Instrumentation

A transducer converts one form of energy into another such as electrical impulses to acoustic energy, and vice versa - microphones do acoustic to electrical, whilst speakers do electrical to acoustic, whilst a transmitter sends electrical impulses, such as a FM transmitter sends energy particles to a FM radio BTW, was this a homework question?

Sounds like homework to me.

but your explanation is a good one. The student should be able to grasp the concepts and maybe relate them to real life.

the analogy of the FM signal being transmitted through the air and then having the radio waves turned into sound by the acoustic transducer (loudspeaker) should help.

LL

Since this is asked in the Instrumentation forum:

A transducer (as said by Bondy111, GA for you) converts one form of energy into another form. For instrumentation, this "another form" is usually electrical in nature and it is usually voltage or resistance. Unfortunately, transducers usually produce very small signals which are not appropriate for sending out over long distances (for transducers, anything over 20 feet is long distance. Some won't even allow 2 feet of distance).

To address the issue of sending signals over long distances, transducers are connected to transmitters which convert the feable transducer signals to a higher voltage or current. These days it's mostly current since they provide transmissions over longer distances, and better immunity to interference. Voltage transmitters are usually okay for panel to panel, should not be over 200 feet, and must use shielded cable. Current transmitters, however, should also use shielded cable since high energy interference can still affect them.

regards,

Vulcan

Transducers

Transducers are voltage-output devices that can be used with simple signal conditioning but are more sensitive to electromagnetic interference. The electrical resistance of the connecting cable can cause significant errors if the cable is long. They require three or four connecting wires to supply power and deliver the output signal.

transmitters

Transmitters are current-output devices and may have two or three wires. Where two wires are used to both receive power and transmit an output signal, significant cost savings can be made where long cables are needed. They are frequently scaled to vary from 4 mA to 20 mA as the pressure varies from minimum to maximum. Thus the on-board electronics has to be capable of operating with a maximum current drain of less than 4 mA. Being 'current driven', the in-built circuitry controls the voltage across the transmitters two terminals to ensure that the appropriate pressure-proportional current is maintained irrespective of line resistance up to a specified limit. Thus these devices are very suitable for use with long cables and are much less susceptible to electromagnetic interference than voltage-output transducers. Sometimes called current loop or serial devices, additional displays at different locations can easily be included in the loop without degrading the output signal. Such devices normally suffer no significant degradation of signal output with distance.