8 Input and Output Transducers

What is an input transducer

An input transducer converts non-electrical quantities to electrical signals.

What is an output transducer

An output transducer converts electrical singals into non-electrical quantities

Describe the graph of a thermistor

Resistance decreases non-linearly with temperature

Describe the graph of an LDR

Resistance decreases non-linearly as light intensity increases

What happens to VLDR when the light intensity increases?

When the light intensity increases, RLDR decreases. Since VLDR = RLDR/R1+RLDR x E, VLDR decreases.

How do microphones works.

It has a thin sheet of material called a diaphgram which vibrated according to the sound waves it recieves. The vibration causes the relatice positions of a coil of wire and a magnet in the microphone to change, which generates electrical output signals.

How can you find the positive and negative terminals of an electret mic?

Measure the resistance between each terminal and the metal casing of the mic. The negative terminal is connected to the metal casing so the resistance measured will be much lower.

How does a DC Motor work

When a current flows into a coil of wire, a magnetic field is produced. This magnetic field interacts with the magnetic field of the magnet to produce a force that rotates the coil and the shaft.

What does a flyback diode do?

Without a diode, a large reverse voltage spike will be produced each time the motor is switched off. This will damage the controlling circuit.

How does an electromagntetic relay work?

When a current flows through the coil, the iron core becomes an electromagnet and attracts the iron armature, which in turn closed the circuit.

What are the benefits of using an electromagnetic relay?

It allows small currents and low voltages to switch in devices that require much larger currents. It also allows two circuits to be isolated.