Active sensor Vs Passive Sensor

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gar

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Ann Arbor, Michigan
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EE
100313-1423 EST

Ham:

A passive sensor would be something like a quartz crystal accelerometer. No external power is required to get an output signal. The signal power is derived from the mechanical input.

A photo sensor using a photovoltaic cell would be passive. A vacuum tube photomultiplier would be an active sensor.

I have not generally thought of a bridge type strain-gage transducer as active, but it seems that I should because this would require an external power source that is modulated by the resistor elements to produce an output signal.

A dynamic microphone would be passive sensor, and an Edison carbon mic an active sensor.

Following is from Wikipedia http://en.wikipedia.org/wiki/Passive_components
Incremental passivity
In circuit design, informally, passive components refer to ones that are not capable of power gain. Under this definition, passive components include capacitors, inductors, resistors, diodes, and transformers. They exclude devices like transistors, vacuum tubes, relays, glow tubes, energy sources like current- or voltage sources, and similar devices. Formally, for a memoryless two-terminal element, this means that the current?voltage characteristic is monotonically increasing. For this reason, control systems and circuit network theorists refer to these devices as locally passive, incrementally passive, increasing, monotone increasing, or monotonic. It is not clear how this definition would be formalized to multiport devices with memory ? as a practical matter, circuit designers use this term informally, so it may not be necessary to formalize it.[nb 1]
I do not know if there is any hard well defined precise definition to uniquely define passive and active.

You can put "passive sensor" and "active sensor" into Wiki and see if any of the references help you. Also do Google searches on these word pairs.

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Hameedulla-Ekhlas

Senior Member
Location
AFG
100313-1423 EST

Ham:

A passive sensor would be something like a quartz crystal accelerometer. No external power is required to get an output signal. The signal power is derived from the mechanical input.

A photo sensor using a photovoltaic cell would be passive. A vacuum tube photomultiplier would be an active sensor.

I have not generally thought of a bridge type strain-gage transducer as active, but it seems that I should because this would require an external power source that is modulated by the resistor elements to produce an output signal.

A dynamic microphone would be passive sensor, and an Edison carbon mic an active sensor.

Following is from Wikipedia http://en.wikipedia.org/wiki/Passive_components

I do not know if there is any hard well defined precise definition to uniquely define passive and active.

You can put "passive sensor" and "active sensor" into Wiki and see if any of the references help you. Also do Google searches on these word pairs.

.

Thanks for information and here I found the below link and it explains clearly

http://wiki.answers.com/Q/What_is_the_difference_between_a_passive_sensor_and_an_active_sensor
 
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