Contents

Menu

 

How it Works - LVDT

 

Displacement

 

 

Electronics

 

 

Load

 

 

Pressure

 

Primary excitation

Secondary 1

Secondary 2

Secondary 1 - Secondary 2

An LVDT Displacement Transducer comprises 3 coils; a 
primary and two secondaries. 
 
The transfer of current between the primary and the 
secondaries of the LVDT displacement transducer is 
controlled by the position of a magnetic core called an 
armature. 
 
On our position measurement LVDTs, the two 
transducer secondaries are connected in opposition. 
 
At the centre of the position measurement stroke, the 
two secondary voltages of the displacement transducer 
are equal but because they are connected in opposition 
the resulting output from the sensor is zero. 
 
As the LVDTs armature moves away from centre, the 
result is an increase in one of the position sensor 
secondaries and a decrease in the other. This results in 
an output from the measurement sensor. 
 
With LVDTs, the phase of the output (compared with 
the excitation phase) enables the electronics to know 
which half of the coil the armature is in.  
 
The strength of the LVDT sensor's principle is that there 
is no electrical contact across the transducer position 
sensing element which for the user of the sensor means 

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How it Works - LVDT

2009-05-20

http://www.rdpe.com/ex/hiw-lvdt.htm

 

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clean data, infinite resolution and a very long life.

Our range of signal conditioning electronics for LVDTs
handles all of the above so that you get an output of
voltage, current or serial data proportional to the
measurement position of the displacement transducer.

All dimensions and specifications are
nominal.

www.rdpe.com/ex/hiw-lvdt.htm

20080110

Due to our policy of on-going development, specifications may change without notice. Any modification may
affect some or all of the specifications for our equipment.

USA & Canada
RDP Electrosense
2216 Pottstown Pike
Pottstown, PA 19465
USA
Tel: [phone]
Tel: [phone]
Fax: [phone]
Email: [e-mail]

Rest of the world
RDP Electronics Ltd
Grove Street, Heath Town
Wolverhampton, West Midlands, WV10 0PY
United Kingdom

Tel: [phone]
Fax: [phone]
Email: [e-mail]
URL: www.rdpe.com

-

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How it Works - LVDT

2009-05-20

http://www.rdpe.com/ex/hiw-lvdt.htm

  

 

 

Contents

Menu

 

How it Works - Strain Gauge Pressure Transducer

 

Displacement

 

 

Electronics

 

 

Load

 

 

Pressure

 

A strain gauge is a long length of conductor arranged in a zigzag 
pattern on a membrane. 
 
When it is stretched, its resistance increases.

Strain gauges are mounted in the same direction as the strain and often in fours to form a full 'Wheatstone Bridge'. 
 
The diagram above represents what might happen if a strip of metal were fitted with four gauges. 
 
An downward bend stretches the gauges on the top and compresses those on the bottom. 
 
A pressure transducer contains a diaphragm which is deformed by the pressure which can be measured by a strain 
gauged element. 

Strona 1 z 2

How it Works - Strain Gauge Pressure Transducer

2009-05-20

http://www.rdpe.com/ex/hiw-sgpt.htm

 

Technical manuals

How it Works

Contact us

Freeware

All dimensions and specifications are
nominal.

www.rdpe.com/ex/hiw-sgpt.htm

20080110

Due to our policy of on-going development, specifications may change without notice. Any modification may affect
some or all of the specifications for our equipment.

USA & Canada
RDP Electrosense
2216 Pottstown Pike
Pottstown, PA 19465
USA
Tel: [phone]
Tel: [phone]
Fax: [phone]
Email: [e-mail]

Rest of the world
RDP Electronics Ltd
Grove Street, Heath Town
Wolverhampton, West Midlands, WV10 0PY
United Kingdom

Tel: [phone]
Fax: [phone]
Email: [e-mail]
URL: www.rdpe.com

-

Strona 2 z 2

How it Works - Strain Gauge Pressure Transducer

2009-05-20

http://www.rdpe.com/ex/hiw-sgpt.htm

  

 

 

Contents

Menu

 

How it Works - Dc LVDT

 

Displacement

 

 

Electronics

 

 

Load

 

 

Pressure

 

Primary excitation

Secondary 1

Secondary 2

Secondary 1 - Secondary 2

An LVDT Displacement Transducer 
comprises 3 coils; a primary and two 
secondaries. 
 
The transfer of current between the 
primary and the secondaries of the LVDT 
displacement transducer is controlled by 
the position of a magnetic core called an 
armature. 
 
On our position measurement LVDTs, the 
two transducer secondaries are 
connected in opposition. 
 
At the centre of the position measurement 
stroke, the two secondary voltages of the 
displacement transducer are equal but 
because they are connected in opposition 
the resulting output from the sensor is 
zero. 
 
As the LVDTs armature moves away from 
centre, the result is an increase in one of 
the position sensor secondaries and a 
decrease in the other. This results in an 
output from the measurement sensor. 
 
With LVDTs, the phase of the output 

Strona 1 z 3

How it Works - Dc LVDT

2009-05-20

http://www.rdpe.com/ex/hiw-lvdtdc.htm

 

Technical manuals

How it Works

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Freeware

(compared with the excitation phase)
enables the electronics to know which
half of the coil the armature is in.

The strength of the LVDT sensor's
principle is that there is no electrical
contact across the transducer position
sensing element which for the user of the
sensor means clean data, infinite
resolution and a very long life.

An oscillator/demodulator circuit built into
the displacement transducer supplies the
excitation and converts the return signal
to a dc voltage.
As the transducer contains internal signal
conditioning electronics, there is no need
for external signal conditioning.

All dimensions and specifications are
nominal.

www.rdpe.com/ex/hiw-lvdtdc.htm

20080110

Due to our policy of on-going development, specifications may change without notice. Any modification may
affect some or all of the specifications for our equipment.

USA & Canada
RDP Electrosense
2216 Pottstown Pike
Pottstown, PA 19465
USA
Tel: [phone]
Tel: [phone]
Fax: [phone]
Email: [e-mail]

Rest of the world
RDP Electronics Ltd
Grove Street, Heath Town
Wolverhampton, West Midlands, WV10 0PY
United Kingdom

Tel: [phone]
Fax: [phone]
Email: [e-mail]

Strona 2 z 3

How it Works - Dc LVDT

2009-05-20

http://www.rdpe.com/ex/hiw-lvdtdc.htm

URL: www.rdpe.com

-

Strona 3 z 3

How it Works - Dc LVDT

2009-05-20

http://www.rdpe.com/ex/hiw-lvdtdc.htm

  

 

 

Contents

Menu

 

How it Works - 4 to 20mA LVDT

 

Displacement

 

 

Electronics

 

 

Load

 

 

Pressure

 

Primary excitation

Secondary 1

Secondary 2

Secondary 1 - Secondary 2

An LVDT Displacement Transducer 
comprises 3 coils; a primary and two 
secondaries. 
 
The transfer of current between the 
primary and the secondaries of the LVDT 
displacement transducer is controlled by 
the position of a magnetic core called an 
armature. 
 
On our position measurement LVDTs, the 
two transducer secondaries are 
connected in opposition. 
 
At the centre of the position measurement 
stroke, the two secondary voltages of the 
displacement transducer are equal but 
because they are connected in opposition 
the resulting output from the sensor is 
zero. 
 
As the LVDTs armature moves away from 
centre, the result is an increase in one of 
the position sensor secondaries and a 
decrease in the other. This results in an 
output from the measurement sensor. 
 
With LVDTs, the phase of the output 

Strona 1 z 3

How it Works - 4 to 20mA LVDT

2009-05-20

http://www.rdpe.com/ex/hiw-lvdtma.htm

 

Technical manuals

How it Works

Contact us

Freeware

(compared with the excitation phase)
enables the electronics to know which
half of the coil the armature is in.

The strength of the LVDT sensor's
principle is that there is no electrical
contact across the transducer position
sensing element which for the user of the
sensor means clean data, infinite
resolution and a very long life.

An oscillator/demodulator circuit built into
the displacement transducer is powered
by and controls the 4-20mA output.
As the transducer contains internal signal
conditioning electronics, there is no need
for external signal conditioning.

All dimensions and specifications are
nominal.

www.rdpe.com/ex/hiw-lvdtma.htm

20080110

Due to our policy of on-going development, specifications may change without notice. Any modification may
affect some or all of the specifications for our equipment.

USA & Canada
RDP Electrosense
2216 Pottstown Pike
Pottstown, PA 19465
USA
Tel: [phone]
Tel: [phone]
Fax: [phone]
Email: [e-mail]

Rest of the world
RDP Electronics Ltd
Grove Street, Heath Town
Wolverhampton, West Midlands, WV10 0PY
United Kingdom

Tel: [phone]
Fax: [phone]
Email: [e-mail]
URL: www.rdpe.com

Strona 2 z 3

How it Works - 4 to 20mA LVDT

2009-05-20

http://www.rdpe.com/ex/hiw-lvdtma.htm

-

Strona 3 z 3

How it Works - 4 to 20mA LVDT

2009-05-20

http://www.rdpe.com/ex/hiw-lvdtma.htm

  

 

 

Contents

Menu

 

How it Works - Magnetostrictive

 

Displacement

 

 

Electronics

 

 

Load

 

 

Pressure

 

The transducer comprises a sensor element (shown in blue), a signal converter (at the right of the diagram) and a 
position magnet. 
 
The signal converter applies an electrical pulse to the sensor element and simultaneously starts a timer. 
 
The magnetic field generated around the sensing element by the electrical pulse interacts with the field of the 
position magnet and produces a mechanical pulse. 
 
The mechanical pulse travels back down the sensing element where a sensor in the signal converter detects it and 
stops the timer. 
 
As the speed of the mechanical pulse is constant, the time taken for the pulse to reach the sensor can be used to 
accurately measure the position of the magnet. 
 

Strona 1 z 2

How it Works - Magnetostrictive

2009-05-20

http://www.rdpe.com/ex/hiw-magneto.htm

 

Technical manuals

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Typically the mechanical pulse travels at 2800m/s and the cycle process is repeated 1000 times per second.

All dimensions and specifications are
nominal.

www.rdpe.com/ex/hiw-magneto.htm

20080110

Due to our policy of on-going development, specifications may change without notice. Any modification may affect
some or all of the specifications for our equipment.

USA & Canada
RDP Electrosense
2216 Pottstown Pike
Pottstown, PA 19465
USA
Tel: [phone]
Tel: [phone]
Fax: [phone]
Email: [e-mail]

Rest of the world
RDP Electronics Ltd
Grove Street, Heath Town
Wolverhampton, West Midlands, WV10 0PY
United Kingdom

Tel: [phone]
Fax: [phone]
Email: [e-mail]
URL: www.rdpe.com

-

Strona 2 z 2

How it Works - Magnetostrictive

2009-05-20

http://www.rdpe.com/ex/hiw-magneto.htm

  

 

 

Contents

Menu

 

How it Works - Strain Gauge Load Cell

 

Displacement

 

 

Electronics

 

 

Load

 

 

Pressure

 

A strain gauge is a long length of conductor arranged in a zigzag 
pattern on a membrane. 
 
When it is stretched, its resistance increases.

Strain gauges are mounted in the same direction as the strain and often in fours to form a full 'Wheatstone Bridge'. 
 
The diagram above represents what might happen if a strip of metal were fitted with four gauges. 
 
An downward bend stretches the gauges on the top and compresses those on the bottom. 
 
A load cell may contain several similar strain gauges elements. 
 

Strona 1 z 2

How it Works - Strain Gauge Load Cell

2009-05-20

http://www.rdpe.com/ex/hiw-sglc.htm

 

Technical manuals

How it Works

Contact us

Freeware

All dimensions and specifications are
nominal.

www.rdpe.com/ex/hiw-sglc.htm

20080110

Due to our policy of on-going development, specifications may change without notice. Any modification may affect
some or all of the specifications for our equipment.

USA & Canada
RDP Electrosense
2216 Pottstown Pike
Pottstown, PA 19465
USA
Tel: [phone]
Tel: [phone]
Fax: [phone]
Email: [e-mail]

Rest of the world
RDP Electronics Ltd
Grove Street, Heath Town
Wolverhampton, West Midlands, WV10 0PY
United Kingdom

Tel: [phone]
Fax: [phone]
Email: [e-mail]
URL: www.rdpe.com

-

Strona 2 z 2

How it Works - Strain Gauge Load Cell

2009-05-20

http://www.rdpe.com/ex/hiw-sglc.htm

  

 

 

Contents

Menu

 

How it Works - Strain Gauge Pressure Transducer

 

Displacement

 

 

Electronics

 

 

Load

 

 

Pressure

 

A strain gauge is a long length of conductor arranged in a zigzag 
pattern on a membrane. 
 
When it is stretched, its resistance increases.

Strain gauges are mounted in the same direction as the strain and often in fours to form a full 'Wheatstone Bridge'. 
 
The diagram above represents what might happen if a strip of metal were fitted with four gauges. 
 
An downward bend stretches the gauges on the top and compresses those on the bottom. 
 
A pressure transducer contains a diaphragm which is deformed by the pressure which can be measured by a strain 
gauged element. 

Strona 1 z 2

How it Works - Strain Gauge Pressure Transducer

2009-05-20

http://www.rdpe.com/ex/hiw-sgpt.htm

 

Technical manuals

How it Works

Contact us

Freeware

All dimensions and specifications are
nominal.

www.rdpe.com/ex/hiw-sgpt.htm

20080110

Due to our policy of on-going development, specifications may change without notice. Any modification may affect
some or all of the specifications for our equipment.

USA & Canada
RDP Electrosense
2216 Pottstown Pike
Pottstown, PA 19465
USA
Tel: [phone]
Tel: [phone]
Fax: [phone]
Email: [e-mail]

Rest of the world
RDP Electronics Ltd
Grove Street, Heath Town
Wolverhampton, West Midlands, WV10 0PY
United Kingdom

Tel: [phone]
Fax: [phone]
Email: [e-mail]
URL: www.rdpe.com

-

Strona 2 z 2

How it Works - Strain Gauge Pressure Transducer

2009-05-20

http://www.rdpe.com/ex/hiw-sgpt.htm