Transducers convert energy from one form into another. They are used for measurement and control.
Sensors (measuring devices) are transducers.
Input Transducers
These are measuring devices. They convert input signals into an electrical signal. Examples include ...
- Antenna for receiving Radio Signals
- Light Dependent Resistor
- Microphone
- Photo Diode / Transistor
- Pressure Pad
- Reed Switch
- Temperature Dependent Resistor
- There are many more ...
Output Transducers
These convert an electrical signal into an output. The output could be visual, audible or it could be mechanical, used to control an industrial system or any device with moving parts. Examples include ...
- Antenna for transmitting Radio Signals
- Buzzer
- Light Emitting Diode
- Loudspeaker
- Motor
- Pump
- Relay
- Solenoid
- Stepper Motor
- Valve to control fluid flow
- There are many more ...
Transducer Drivers
- A small current can actuate a relay. The relay switches a large current. (Slow and not too reliable).
- An op amp wired as a voltage follower can be used to drive a transducer. Quite fast and cheap. Not suitable for very high powers.
- A MOSFET or pair of MOSFETS can be wired as source follower/s and used to drive transducers. Suitable for quite high power applications. Very fast switching.
- Bipolar transistors can be used as emitter followers in a similar way to MOSFETS as source followers. Suitable for quite high power applications. Does not switch as fast as a MOSFET.
Examples
Humidity Sensor (input)
Motor (output rotation)
Servo (output movement)
Strain Guage (input - for weighing objects)
Solenoid (output movement)
