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Transformers are electrical devices, which by electromagnetic induction, transform electrical energy from one or more circuits to one or more other circuits at the same frequency, but usually at a different voltage and current value.
400 Hz Transformers (143 Companies)
Transformers which are designed to operate at a nominal input voltage frequency of 400 Hz. Used primarily in aircraft and military equipment power supplies since the core and winding weight is much reduced for these higher frequencies.
Small transformer assemblies to step-down input line voltage to low AC voltages for small desktop electronic products. Often designed with AC plug to fit into line socket. Output connector designed to plug directly into desired product.
Audio Transformers (164 Companies)
Used in the audio frequency range for transmission of voice or sound signals. Also used to couple stages of amplifiers and to match devices e.g. microphones and speakers to the impedance of amplifiers. Features wide frequency bandwidth and low distortion.
Transformer with one winding and at least three taps. Source and load are each connected to two taps. One tap at end of winding is common to both circuits. Each tap corresponds to different source or load voltage. Used for step-up/step-down applications.
Balun Transformers (70 Companies)
A balanced to unbalanced transformer. Generally used to match a balanced antenna (e.g. dipole) to an unbalanced (with respect to ground) transmission line, e.g. coaxial cable.
Often constructed by passing a single primary turn through toroidal core wrapped with many turns of wire. Provides a current in secondary coil proportional to the current flowing in primary. Isolates circuitry from high voltages on circuit being measured.
Class 2 Transformers (63 Companies)
Refers to small general purpose energy-limited step-down transformers for many consumer applications, e.g. security systems, doorbells, landscape lighting, furnaces, appliances, etc. mostly for indoor use.
Common Mode Transformers (56 Companies)
Transformer wired so current in each winding produces opposing magnetic flux which cancel each other. Resultant flux nearly zero–allowing for some degree of non-perfect coupling between windings. Capable of carrying high DC current without saturating.
Commonly part of measurement device providing current in its secondary coil proportional to the current flowing in its primary. Also, due to its isolation qualities, used in metering and protection–facilitating safe measurement of large currents.
Data bus coupling of multiple high frequency data buses in a communications system requires transformers and other circuit components. In particular these transformers are commonly required in applications with avionics and military data bus standards.
In the design of DC to DC converter switch mode power supplies, the DC to DC converter transformers used in the circuitry provides isolation between the input and the output besides assisting in the voltage conversion process.
Differential Transformers (70 Companies)
A transformer used to join two or more signal sources to a common transmission line. Also known as a linear-variable differential transformer and is a type of electrical transformer used for measuring linear displacement.
Transformers designed to be used with devices and circuitry that follow analog to digital audio standards; primarily AES/EBU, AES3, or S/PDIF standards.
Used in the solid-state circuitry to provide the proper starting and operating conditions to power one or more fluorescent lamps and high intensity discharge lamps.
Encapsulated Transformers (122 Companies)
Encapsulated transformers have a protective coating of cured plastic or epoxy which encloses the unit, seals it and provides weatherproofing.
Filament Transformers (40 Companies)
A step-down transformer that converts the AC line voltage to a lower voltage for energizing tube filaments or other applications. Secondary voltages are low, usually 6.3 volts. Transformer may be furnished with a center tap.
Flyback Transformers (123 Companies)
A flyback transformer is a type of transformer used in the power supply of a cathode ray tube that generates the high voltage needed to drive the monitor. Flyback transformers are also found in the power supply section for plasma devices.
High Frequency Transformers (112 Companies)
General term referring to transformers that are used to transfer signals, usually above the audio range, and not associated with power supply applications.
Defined as transformers whose windings which can exceed a voltage potential of 500 volts or more. Used in power supplies, power distribution systems, converters, X-ray devices, military, medical applications, etc.
IF Transformers (66 Companies)
A transformer designed for use in the intermediate frequency (IF) amplifier section of superheterodyne receivers. Usually filter circuitry accompanies the transformer in order to improve receiver selectivity between adjacent stages.
Instrument Transformers (146 Companies)
Used to step down current or voltage to measurable values. Provides standardized, useable levels of current or voltage in a various power monitoring and measurement applications. Often designed into test and measurement equipment, and control circuitry.
Transformer used for matching impedances and interstage power coupling.
Convert power-level voltages from one voltage or phase configuration to another. Outside of North America, primary frequency of incoming voltage signals is nominally 50 Hz, with voltages ranging from 220–240 VAC.
Inverter Transformers (120 Companies)
Inverters produce AC power by switching or chopping polarity of DC input source to produce pulsating AC output. Transformers used in inverter circuits are called inverter transformers. Inverters used in applications where DC power is readily available.
Isolation Transformers (240 Companies)
A transformer which is used to decouple two circuits. Isolation transformers block transmission of DC signals from one circuit to the other, but allow AC signals to pass. Also block interference caused by ground loops.
An isolation transformer which is used to primarily in LAN networks, Ethernet, 10Base-T, AUI applications, etc.
Transformers that are used in applications concerning power supply conversion at domestic and international power line frequencies.
Low Frequency Transformers (182 Companies)
General term referring to transformers that are used to transfer signals, usually including the audio range and frequencies below. Associated with applications concerning power supply conversion at power line frequencies and DC.
Low Voltage Transformers (178 Companies)
General term applicable to power line step down transformers which reduce the output voltage to operate with relatively low-voltage devices (e.g. doorbells, toy electric trains, lighting, outdoor photosensors, etc.).
Used in the construction of magnetic amplifiers. The transformer, which is employed as a saturable reactor, is an iron-core transformer. The amplifier design makes use of the magnetic saturation of the transformer core.
Matching Transformers (67 Companies)
A transformer used for matching impedances between a source and load for maximum power transfer. Commonly found in audio applications to match output amplifiers to speakers.
Microphone Transformers (54 Companies)
Transformers utilized in audio circuitry to match the high impedances of microphones. Requires wide bandwidth and low saturation for good coupling of the microphone to the pre-amplifier stage.
Mixing Transformers (57 Companies)
Transformers utilized primarily in audio circuitry to mix, or blend, two or more audio inputs into a common composite output signal.
Couples a data signal between the power line and a communication device such as a modem.
Modulation Transformers (47 Companies)
An audio frequency transformer which matches impedances and transmits audio frequencies from an audio output stage and the input to the modulating amplifier.
PCB Mounting Transformers (59 Companies)
PC mount transformers refers to transformers that are packaged to be mounted directly on a PCB. As such they offer a small footprint and size to the designer.
Plate Transformers (57 Companies)
A step-up transformer is used in power supplies that supply the high DC plate voltage needed for tubes or other applications. Secondary voltages are usually several hundred volts but many exceed 1000 volts for high power tubes or high voltage designs.
Plug-In Transformers (73 Companies)
Small transformer assemblies to step-down input line voltage to low voltages for small desktop electronic products, e.g. lamps, radios, calculators, computer peripherals, etc. Often designed with AC plug to fit into line socket–referred to as "wall wart."
Generally refer to pole-type transformers that supply power to residences. Used at the end of an electrical utility’s delivery system, the voltage is stepped down from the high mains. Both single-phase and three-phase transformers are common.
Power Transformers (250 Companies)
Convert power-level voltages from one voltage or phase configuration to another. In North America, primary frequency of incoming voltage signals is nominally 60 Hz, with voltages ranging from 120–230 VAC.
Pulse Transformers (165 Companies)
A transformer that is optimized for transmitting rectangular electrical pulses (i.e. pulses with fast rise and fall times and relatively constant amplitude). Applications include digital, data processing, thyristor/triac firing circuits, etc.
Ratio Transformers (77 Companies)
Decade ratio transformers are used in the calibration of voltmeters, servo components, and devices that require precise division of AC signals in the audio frequency range.
RF Transformers (124 Companies)
Transformers utilized in radio frequency range (defined from 3 MHz to 300 MHz). From a practical usage they are in use from audio to microwave frequencies.
Shielded Transformers (105 Companies)
General term for transformers which are specially constructed to reduce the external flux leakage from affecting circuit quality nearby components. Often a grounded shield is interposed between the primary and the secondary windings to improve isolation.
Split Bobbin Transformers (151 Companies)
Are concentrically wound with primaries and secondaries side-by-side. Unlike the secondary-on-top-of-primary designs of standard PC board transformers, the split bobbin winding and low capacitive coupling eliminate costly electrostatic shielding.
Discrete transformers which are packaged without leads and fastened directly to foil patterns.
Switch Power Transformer (176 Companies)
Used mainly in switching power supplies and DC-DC converters. They transfer energy from one or more devices, which are alternately placed in the off and on states as required in switching power supplies, regulators and converters.
Also called telephone line matching transformers or audio matching transformers, are components to connect to network telephone lines. Applications are modems, FAX machines, telephones, answering machines, alarms, credit card verification machines, etc.
Three-Phase Transformers (68 Companies)
In power distribution systems three phase transformers are often used to distribute the power. Circuits energized by AC currents differ in phase by 120 electrical degrees. Several winding configurations result with different attributes and phase shifts.
Toroidal Transformers (218 Companies)
Toroidal transformers typically consist of copper wire wrapped around a doughnut-shaped cylindrical core. This design prevents the magnetic flux that occurs within the coil from leaking and affecting external components.
Transistor Transformers (76 Companies)
Generic term referring to transformers that are used in circuit design with transistors. Generally transformers are of low voltage and are found in various applications, e.g. impedance matching, mixing signals, driving output amplifiers, etc.
Variable Transformers (53 Companies)
An iron-core transformer with provision for varying output voltage over a full or limited range–generally by movement of contact arm along exposed turns of secondary winding. Used in control of voltage, current, power, etc. Often referred to as a Variac®.
Saturated-core type of transformer which holds output voltage to within a few percent (5% above or below normal) with input variations up to 20% above or below nominal; considerable harmonic distortion results unless extensive filters are employed.
Wideband Transformers (113 Companies)
Relative term applying to signal transformers. Used for transformers capable of working over broad range of frequencies or data transmission rates–often over several decades. Also used to handle complex waveforms rather than simple sinusoidal waveforms.
An xDSL or DSL transformer uses the extended digital subscribe loop (xDSL) or digital subscriber loop (DSL) for telecommunication protocols. Transformers require high bandwidths, fast switching speeds and good isolation between windings.

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