Transducers Convert Energy To or From Electrical Energy
Input Transducers or Sensors
These measure the world and generate a proportional electrical voltage or current.
There are many examples. Here a few ...
Sound - Microphone - Convert sound energy into a proportional voltage
Temperature - Thermistor - Convert temperature into a proportional voltage
Light - Light Dependent Resistor (LDR) - Convert light level into a proportional voltage
CCD sensor ( as used in digital cameras ). Charge Coupled Devices.
Angle - Potentiometer - Convert angular position into a proportional voltage
Pressure - The resistance of a piezo-resistive material changes when pressure is applied.
Moisture - Wet materials have a lower resistance that dry.
Presence - Switches - If an object is present it activates a switch or breaks a light beam, optical switch.
Ultrasound sensors can measure distance and movement.
Passive infra-red sensors are used to detect movement.
Convert an electrical voltage or current into sound, light, movement or temperature. There are many examples. Here are several ...
Loudspeaker - Convert alternating electric currents into sound energy
Heater - Convert current into heat and cause the temperature to rise
LED or Bulb - Convert an electric current into light using a bulb, LED or other type of display.
Actuators - Convert an electric current into movement using a
solenoid - small straight line movements
motor - continuous spinning motion
stepper motor - precise angular stepped motion
servo - 90o movement controlled by a stream of pulses
Most processing circuits can not provide enough power to drive motors, loudspeakers, lighting systems and so on. Drivers are needed to boost the small signal from the processing circuit. Drivers capable of working at larger currents and voltages include ...
Bipolar Junction Transistors
Categorising Input Transducers
Active Sensors - Contain Semiconductors
Electret Microphone - contains an FET pre-amp
Accelerometer - Detect the orientation of a phone
Light Dependent resistor
Moving Coil Microphone
Conducting Polymer - Changes resistance when deformed.
Hall effect sensor - Measures magnetic fields.
Capacitor - Capacitance changes with the input
plate overlap might change
plate spacing might change
material between the plates might change
Optical Switch - IR-LED with photodiode and a transistor switch
Switch - Resistance = zero or infinity.
Any kind of switch
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