smoke, signaling a potential fire. “a Detector might trigger an alarm, while a Sensor would provide a specific reading of the detected condition”  A transducer is a device that converts one form of energy into another, a process known as transduction. Typically, a transducer transforms a signal from one state or type of energy to another. For example, a transducer might convert electrical energy into mechanical movement.  General term for any device converting energy from one form to another. Tra n s d u c e rs a r e c o m m o n l y u s e d i n v a r i o u s applications, including measurement systems, control systems, and automation.  Transducers are a broad category encompassing all devices that convert energy from one form to another. Sensors are transducers that detect changes in the environment and provide a readable signal, typically electrical. “While all sensors are transducers, not all transducers are sensors.”  Transducers can be classified into different categories based on various parameters, such as the nature of the energy they convert and the type of operation they perform.  Mechanical Transducer: – C o nve r t s a p hys i ca l q u a nt i t y i nto i t s m e c h a n i ca l counterpart. – Example: Pressure gauge, which converts pressure into mechanical displacement. Electrical Transducer: – Converts a physical quantity into its electrical counterpart. – Example: Thermocouple, which converts temperature into an electrical voltage.  Input Transducer: – Converts a physical quantity or parameter into a readable signal, usually in electrical form. – Example: Microphone, which converts sound waves into electrical signals that can be amplified or processed. Output Transducer: – Converts an electrical signal into another form of energy. – Example: Lamp, which converts electrical energy into light.  A device that converts a physical phenomenon into an electrical signal. Convert a Signal or Stimulus (Representing a Physical Property) into an Electrical Output Represents part of the interface between the physical world and the world of electrical devices such as computers.  The quantity, property, or condition that is received and converted into an electrical signal.  Converts energy from one form to another. Converts electrical signals into physical phenomena. Process Diagram Process Input Output Diagram showing sensors’ role in converting inputs to outputs in control systems Process Control Loop Input Output Actuator Process Sensor Controller Sensors provide feedback to the controller, which then adjusts the actuators to maintain the desired system output.  A marketing document typically designed to highlight a positive attributes of a particular sensor and emphasize some of the potential uses of sensor. - Nature of Output. - Requirement of power source. - Input being measured. Analog Sensor Digital Sensor  Analog sensors are the devices that produce analog output in correspondence to the quantity being calculated. These sensors also observe the change in external factors such as light intensity, speed of the wind, and solar radiation, and others. And the output ranges between 0V to 5V. Converts a variable physical quantity into a signal that the control system can understand – voltage or current. Continuously measures and outputs varying signals over time. Unlike digital sensors that output discrete values (like 0s and 1s), analog sensors provide a smooth, continuous range of values. Examples: Accelerometers, Light Sensors, Sound Sensors  Accelerometers Type of analog sensors where those can be utilized to detect changes in acceleration applied on the sensor. Sample applications: Smartphones and wearable devices.  Light Sensors These are the kind of photoelectric devices where the detected light energy is converted to that of electrical energy which means that photons are converted as electrons. Mostly, light sensors are implemented for robotic intelligence and motion lights. Light Sensors Types: Photovoltaic Light Dependent Photo Diode Proximity  Sound Sensors Sound sensors are considered as the modules to find out sound waves by the intensity and converting those into electrical signals. Sample applications: Door alarms, Music systems, Burglar alarms, Computers  Pressure Sensors Pressure sensors measure the pressure levels of liquids or gases by converting the physical pressure into an electrical signal, typically a continuous, varying voltage or current that corresponds directly to the pressure level. They are considered analog sensors because their output is proportional to the measured pressure and provides a continuous range of values rather than discrete steps. Pressure sensors can also function as pressure switches, where they trigger an "On" or "Off" state when a specific pressure threshold is reached. However, their primary role as analog sensors lies in their ability to provide detailed, variable measurements across a range of pressures. Analog Temperature Sensor These sensors deliver analog output voltage or current signals in linear to the temperature levels. The usage of these devices is so simple, and no need for complicated circuits to construct. Converts Temperature to voltage Digital sensors are the kind of electrochemical or electrical sensors where the information is converted to digital form and then transmitted. The output of a digital sensor is the distinct digital signal of the quantity which is being measured. The output is in the form of 1’s and 0’s where ‘1’ represents ON condition and ‘0’ represents OFF condition. Examples: Digital accelerometers, Digital temperature sensors  Digital sensors output data in binary form, which is either a high state (1) or a low state (0). The image shows a waveform that could represent a digital signal output, where the high voltage (5V/3.3V) represents a binary "1" and the low voltage (Ground) represents a binary "0." This type of signal is crucial in conveying information from the sensor to a microcontroller or processing unit.  Digital accelerometers Digital Temperature Sensor  Active Sensors: These require an. Examples include resistor-based sensors like thermistors, RTDs (Resistance Temperature Detectors), and strain gauges. These to be passed through them, and the resulting voltage is measured. Alternatively, they can be used in bridge circuits, but an external current or voltage is still necessary.  Passive Sensors: Also known as , these produce their own electrical output signal without needing external voltages or currents. Examples include thermocouples and photodiodes. Thermocouples generate thermoelectric voltages, while photodiodes produce photocurrents. These outputs are independent of external circuits.