Inducing the Current
The primary consists of a thick wire wound in a small number of turns. It is serially connected to the conductor which bears the current. The secondaries, on the other hand, are made of fine wires with a large number of turns.

What induces a voltage in each secondary coil is the alternating current that is directed through the primary coil. This amount of voltage is relative to each secondary’s reciprocal inductance with the primary. The frequency typically ranges from 1 to 10 kilohertz.

Shunts
Reliable conversion is possible with the AC current transducer because of the shunt. A shunt is an inserted device that lets the current to go around the circuit. It is low-resistant and is serially connected with the primary, the electricity carrier. The measure is determined by the voltage decline across the shunt. This is also what shunts do to high-frequency electrical noise, that is, redirect it to the ground, before it spreads to other parts of the circuit.

Shunt applications are varied. They are used to ensure the bypass of electricity through defective points in the circuit. But they are also used for circuit protection. In tower antennas, shunts act as lightning arrestors. They protect transmitters from the huge voltage influx every time the tower is struck by lightning by conducting it to the ground.

Clamp-on Sensor
A large voltage of alternating current can be measured even without direct contact with the conductor by means of a clamp-on sensor. This sensor is fashioned by allowing the current from the primary to pass through a ferrite core. The output obtained is a precise representation of the actual current in the conductor.

AC current transducer-using devices like amplifiers and galvanometers are equipped with usually low-resistant circuits. In some current meters, the current controls the field of the contained electromagnet.

In the Atmosphere and in Space
As the name implies, the aerospace pressure transducer is used for applications that relate to vehicles, vessels and equipments that operate in the atmosphere and outer space, be it for transportation, research and data gathering, exploration, and other endeavors. It is required in business and general aviation, the military and defense sectors, and space travel. The aerospace pressure transducer can be found in aircrafts like jets and helicopters, missile and surface systems, flight control towers, space probes, and the Space Shuttle.

The aerospace pressure transducer monitors the pressure of fluids, gases and even solids that are found in pipes, engines or the surrounding environment. It is typically small and lightweight, but nevertheless unyielding to the harsh effects of shock, vibration and acceleration. This is all made possible because of the principle of piezoresistance of silicon semiconductors, which can be micro-machined for a compact design.

Measurement References
Any pressure applied to the transducer causes tiny deformations that set off increases or decreases in conducted electricity. This charge, which is associated with the strain intensity, is then passed on to a computer which displays the output on a screen for analysis.

An aerospace pressure transducer can measure pressure using any of three reference points.
The absolute pressure sensor refers to a perfect vacuum, where pressure is equal to zero. The gauge pressure sensor makes pressure measurements relative to an ambient pressure—the atmospheric pressure of the gas or fluid that surrounds it. Two or more pressures can be inputted in differential pressure sensors, which then measure the difference.

New Challenges
As applications for the aerospace pressure transducers grow, so do the demands. Business and military jets are now flying faster at higher altitudes with greater maneuverability. Measurement requirements of ground and flight tests are getting raised so as to improve performance, stability and safety.

The interface with engines and control instruments are posing new challenges every day as the advancing technology of the aerospace pressure transducer brings in more complexity.

Four Basic Types
The most direct measurement of air flow is done by a true mass air flow transducer using, for instance, a thermal meter. Differential pressure air flow transducers, like rotameters and Venturi tubes, gauge the flow rate by calculating the square root of the discrepancies in pressure.

With velocity meters, on the other hand, square root relationships are not extracted, making the equation completely linear. Electromagnetic meters and sonar-based devices are examples of velocity meters. Oval gear meters are an example of positive displacement devices. Measurement is done by mechanically counting the increments of air flow.

Automotive Application
One of the common types of air flow transducers is used in fuel-injected engines of automobiles. This sensor determines the mass of air that enters the engine. Air density can change and air expands because the temperature rises and as the heat subsides, it contracts. Pressure, brought about by changes in altitude also contributes to changes in density.

Pressure is measured to ascertain balance within the engine. As long as air flow is identified, the control unit, which delivers fuel to the engine, can determine the right amount of fuel needed at any given time. The air flow transducer feeds the engine control unit electrical signals that represent the measurement.

While the air flow transducer measures the volume of incoming air, it does not control it. Regulation of the air flow is done by another component, the engine throttle plates.

Vane Air Flow Sensor
Gasoline engines use any of a few types of air flow transducers. The Vane Air Flow sensor is perhaps the most common kind. It measures air volume rather than air mass. It has an air flap that rotates when incoming air pushes against it.

The rotation of the Vane Air Flow sensor causes contact with signal-producing resistors. The resulting voltage output is therefore directly proportional to the air volume. Some vane air flow transducers are also equipped with heat sensors which make them more useful.

The Airmar Quality
The Airmar transducer is fabricated using state-of-the-art facilities, only with the best materials, and under procedures that comply with ISO 9001 standards. Be it jet-ski transducers or tanker sensors, Airmar products undergo rigorous pre-delivery tests so that maximum customer satisfaction is guaranteed. The company goes the extra mile to put in the little details that enhance performance.

Airmar has a team of highly-respected engineers and designers who employ a multi-disciplinary approach to research and development. They are consistently working to develop new technologies that present effective and practical solutions to various applications. The friendly, trained and professional support personnel are just as committed to serve Airmar clients.

Behind every unit of Airmar transducer is a brand name that corresponds to progressive research, design integrity and dedicated craftsmanship. This quality guarantee extends to all Airmar transducers in all pertinent industries and applications.

Broad Applications
Airmar offers transducers for every type of fishing application. It has reliable measuring instruments suitable at cruising speed or for sailing purposes, including GPS antennas, converters and cables and connectors. Airmar’s proprietary Smart and WeatherStation sensors contain features unmatched in the market.

Airmar’s ultrasonic sensors use echoes reflected by a flying target to calculate the target’s position and distance. On the other hand, the company’s industrial transducers compute levels and flows, proximity and position, and are also applicable to automation controls.

Navigation and survey application transducers are also available. Pick from a wide array of sensors with varying options in frequency and power levels, survey depth capabilities, casing styles and mounting preferences.

Airmar accepts orders for custom transducers which are built based on clients’ unique specifications. Customers have the choice between derivatives, which are actually modified standard models, or totally new, inexistent designs. Airmar builds customized transducers for fluid flow/speed sensing, commercial fisheries, multibeam, split beam, phased array, side scan, and industrial air applications.

Solenoid Beginnings
The cruise control transducer was and is also known as a solenoid— a coil of wire wound around a metal core. What it does is to change electricity into magnetism. The type of cruise control used by many automobiles is really solenoid technology put into good use to control the speed of a car.

The first cruise control using a solenoid was made by a blind engineer named Ralph Teetor. The solenoid acted as a switch in response to the number of revolutions made by the driveshaft for a measure of time. That was how it was done in 1958.

More Input Sources
Modern cruise controls get their cue for maintaining a constant speed not only from the driveshaft, but also from the speedometer, wheel speed sensor, and even engine RPM. Variations and special features are used for different brands and car models. A common ground for all is the facility to maintain a constant speed starting at around 30 mph.

Standard cruise control transducer types are divided between the resume type, the non-resume type, and the electronic type, which is now standard for new vehicles. All cruise controls give way to manual speed control whenever the driver performs actions, like braking. Otherwise, the cruise control is disengaged using finger switches. These are usually on the steering wheel or to the sides on the dashboard.

Servo Controller
The modern cruise control transducer in most cars has a servo mechanism which controls the throttle. It gets information on the speed of the car and then changes the level of vacuum in the engine manifold that’s applied to the vacuum servo. The level of vacuum is what dictates the servo position.

It’s the servo that gives force to the throttle once the cruise control transducer is engaged. It’s able to do this courtesy of a cable, chain, link, or rod. A constant level of vacuum as specified by the transducer is what keeps the throttle at a fixed position, resulting in a constant speed for the car.

If your car gets problems with maintaining speed with the cruise control transducer on, then you may need to get it fixed.

High and Low
A DC voltage transducer is designed for checking low voltages, like those in electrical wiring, and high voltages present in the trip circuits of capacitors. In both cases, they directly measure DC currents, but a shunt may be necessary when measuring voltages much higher than the typical.

DC voltage transducers get their power from either an AC or a DC source. This is why isolation of the DC input and output signals are needed to prevent what is called an earth loop—a current in the ground resulting in potential voltage differences coming from the electrical sources.

Output Signal
The output signal of a DC voltage transducer can be translated for interpretation with an analog/digital meter or by using a number of current management systems. Output is directly proportional to the value of the electrical signal input. Thus, the high-voltage that’s being tested in a system is reflected in the output.

The use of a DC voltage transducer for high-voltage testing is generally for determining if insulation is sufficient for the voltages involved. Low- or medium-voltage testing does not show the weaknesses of insulation since the testing is done below the working voltage level. This is used for less demanding electrical systems.

Above-Normal Helps
The meter of a DC voltage transducer may be calibrated to output for resistance of the insulation to be tested or for the current running through the apparatus. In DC high-voltage tests on insulation, it’s always wise to test above the normal levels expected to determine electrical safety levels.

The practice of over testing covers events like electrical surges, which can be damaging if the insulation is insufficient. The above-normal voltage to be tested can be calculated by multiplying normal peak voltage by a number; the higher the multiplier, the higher the voltage. Just make sure your DC voltage transducer is up to it.

Pressure Is No Problem
At present, there’s a wide range of Druck pressure transducer lines and transmitters, ranging from the relatively low cost Original Equipment Manufacturer (OEM) devices to very high-accuracy resonant silicon barometric sensors. OEM refers to companies that make products for other companies to repackage and sell.

Depending on the kind of device available, Druck pressure transducers can measure pressures from less than 0.015 psi to 15,000 psi in some of the most demanding environments. As a comparison, the standard atmospheric pressure on the earth’s surface at sea level is only 14.7 psi.

A Reputation
The company also manufactures calibration units for pressure, temperature and electricity. Its pressure calibrators and indicators are used worldwide for testing pressure-based instrumentation in laboratories, and include hand-held barometers and automatic pitot-static Air Data Test systems.

The company has made its reputation for making reliable precision pressure sensors as well as the related test and calibration units for these. As a result, Druck pressure transducer and related products are specified by a varied body of organizations which include national and international military forces, civil airlines, and ground service organizations worldwide.

Druck subsidiaries in the Americas, Europe, South Asia and the Far East support the maintenance and sale of all Druck pressure transducer products. In keeping with the nature of OEM, Druck transducers are also sold through such companies as GE Sensing and Inspection Technologies, Biolab—Industrial Technologies of Australia, and Thermx, which includes the websites of these companies as well.

The Heart of the Matter
The essential part of each Druck pressure transducer is a piezo-resistive silicon element which is mounted within a metallic pressure module. The module and all its elements are made from Druck’s own silicon processing facility, thus ensuring the high performance that Druck pressure transducer products are known for.

Examples of Transducers
In the simplest definition: A transducer is a device that changes one form of energy to another. Sound to electricity, for example—which is what a microphone does, or electricity to sound—which is the function of a speaker. Yes, a speaker is essentially an electromechanical transducer and it uses magnets to change electrical pulses into audible vibrations.

Note that, in the word “electromechanical,” the “electro” refers to the type of energy coming into the speaker, which is electrical energy, and the “mechanical” refers to the type of energy coming out of the speaker. Another example is if the source of energy comes from underwater and the end result desired is an electrical signal. In this case, you’re talking about an acoustic hydrophone.

For Detecting Changes
A transducer can be used to detect pressure (such as air pressure), temperature, flow, acceleration, velocity, and the like, from a particular location where such things can be sensed and relayed to another place, such as a control room, where the resulting signal can be seen and interpreted. Modern day aircraft, for example, use transducers mounted in their fuselages and wings to give the pilots in the cockpit information on how high they’re flying and how fast they’re flying.

The signal that the transducers receive usually varies quickly. Think of the wind buffeting an airplane’s wing, for example. There will be small, local gusts or eddies throughout the wing, and even over only several seconds, the wind pressure on one part of the wing will change quickly—up and down. This creates what is called “noise,” and noise creates a very messy signal. To clean up this signal, a signal-conditioning unit is used to filter it, and, if the signal is too weak, to amplify it so that it can be easily seen by whomever’s watching.

Physiological Transducers
It’s also interesting to note that our biological senses are essentially transducers. Whatever the sense—touch (a mechanical input), hearing (a mechanical input, based on the frequency of sound waves in the air), smell (a chemical input) and sight (a light energy input)—these are immediately converted to electrical signals which our brain can make sense of, so that we can sense and interpret the world at large.

The next time you wonder how “does a transducer work,” keep in mind that it can be as simple as a microphone and that it can be as complicated as human sight!

Mounting a Hummingbird Transducer
Always mount a Hummingbird transducer straight down in the water. Never mount it near motors or anything in the hull that can obstruct it. It can be positioned on the transom or on the trolling motor. When properly mounted the Hummingbird transducer will provide a clear picture of the fish and the structures below your boat.

Sonars
While the appropriate Hummingbird transducer model is required for every particular type of fishfinder unit, all models are equipped with the latest sonar technology. Single and Double Beam Sonars offer you an optimized look below with a 20-degree to 60-degree sonar beams. They do not have the wide beams from left to right but are more focused and can reach greater depths.

The TriBeam and QuadraBeam PLUS Sonar, on the other hand, give you complete 90-degree fish coverage. They provide visual confirmation of the actual location of the fish, whether they are at your left, right, or right below. With the ability to pinpoint where the fish and structure are, deciding where to cast becomes a no brainer.

3D Plus
The Hummingbird transducer 3D PLUS uses six different sonar beams to produce a real-time, three-dimensional view of the bottom. The fish, the contours, and all other visible features below are rendered in ways traditional sonar cannot, allowing for better analysis and understanding. It also lets you to mark the GPS location of any point covered by the sonar beams.

Wide Side Technology
Of course, even if you are not into deep-sea fishing, there is still a Hummingbird transducer for you. Hummingbird’s Wide Side technology makes it possible to send out 16-degree conical beams to either side of your boat, a specification custom-made for fishing in shallow waters.

Primary and Secondary Coils
A linear displacement transducer is basically made up of three coils. These loops of wire are classified as primary and secondary. The transducer has one primary coil which creates a magnetic field, and two secondary coils which are placed opposite to one another on either side of the primary coil. The two secondary coils are symmetrical, meaning they are wound in opposite directions.

When alternating current is driven to the primary coil, voltage is inevitably induced in each secondary coil. The manner in which the current is transmitted depends on the position of a mobile armature, which is actually a magnetic core. As long as the armature remains at the center, the voltages of the two secondary coils are the same. But since they are on opposite sides, the voltages cancel out and the voltage output is zero.

Displacement of the Core
But every time the armature is displaced from the balanced position, it necessarily strays away from the center. The balance of voltages shifts when this happens. The voltage increases on one secondary sensor while decreasing on the other. The primary coil records this imbalance and an output that represents this movement is thus obtained from the sensor. This is why the voltage output of a linear displacement transducer is a direct function of the input, which is actually the displacement of the moveable magnetic armature.

The level of voltage output is always proportional to the displacement—the distance moved by the core. This is why the displacement being measured by the transducer is considered linear. The direction of displacement is determined through the phase of the voltage. The core moves without friction making the displacement measurement reliable.

The linear displacement transducer is normally housed in a casing highly permeable to magnetic forces. This protects the internal components from external magnetic fields, thereby ensuring that the output attained is clean data.