1. Transducers Flashcards
function of a signal conditioning circuit
alter the signal (usually amplify) so it is easier to manipulate
function of an output transducer and state alternative name
controls a non electrical output, aka actuator
four differences between resistance thermometers and thermistors
resistance thermometers: metal, resistance increases with temp. , less sensitivity (gradient), relatively large
thermistors: semiconductor, resistance decreases with temp., higher sensitivity, much smaller
define the function of an input transducer and state another name
converts non-electronic signal into a (usually small) electrical signal. aka sensor
what is the thermoelectric effect? what transducer uses this?
when two dissimilar metals are in contact, an emf is generated that is proportional to the temperature of the junction. thermocouples
metals used and max temperature of a typical thermocouple
iron and constantan (copper nickel alloy), up to 800 degrees
define a thermopile and state its function
combined thermocouples - increases sensititivity. more thermocouples = increased sensitivity
describe the piezoelectric effect
pressure/force on a piezoelectric material will produce a potential difference across it proportional in sign and magnitude to the applied stress
define electrostriction
applying a pd across a piezoelectric effect produces constriction/tension
two examples of resistance transducers
resistance thermometers, thermistors
current transducer example
photocells/photodiodes/phototransistors that generate a current proportional to the light on it
example of a voltage transducer
thermocouple
define capacitive input transducers + an example
devices that change in capacitance in relation to the parameter being measured. ie changing of thickness of a plastic sheet as its rolled through springloaded capacitor plates
what kind of transducer is used mainly in sound measurement? explain how it works
capacitive transducer, sound pressure forces a diaphragm to move in and out relative to a fixed plate. the diaphragm and fixed plate form the capacitance plates. the capacitance change can be turned into a voltage for measuring or to send to speakers
give the main example of an inductive input transducer and explain
rotating coil generator, the resulting current is directly related to the relative velocity of the drive shaft
