High Frequency
High Frequency
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CellularFactory: Home & decor Home & Decor Ultrasonic Electronic Pest/Mosquito/Insect/Rodent/Rat Repeller $0.76 This Ultrasonic Pest Repeller is controlled by microcomputer carrier wave pulse circuitry and carrier high frequency sonic waves, repels pest such as mosquitoes, cockroaches, rats, spiders, lice, lizards, ants, and so on. Electronics Pest Repeller emits high frequency pulse accoustic waves and pulse electromagnetic waves which can stimulate and chase away the pests effectively for about 50-80 squa... |
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Panasonic NN-SD967S 2.2 cuft, 1250 Watt Stainless Steel Microwave Oven, Inverter Technology $189.95 2.2 cu ft; 1250W cooking power; stainless front and silver body; pop-out dial; reflective door; one-touch sensor cooking (18 categories); one-touch sensor reheat; inverter turbo defrost; 6 digit display; keep warm setting; popcorn key; quick minute; more/less control... |
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Extech EX450 True RMS Autoranging Multimeter with Infrared Thermometer $119.99 Comes with: CAT III test leads, Multi-position tilt stand and hanging strap, Protective holster with test lead holder, Bead wire temperature probe (except 450), and 9V battery.... |
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High Frequency [VHS] $13.44 ... |
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Etymotic Research ER20 ETYPlug Hearing Protection Earplugs, Standard Clear Stem with Blue Tip (Clear) $10.99 Benefits Reduces sound levels evenly so that music and speech are clear and natural, not muffled as with other earplugs |
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P3 International P4400 Kill A Watt Electricity Usage Monitor $50.00 Empowers You to Save Hundreds on Electric Bills Electricity bills are rising. Now you can cut down on costs and find out what appliances are actually worth keeping plugged in. Simply connect these appliances to the Kill A Watt, and it will assess how efficient they really are. The large LCD display counts consumption by the kilowatt-hour, the same as your local utility. You can calculate your elec... |
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Peltor 97010 Ultimate-10 Hearing Protector $19.99 The Peltor(r) Ultimate 10 hearing protector offers powerful protection that's designed for use with large caliber or Magnum rounds. It provides maximum high- and low-frequency attenuation and is crafted with pivoting cups and a padded headband for all-day comfort.... |
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Preschool Prep & Sight Words 7 DVD Pack (Meet the Letters, Meet the Numbers, Meet the Shapes, Meet the Colors, Meet the Sight Words 1, Meet the Sight Words 2, Meet the Sight Words 3) $54.20 Preschool Prep & Sight Words Pack - 7 DVD Boxed Set (Meet the Letters, Numbers, Shapes & Colors, Sight Words 1, 2 & 3)Learning Has Never Been This Easy!A study of over 50 babies and toddlers, who watched Meet the Letters, resulted in over 90% of these children having complete upper and lowercase letter recognition. Many learned in less than two weeks! Numbers, shapes and colors and sight words ... |
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Meet the Sight Words 1 $9.05 Meet the Sight Words 1TM DVDLearning Sight Words Has Never Been This Easy!Many words don't follow basic decoding rules and are taught in pre-k and kindergarten classrooms as "sight words", "instant words", "high frequency words" or "star words." A new reader finds sight words very frustrating until they are memorized. A good reader will be able to instantly recognize sight words without having to ... |
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Facial Equipment Techniques $53.26 In this instructional aesthetician training video, Rita Page, an award-winning CIDESCO diplomat, successfully navigates through the confusing world of facial equipment in this jam-packed aesthetic training DVD. While performing a complete professional facial, Rita effectively demonstrates how to use each function of an 8-in-1 facial machine: magnifying lamp, Wood's lamp, steamer with ozone, vacuum... |
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Hearos Ultimate Softness, 20-Pair Foam (Pack of 2) $9.24 Experience the world class quality and comfort of the HEAROS 20 pair Ultimate Softness Series. HEAROS are the nation's most popular brand of ear plugs. High Noise Reduction Rating of 32 decibels. Neutral color blends in with many skin tones. Ideal for all hearing protection and noise reduction needs. Great value on a per pair basis.... |
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NeilMed Sinus Rinse - 2 Bottles - 250 Premixed Packets - Value Pack $15.00 Nasal Wash is a natural soothing saline nasal wash. A large volume low positive pressure nasal wash is the most effective way to irrigate the nose based on current medical studies. Nasal Irrigation is an excellent way to clean mucus from the nose making medication more effective. They also clean allergens, irritants, bacteria and viruses from the nose reducing the frequency of infection. Furthermo... |
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Braun Se 3170 Silk Epil 3 Epilator, Pink $41.99 The new Silk-epil soft perfection lets you enjoy silky smooth skin from top to toe for up to 4 weeks! It offers the latest in removing hair at the root. With its unique softlift system giving you an extra close epilation for smoother skin. And its 4-way moving pain softener makes epilation also extra gentle.... |
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ASUS Black Diamond Dual-Band Wireless-N 600 Router (RT-N56U) $115.99 Asus RT-N56U Wireless-N Router Dual Band Multimedia Ultra Slim Gigabit 802.11a/b/g/n 300Mbps support USB Storage, Print and Media Server (top performance review at smallnetbuilder.com)... |
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Logitech S150 USB Speakers with Digital Sound $8.88 Light pact design for portability Satellite base designVolume mute LED indicator controls2" dynamic drivers90Hz 20kHz frequency responseNo batteries required3-year limited warranty... |
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AirLink101 AWLL5088 Wireless N 150 Ultra Mini USB Adapter $8.90 150 Mbps - External... |
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Puma High Frequency T-Shirt (Sizes 4 - 7) This Puma T-shirt is perfect for his sporty style! Made of a soft cotton blend, it features radar circle graphics overlaid with a plastisol cat logo. An embroidered cat logo adorns the back neck. Be sure to check out our full line of Puma to find some perfect matches! 60% Cotton, 40% Polyester Machine Wash Cold Made in China... |
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Keyspan by Tripp Lite PR-US2 Presentation Remote Wireless w Laser, Mouse $44.44 Works up to 60' with plug-and-play pliant with USB connectivity for PC or Mac Features a laser safe pointer audio control and 2-button mouse control with cursor controlControls Windows Media Player iTunes and QuickTimeTravel pouch for carrying the remote and receiver... |
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Velo Men's Transit The Edge 30 Waterproof Messenger Bicycle Backpack Our front Storm Shield tucks away when not in use and zips down when needed for rain protection or a high visibility panel in traffic.... |
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Newest DH 9053 26 Inches Volitation 3.5 Channel Outdoor Metal Gyro RC Helicopter $39.85 Double Horse 9053 The newest model with the latest Gyroscope technology. The regular 3 channels allow you to fly : up, down, turn left, turn right, move forward, backward. This new 3.5 channels does all that, plus it let you control the speed, you can either fly in low or high speed by simply switch the speed control button. There are not many flying around, be the first to own 1 of this beautiful... |
what are the advantages of high frequency AC?
Lets say if the entire power grid used a higher frequency of AC then 50-60hz. What would be the advantages of doing that? Would it be more efficient? Would transformers and other high voltage power equipment be cheaper or not? Would it be safer? Would the power grid have to use higher or lower voltages compared to now?
Transformers, filter capacitors and coils in dc power supplies for all electronic equipment could be smaller and cheaper. Converting back and forth between dc and a higher frequency ac would be cheaper.
I know you did not ask for disadvantages but the initial cost of changing to a higher frequency essentially prohibits the change even if it could be shown that 50 or 60 Hz is not the optimum frequency for highest efficiency. I don`t think the frequency could be raised much if any at all until the disadvantages would greatly outweigh the advantages.
1. A higher frequency would probably be more efficient.
2. Transformers and capacitor banks could be built smaller and cheaper. Support poles and hardware for pole mounted transformers could be lighter and cheaper.
3. It would not be any safer.
4. I don`t think it would affect the optimum Voltage Amplitude. The same considerations for selecting the optimum Voltage amplitude would be in effect.