how a sensor can convert into transducer
Hi,
I would rather cast my vote in favour of the second book. Literally a sensor should mean a device whose property changes with respect to a variable.
For example the resistance of a strain guage varies with applied force. You can convert it to a voltage variation ( from mechanical to electrical form), if you use it in the arm of a DC bridge and thereby realising a transducer function.
If you used the resistance variation in an oscillator to change its frequency, you could have got a force to frequency converter, still another form of mechanical to electrical transducer, your sensor is still the same. Here, the resistance variation of strain guage is the sensing property and the strain guage+bridge, or strain guage+oscillator performs the transducing function. We are little confused at this point because resistance itself is very close to electrical energy, but you get actual transducing function only in combination with additional circuits.
Now, let us consider if the same force were to be applied to a spring, whose length changes with applied force. We can still measure the force, here the spring is a sensor, not a transducer.
And now a dynamic speaker is a born tranducer which converts sound pressure into electrical signal, so is the case with a thermocouple, converting heat into electricity. A mecury thermometer is using mercury as a sesor to measure temperature.
A resistor used to give current or voltage feed back in a power supply circuit is only a sensor, not a transducer, we also use current and voltage transformers as sensors in AC measuring circuits.
Now, coming to signal conditioner, it is a fuction outside sensing and transduction?, its function is to bring the signal level to within the range of the measuring circuit.
This kind of arguments over strict definitions will always continue so long as there are scientists and engineers in this world. If a question is asked as ' If X approaches Y at the rate of half the remaining distance per hour,for a given finite initial distance, how long it will take for X to reach Y ?', a scientist will say that X will never reach Y during his life time where as an engineer will say ' that for all practical purposes, X will reach Y within .... hours'. So do not worry too much about literal definitions and start designing circuits using sensors, transducers or both and give it to the scientist to use.
Regards,
Laktronics