Sensor ? Transducer ?

[zawminoo]

difference between sensor and transducer

Hi everybody,

I found the descrition of sensor, transducer and their different.
But there are two books say two different.
What is Right?

The first book say......

Transducers are the physical element which is a part of a sensor. A sensor is merely a sophisticated transducer in the sense that it contains some signal conditioning circuit capable of amplifying and refining the weak and raw signal that is available at the output of the transducer.

The second book say....

A sensor id defined as a device that is sensitive to motion, heat, light, pressure and other types of energy. A transducer is defined as a device that can receive one type of energy and convert it to another type of energy. This means that a transducer may include a sensor to include a sensor to sense the amount of pressure, and a circuit to convert the amount of pressure to an electrical signal.

I would like to know the true...

( transducer + signal conditioning circuit = sensor ) ????????
( sensor + signal conditioning circuit = transducer ) ????????


Thank
zawminoo

 

[manish12]

transducer books

i think both are ok ?

while Transducer is first come , which is in action for conversion then signal and condition comes to make signal usable .

while Sensor is a complete box which provide signal in usable form i.e ready to use

 

[zawminoo]

transducer sensor difference

( transducer + signal conditioning circuit = sensor ) ????????
( sensor + signal conditioning circuit = transducer ) ????????

 

[manish12]

sensor transducer difference

transducer + signal conditioning circuit = sensor ?
sensor + signal conditioning circuit = transducer ?

 

[rikie_rizza]

difference in sensors and transducer

Wow, where did you learn that?
Sensor is a device where you turn physical unit into electricity unit (eg. Pressure to Voltage, Temp to Resistance, etc).
Transducer is a device that gave information to a system by means of communication.

Pressure transducer transmit pressure value to a computer (such as PLC or Instrument system).

Pressure sensor send signal respectively to physical changes, such as differential pressure. The signal is an electrical property like resistance, current (eg. 4-20mA), or voltage (eg. 0,2-5V).

 

[laktronics]

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

 

[kender]

electronics project

Sensors vs. Transducers

Here’s a write-up that I made for the SensorForum group last Spring. The original discussion start here: **broken link removed** (the message archive is public)


Several books (from 60s and 70s) define the transducer as devices that converts some form of energy into another. This is a nice rigorous definition of transducer. The sensors convert some form of energy into electric energy. But then the question is: what counts as electric energy? Well, voltages, currents and charges undoubtedly count as electric energy. Strictly speaking, parameters such as resistance and capacitance are not energy, but we use the terms such as “capacitive sensor” and “resistive sensor” all the time.

Interestingly, by these definitions both sensors and actuators are transducers.

Every sensor has a transducer in it. Usually sensors also have built-in excitation and signal conditioning. The same transducer can work in different sensors and different industries. Transducer usually takes care of the physics of sensing only. Sensor is a product that’s built for easy integration into larger system.

A good example that illustrates the practical difference between transducers and sensors is acoustic. Acoustic (ultrasonic) transducers are used in a variety of sensors measure quite different values (e.g.: range and flow speed). Imagine that you want to measure flow speed of air in a pipe. If you buy only a transducer in your hand, you will have to spend an appreciable amount of time before you become capable of making measurement (i.e. you will turn the transducer into a sensor). On the other hand, if you buy a sensor, you might be able to make a measurement immediately after the installation procedures (that is, of course, if you bought an appropriate sensor, also the sensor might require calibration).

My personal (very practical, almost mercenary) way of telling a transducer from a sensor works like this. If it has a digital output – it’s definitely a sensor. If I can read the parameter of interest with a fairly generic A/D (in a PIC on a PC DAQ card) after a day of electrical interfacing – it’s a sensor. Otherwise it’s a transducer.

By the way, here’s a glossary of term related to sensors. **broken link removed**... It has a definition of a transducer, but it doesn’t have a definition of a sensor.

Finally, here is the definition that I, personally, like the best. A sensor collects information from the real world. A transducer only converts energy from one form to another.

© Nick Alexeev, San Carlos, CA, April 2007

 

[s_cihan_tek]

transducer sensor differences

transducer + signal conditioning circuit = sensor

 

[fsahmed]

best transducer book forum

A sensor is a device whose electrical property changes in response to the stimulus, (eg. an RTD shows change in resistance, a diaphram changes capacitance), however in order to read this change, u need an additional circuit that converts the change in property into an electrical quantity, which r voltage, current and in some cases frequency.

A transducer is a device that gives its output DIRECTLY in form of electrical quantity. Hence the answer of the second book is nearly accurate, that a sensor and an added circuitry would form a transducer, however,devices such as thermocouples and hall effect transducers are transducers naturally.

 

[hamran]

definition of sensor tranducer

transducer + signal conditioning circuit = sensor
as the sensor is a complex set while the transducer is simple and can be included in the sensor...........this is what you find in practice.