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Technical Discussions
Craig Dobson
Craig Dobson
01:48 Aug-30-2006
Pulsed transducer for constant output

Hi, can anyone please tell me if I can use a pulsed transducer for constant output, and how I can calculate how much I will need to reduce power so it won't burn out?

Thanks,



 
 Reply 
 
Joe Buckley
Consultant, ASNT L-III, Honorary Secretary of BINDT
Level X NDT, BINDT, United Kingdom, Joined Oct 1999, 528

Joe Buckley

Consultant, ASNT L-III, Honorary Secretary of BINDT
Level X NDT, BINDT,
United Kingdom,
Joined Oct 1999
528
09:00 Aug-31-2006
Re: Pulsed transducer for constant output
Simple answer is yes you can.
calculating the power is very difficult.

Most average sized transducers will take a watt or two 'average power' but how this corresponds to a specific voltage is tricky - the impedance of transducers near their resonant frequency can be quite erattic. Best drive with a (High Power) series resistor around 50 ohms and aim the voltage so that you have maybe one or two watts into an assumed 100 ohms.
(i.e max around 10 - 14 volts or so, if its genuinely continuous, maybe more if its only on for a few seconds)

All you can do after that is to see how much it warms up in practice.

How much power a transducer will take depends on how it is made, and how it is mounted (e.g if it is immersed it will obviously cool better)

You may get other issues from overheating (e.g. face separataion after long use - the ultrasonic cleaner effect}

Two caveats:

1. Dont expect it to last forever - dont use an expensive transducer

2. Apply a big common sense filter to everything - If its a small transducer it will take less power

Good luck

Joe


----------- Start Original Message -----------
: Hi, can anyone please tell me if I can use a pulsed transducer for constant output, and how I can calculate how much I will need to reduce power so it won't burn out?
: Thanks,
------------ End Original Message ------------




 
 Reply 
 
Ed Ginzel
R & D, -
Materials Research Institute, Canada, Joined Nov 1998, 1303

Ed Ginzel

R & D, -
Materials Research Institute,
Canada,
Joined Nov 1998
1303
06:11 Aug-31-2006
Re: Pulsed transducer for constant output
Good advice Joe!
In my Schlieren studies I had need for a continuos wave (CW) output. The most convenient source was a simple signal generator operating at its maximum output (20Vpp). Although some heat generation can be expected I did not burn out any probes. This may have been at least in part due to the fact i was using them under water. The Signal Generator is an interesting tool to observe the effects of frequency tuning. You can observe the natural frequency (maximum output) and the effects of driving the probe "off-frequency".
Regards
Ed

----------- Start Original Message -----------
: Simple answer is yes you can.
: calculating the power is very difficult.
: Most average sized transducers will take a watt or two 'average power' but how this corresponds to a specific voltage is tricky - the impedance of transducers near their resonant frequency can be quite erattic. Best drive with a (High Power) series resistor around 50 ohms and aim the voltage so that you have maybe one or two watts into an assumed 100 ohms.
: (i.e max around 10 - 14 volts or so, if its genuinely continuous, maybe more if its only on for a few seconds)
: All you can do after that is to see how much it warms up in practice.
: How much power a transducer will take depends on how it is made, and how it is mounted (e.g if it is immersed it will obviously cool better)
: You may get other issues from overheating (e.g. face separataion after long use - the ultrasonic cleaner effect}
: Two caveats:
: 1. Dont expect it to last forever - dont use an expensive transducer
: 2. Apply a big common sense filter to everything - If its a small transducer it will take less power
: Good luck
: Joe
:
:
: : Hi, can anyone please tell me if I can use a pulsed transducer for constant output, and how I can calculate how much I will need to reduce power so it won't burn out?
: : Thanks,
------------ End Original Message ------------




 
 Reply 
 
Craig Dobs
Craig Dobs
09:49 Sep-07-2006
Re: Pulsed transducer for constant output
----------- Start Original Message -----------
: Hi, can anyone please tell me if I can use a pulsed transducer for constant output, and how I can calculate how much I will need to reduce power so it won't burn out?
: Thanks,
------------ End Original Message ------------

Hi, I just wanted to thank both Joe and Ed for answering my question and helping me with this. Thanks very much.



 
 Reply 
 

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