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Power Transformer

You've all heard it, that dreaded 60Hz hum through the speakers of a home theater or house audio system. Hopefully you heard it at a friend's house and not your own. It can drive you completely nuts. You may have even tried, unsuccessfully, to fix the little noise problem. That can make you even more crazy. What causes that horrendous noise through your speakers?

More often than not humming through your speakers is caused by a grounding problem. There are three main ground problems that cause problems in an audio / video system. These are ground loops, improper grounding and lack of a ground altogether. The other possible culprits that can cause noise are bad cables, a faulty piece of equipment or electrical noise from a lighting dimmer or electric motor. There are steps you can take to troubleshoot the noise and eliminate it from you theater.

The first step is find out where it is coming from. Disconnect your source and display equipment from your receiver or surround sound processor. If the noise stops, connect them back to the receiver or processor on at a time until the noise returns. When the hum comes back, you found where the noise is entering your system. Note that if you are connecting remote equipment, such as running the signal from your theater room DVD player to the TV in the bedroom, your chances to pick up noise increase dramatically. With such long runs, noise can be induced into the long cable runs from adjacent electrical wiring. It is also easy to create a ground loop, because the equipment is plugged into two different, widely separated outlets, on different electrical circuits.

If the noise is caused by a cable box, the noise is likely caused by the cable TV ground. To test this theory, disconnect the incoming cable TV feed to the rear of the cable box or TV while they are still connected to the rest of the system. If the noise is eliminated by disconnecting the TV cable, the problem is the cable TV ground. You can electrically decouple the cable TV feed from your system with a ground breaking transformer. These are available from many sources. Be advised that many newer, digital cable TV systems require any device in the signal chain to pass a full 1,000 Mhz. Some of the older ground break transformers will not do this. Be sure to check the specifications of whatever device you are purchasing to verify it will pass the digital cable TV signal.

If the noise is from your projector, TV, or monitor, it is most likely caused because the video display device is plugged into a different outlet than the other a/v equipment. It could be on a different circuit as well. These circuits may have two different ground potentials. That is, the resistance to ground is different on each circuit. A difference in resistance to ground from one ground point to another can cause the dreaded ground loop. If you get a ground loop, current flows between the two components. If the current flows through the components internal audio signal ground, you will get a hum.

You can use an isolation transformer, similar to the type used for cable TV ground problems, to eliminate the electrical connection from one component to the other. These transformers are inserted in line with the audio signal connection between the two components. If there is no audio connection between the components, the problem may be current flowing through the video portion. In this case, a video isolation transformer should be used to eliminate the ground loop.

Sometimes power conditioners will stop noise problems by placing equipment on different, electrically isolated outlets. This is done using isolation transformers. Sometimes this is ineffective however, due to the differences in internal construction of different power conditioning equipment. Some safety regulations, such as UL 1950, specify that an isolation transformer is only allowed to isolate the hot and neutral wires; the grounding wire must be passed straight through. If this is the case, the ground loop problem may still exist because many communication circuits are connected to the grounding conductor and not the neutral. In this case, the isolation transformer, or any power conditioner or UPS with an isolation transformer will have absolutely no affect on the grounding problem.

The noise may be generated externally, from a dimmer or refrigerator compressor for example, and coming in through the main power input on the audio video equipment. In this case, a high quality power conditioner may be effective in reducing or eliminating the noise problem. You may also find that one of the signal interconnecting cables in your system is faulty. This can also cause noise problems. Check for this by swapping the cables with one that you know to be good.

You can solve most noise problems in your home theater or multi room audio/video system by taking the systematic, step-by-step approach. Work your way up the signal chain, eliminating each piece of equipment as you go. If you have nothing connected to your speakers except the speaker wiring, and they still hum, the problem is noise induced into the speaker wiring from adjacent power cables. Other than that case, most problems are caused by ground problems, which you can find, and solve, if you take it one step at a time.

Steve has 15 yrs in the consumer electronics industry. He is a CEDIA certified designer with ISF and THX certificates. His experience includes: installer and programmer; system designer; business unit director for an a/v importer; sales rep for a CE distributor; and principal of a $1.5M+ CEDIA firm. He's now senior sales engineer for Digital Cinema Design in Redmond, WA. For more information on how to make your home theater better, and what's on the horizon, including CEDIA and CES show reports, see The Home Theater and Automation Guide

Cisco / IE 3000 POWER TRANSFORMER / PWR-IE3000-AC= $294.6 Cisco - IE 3000 POWER TRANSFORMER - PWR-IE3000-AC=

Electric Power Transformer Engineering $119.95 Covering the fundamental theory of electric power transformers, this book provides the background required to understand the basic operation of electromagnetic induction as applied to transformers. The book is divided into three fundamental groupings: one stand-alone chapter is devoted to Theory and Principles, nine chapters individually treat major transformer types, and fourteen chapters cover many ancillary topics associated with power transformers. Throughout the book, tables, charts, photographs, and equations describe the operation and performance of power transformers and facilitate the reader's understanding of the technical material.

Transformer $6.49 Transformer

The Transformer $7.49 The Transformer

Welch Allyn AC Power Transformer for Spot Vital Signs LXi $134.05 Welch Allyn AC Power Transformer for Spot Vital Signs LXi

Welch Allyn 110 V AC Power Transformer for Spot Vital Signs $101.93 Welch Allyn 110 V AC Power Transformer for Spot Vital Signs

Welch Allyn AC Power Transformer/Battery Charger for Vital Signs 300 $111.89 Welch Allyn AC Power Transformer/Battery Charger for Vital Signs 300

Cisco / 7900 SERIES TRANSFORMER POWER / CP-PWR-CORD-NA= $6.25 Cisco - 7900 SERIES TRANSFORMER POWER - CP-PWR-CORD-NA=

American Power Conversion / STEP DOWN TRANSFORMER 208V IN / AP9627 $724.19 American Power Conversion - STEP DOWN TRANSFORMER 208V IN - AP9627

Cisco 7900 Series Transformer Power Cord Japan Cppwrcordjp= $12.72 Cisco 7900 Series Transformer Power Cord Japan Cppwrcordjp=

Cisco IP Phone Power Transformer For 7900 Series Phones Cppwrcube $32.05 Cisco IP Phone Power Transformer For 7900 Series Phones Cppwrcube

Cisco IP Phone Power Transformer f/ the 7900 Phone Series CPPWRCUBE3 $40.9 Cisco IP Phone Power Transformer f/ the 7900 Phone Series CPPWRCUBE3

110V~220V Bidirectional AC Power Transformer Adapter (80-Watt Max) $12.3 110V~220V Bidirectional AC Power Transformer Adapter (80-Watt Max)

Travel Electrical Power Converter Adapter Adaptor Transformer $17.99 Description:This Power Transformer is made from import H50 steel chip material inside.Electronic straining wavePower Adapter without exchange soundLED indicatorWhen the switch lift on AC117V, Input: AC110V 50/60Hz, Output: AC220V 50/60HzWhen the switch lift on AC230V, Input: AC220V 50/60Hz Output: AC110V 50/60HzMax. 80WattSize of the Power Converter: 5.3 x 7.2x 4.1cmWeight: 325gPackage content:1 x Travel Transformer

50W 110V to 220V Power Transformer $6.5 Converts 110V power into 220V power50W max capacityCompact convertor (adapter) design

HX-21A 50W 110V to 220V AC Power Transformer(US Plug) $7.06 - Converts 110V power into 220V power- 50W max capacity- Compact convertor (adapter) design- US plug power transformer, used indoor only

HX-203A 100W 110V to 220V AC Power Transformer(US Plug) $12.93 - Converts 110V power into 220V power- 100W max capacity- Compact convertor (adapter) design- US plug power transformer, used indoor only

150w Electronic Transformer $240 All LBL remote transformers are encased in black metal housings complete with mounting feet and conduit knockouts. Typically, remote transformers are used when a cleaner installation appearance is desired. A remote transformer must be installed in an accessible remote location, and the bulkier ceiling-mounted surface transformer housing appearance is simply replaced by a remote canopy flat plate and flexible coaxial power feed cable. This 12V 150W electronic transformer is good for shorter distances (the last light source should not exceed 15 feet from the transformer). For dimming, an electronic low voltage dimmer is required (sold separately). 8.25"L X 1.75"W X 2"H.

Welch Allyn 3.5V Transformer-style Rechargeable Handle $126.99 Welch Allyn Transformer-style Rechargeable Handle with a 3.5v Power Source.

300W Recessed Remote Transformer $515 This remote magnetic transformer converts standard 120 or 277 volt line voltage to 12/24 volts, providing the necessary voltage for powering MonoRail, Kable Lite, Wall MonoRail or FreeJack low-voltage lighting systems. This transformer can be used to power lamps totaling up to 300 watts and is equipped with fast-acting secondary circuit breaker that will safely turn off the system should a short occur. Once the short has been removed the breaker can be reset. Compatible with Tech Lighting's LED elements. This transformer provides a single 300 watt output and must be used with a single-feed canopy or other power feed option (sold separately).

600W Recessed Remote Transformer $690 This remote magnetic transformer converts standard 120 or 277 volt line voltage to 24 volts, providing the necessary voltage for powering MonoRail, Kable Lite, Wall MonoRail or FreeJack low-voltage lighting systems. This transformer can be used to power lamps totaling up to 600 watts and is equipped with fast-acting secondary circuit breaker that will safely turn off the system should a short occur. Once the short has been removed the breaker can be reset. This transformer provides a single 600 watt output and must be used with a single-feed canopy or other power feed option (sold separately).

AMERICAN POWER CONVERSION AP9627 APC StepDown Transformer Transformer 5000 VA $877.04 APC StepDown Transformer Input: 208V Input Connections: NEMA L630P Hard Wire 3wire Cord Length: 2 feet ( 0.61 meters ) Output: 120V Output Connections: NEMA L520RPrimary InformationPower Device Typenbsp;:nbsp;nbsp;Transformernbsp;Voltage Providednbsp;:nbsp;nbsp;120 Vnbsp;Voltage Requirednbsp;:nbsp;nbsp;208 Vnbsp;Power Providednbsp;:nbsp;nbsp;5000 VAnbsp;Output Connector(s)nbsp;:nbsp;nbsp;(4) NEMA L520Rnbsp;Widthnbsp;:nbsp;nbsp;17.50 Inchnbsp;Depthnbsp;:nbsp;nbsp;24.00 Inchnbsp;Heightnbsp;:nbsp;nbsp;3.50 Inchnbsp;Service Support Typenbsp;:nbsp;nbsp;2 years repair or replacenbsp;UNSPSC CodeUNSPSC Codenbsp;:nbsp;nbsp;39121000nbsp;Product IDUPC:nbsp;nbsp;731304249146Manufacturer Part:nbsp;nbsp;AP9627

150w Magnetic Transformer $320 All LBL remote transformers are encased in black metal housings complete with mounting feet and conduit knockouts. Typically, remote transformers are used when a cleaner installation appearance is desired. A remote transformer must be installed in an accessible remote location, and the bulkier ceiling-mounted surface transformer housing appearance is simply replaced by a remote canopy flat plate and flexible coaxial power feed cable. This 12V 150W magnetic transformer is good for longer distances (contact tech support for voltage drop information). For dimming, a magnetic low voltage dimmer is required (sold separately). 9.5"L X 5"W X 5"H.

300w Magnetic Transformer $300 All LBL remote transformers are encased in black metal housings complete with mounting feet and conduit knockouts. Typically, remote transformers are used when a cleaner installation appearance is desired. A remote transformer must be installed in an accessible remote location, and the bulkier ceiling-mounted surface transformer housing appearance is simply replaced by a remote canopy flat plate and flexible coaxial power feed cable. This 12V 300W magnetic transformer is good for longer distances (contact tech support for voltage drop information). For dimming, a magnetic low voltage dimmer is required (sold separately). 9.5"L X 5"W X 5"H.

600w Magnetic Transformer $415 All LBL remote transformers are encased in black metal housings complete with mounting feet and conduit knockouts. Typically, remote transformers are used when a cleaner installation appearance is desired. A remote transformer must be installed in an accessible remote location, and the bulkier ceiling-mounted surface transformer housing appearance is simply replaced by a remote canopy flat plate and flexible coaxial power feed cable. This 2 X 12V 300W magnetic transformer is good for longer distances (contact tech support for voltage drop information). For dimming, a magnetic low voltage dimmer is required (sold separately). 10.5"L X 6"W X 6"H.

75w Electronic Transformer $75 All LBL remote transformers are encased in black metal housings complete with mounting feet and conduit knockouts. Typically, remote transformers are used when a cleaner installation appearance is desired. A remote transformer must be installed in an accessible remote location, and the bulkier ceiling-mounted surface transformer housing appearance is simply replaced by a remote canopy flat plate and flexible coaxial power feed cable. This 12V 75W miniature electronic transformer recesses neatly in most electrical boxes. For dimming, an electronic low voltage dimmer is required (sold separately). 2.125"L X 1.25"W X .75"H.

GTMax Black Rapid Home Travel Power Charger for Asus Transformer Prime TF201, Eee Pad Transformer TF101 Tablet $14.99 Brand new generic Charger. Input: 100~240V 0.3A 50/60Hz; Output: 15V 1.2A This custom made wall charger is for ASUS Transformer tablet for house using. Intelligent IC chip inside recognizes a fully charged battery and automatically switches to a saver mode to prevent overcharging and short circuit. US plug version. It needs a plug converter for EU/AU/UK using. Accessory ONLY. Tablet PC not included. Compatibility: Asus Transformer TF300 / Asus Transformer Prime TF201 / Asus Eee Pad Transformer TF101 Type: Power / Batteries / Cables Features: This custom made wall charger is for ASUS Transformer tablet for house using. Input: 100~240VAC, 0.3A, 50/60Hz. Output: 15V DC, 1.2A. Compatibility: Asus EeePad Transformer TF101, Prime TF201, Slider SL101

J & P Transformer Book $275 Maintaining appropriate power systems and equipment expertise is necessary for a utility to support the reliability, availability, and quality of service goals demanded by energy consumers now and into the future. However, transformer talent is at a premium today, and all aspects of the power industry are suffering a diminishing of the supply of knowledgeable and experienced engineers. Now in print for over 80 years since initial publication in 1925 by Johnson & Phillips Ltd, the J & P Transformer Book continues to withstand the test of time as a key body of reference material for students, teachers, and all whose careers are involved in the engineering processes associated with power delivery, and particularly with transformer design, manufacture, testing, procurement, application, operation, maintenance, condition assessment and life extension. Current experience and knowledge have been brought into this thirteenth edition with discussions on moisture equilibrium in the insulation system, vegetable based natural ester insulating fluids, industry concerns with corrosive sulphur in oil, geomagnetic induced current (GIC) impacts, transportation issues, new emphasis on measurement of load related noise, and enhanced treatment of dielectric testing (including Frequency Response Analysis), Dissolved Gas analysis (DGA) techniques and tools, vacuum LTCs, shunt and series reactors, and HVDC converter transformers. These changes in the thirteenth edition together with updates of IEC reference Standards documentation and inclusion for the first time of IEEE reference Standards, provide recognition that the transformer industry and market is truly global in scale. -- From the foreword by Donald J. Fallon Martin Heathcote is a consultant specializing in power transformers, primarily working for utilities. In this context he has established working relationships with transformer manufacturers on several continents. His background with Ferranti and the UK's Central Electricity Generating Board (CEGB) included transformer design and the management and maintenance of transformer-based systems. *The definitive reference for all involved in designing, installing, monitoring and maintaining high-voltage systems using power transformers (electricity generation and distribution sector; large-scale industrial applications) *The classic reference work on power transformers and their applications: first published in 1925, now brought fully up to date in this thirteenth edition *A truly practical engineering approach to design, monitoring and maintenance of power transformers in electricity generation, substations, and industrial applications.

Samsung - Class II Plug-In Transformer $6.99 110 V AC 120 V AC 24 V AC 240 mA Input Current 40 VA 50 Hz 60 Hz Screw Terminals Led For Power Supervision Secondary Fused UL Listed Class II Plug-In Transformer GV-TRAN-24-40LED Samsung Step Down Transformer www.samsungusa.com

100W US Travel AC Power Voltage Convertor Transformer 117V to 230V $17.99 Description:When you travel in America, you can use this AC Power Transformer with your appliance/equipment from Canada, UK, Euro, Australia, Aisa.... or other countries......that you want to plug into the US wall power outletTwo flat pinWhen the switch lift on AC117V, Input: AC 200/240V 50/60Hz, Output: AC100V/120V 50/60HzWhen the switch lift on AC230V, Input: AC100V/120V 50/60Hz Output: AC200/240V 50/60HzMaximum Loading: 100WThermal fuse installed for safety protection from overloadingPower Voltage Convertor with international safety standardSize of the Travel Power Transformer: 9 x 4.2 x 4.5cmWeight: 434.5gPackage content:1 x 100W Voltage Transformer

Spotlight on Modern Transformer Design (Hardcover) $535.06 Spotlight on Modern Transformer Design introduces a novel approach to transformer design using artificial intelligence (AI) techniques in combination with finite element method (FEM). Today, AI is widely used for modeling nonlinear and large-scale systems, especially when explicit mathematical models are difficult to obtain or completely lacking. Moreover, AI is computationally efficient in solving hard optimization problems.Many numerical examples throughout the book illustrate the application of the techniques discussed to a variety of real-life transformer design problems, including:? problems relating to the prediction of no-load losses;? winding material selection;? transformer design optimisation;? and transformer selection.Spotlight on Modern Transformer Design is a valuable learning tool for advanced undergraduate and graduate students, as well as researchers and power engineering professionals working in electric utilities and industries, public authorities, and design offices.

Biorb 12 Volt Transformer $20.99 All aquariums need electrical power to operate their lighting and filtration systems and most use mains electricity at 120 volts. This can cause serious electric shock should the Fishkeeper drop or drench the electrical items in the aquarium water. The Reef One range of aquariums is designed to be extremely safe and therefore all its electrical items operate at the safe low level of 12 volts ac. To protect the Fishkeeper and children from electric shock, biOrb and biUbe aquariums use a plug top AC transformer that plugs into your electrical main socket and 'steps down' the voltage to a much safer 12 volts AC. The 12 volts is made available in the bottom of the AC transformer through two din sockets. Either socket can be used for the halogen light wire plug or the air pump wire plug as both sockets are interchangeable. The LED light if used in place of the halogen light can be plugged into either socket. Product Features The Twin Outlet Transformer Unit delivers power to both the light and air pump using only one plug US Type 120 Volts

50W 220V to 110V Power Transformer $6 - 220V to 110V Step Down Convertor- Maximum Load: 50W- Input: AC 220V- Output: AC 110V